African humid period
The African humid period (AHP, also known by other names) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, trees and lakes was caused by changes in Earth's orbit around the Sun; changes in vegetation and dust in the Sahara which strengthened the African monsoon; and increased greenhouse gases, which may imply that anthropogenic global warming could result in a shrinkage of the Sahara desert.
During the preceding last glacial maximum, the Sahara contained extensive dune fields and was mostly uninhabited. It was much larger than today, but its lakes and rivers such as Lake Victoria and the White Nile were either dry or at low levels. The humid period began about 14,600–14,500 years ago at the end of Heinrich event 1, simultaneously to the Bølling-Allerød warming. Rivers and lakes such as Lake Chad formed or expanded, glaciers grew on Mount Kilimanjaro and the Sahara retreated. Two major dry fluctuations occurred; during the Younger Dryas and the short 8.2 kiloyear event. The African humid period ended 6,000–5,000 years ago during the Piora Oscillation cold period. While some evidence points to an end 5,500 years ago, in the Sahel, Arabia and East Africa the period appears to have taken place in several steps such as the 4.2 kiloyear event.
The AHP led to a widespread settlement of the Sahara and the Arabian Deserts, and had a profound effect on African cultures, such as the birth of the Pharaonic civilization. They lived as hunter-gatherers until the agricultural revolution and domesticated cattle, goats and sheep. They left archeological sites and artifacts such as one of the oldest ships in the world, and rock paintings such as those in the Cave of Swimmers and in the Acacus Mountains. Earlier humid periods in Africa were postulated after the discovery of these rock paintings in now-inhospitable parts of the Sahara. When the period ended, humans gradually abandoned the desert in favour of regions with more secure water supplies, such as the Nile Valley and Mesopotamia, where they gave rise to early complex societies.
Herodotus in 440 BC and Strabo in 23 AD discussed the existence of a greener Sahara, although their reports were at first questioned owing to their anecdotal nature. In 1850 the researcher Heinrich Barth discussed the possibility of past climate change leading to increased wetness in the Sahara after discovering petroglyphs in the Murzuq Desert, and further discoveries of petroglyphs led desert explorer László Almásy to coin the concept of a Green Sahara in the 1930s. Later in the 20th century, conclusive evidence of a past greener Sahara, the existence of lakes and higher Nile flow levels was increasingly reported and it was recognized that the Holocene featured a humid period in the Sahara.
The idea that changes in Earth's orbit around the Sun influence the strength of the monsoons was already advanced in 1921, and while the original description was partly inaccurate, later widespread evidence for such orbital controls on climate was found. At first it was believed that humid periods in Africa correlate with glacial stages ("pluvial hypothesis") before radiocarbon dating became widespread.
The development and existence of the African humid period has been investigated with archeology, climate modelling and paleoproxies, with archeological sites, dunes and deposits left by lakes, aeolian deposits and leaf wax in the sea and wetlands playing an important role. Pollen, lake deposits and former levels of lakes have been used to study the ecosystems of the African humid period, and charcoal and leaf impressions have been used to identify vegetation changes. The time 6,000 years ago has received particular attention, especially since that period of the AHP has been used as an experiment in the Paleoclimate Modelling Intercomparison Project.
While the precipitation changes since the last glacial cycle are well established, the magnitude and timing of the changes are unclear. Depending on how and where measurements and reconstructions are made, different beginning dates, ending dates, durations and precipitation levels have been determined for the African humid period. The amounts of precipitation reconstructed from paleoclimate records and simulated by climate modelling are often inconsistent with each other; in general, the simulation of the Green Sahara is considered a problem for earth system models. Erosion of lake sediments and carbon reservoir effects make it difficult to date when they dried up. Vegetation changes by themselves do not necessarily indicate precipitation changes, as changes in seasonality, plant species composition and changes in land use also play a role in vegetation changes. Isotope ratios such as the hydrogen/deuterium ratio that have been used to reconstruct past precipitation values likewise are under the influence of various physical effects, which complicates their interpretation.
Earlier humid periods are sometimes known as "African humid periods" and a number of dry/wet periods have been defined for the Central Africa region. In general, these types of climate fluctuations between wetter and drier periods are known as "pluvials" and "interpluvials", respectively.[a][b] Because the AHP did not affect all of Africa, Williams et al. 2019 recommended that the term be dropped.
Background and beginningEdit
The African humid period took place in the late Pleistocene and early-middle Holocene, and saw increased precipitation in Northern and Western Africa due to a northward migration of the tropical rainbelt. The AHP is the most profound climate change of the low latitudes during the last 100,000 years and stands out within the otherwise relatively climatically stable Holocene. It is part of the so-called Holocene climatic optimum, during which summers in the Northern Hemisphere were warmer than today.[c] Liu et al. 2017 subdivided the humid period into an "AHP I" which lasted until 8,000 years ago, and an "AHP II" from 8,000 years onward, with the former being wetter than the latter.
The African humid period was not the first such phase; evidence for about 230 older such "green Sahara"/wet periods exist going back perhaps to the first appearance of the Sahara 7–8 million years ago, for example during Marine Isotope Stage 5 a and c. Earlier humid periods appear to have been more intense than the AHP of the Holocene, including the exceptionally intense Eemian humid period which provided the pathways for early humans to cross Arabia and Northern Africa and which, together with later moist periods, has been linked to expansions of the Aterian populations. Such humid periods are usually associated with interglacials, while glacial stages correlate to dry periods.
The Bølling-Allerød warming appears to be synchronous with the onset of the African humid period as well as to increased humidity in Arabia. Later, in the Blytt–Sernander sequence the humid period coincides with the Atlantic period.
Conditions before the African humid periodEdit
During the Last Glacial Maximum, the Sahara and Sahel had been extremely dry with less precipitation than today as reflected by the extent of dune sheets and water levels in closed lakes. The Sahara was much larger, extending 500–800 kilometres (310–500 mi) farther south, a difference of 5° latitude. Dunes were active much closer to the equator,[d] and rainforests had retreated in favour of afromontane and savannah landscapes as temperatures, rainfall, and humidity decreased.
There is little and often equivocal evidence of human activity in the Sahara or Arabia at that time, reflecting its drier nature. The aridity during the Last Glacial Maximum appears to have been the consequence of the colder climate and larger polar ice sheets, which squeezed the monsoon belt to the equator and weakened the West African Monsoon. The atmospheric water cycle and the Walker and Hadley circulations were weaker as well. Exceptional dry phases are linked to Heinrich events when there are a large number of icebergs in the North Atlantic; the discharge of large amounts of such icebergs between 11,500 and 21,000 years before present coincided with droughts in the subtropics.
Before the onset of the AHP, it is thought that the Lake Victoria, Albert, Edward, Turkana and the Sudd swamps had dried out. The White Nile had become a seasonal river whose course along with that of the main Nile may have been dammed by dunes. The Nile Delta was partially dry, with sandy plains extending between ephemeral channels and exposed seafloor, and it became a source of sand for ergs[e] farther east. Other lakes across Africa, such as Lake Chad and Lake Tanganyika, also had shrunk[f] during this time, and both the Niger River and Senegal River were stunted.
Early humidity increasesEdit
Whether some parts of the desert such as highlands like the Red Sea Hills were reached by the westerlies or weather systems associated with the subtropical jet stream—and thus received precipitation—is contentious. It is only clearly supported for the Maghreb in northwestern Africa, though river flow/terrace formation and lake development in the Tibesti and Jebel Marra mountains and residual Nile flow may be explained in this way. The highlands of Africa appear to have been less affected by drought during the last glacial maximum.
The end of the glacial drought occurred between 17,000 and 11,000 years ago, with an earlier beginning noted in the Saharan mountains (possibly) 18,500 years ago. In southern and central Africa earlier starts 17,000 and 17,500 years ago, respectively, may be linked to Antarctic warming, while Lake Malawi appears to have been low until about 10,000 years ago.
High lake levels occurred in the Jebel Marra and Tibesti Mountains between 15,000 and 14,000 years ago and the youngest stage of glaciation in the High Atlas mountains took place at the same time as the early African humid period. Around 14,500 years ago, lakes started to appear in the arid areas.
The humid period began about 15,000-14,500 years ago.[g] The onset of the humid period took place almost simultaneously over all of Northern[h] and Tropical Africa, with impacts as far as Santo Antão on Cape Verde. In Arabia, wet conditions apparently took about two millennia to advance northward, a gradual advance is supported by tephrochronological data.
Lake Victoria reappeared and overflowed; Lake Albert also overflowed into the White Nile 15,000–14,500 years ago and so did Lake Tana, into the Blue Nile. The White Nile flooded part of its valley and reconnected to the main Nile.[i] In Egypt widespread flooding by the "Wild Nile" took place; this "Wild Nile" period led to the largest recorded floods on this river, sedimentation in floodplains, and probably also impacted human populations along the river. Even earlier, 17,000–16,800 years ago, meltwater from glaciers in Ethiopia – which were retreating at that time – may have begun to increase the flow of water and sediment in the Nile. In the East African Rift water levels in lakes began to rise by about 15,500/15,000-12,000 years ago; Lake Kivu began overflowing into Lake Tanganyika by about 10,500 years ago.
About the same time that the AHP started, the cold glacial climate in Europe associated with Heinrich event 1 ended with climate changing as far as Australasia. A warming and retreat of sea ice around Antarctica coincides with the start of the African humid period, although the Antarctic Cold Reversal also falls into this time and may relate to a drought interval recorded in the Gulf of Guinea.
The African humid period was caused by a stronger West African Monsoon directed by changes in solar irradiance and in albedo feedbacks. These lead to increased moisture import from both the equatorial Atlantic into West Africa, as well as from the North Atlantic and the Mediterranean Sea towards the Mediterranean coasts of Africa. There were complex interactions with the atmospheric circulation of the extratropics and between moisture coming from the Atlantic Ocean and the Indian Ocean, and an increased overlap between the areas wetted by the monsoon and those wetted by extratropical cyclones.
Climate models indicate that changes from a dry to a green Sahara and back have threshold behaviour, with the change occurring once a certain level of insolation is exceeded; likewise, a gradual drop of insolation often leads to a sudden transition back to a dry Sahara. This is due to various feedback processes which are at work, and in climate models there is often more than one stable climate-vegetation state. Sea surface temperature and greenhouse gas changes synchronized the beginning of the AHP across Africa.
The African humid period has been explained by increased insolation during Northern Hemisphere summer. Due to precession, the season at which Earth passes closest to the Sun on its elliptical orbit – the perihelion – changes, with maximum summer insolation occurring when this happens during Northern Hemisphere summer. Between 11,000 and 10,000 years ago, Earth passed through the perihelion at the time of summer solstice, increasing the amount of solar radiation by about 8%, resulting in the African monsoon becoming both stronger and reaching farther north. Between 15,000 and 5,000 years ago, summer insolation was at least 4% higher than today. The obliquity also decreased during the Holocene but the effect of obliquity changes on the climate is focused on the high latitudes and its influence on the monsoon is unclear.
During summer, solar heating is stronger over the North African land than over the ocean, forming a low pressure area that draws moist air and precipitation in from the Atlantic Ocean. This effect was strengthened by the increased summer insolation, leading to a stronger monsoon that also reached farther north. The effects of these circulation changes reached as far as the subtropics.
Obliquity and precession are responsible for two of the foremost Milankovich cycles and are responsible not only for the onset and cessation of ice ages but also for monsoon strength variations. Southern Hemisphere monsoons are expected to have the opposite response of Northern Hemisphere monsoons to precession, as the insolation changes are reversed; this observation is borne out by data from South America. The precession change increased seasonality in the Northern Hemisphere while decreasing it in the Southern Hemisphere.
According to climate modelling, orbital changes by themselves cannot increase precipitation over Africa enough to explain the formation of the large desert lakes such as 330,000 square kilometres (130,000 sq mi) Lake Megachad[j] or the northward expansion of vegetation unless ocean and land surface changes are factored in.
Decreasing albedo resulting from vegetation changes is an important factor in the precipitation increase. Specifically, increased precipitation increases the amount of vegetation; vegetation absorbs more sunlight and thus more energy is available for the monsoon. In addition, evapotranspiration from vegetation adds more moisture, although this effect is less pronounced than the albedo effect. Heat fluxes in the soil and evaporation are also altered by the vegetation.
Reduced dust generation from a wetter Sahara influences the climate by reducing the amount of light absorbed by dust and also modifying cloud properties, making them less reflective and more efficient at inducing precipitation. In climate models, reduced amounts of dust in the troposphere together with vegetation changes can often but not always explain the northward expansion of the monsoon. There is not universal agreement on the effects of dust on precipitation in the Sahel, however.
In addition to raw precipitation changes, changes in precipitation seasonality such as the length of dry seasons need to be considered when assessing the effects of climate change on vegetation, as well as the fertilizing effects of increased carbon dioxide concentrations in the atmosphere.
Other sources of albedo changes:
- Changes in soil properties result in changes in the monsoon; replacing desert soils with loamy ones results in increased precipitation, and soils that are wet or contain organic matter reflect less sunlight and accelerate the moistening process. Desert sand changes also modify the albedo.
- Albedo changes caused by lakes and wetlands can alter precipitation in climate models.
Intertropical Convergence Zone changesEdit
Warmer extratropics during summer may have drawn the Intertropical Convergence Zone (ITCZ) northward, resulting in precipitation changes. Sea surface temperatures off North Africa warmed under orbital effects and through weaker trade winds, leading to a northward movement of the ITCZ and increasing moisture gradients between land and sea. Two temperature gradients, one between a cooler Atlantic during spring and an already warming African continent, the other between warmer temperatures north of 10° latitude and cooler south, may have assisted in this change. In Eastern Africa, ITCZ changes had relatively little effect on precipitation changes. The past position of the ITCZ in Arabia is also contentious.
Precipitation changes in East AfricaEdit
The African humid period that took place in East Africa appears to have been caused by different mechanisms. Among the proposed mechanisms are decreased seasonality of precipitation due to increased dry season precipitation, shortening of the dry season, increased precipitation and increased inflow of moisture from the Atlantic and Indian Oceans. The Atlantic moisture inflow was in part triggered by a stronger West African and Indian monsoon, perhaps explaining why the effects of the AHP extended into the Southern Hemisphere. The behaviour of the easterly trade winds is unclear; increased moisture transport by easterly trade winds may have aided in the development of the AHP but alternatively a stronger Indian Monsoon that draws easterly winds away from East Africa may have occurred.
Changes in the Congo Air Boundary[k] or increased convergence along this boundary may have contributed; the Congo Air Boundary would have been shifted east by the stronger westerly winds directed by lower atmospheric pressure over Northern Africa, allowing additional moisture from the Atlantic to reach East Africa. The parts of East Africa that were isolated from Atlantic moisture did not become significantly wetter during the AHP although at one site in Somalia the seasonality of precipitation may or may not have decreased.
Various contributing factors may have led to the increased humidity in East Africa, not all of which were necessarily operating simultaneously during the AHP. That the "African humid period" reached this part of Africa has been doubted. Finally, increased greenhouse gas concentrations may have been involved in directing the onset of the AHP in tropical southeastern Africa; there, orbital changes would be expected to lead to climate variations opposite to those in the Northern Hemisphere. The pattern of humidity changes in south-eastern Africa are complex.
- Climate change in the far northern latitudes may have contributed to the onset of the AHP. The shrinkage of the Scandinavian and the Laurentide Ice Sheets occurred at its beginning, and in climate models, a retreat of the ice sheets is often required to simulate the humid period. Their existence might also explain why the AHP did not start immediately with the early insolation peak, as still existing ice sheets would have cooled the climate.
- Sea surface temperature changes in the Atlantic influence the African monsoon and may have influenced the onset of the AHP. Weaker trade winds and higher insolation would lead to warmer sea surface temperatures, increasing precipitation by increasing moisture gradients between land and sea. Changes in North Atlantic temperature gradients were also involved.
- Warming of the Mediterranean Sea increases the amount of Sahel precipitation; this effect is responsible for the recent anthropogenic global warming mediated increase in Sahel precipitation. Warmer sea surface temperatures there might also explain the increased precipitation recorded in the Mediterranean during the AHP.
- Increased precipitation during winter is correlated with a larger spatial extent of Mediterranean precipitation and might have aided in the establishment of the AHP, especially in North Africa, Northern Egypt, around the northern Red Sea, in the Tibesti and in northern Arabia and generally at higher latitudes where the monsoon did not arrive. This precipitation may have extended to other parts of the Sahara; such would have led to the areas of summer and winter precipitation overlapping and the dry area between the monsoonal and westerlies-influenced climate zones becoming wetter or disappearing altogether. Such changes in Mediterranean-derived precipitation may correlate with changes in the North Atlantic and Arctic Oscillations.
- Trough-mediated northward transport of moisture during autumn and spring has also been proposed to explain the increased precipitation and its underestimation by climate models. In one climate model, increased northward moisture transport by such troughs increases autumn rainfall in the Sahara, especially in the mid-Holocene and when the climate is already moister than usual there.
- Weaker subtropical anticyclones were proposed as an explanation during the 1970s–1980s.
- In montane regions such as the Meidob volcanic field cold temperatures after the last glacial maximum may have reduced evaporation and thus allowed an early onset of humidity.
- Changes in the Earth's geomagnetic field may be linked to the humidity changes.
- Increased moisture supply from larger lakes like Lake Megachad may have increased the precipitation, although this effect is probably not adequate to explain the entire AHP. A similar role has been attributed to the extensive wetlands, drainages and lakes in the Eastern Sahara and to the ecosystem in general.
- Two high elevation winds, the African Easterly Jet and the Tropical Easterly Jet modulate atmospheric air flows over Africa and thus also the amount of precipitation; the Tropical Easterly Jet comes from India and is powered by temperature gradients between the tropics and the subtropics while the African Easterly Jet is powered by temperature gradients in the Sahel. A stronger West African Monsoon resulted in a weaker African Easterly Jet and thus decreased transport of moisture out of Africa.
- Increased atmospheric carbon dioxide concentrations may have played a role in triggering the AHP, especially its extension across the equator, as well as its resumption after the Younger Dryas and Heinrich event 1 through increased sea surface temperatures.
- In some parts of the Sahara increased water supply from montane regions may have assisted in the development of moist conditions.
- Larger forests in Eurasia may have led to a northward shift of the ITCZ.
- Other proposed mechanisms involve convection occurring above the atmospheric boundary layer, increased latent heat fluxes, low pressure in northwestern Africa drawing moisture into the Sahara, changes in the solar cycles and complex atmospheric flow phenomena.
The African humid period extended over the Sahara as well as eastern, southeastern and equatorial Africa. In general, forests and woodlands expanded through the continent. A similar wet episode took place in the tropical Americas,[l] China, Asia,[m] India, the Makran region, the Middle East and the Arabian Peninsula and appears to relate to the same orbital forcing as the AHP. An early Holocene monsoonal episode extended as far as the Mojave Desert in North America. In contrast, a drier episode is recorded from much of South America where Lake Titicaca, Lake Junin, the discharge of the Amazon River and water availability in the Atacama were lower.
The discharge of the Congo, Niger, Nile, Ntem, Rufiji, and Sanaga Rivers increased. Runoff from Algeria, equatorial Africa, northeastern Africa and the western Sahara was also larger. Changes in the morphology of the river systems and their alluvial plains occurred in response to the increased discharge, and the Senegal River breached dunes and re-entered the Atlantic Ocean.
Flora and fauna of the SaharaEdit
During the African humid period, lakes, rivers, wetlands and vegetation including grass and trees covered the Sahara and Sahel creating a "Green Sahara" with a land cover that has no modern analogues. Evidence includes pollen data, archeological sites, evidence of faunal activity such as diatoms, mammals, ostracods, reptiles and snails, buried river valleys, organic-rich mats, mudstones, evaporites as well as travertines and tufas deposited in subaqueous environments.
The vegetation cover then extended over almost all of the Sahara and consisted of an open grass savannah with shrubs and trees. In general, the vegetation expanded northward to 27–30° northern latitude in West Africa with a Sahel boundary at about 23° north, as the Sahara was populated by plants that today often occur about 400–600 kilometres (250–370 mi) farther south. The northward movement of vegetation took some time and some plant species moved faster than others. Plants that perform C3 carbon fixation became more common and the fire regime of the vegetation changed.
Forests and plants from the humid tropics were concentrated around lakes and rivers. The landscape during the AHP has been described as a mosaic between various vegetation types of semi-desert and humid origin rather than a simple northward displacement of plant species, and some brown or yellow vegetation communities persisted. Pollen data often show a dominance of grasses over humid tropics trees. The tree Lophira alata and others may have spread out of the African forests during the AHP, and the Lactuca plants may have split into two species under the effects of the AHP and other climate changes in Africa during the Holocene.
The Sahara climate did not become entirely homogeneous; its central-eastern parts were probably drier than the western and central sectors and the Libyan sand sea was still a desert although pure desert areas retreated or became arid/semiarid. An arid belt may have existed north of 22° latitude, or the vegetation and the African monsoon might have reached 28–31° northern latitude; in general conditions between 21° and 28° northern latitude are poorly known. Dry areas may have persisted in the rain shadows of mountains and could have supported arid climate vegetation, explaining the presence of its pollen in sediment cores. In addition, north–south gradations in vegetation patterns have been reconstructed from charcoal and pollen data.
Fossils record changes in the animal fauna of the Sahara. This fauna included antelopes, baboons, cane rats, catfish, clams, cormorants, crocodiles, elephants, frogs, gazelles, giraffes, hartebeest, hares, hippos, molluscs, Nile perches, pelicans, rhinoceroses, snake-eagles, snakes, tilapia, toads, turtles and many more animals, and in Egypt spotted hyenas, warthogs, water buffaloes, wildebeest and zebra occurred. Additional birds include brown-necked raven, coot, common moorhen, crested grebe, glossy ibis, long-legged buzzard, rock dove, spur-winged goose and tufted duck. Large herds of animals lived in the Sahara. Some animals expanded over the whole desert, while others were limited to places with deep water. Earlier humid periods in the Sahara may have allowed species to cross the now-desert. A reduction in open grasslands at the beginning of the AHP may explain a population bottleneck in cheetahs at the start of the humid period, while the humid period led to the expansion of some animal populations such as Hubert's multimammate mouse.
Lakes and rivers of the SaharaEdit
A number of lakes formed or expanded in the Sahara. The largest of them was Lake Chad which increased to at least ten times its present-day size to form Lake Megachad. This enlarged Lake Chad reached dimensions of 1,000 by 600 kilometres (620 mi × 370 mi) in north–south and east–west direction respectively, covering the Bodélé Depression and perhaps as much as 8% of the present-day Sahara desert. It influenced the climate itself; for example rainfall would have been reduced at the centre of the lake and increased at its margins. Lake Chad was possibly fed from the north by rivers draining the Hoggar (Taffassasset drainage) and Tibesti Mountains, from the Ennedi Mountains in the east through the "Eastern palaeorivers" and from the south by the Chari-Logone and Komadugu Rivers. The Chari River was the main tributary while the rivers draining the Tibesti formed alluvial fans/the Angamma river delta at their entry into northern Lake Chad. Skeletons of elephants, hippos and hominins have been found in the Angamma delta, which is the dominant shoreline feature of northern Lake Chad. The lake overflowed into the Niger River during highstand through the Mayo Kebbi and the Benue River, eventually reaching the Gulf of Guinea. Older dune systems were submerged by Lake Chad.
Among the large lakes which may have formed in the Sahara are Lake Megafezzan in Libya and Lake Ptolemy in Sudan. Quade et al. 2018 raised some doubts about the size and existence of some of these lakes such as Lake Ptolemy, Lake Megafezzan, Lake Ahnet-Mouydir, especially for Lake Megafezzan. Other lakes are known from Adrar Bous in Niger, I-n-Atei in the Hoggar, at Ine Sakane and in Taoudenni[n] in Mali, the Garat Ouda and Takarkori Lakes in the Acacus Mountains, Chemchane in Mauretania, at Sebkha Mellala close to Ouargla in Algeria, at Bilma, Dibella, Fachi and Gobero in the Ténéré, Seeterrassental in Niger and at "Eight Ridges", El Atrun, Lake Gureinat, Merga, "Ridge", Sidigh, at Wadi Mansurab, Selima and Oyo in Sudan. Lake Yoa of the Lakes of Ounianga overflowed, either above surface or underground. Mosaics of small lakes developed in some regions. Wetlands also expanded during the AHP, but both their expansion and subsequent retreat were slower than that of lakes.
In some parts of the Sahara ephemeral lakes formed such as at Abu Ballas, Bir Kiseiba, Bir Sahara, Bir Tarfawi and Nabta Playa[o] in Egypt, which may relate to later Egyptian religions, or swamp-lakes such as at Adrar Bous close to the Air Mountains. Ephemeral lakes developed between dunes, and a "freshwater archipelago" appears to have existed in the Murzuq basin. All these lake systems left fossils such as fish, limnic sediments and fertile soils that were later used for agriculture (El Deir, Kharga Oasis). Finally, crater lakes formed in volcanic fields and sometimes survive to this day as smaller remnant lakes such as Malha crater in the Meidob volcanic field. Potentially, the increased availability of water during the AHP may have facilitated the onset of phreatomagmatic eruptions such as maar formation in the Bayuda volcanic field, although the chronology of volcanic eruptions there is not well known enough to substantiate a link to the AHP.
The large Tamanrasset River flowed from the Atlas Mountains and Hoggar westward towards the Atlantic and entered it in the Bay of Arguin in Mauretania. It once formed the 12th largest watershed in the world and left a submarine canyon and riverine sediments. Together with other rivers it formed estuaries and mangroves in the Bay of Arguin. Other rivers in the same area also formed submarine canyons, and sediment patterns in marine sediment cores and the occurrence of submarine landslides in the area have been related to the activity of these rivers.
Rivers such as the Irharhar in Algeria, Libya and Tunisia and the Sahabi and Kufra rivers in Libya were active during this time although there is some doubt that they had perennial flow; they appear to have been more important in earlier humid periods. Small watersheds, wadis and rivers discharging into endorheic basins such as Wadi Tanezzuft also carried water during the AHP. In the Air, Hoggar and Tibesti Mountains, the so-called "Middle Terrace" was emplaced at this time. The rivers of the Sahara, lakes and their watersheds may have acted as pathways for the spread of humans and animals; the rivers were often connected to each other by alluvial fans. Proposed examples of animals that spread through rivers are the Nile crocodile and the fish Clarias gariepinus and Tilapia zillii. It is possible that the name Tassili n'Ajjer, which means "plateau of the rivers" in Berber, is a reference to past river flows. On the other hand, intense flows of these rivers may have made their shores dangerous to humans and thus created additional impetus for human movement.
Humans of the SaharaEdit
Conditions and resources were ripe for first hunter-gatherers, fishermen and, later, pastoralists. which arrived in the Sahara at the time where lakes developed. They may have come either from the north (Maghreb or Cyrenaica) where the Capsian culture was located, the south (Sub-Saharan Africa), or the east (Nile Valley). Traces of human activity have been found in the Acacus Mountains where caves and rock shelters were used as basecamps for humans, such as the Uan Afuda cave and the Uan Tabu and Takarkori rock shelters. The first occupation in Takarkori took place between 10,000 and 9,000 ago; about five millennia of human cultural evolution are recorded there. At Gobero in the Ténéré desert a cemetery has been found, which has been used to reconstruct the lifestyle of these former inhabitants of the Sahara, and at Lake Ptolemy in Nubia humans settled close to the lake shore, using its resources and perhaps even engaging in leisure activities. At that time, many humans appear to have depended on water-bound resources, seeing as many of the tools left by the early humans are associated with fishery; hence this culture is also known as "aqualithic" although substantial differences between the cultures of various places have been found. The greening of the Sahara led to a demographic expansion and especially in the Eastern Sahara human occupancy coincides with the AHP. Conversely occupation decreased along the Nile valley, perhaps due to wetlands expanding there.
Humans were hunting large animals with weapons that have been found in archeological sites and wild cereals occurring in the Sahara during the AHP such as brachiaria, sorghum and urochloa were an additional source of food. Humans also domesticated cattle, goats and sheep; cattle domestication occurred especially in the more environmentally variable Eastern Sahara. Animal husbandry picked up in earnest around 7,000 years ago when domestic animals came to the Sahara, and a population boom may be linked to this change in cultural practice; cattle and goat spread southwestwards from northeasternmost Africa from 8,000 years before present. Dairying has been demonstrated in some locations and cattle-husbandry is supported by the frequent depiction of cattle in rock paintings. The Dufuna canoe, one of the oldest known ships in the world, appears to date to the Holocene humid period and implies that the waterbodies of that time were navigated by humans. The cultural units "Masara" and "Bashendi" existed in Dakhleh Oasis during the AHP. In the Acacus Mountains, several cultural horizons known as Early and Late Acacus and Early, Middle, Late and Final Pastoral have been identified while in Niger the Kiffian culture has been related to the beginning of the AHP. Ancient civilizations thrived, with farming and animal husbandry taking place in Neolithic settlements. Possibly, the domestication of plants in Africa was delayed by the increased food availability during the AHP, it only took place around 2,500 BC.
Humans created rock art such as petroglyphs and rock paintings in the Sahara, perhaps the largest density of such creations in the world. Scenes include animals and everyday life such as swimming which supports the presence of past wetter climates. One well-known such petroglyph location is the Cave of Swimmers in the Gilf Kebir mountains of Egypt; other well known sites are the Gabal El Uweinat mountains also of Egypt, Arabia and the Tassili n'Ajjer in Algeria where rock paintings from this time have been discovered. Humans also left artifacts such as Fesselsteine[p] and ceramics in what today are inhospitable deserts. North Africa together with East Asia is one of the first places where pottery was developed probably under the influence of increased availability of resources during the AHP. The humid period also favoured its development and spread in West Africa during the 10th millennium BC; the so-called "wavy line" or "dotted wavy-line" motif was widespread across Northern Africa and as far as Lake Turkana.
These populations have been described as Epipaleolithic, Mesolithic and Neolithic and produced a variety of lithic tools and other assemblages. Genetic and archeological data indicate that these populations which exploited the resources of the AHP Sahara probably originated in Sub-Saharan Africa and moved north after some time, after the desert got wetter; this may be reflected in the northward spread of Macrohaplogroup L and Haplogroup U6 genomic lineages. In return, the AHP facilitated the movement of some Eurasian populations into Africa. These favourable conditions for human populations may be reflected in paradise myths such as the Garden of Eden in The Bible and Elysium and the Golden Age in Classical Antiquity, and in the spread of the Nilo-Saharan languages.
Additional manifestations in the SaharaEdit
The expanded vegetation and soil formation stabilized previously active dunes, eventually giving rise to the present-day draa dunes in the Great Sand Sea of Egypt for example, although there is uncertainty about whether this stabilization was widespread. Soil development and biological activity in soils are attested in the Acacus Mountains and the Mesak Settafet area of Libya, but evidence of soil formation/pedogenesis such as bog iron are described from other parts of the Sahara as well. In the Selima Sand Sheet, the landscape underwent erosional truncation and bioturbation. The Central and Southern Sahara saw the development of alluvial deposits while sebkha deposits are known from the Western Sahara. Lightning strikes into soil left lightning-altered rocks in parts of the Central Sahara.
The increased precipitation also resulted recharged aquifers such as the Nubian Sandstone Aquifer; presently, water from this aquifer maintains several lakes in the Sahara, such as the Lakes of Ounianga. Other groundwater systems were active at that time in the Acacus Mountains, Air Mountains, in the Fezzan and elsewhere in Libya and the Sahel. Raised groundwater tables provided water to plants and was discharged in depressions, lakes and valleys, forming widespread carbonate deposits[q] and feeding lakes.
The formation of lakes and vegetation reduced the export of dust from the Sahara. This has been recorded in marine cores, including one core where dust export decreased by almost half. In coastal places, such as in Oman, sea level rise also reduced the production of dust. In the Mediterranean, a decreased dust supply was accompanied by increased sediment input from the Nile, leading to changes in marine sediment composition.
Whether the strengthening of the monsoon enhanced or reduced upwelling off Northwestern Africa is debatable, with some research suggesting that the strengthening in upwelling decreased sea surface temperatures and increased the biological productivity of the sea, while other research suggests that the opposite occurred; less upwelling with more moisture. However, regardless of whether upwelling increased or decreased, it is possible that the strengthening of the monsoon boosted productivity off the coasts of Northern Africa because the increased river discharge delivered more nutrients to the sea.
Precipitation in Dhofar and southwestern Arabia is brought by the African monsoon, and a change to a wetter climate resembling Africa has been noted in southern Arabia and Socotra from cave and river deposits. It possibly reached as far as Qatar. Holocene paleolakes are recorded at Tayma, Jubbah, in the Wahiba Sands of Oman and at Mundafan. In the Rub al-Khali lakes formed between 9,000 and 7,000 years ago and dunes were stabilized by vegetation, although the formation of lakes there was less pronounced than in the Pleistocene. The Wadi ad-Dawasir river system in central Saudi Arabia became active again with increased river runoff into the Persian Gulf. Wadis in Oman eroded across LGM dunes and formed accumulation terraces. Episodes of increased river discharge occurred in Yemen and increased precipitation is recorded in the caves of Hoti, Qunf in Oman, Mukalla in Yemen and Hoq cave in Socotra. Freshwater sources in Arabia during the AHP became focus points of human activity and herding activity between mountains and lowlands occurred. In addition, karstic activity took place on exposed coral reefs in the Red Sea and traces of it are still recognizable today. Increased precipitation has been also invoked to explain decreased salinities in the Red Sea. Archeological sites such as cairns appeared with the beginning of the humid period.
The humid period in Arabia did not last as long as in Africa, deserts did not retreat as much and precipitation may not have reached the central and northern part of the peninsula past the Yemen Highlands; northern Arabia remained somewhat drier than southern Arabia, droughts were still common and the land and still produced dust. One study has estimated that the amount of rainfall in the Red Sea did increase to no more than 1 metre per year (39 in/year). Whether some former lakes in Arabia were actually marshes is contentious.
Nile discharge was higher than today and during the early African humid period, the Nile in Egypt flooded up to 3–5 metres (9.8–16.4 ft) higher than it did recently before flood control; the increased flooding may explain why many archeological sites along the Nile were abandoned during the AHP, with violent conflicts reconstructed from the Jebel Sahaba archeological site. Waters from the Nile[r] filled depressions like the Fayum Depression to form a deep lake with anoxic bottom waters and reaching 20 metres (66 ft) above sea level, probably once a geomorphic barrier was breached. Wetlands and anastomosing channels developed in the Nile Delta as sediment supply increased. In addition, Nile tributaries in northwestern Sudan such as Wadi Al-Malik, Wadi Howar[s] and Valley of the Queens became active during the AHP. Wadi Howar was active until 4,500 years ago, and at the time often contained dune-dammed lakes, swamps and wetlands; it was the largest Saharan tributary of the Nile and constituted an important pathway into sub-Saharian Africa. Conversely it appears that Lake Victoria and Lake Albert were not overflowing into the White Nile for all of the AHP, and the White Nile would have been sustained by overflow from Lake Turkana. There appears to be a tendency over the course of the AHP for the discharge of the Blue Nile to decrease relative to that of the White Nile. The Blue Nile built an alluvial fan at its confluence with the White Nile, and incision by the Nile reduced flooding risk in some areas which thus became available for human use.
Closed lakes in East Africa rose, sometimes by hundreds of metres. Lake Suguta developed in the Suguta Valley, accompanied by the formation of river deltas where rivers such as the Baragoi River entered the lake. In turn, Lake Suguta overflowed into the Kerio River, this adding water to Lake Turkana where increased discharge by the Turkwel River led to the formation of a large river delta. Over half of the water in Lake Turkana came from the Omo River, a decline compared to present-day conditions. Lake Turkana itself overflowed on its northwestern side through the Lotikipi Swamp into the White Nile. Deposits from this lake highstand form the Galana Boi Formation. This overflowing large lake was filled with freshwater and was populated by humans; the societies there engaged in fishery but could probably also fall back on other resources in the region.
The Ethiopian Lake Abhe expanded to cover an area of 6,000 square kilometres (2,300 sq mi), much larger than the present-day lake, in the "Abhe IV"-"Abhe V" lake cycle. The enlarged lake covered a large area west of the present-day lake, present-day lakes Afambo, Gamari and Tendaho, reducing Borawli, Dama Ale and Kurub to islands. The maximum water level was reached during the early Holocene as river discharge increased, but was later limited by partial overflow and did not rise above 380 metres (1,250 ft) again. Deep thermal groundwater recharge occurred in the region. About 9,000 years of human occupation are documented at the lake. Archeological sites indicate that people obtained resources from the lake and followed its rise and decline. The cultural traditions at Lake Abhe appear to be unusual by AHP/African standards.
Lake Zway and Lake Shala in Ethiopia joined with Lake Abiyata and Lake Langano to form a large waterbody which began overflowing into the Awash River. Other lakes that expanded include Lake Ashenge and Lake Hayq also in Ethiopia, Lake Bogoria, Lake Naivasha and Lake Nakuru/Lake Elmenteita all in Kenya, Lake Masoko in Tanzania, and a lake formed in the caldera of the Menengai volcano. Overflow of several of these lakes allowed animals including Nile crocodiles and fish to propagate to the individual lake basins. A 1,600 square kilometres (620 sq mi) large and 50 metres (160 ft) deep Lake Magadi formed in the early Holocene, and in the Danakil Depression of Ethiopia freshwater conditions became established. Finally, lakes formed in depressions on the mountains around Lake Kivu.
Glaciers stopped retreating or briefly expanded in East Africa at the beginning of the AHP before continuing retreat. On Mount Kilimanjaro they may have expanded during the AHP after a phase during the Younger Dryas where the mountain was ice free, but the tree line also rose at that time, accompanied by soil formation. The wetter climate may have destabilized the neighbouring Mount Meru volcano, causing a giant landslide that removed its summit.
Erosion in catchments of East Africa increased with the beginning of the humid period but then decreased even before its end, as the increased weathering led to the formation of soils, these in turn to the establishment of a vegetation cover that subsequently reduced additional erosion. Increased weathering resulted in the increased consumption of atmospheric CO2 during the AHP.
Surprisingly, and contrary to the patterns expected from precessional changes, the East African Rift also experienced a wetter climates during the AHP, reaching as far south as Lake Rukwa and Lake Cheshi into the Southern Hemisphere. In the region of the African Great Lakes, pollen evidence points to the occurrence of forests including rainforest vegetation due to the increased precipitation, while today they occur only in limited areas there. Denser vegetation also occurred at Lake Turkana, with wooden vegetation covering almost half of the dry land although grasslands remained dominant. Development of forest vegetation around the African Great Lakes created an interconnected environment where species spread, increasing biodiversity with effects on the future when the environment became fragmented. Vegetation cover also increased in the Afar region. Forests and moisture-requiring vegetation expanded in the Bale Mountains. Different types of vegetation, including dryland vegetation, existed at Lake Malawi and Lake Tanganyika however, and vegetation did not change much. A wetter climate is recorded from a soil in the Afar region.
In East Africa, the AHP led to improved environmental conditions in terms of food and water supply from large lakes, allowing early human populations to survive and grow in size without requiring major changes in food gathering strategies. Pottery techniques such as the "dotted wavy line" and "Kanysore" are associated with fishing and foraging communities. Earlier wet and dry periods in East Africa may have influenced the evolution of humans and allowed their spread across the Sahara and into Europe.
Other parts of Africa and the rainforest realmEdit
Lake Bosumtwi in Ghana rose during the AHP.[t] Evidence there also suggests a decrease in wildfire activity took place. Tropical forests expanded in the Adamawa Plateau of Cameroon and moved upward at Lake Bambili also in Cameroon. The core of the rainforest was probably unaltered by the African humid period, perhaps with some changes in species and an expansion of their area, although the peatlands of Central Congo started developing during the African humid period and peat continues to accumulate there to this day, albeit with a slowdown in the Cuvette Centrale after the end of the African humid period. In the Canary Islands, there is evidence of a moister climate on Fuerteventura, the laurel forests changed perhaps as a consequence of the AHP. Recharge of groundwater levels have been inferred from Gran Canaria also in the Canary Islands, followed by a decrease after the end of the AHP. Choughs may have reached the Canary Islands from North Africa when the latter was wetter.
Levant and MediterraneanEdit
High latitude Africa has not undergone large scale changes in the past 11,700 years; the Atlas Mountains may have blocked the monsoon from expanding further north. However, cave deposits showing a moister climate in southern Morocco, vegetation changes in the Middle Atlas, several floods in Tunisian rivers and ecosystem changes which impacted steppe-dependent rodents of Northern Africa have been linked to the AHP.
In the Pleistocene and Holocene humidity in the Mediterranean is often correlated to humidity in the Sahara, and the early-mid Holocene climate of Iberia, Italy, Negev and Northern Africa was wetter than today; in Sicily wettening correlates with ITCZ changes in Northern Africa. Mediterranean precipitation is brought by Mediterranean cyclones and the westerlies; either increased precipitation from the westerlies, northward moisture transport from Africa or monsoonal precipitation extending into the Mediterranean may have rendered it wetter. The connection between the African Monsoon and Mediterranean precipitation is unclear and it was winter rainfall that increased predominantly.
The Mediterranean Sea became less saline during the AHP, in part due to increased precipitation from the westerlies but also from increased river discharge in Africa, leading to the formation of sapropel layers when the increased runoff led to the Mediterranean becoming more stratified. The S1 sapropel layer is specifically associated with the AHP and with increased discharge of the Nile and other African rivers. This together with decreased dust transport by wind led to changes in the sediment patterns and an increased marine food web productivity in the Mediterranean, which impacted the development of deep-sea corals.
In the Levant, wetter conditions during the AHP are recorded from Jeita Cave in Lebanon and Soreq Cave in Israel while the Dead Sea and other southern European lakes were low during this period. This is unlike some earlier wet periods in the Sahara; possibly the stronger winter-summer insolation gradient in these earlier wet periods created a different moisture pattern than during the Holocene.
The effects, if any, of the African humid period on Southern Africa have been unclear. Originally it was proposed that the orbitally driven changes would imply a dry period in Southern Africa which would have given way to moister conditions as the northern AHP ended, as the ITCZ should shift its average position between the two hemispheres. However, the lack of paleoclimatology data with sufficient time resolution from Southern Africa has made it difficult to assess the climate there during the AHP. More recently obtained paleoclimate data have suggested however that southern Africa was actually wetter during the AHP rather than drier, perhaps reaching as far as north and northwest Madagascar, 23° south and as far as the catchment of the Orange River. The area between Lake Tanganyika and Lake Malawi has been interpreted as the limit of the AHP's influence.
Conversely, and consistent with the opposite reaction pattern of the Southern Hemisphere, the Zambezi River reached its lowest discharge during the AHP, and the AHP did not reach southern or southeastern Africa. There may have been opposite changes in precipitation between southeast Africa and tropical East Africa, separated by a "hinge zone". Particular changes occurred in central southern Africa, where a dry period co-occurred with an expansion of Lake Makgadikgadi; presumably increased wetness over the Okavango River catchment in the Angolan Highlands due to the AHP nourished the lake during a dry interval. In general there is little consistency between Northern and Southern Africa in terms of hydrological changes during the Holocene, and nowhere are both the start and end of the AHP apparent. Orbitally-mediated changes in Northern Hemisphere climate affected the Southern Hemisphere through oceanic pathways involving sea surface temperatures. Additionally, wetter periods unrelated to the AHP may have occurred after deglaciation in Southern Africa.
Estimates of the exact amount of increased precipitation vary widely. During the African humid period, Saharan rainfall increased to 300–400 millimetres per year (12–16 in/year), and values exceeding 400 millimetres per year (16 in/year) may have spread to 19–21° northern latitude. In the eastern Sahara, a gradient from 200 millimetres per year (7.9 in/year) increment in the north to 500 millimetres per year (20 in/year) in the south has been identified. An area with less than 100 millimetres per year (3.9 in/year) may have remained in the Eastern Sahara however, although its driest parts may have received 20-fold more precipitation than today. Precipitation in the Sahara probably reached no more than 500 millimetres per year (20 in/year), with large uncertainty.
Other reconstructed values of the precipitation increase indicate an annual increase of about 150–320 millimetres (5.9–12.6 in) in Africa, with strong regional variation. From lake levels precipitation increases of 20–33% or 50–100%/40-150% have been inferred for East Africa, with an increase of 40% reconstructed for Northern Africa. In the early Holocene, there appears to have been an eastward- and northward-decreasing trend of humidity. Additionally, at Tayma in Arabia a threefold increase appears to have occurred and precipitation in the Wahiba Sands of Oman may have reached 250–500 millimetres per year (9.8–19.7 in/year).
Effect on other climate modesEdit
One climate model has indicated that a greener Sahara and reduced dust output would have increased tropical cyclone activity, especially over the Atlantic but also in most other tropical cyclone basins. Changes in the intensity of the storms, decreases in wind shear, changes in atmospheric circulation and less dust in the atmosphere, which results in warmer oceans, are responsible for this phenomenon, despite an expected decrease of tropical wave activity over the Atlantic in climate models. The net effect could be a global increase in tropical cyclone activity and a westward shift. While there are no good paleotempestology data for the time of the African humid period that could confirm or refute this theory and many of these records are specific for particular locations, hurricane activity including past strikes in Puerto Rico and in Vieques appear to correlate with the strength of the West African Monsoon. On the other hand, at Grand Bahama Bank and the Dry Tortugas of South Florida a decrease of hurricane activity took place during the AHP and dust emission is not always anti-correlated to hurricane activity. Finally, the northward movement of the ITCZ during the AHP may have caused a corresponding northward movement of tropical cyclogenesis areas and storm tracks in the Atlantic Ocean, which could also explain decreased hurricane activity in the Bahamas and Dry Tortugas.
The El Niño–Southern Oscillation is a major climate variability mode. Paleoclimatology records from Ecuador and the Pacific Ocean indicate that during the early and middle Holocene ENSO variability was suppressed by about 30–60%, which can be only partially explained through orbital forcing. The Green Sahara may have suppressed ENSO activity, forcing a La Niña–like climate state, in a climate model this is accompanied by decreased upwelling and deepening of the thermocline in the Eastern Pacific as the Walker circulation shifts westward. In addition, Atlantic Niño sea surface temperature patterns develop in the Atlantic Ocean.
Remote effects of the AHP on the monsoons of the Northern Hemisphere have also been studied. In climate models, the strengthened and expanding monsoons of Africa and Asia alter the atmospheric circulation of the planet, inducing a wetter East Asian Monsoon and drying across tropical South America and central-eastern North America. The reduced dust emission warms the North Atlantic and increases westerly flow into the North American Monsoon, strengthening it. The far-field precipitation changes reach as far as Europe and Australia. Discrepancies between modelled and reconstructed northward extension and precipitation in the Asian monsoon regions and the North American Monsoon area may be explained through these remote effects.
Sun et al. 2020 proposed that the greening of the Sahara during the AHP can increase precipitation over the Middle East even if neither the African nor the Indian monsoons reach it. During spring, the increased vegetation forces anomalous atmospheric circulations that direct moisture transport from the Mediterranean, the Red Sea and eastern tropical Africa into the Middle East, increasing precipitation and agricultural productivity there. This could explain increased precipitation in the Middle East during the AHP: A wet climate occurred in the Middle East during the early Holocene, leading to the Ubaid period of settlement in Mesopotamia, followed by dry phases around 5,500 years ago and a concomitant reduction in simulated wheat yield.
Some gaps with less precipitation took place during the late glacial and the Holocene. During the Younger Dryas 12,500–11,500 years ago, the North Atlantic and Europe became much colder again and there was a phase of drought in the area of the African humid period, extending over both East Africa,[u] where lake levels dropped in many places, southern Africa and West Africa. The dry interval extended to India and the Mediterranean where dune activity occurred in the Negev. At the end of the Younger Dryas, precipitation, lake levels and river runoff increased again, although south of the equator the return of humid conditions was slower than the relatively abrupt change to its north.
Another dry phase took place about 8,200 years ago, spanning East Africa and Northern Africa[v] as documented by various lines of evidence such as decreased water levels in lakes. It coincided with cooling in the Northern Atlantic, in surrounding landmasses such as Greenland and around the world; the drought may be related to the 8.2 kiloyear event which separates the Greenlandian and Northgrippian stages of the Holocene and lasted for about one millennium. The 8,200 year event has also been noted in the Maghreb, where it is associated with a transition of the Capsian culture as well as with cultural changes both in the Sahara and the Mediterranean; at the Gobero cemetery a population change occurred after this dry interruption but the occurrence of widespread cultural changes appears to be questionable. This episode appears to have been caused by the draining of ice-dammed lakes in North America  although a low latitude origin has also been suggested.
Cooling of the Northern Atlantic during Heinrich event 1 and the Younger Dryas associated with a weaker Atlantic meridional overturning circulation leads to atmospheric pressure anomalies that shift the Tropical Easterly Jet and precipitation belts south, making Northern Africa drier.  Storm tracks shift north away from the Mediterranean. Earlier Heinrich events were also accompanied by drought in North Africa. Likewise, a weakening of moisture transport and a less eastward position of the Congo Air Boundary contributed to reducing precipitation in East Africa although some parts of southern Africa at Lake Malawi were wetter during the Younger Dryas.
Many humidity fluctuations in the early Holocene appear to be caused by the discharge of meltwater from the Laurentide Ice Sheet into the Atlantic, which weakens the Atlantic meridional overturning circulation. Some dry periods in marine cores in the Gulf of Guinea appear to coincide with events recorded in Greenland ice cores. Other variations in precipitation observed in records have been attributed to solar activity changes, water levels of Lake Turkana for example appear to reflect the 11-year solar cycle.
In Lake Turkana, water level fluctuations took place between 8,500 and 4,500 years before present, with highstands before 8,400, around 7,000 and between 5,500 and 5,000 and lowstands around 8,000, 10,000 and 12,000 years before present. The highstands appear to be controlled by sea surface temperature patterns in the Atlantic and Indian Oceans, but also by overflow of water from Lake Suguta and - intermittently - the Chew Bahir basins into Lake Turkana, which themselves received water from additional lakes. Volcanic and tectonic phenomena occur at Lake Turkana, but do not have the magnitude required to explain large changes in lake level. Water level fluctuations have also been inferred for Lake Chad on the basis of pollen data, especially towards the end of the AHP. In the Taoudenni lake fluctuations of about a quarter-millennium have been recorded and frequent droughts occurred in the Eastern Sahara.
Other variations appear to have occurred 9,500–9,000 and 7,400–6,800 as well as 10,200, 8,200, 6,600 and 6,000 years before present; they were accompanied by decreased population density in parts of the Sahara, and other dry interludes in Egypt have been noted 9,400–9,300, 8,800–8,600, 7,100–6,900 and 6,100–5,900 years ago. The duration and severity of dry events is difficult to reconstruct and the impact of events like the Younger Dryas is heterogeneous even between neighbouring areas. During dry episodes, humans might have headed to waterbodies which still had resources, and cultural changes in the central Sahara have been linked to some dry episodes. Aside from fluctuations, a southward retreat of the humid period may have been underway after 8,000 years ago with a major drought around 7,800 years ago.
The African humid period ended about 6,000–5,000 years ago, an ending date of 5,500 years before present is often used. After vegetation declined, the Sahara became barren and was claimed by sand. Wind erosion increased in northern Africa, and dust export from the now-desert and from dried up lakes such as the Bodélé Basin grew; Bodélé today is the largest single source of dust on Earth. The lakes dried up, mesic vegetation disappeared, and sedentary human populations were replaced by more mobile cultures. The transition from the "green Sahara" to the present-day dry Sahara is considered to be the greatest environmental transition of the Holocene in northern Africa; today almost no precipitation falls in the region. The end of the AHP but also its beginning could be considered a "climate crisis" given the strong and extended impact. Drying extended as far as the Canary Islands and southeastern Iran, and there is evidence of climate change on São Nicolau, Cape Verde.
The Piora Oscillation cold period in the Alps coincides with the end of the AHP; the period 5,600–5,000 calibrated years ago was characterized by widespread cooling and more variable precipitation changes around the world and was possibly forced by changes in solar activity and orbital parameters. Some changes in climate possibly extended into southeastern Australia, Central America and into South America. The neoglacial began.
A major pan-tropical environmental change took place about 4,000 calibrated years ago. This change was accompanied by the collapse of ancient civilizations, severe drought in Africa, Asia and the Middle East and the retreat of glaciers on Mount Kilimanjaro and Mount Kenya.
Whether the drying happened everywhere at the same time and whether it took place in centuries or millennia is unclear in part due to disagreeing records and has led to controversy, and such a disagreement on timing also exists with respect to the expected vegetation changes. Marine cores usually indicate an abrupt change but not without exceptions while pollen data do not, perhaps due to regional and local differences in vegetation. Groundwater and local vegetation can modify local conditions; groundwater-fed water bodies for example persisted longer than those nourished by rain. The debate on how quickly the Sahara formed goes back to 1849, when the Prussian naturalist Alexander von Humboldt suggested that only a quick drying could form the desert.
Most recently, the idea has taken hold that the end of the African humid period occurred from north to south in a stepwise fashion. In the western Sahara and east Africa it ended within 500 years with a one-step drying 6,000 – 5,000 years ago north of the present-day monsoon belt. Farther south, precipitation decrease was more protracted and closer to the equator the AHP ended between 4,000 and 2,500 years ago. In East Africa, pronounced drying occurred between 4,500 and 3,500 years ago, centered on 4,000 years ago; Egypt during the Old Kingdom was still wetter than today. A later end in northeast Africa about 4,000 years ago may reflect the different configuration of landmasses and thus monsoon behaviour, while other research has found a westward propagating drying trend.
Some evidence points to a two-phase change in climate with two distinct dry transitions caused by the existence of two different steps of insolation decrease at which climate changes. Distinct environmental changes may have occurred in Central Africa, Western Africa and East Africa. Finally, sometimes the 4.2 kiloyear event - the transition from the Northgrippian to the Meghalayan stage of the Holocene - is considered to be the true end of the AHP, especially in central Africa.
Increased variability in precipitation may have preceded the end of the AHP; this is commonly observed before a sudden change in climate. In Gilf Kebir, between 6,300 and 5,200 years ago apparently a winter rainfall regime became established as the AHP ended. Later fluctuations in climate that produced brief humid spells also took place, such as a moister period between 500 BCE – 300 CE in Roman Northern Africa and along the Dead Sea and an earlier one 2,100 years before present in the western Sahel.
Sahara and SahelEdit
After a first brief lake level drop between 5,700 and 4,700 calibrated years ago that might reflect climate variability towards the end of the African humid period, water levels in Lake Megachad decreased quickly after 5,200 years before present. It shrank to about 5% of its former size, with the deeper northern Bodele basin drying up entirely about 2,000-1,000 years ago as it was disconnected from the southern basin where its major tributary, the Chari River, enters Lake Chad. The dried out basin was now exposed to the Harmattan winds, which blow dust out of the dry lake bed, making it the single largest source of dust in the world. Dunes formed in the dried-up Sahara or began moving again after stabilizing during the AHP.
The tropical vegetation was replaced by desert vegetation, in some places suddenly and in others more gradually. Along the Atlantic coast, the vegetation retreat was slowed by a stage of sea level rise that increased soil moisture levels, delaying the retreat by about two millennia. In Libya at Wadi Tanezzuft the end of the humid period was also delayed by leftover water in dune systems and in the Tassili mountains until 2,700 years ago, when river activity finally ceased. A brief moist pulse between 5,000 – 4,000 years ago in the Tibesti led to the development of the so-called "Lower Terrace". The Egyptian Sahara might still have been vegetated until 4,200 years ago, based on depictions of savanna environments in Fifth Dynasty tombs in Egypt.
At Lake Yoa, which is groundwater-fed, vegetation decreased and became desert vegetation between 4,700–4,300 and 2,700 years ago, while the lake became hypersaline 4,000 years ago. However, the climate there may have been affected by the Tibesti Mountains and the end of the AHP thus delayed, and fossil groundwater left by the AHP nourishes the lake to this day. In the central Sahara, water resources in the mountains persisted longer.
East Africa and ArabiaEdit
In northern East Africa, water levels dropped rapidly about 5,500 years ago while in Hoti cave in Arabia a southward retreat of the Indian Monsoon took place about 5,900 years ago. Drying is also documented from Oman, and rivers and lakes of Arabia became intermittent or entirely dry. The Blue Nile basin became less moist with a noticeable decrease of Nile discharge about 4,000 years ago. Decreased discharge of the Nile led to the cessation of sapropel deposition and turbidite activity off its delta.
Some data from Ethiopia and the Horn of Africa indicate that drying there may have begun already 7,000–8,000 years ago or earlier. Reconstructions from Lake Abiyata in Ethiopia suggest that the end of the African humid period took the form of severe droughts rather than a gradual decrease of precipitation. Drying in Arabia commenced about 7,000 calibrated years ago and there are large disparities in the timing between various parts of Arabia but a tendency towards an arid climate between 6,000 and 5,000 years ago has been observed which continued until 2,700 years ago. In the Bale Mountains and the Sanetti Plateau of Ethiopia vegetation changes signalling a drier climate took place around 4,600 years ago.
Forest cover in the area of the African Great Lakes decreased between 4,700 and 3,700 years ago, although drying at Lake Victoria had begun around 8,000 years ago, at Lake Rukwa 6,700 years ago, at Lake Tanganyika about 6,000 years ago and at Lake Edward major changes in lake chemistry consistent with drying are noted 5,200 years ago. There a minor recovery in vegetation took place between 2,500 and 2,000 years ago, followed by a much more rapid appearance of grasses accompanied also by substantial wildfire activity. This might have been the most severe drought of the Lake Edward region in the Holocene, with many lakes such as Lake George dropping significantly or drying up altogether. Other lakes such as Nakuru, Turkana, Lake Chew Bahir, Lake Abbe and Lake Zway also dropped between 5,400 and 4,200 years ago. Decreased vegetation cover in the catchment of the Blue Nile has been correlated with increased sediment transport in the river beginning 3,600 – 4,000 years ago.
The end of the AHP at Lake Turkana occurred about 5,300 years before present, accompanied by a lake level decline and the cessation of overflow from other lakes in its area into Lake Turkana. Between 5,000 and 4,200, Lake Turkana became more saline and its water levels decreased below the level of outflow to the Nile. Towards the end of the AHP water temperatures in the lake and in other regional lakes appear to have increased, followed by a drop after its end possibly resulting from the insolation seasonality pattern that was in force at the time of the end of the AHP. The decrease of water levels in Lake Turkana also impacted the Nile and the Predynastic societies dependent on it.
Libya and the Middle Atlas became gradually more dry, and drying in Morocco took place about 6,000 radiocarbon years ago, Drier conditions in Iberia accompanied the end of the African humid period between 6,000 and 4,000 years ago, perhaps as a consequence of increasingly frequent positive North Atlantic Oscillation episodes and the shift of the ITCZ. More complicated changes have been found for the northern margin of the Mediterranean. A 4.2 kiloyear event is recorded in dust records from the Mediterranean and might have been caused by changes in the circulation of the Atlantic Ocean.
Tropical West AfricaEdit
In Lake Bosumtwi the African humid period ended about 3,000 years ago after a brief moistening between 5,410 ± 80 years ago that ended 3,170 ± 70 years ago. This, earlier but similar changes off western Senegal and later but similar changes in the Congo Fan appear to reflect a southward shift of the precipitation zone over time. Some drying occurred simultaneously between the Sahel and the Gulf of Guinea. Some lakes in the Guineo-Congolian region dried out, while others were relatively unaffected.
A general tendency towards a drier climate is observed in West Africa at the end of the AHP. There, dense vegetation became progressively thinner between 5,000 and 3,000 years ago, and major perturbations of the vegetation took place around 4,200 and 3,000–2,500/2,400 calibrated years ago. A brief return of moister conditions took place 4,000 years ago while a substantial dry phase occurred between 3,500 and 1,700 years ago. Aridity became established between 5,200 and 3,600 years ago in the Sahara. In Senegal modern-type vegetation arose about 2,000 years ago.
Farther south at the equator between 6,100 and 3,000 calibrated years before present savannah expanded at the expense of forests, with the transition possibly lasting until 2,500 calibrated years before present; a different time course estimate for the area between 4° southern and 7° northern latitude states that forest cover decreased between 4,500 and 1,300 years ago. In the Adamawa Plateau (Cameroon), the Ubangui Plateau (Central African Republic) and the Cameroon Volcanic Line montane forests disappeared at the end of the African humid period. In the Adamawa Plateau savannah has continuously expanded since 4,000 calibrated years ago. Such a change took also place in Benin and Nigeria between 4,500 and 3,400 calibrated years ago. Many vegetation changes in the tropical regions were probably caused by a longer dry season and perhaps a smaller latitudinal range of the ITCZ.
Southern Hemisphere AfricaEdit
In the Southern Hemisphere at Lake Malawi drying began later – 1,000 years before present – as did the African humid period which there began only about 8,000 years ago. Contrarily, increased water levels in Etosha Pan (Namibia) appear to relate to a southward movement of the ITCZ at the end of the AHP although stalagmite growth data in Dante Cave also in Namibia has been interpreted as indicating a wetter climate during the AHP.
The end of the humid period appears to reflect the changes in insolation during the Holocene, as a progressive decrease of summer insolation caused the insolation gradients between Earth's hemispheres to decrease. However, the drying appears to have been much more abrupt than the insolation changes; it is not clear whether non-linear feedbacks led to abrupt changes in climate and it is also unclear whether the process, driven by orbital changes, was abrupt. Also, the Southern Hemisphere warmed and this resulted in a southward shift of the ITCZ; orbitally-driven insolation has increased over the Holocene in the Southern Hemisphere.
As precipitation decreased, so did vegetation, in turn increasing the albedo and further decreasing precipitation. Furthermore, vegetation may have responded to increased variations in precipitation towards the end of the AHP although this view has been challenged. This could have directed sudden changes in precipitation, although this view has been cast in doubt by the observation that in many places the end of the African humid period was gradual rather than sudden. Plants at higher and lower latitudes might respond differently to climate change; for example more diverse plant communities might have slowed down the end of the AHP.
Other proposed mechanisms:
- Decreases in polar insolation through altered cosmic ray fluxes might promote the growth of sea ice and cooling at high latitudes, which in turn result in stronger equator-to-pole temperature gradients, stronger subtropical anticyclones and more intense upwelling in for example the Benguela current.
- Changes in the circulation of high latitude oceans may have played a role, such as the potential occurrence of another meltwater/ice rafting pulse around 5,700 years before present. The decreased insolation during the mid-Holocene may have made the climate system more sensitive to changes, explaining why earlier comparable pulses did not terminate the humid period for good.
- There is evidence that glaciers in Tibet such as at Nanga Parbat expanded during the Holocene, especially towards the end of the AHP. In climate models, increased snow and ice on the Tibetan Plateau can lead to a weakening of the Indian and African monsoons, with the weakening of the former preceding that of the latter by 1,500–2,000 years.
- Decreases in sea surface temperatures of the Indian Ocean may be involved in the drying of East Africa, but there is no agreement on the temperature records from that ocean. Moreover, there is no evidence of temperature changes in the Gulf of Guinea at the critical time that might explain the end of the AHP.
- Additional feedback processes may have included the drying of soils and loss of vegetation after decreased rainfall, which would have led to wind-driven deflation of the soils.
- An expansion of sea ice around Antarctica about 5,000 calibrated years ago may have provided another positive feedback.
- The expanding dry belt of the Sahara pushed the regions of cyclogenesis in the Mediterranean northwest-northward, resulting in wind changes and precipitation regime changes in parts of Italy.
- Climate change at high latitudes has been proposed as a cause for the end of the AHP. Specifically, about 6,000–5,000 years ago the Arctic became colder, with sea ice expanding, temperatures in Europe and off Northern Africa decreasing and the Atlantic meridional overturning circulation weakening. This cooling tendency may have weakened the Tropical Easterly Jet and thus reduced the amount of precipitation falling over Africa.
The orbitally-induced changes of precipitation may have been modified by the solar cycle; specifically, solar activity maxima during the ending phase of the AHP may have offset the orbital effect and thus stabilized precipitation levels, while solar activity minima compounded the orbital effects and thus induced rapid decreases in water levels of Lake Turkana. At Lake Victoria on the other hand, solar variations appear to sometimes lead to drought and sometimes lead to wetness, probably due to changes in the ITCZ.
Potentially human-mediated changesEdit
Major changes in vegetation in East Africa about 2,000 years ago may have been caused by human activity, including large-scale deforestation for iron production during the Iron Age. Similar changes have been observed on the Adamawa Plateau (Cameroon) but later dating of archeological sites has found no correlation between human expansion in Cameroon and environmental degradation. Similar rainforest degradation across Western African took place between 3,000 and 2,000 years ago and the degradation is also known as "third millennium rainforest crisis". Climate-mediated processes may have increased the impact of land use changes in East Africa. In the Sudanian and Sahelian savannah on the other hand human activity seems to have had little impact, and in Central Africa forest changes were clearly triggered by climate change with little or no evidence of anthropogenic changes. The question has led to intense debate among paleoecologists and archeologists.
While humans were active in Africa during the end of the African humid period, climate models analyzed by Claussen and colleagues 1999 indicate that its end does not need any human activity as an explanation although vegetation changes may have been induced by human activity. Later it was suggested that overgrazing may have triggered the end of the AHP around 5,500 years ago; human influence might explain why the Sahara became a desert without the accompanying onset of an ice age; usually the existence of a Sahara desert is associated with the expansion of high latitude glaciers. Later research has on the contrary suggested that human pastoralism may have actually delayed the end of the AHP by half a millennium as moving herds of animals driven by humans seeking good pasture conditions may lead to more balanced impacts of pastures on the vegetation and thus to greater vegetation quality. However, increased grazing has been invoked to explain the increase in dust emissions after the end of the AHP. The effects of grazing on vegetation cover are context-dependent and hard to generalize over wider region.
A general drying tendency is observed in the northern tropics and between 5,000 – 4,500 calibrated years ago the monsoons weakened. Asian monsoon precipitation declined between 5,000 and 4,000 years ago. A drought 5,500 years ago is recorded in Mongolia and eastern America, where drought conditions around 5,500–5,000 years ago occurred in places like Florida, New Hampshire and Ontario. A drying tendency is also noted in the Caribbean and the Central Atlantic.
Conversely, in South America there is evidence that the monsoon behaves in an opposite fashion consistent with precessional forcing; water levels in Lake Titicaca were low during the middle Holocene and began to rise again after the end of the AHP. Likewise, a trend towards increased wetness took place in the Rocky Mountains at this time although it was accompanied by a drier phase around Lake Tahoe, California and in the Western United States.
As observed in archeological sites, population in Northern Africa decreased between 6,300 and 5,200 years ago over less than a millennium, beginning from the north. In inner Arabia many settlements were abandoned about 5,300 years ago. Some Neolithic people in the desert persisted for longer thanks to the exploitation of groundwater.
Different human populations responded to the drying in diverse manners, with responses in the Western Sahara being distinct from those in the Central Sahara. In the Central Sahara, pastoralism replaced hunter-gatherer activity and a more nomadic lifestyle replaced semi-sedentary lifestyles as observed in the Acacus Mountains of Libya. Nomadic lifestyles also developed in the Eastern Sahara/Red Sea Hills in response to the end of the AHP. There was a shift in domestic animal use from cattle to sheep and goats as these are more suited in arid climates, a change reflected in rock art from which cattle disappeared at this time.
The development of irrigation systems in Arabia may have been an adaptation to the drying tendency. The decreased availability of resources forced human populations to adapt, in general fishing and hunting declined in favour of farming and herding. However, the effects of the end of the AHP on human food production have been subject to controversy.
The warm episode and coinciding drought may have triggered animal and human migration to less inhospitable areas and the appearance of pastoralists where previously fishery-dependent societies had existed, as happened at Lake Turkana. Humans moved to the Nile,[w] where the society of Ancient Egypt with pharaohs and pyramids was eventually forged by these climate refugees perhaps reflecting renewed exuberance; thus the end of the AHP can be considered responsible for the birth of Ancient Egypt. Lower water levels in the Nile also aided the settlement of its valley as has been observed at Kerma. A similar process may have led to the development of the Garamantian civilization. Such human migrations towards more hospitable conditions along rivers and the development of irrigation also took place along the Euphrates, Tigris and Indus, leading to the development of the Sumerian and Harappan civilizations. Population shifts into mountain areas have also been reported for the Air Mountains, Hoggar and Tibesti. In other places, such as the Acacus Mountains populations conversely remained in oases and hunter-gatherers also stayed in the Horn of Africa.
The Nile itself was not totally unaffected however; the 4.2 kiloyear event and the end of the AHP may be linked to the collapse of the Old Kingdom in Egypt when the Nile floods failed for three decades around 4,160 years before present and the final drying occurred. The ongoing decrease of precipitation after the end of the AHP could be the cause of the end of the Akkadian Kingdom in Mesopotamia. The end of the Garamantian civilization may also relate to climate change although other historical events were probably more important; at Tanezzuft oasis after 1,600 years ago it certainly relates to the drying trend.
In Central Africa, forests became discontinuous and savannahs formed in some places, facilitating the movement and growth of Bantu speaking populations; these in turn may have affected the ecosystem. The vegetation changes may have aided in the establishment of agriculture. The relatively slow decline of precipitation gave humans more time to adapt to the changing climate conditions.
Cultural changes may also have occurred as a consequence of climate change, such as changes in gender roles, the development of elites, the increased presence of human burials where formerly cattle burials predominated, as well as an increase of monumental architecture in the Sahara may have also been a response to increasingly adverse climates. A spread in cattle domestication at the time of climate change and as herders escaped the drying Sahara southwards may also relate to these events, although the details of the exact process by which cattle domestication spread are still controversial. Finally, changes in agricultural practices at the end of the AHP may be associated with the propagation of malaria and one of its causative pathogens Plasmodium falciparum; in turn these may correlate with the origin of human genome variants such as sickle cell disease that are linked to malaria resistance.
In the Sahara, animal and plant populations were fragmented and restricted to certain favoured areas such as moist areas of mountain ranges; this happened for example to fish and crocodiles which only persist in isolated water bodies. Mediterranean plants such as cypresses too persist only in mountains, along with some reptiles that may have also been stranded in mountains by the drying. The whip spider Musicodamon atlanteus is probably also a relic of past wetter conditions. The buffalo species Syncerus antiquus probably went extinct from the increased competition of pastoralists triggered by the climate drying. The drying of the African Great Lakes region split gorilla populations became split into western and eastern populations, and a similar population split between the insect species Chalinus albitibialis and Chalinus timnaensis in Northern Africa and the Middle East may have also been caused by the expansion of deserts there. Some aquatic species disappeared from the Sahara. Giraffes, widespread in the Sahara during the AHP, may have been forced to migrate into the Sahel; this together with the separating effect of Lake Megachad may have influenced the development of giraffe subspecies. Climate change together with human impacts may have led to the extinction of a number of large mammals in Egypt. On the other hand, the decline of tree cover may have grown the niche available to domestic animals and some drought-tolerant plant species may have expanded their range.
The Dahomey Gap[x] formed 4,500–3,200 years before present, correlative to the end of the AHP. The harbour porpoise declined in the Mediterranean due to a switch to oligotrophic conditions as discharge from African rivers decreased. Desert varnish formed on exposed rocks in the Sahara.
The shrinkage of subtropical wetlands probably led to a drop in atmospheric methane concentrations between 5,500 and 5,000 years ago, before boreal wetlands expanded and offset the loss of subtropical wetlands, leading to a return of higher atmospheric methane concentrations. Conversely, increases in atmospheric methane concentrations, detected in Greenland ice cores about 14,700 years ago, and atmospheric carbon dioxide decreases in the early Holocene may relate to the vegetation expansion caused by the AHP. Carbon dioxide concentration then increased after about 7,000 years as the biosphere began releasing carbon in response to increasing aridity.
A sudden increase in the amount of land-originating dust in an oceanic drill core off Cape Blanc, Mauritania, has been interpreted as reflecting the end of the AHP 5,500 years ago occurring in only a few centuries. Potentially, dried up lake basins became an important source for dust and silt-sized particles. Today, the Sahara is the single largest source of dust in the world, with far ranging effects on climate and ecosystems, such as the growth of the Amazon rainforest.
In one climate model, the desertification of the Sahara at the end of the AHP reduces the amount of heat transported in the atmosphere and ocean towards the poles, inducing cooling of 1–2 °C (1.8–3.6 °F) especially in winter in the Arctic and an expansion of sea ice. Reconstructed temperatures in the Arctic indeed show a cooling, although less pronounced than in the climate model. Further, this climate transition in the climate model is accompanied by increased negative Arctic Oscillation states, a weaker subpolar gyre and increased precipitation and cold air outbreaks in much of Europe; such changes have also been observed in paleoclimate data. These findings imply that the vegetation state of the Sahara influences the Northern Hemisphere climate. In turn, this high latitude cooling may have further reduced precipitation over Africa.
Presently, the African Monsoon still influences the climate between 5° south and 25° north latitude; the latitudes around 10° north receive the bulk of their precipitation from the monsoon[y] during summer, with smaller amounts of rainfall occurring farther north. Thus farther north deserts can be found while the moister areas are vegetated. In the Central Sahara, annual precipitation reaches no more than 50–100 millimetres per year (2.0–3.9 in/year). Even farther north, the margin of the desert coincides with the area where the westerlies bring precipitation; they also influence southernmost Africa. Subsidence of air over parts of Northern Africa is responsible for the existence of deserts, which is further increased by the radiative cooling over the desert. Climate variability exists to this day, with the Sahel suffering from droughts in the 1970s and 1980s when precipitation decreased by 30% and the flow of the Niger River and Senegal River even more, followed by an increase of precipitation. The droughts are one of the most significant climate anomalies of the 20th century. Sea surface temperatures and feedbacks from land surface conditions modulate the strength of the monsoon and the droughts may have been triggered by sea surface temperature changes forced by anthropogenic aerosols. A large increase in dust fluxes after 1800 AD has been explained with changed agricultural practices.
In East Africa the monsoon leads to two rain seasons in the equatorial area, the so-called "long rains" in March–May and the "short rains" in October–November when the ITCZ moves northward and southward over the region, respectively; in addition to the Indian Ocean-sourced precipitation there is also Atlantic[z]- and Congo-sourced precipitation west of the Congo Air Boundary. In Arabia, the monsoon does not penetrate far from the Arabian Sea and some areas are under the influence of winter precipitation brought by cyclones from the Mediterranean Sea. East Africa is also under the influence of monsoon circulations.
Implications for future global warmingEdit
Some simulations of global warming and increased carbon dioxide concentrations have shown a substantial increase in precipitation in the Sahel/Sahara. This and the increased plant growth directly induced by carbon dioxide could lead to an expansion of vegetation into present-day desert, although it would be less extensive than during the mid-Holocene and perhaps accompanied by a northward shift of the desert, i.e. a drying of northernmost Africa. Such a precipitation increase may also reduce the amount of dust originating in Northern Africa, with effects on hurricane activity in the Atlantic and increased threats of hurricane strikes in the Caribbean, the Gulf of Mexico and the East Coast of the United States of America.
The Special Report on Global Warming of 1.5 °C and the IPCC Fifth Assessment Report indicate that global warming will likely result in increased precipitation across most of East Africa, parts of Central Africa and the principal wet season of West Africa, although there is significant uncertainty related to these projections especially for West Africa. In addition, the end of the 20th century drying trend may be due to global warming. On the other hand, West Africa and parts of East Africa may become drier during given seasons and months. Currently, the Sahel is becoming greener but precipitation has not fully recovered to levels reached in the mid-20th century.
Climate models have yielded equivocal results about the effects of anthropogenic global warming on the Sahara/Sahel precipitation. Human-caused climate change occurs through different mechanisms than the natural climate change that led to the AHP, in particular through increased inter-hemispheric temperature gradients. The direct effect of heat on plants may be detrimental. Non-linear increases in vegetation cover are also possible. One study in 2003 showed that vegetation intrusions in the Sahara can occur within decades after strong rises in atmospheric carbon dioxide but would not cover more than about 45% of the Sahara. That climate study also indicated that vegetation expansion can only occur if grazing or other perturbations to vegetation growth do not hamper it. On the other hand, increased irrigation and other measures to increase vegetation growth such as the Great Green Wall could enhance it.
Plans to geoengineer the Sahara to increase its vegetation cover and precipitation have been proposed since the 19th century. The mechanisms and consequences of the AHP are important context to evaluate such proposals and their ramifications; precipitation may increase but the consumption of carbon dioxide would be small and there could be detrimental impacts on climate and dust fluxes in the far-field. Building large solar farms in the Sahara desert would also act to decrease its albedo and may trigger similar climate responses.
A greening of the Sahara on the one hand may allow agriculture and pastoralism to expand into hitherto unsuitable areas, but increased precipitation can also lead to increased water borne diseases and flooding. Expanded human activity resulting from a wetter climate may be vulnerable to climate reversals as demonstrated by the droughts that followed the mid-20th century wet period.
- Other terms that have been applied to the Holocene AHP or correlative climate phases are "Holocene humid period", which also covers an analogous episode in Arabia and Asia; "Holocene Pluvial"; "Holocene Wet Phase"; "Kibangien A" in Central Africa; "Makalian" for the Neolithic period of northern Sudan; "Nabtian Wet Phase" or "Nabtian period" for the 14,000–6,000 humid period over the Eastern Mediterranean and Levant; "Neolithic pluvial"; "Neolithic Subpluvial"; "Nouakchottien" of the Western Sahara 6,500 – 4,000 years before present; and "Tchadien" in the Central Sahara 14,000 – 7,500 years before present.
- The terms "Léopoldvillien" and Ogolien have been applied to the dry period in the last glacial maximum, the latter is equivalent to the "Kanemian"; "Kanemian dry period" refers to a dry period between 20,000–13,000 years before present in the Lake Chad area.
- The hypsithermal, which coincides with the AHP, has been recorded from Arabia, the Caribbean and the Mediterranean. At Lake Ashenge, the onset of the AHP was accompanied by climatic warming while in Senegal, temperatures during the AHP were 1 °C (1.8 °F) lower than today there.
- Active dunes also formed in Arabia, Israel and the exposed seafloor of the Persian Gulf where dust generation increased.
- Dune-covered areas.
- However, some lakes persisted in areas where colder temperatures had decreased evaporation.
- Earlier it was thought that it had started about 9,000 years ago, before it was found that it probably began earlier and was interrupted by the Younger Dryas; the older hypothesis has not been entirely abandoned. Some lake level curves indicate a stepwise increase of lake levels 15,000 ± 500 and 11,500–10,800 years ago, before and after the Younger Dryas.
- Whether it commenced first in the eastern Sahara is unclear.
- This was originally believed to have occurred 7,000 or 13,000 years before present, but a more recent suggestion indicates a reconnection of the Nile 14,000–15,000 years ago.
- Lake Megachad is an expanded Lake Chad which had a size comparable to the Caspian Sea which is today's largest lake.
- The Congo Air Boundary is the point at which moisture bearing winds from the Indian Ocean collide with those from the Atlantic Ocean.
- In the Caribbean, a wet period has been identified in the mid-Holocene which correlated with the African wet period and was preceded and followed by drier conditions.
- Where the Monsoon of South Asia penetrated farther inland and was more intense starting about 14,800 years ago.
- Salt deposits left there were mined beginning in the 16th century.
- Both Bir Kiseiba and Nabta Playa feature archeological sites; Nabta may have been a religious centre of regional importance.
- Fesselsteine are stony artifacts, that are interpreted as tools for restraining animals.
- In the form of calcretes, "lake chalks", rhizoliths, travertines and tufa.
- Local runoff contributed to the filling of the Fayum Depression.
- Also known as the Yellow Nile
- A lake level drop 8,000 years ago has been related to the northward movement of the rainbelt.
- There is conflicting evidence on whether the Younger Dryas was wetter or drier in tropical southeastern Africa.
- Whether it also took place in Asia is unclear; perhaps it was too short to trigger climate changes recognizable in records but some evidence has been found.
- At the time of the Gerzeh culture
- The Dahomey Gap is a region without forests in southern Benin, Ghana and Togo that forms a gap in the Guineo-Congolian forest belt.
- The main area of monsoon rains does not coincide with the ITCZ.
- The Atlantic Ocean is also the source of monsoon rainfall for the Sahel.
- Bader, Jürgen; Dallmeyer, Anne; Claussen, Martin (29 March 2017). "Theory and Modeling of the African Humid Period and the Green Sahara". Oxford Research Encyclopedia of Climate Science. 1. doi:10.1093/acrefore/9780190228620.013.532.
- Hoelzmann & Holmes 2017, p. 3.
- McCool 2019, p. 5.
- Dawelbeit, Jaillard & Eisawi 2019, p. 12.
- Wendorf, Karlén & Schild 2007, p. 190.
- Timm et al. 2010, p. 2612.
- Hoelzmann et al. 2001, p. 193.
- Chandan & Peltier 2020, p. 1.
- Stivers et al. 2008, p. 2.
- Watrin, Lézine & Hély 2009, p. 657.
- Chandan & Peltier 2020, p. 2.
- Lézine, Duplessy & Cazet 2005, p. 227.
- Junginger et al. 2014, p. 1.
- Skinner & Poulsen 2016, p. 349.
- Hopcroft et al. 2017, p. 6805.
- Menocal et al. 2000, p. 348.
- Peck et al. 2015, p. 140.
- Hoelzmann & Holmes 2017, p. 11.
- Krüger et al. 2017, p. 1.
- Sangen 2012, p. 144.
- Médail et al. 2013, p. 1.
- Lézine et al. 2017, p. 68.
- Runge 2013, p. 81.
- Olsen 2017, p. 90.
- Sangen 2012, p. 213.
- Spinage 2012, p. 71.
- Said 1993, p. 128.
- Revel et al. 2010, p. 1357.
- Brass, Michael (1 March 2018). "Early North African Cattle Domestication and Its Ecological Setting: A Reassessment". Journal of World Prehistory. 31 (1): 86. doi:10.1007/s10963-017-9112-9. ISSN 1573-7802.
- Baumhauer & Runge 2009, p. 10.
- Sangen 2012, p. 211.
- Soriano et al. 2009, p. 2.
- Pachur & Altmann 2006, p. 32.
- Sepulchre et al. 2008, p. 42.
- Garcea, Elena A.A. (2020). The Prehistory of the Sudan. SpringerBriefs in Archaeology. Cham: Springer International Publishing. p. 10. doi:10.1007/978-3-030-47185-9. ISBN 978-3-030-47187-3.
- Menocal et al. 2000, p. 347.
- Quade et al. 2018, p. 1.
- Costa et al. 2014, p. 58.
- McGee & deMenocal 2017, p. 3.
- Blanchet et al. 2013, p. 98.
- Petoukhov et al. 2003, p. 99.
- Badino, Federica; Ravazzi, Cesare; Vallè, Francesca; Pini, Roberta; Aceti, Amelia; Brunetti, Michele; Champvillair, Elena; Maggi, Valter; Maspero, Francesco; Perego, Renata; Orombelli, Giuseppe (April 2018). "8800 years of high-altitude vegetation and climate history at the Rutor Glacier forefield, Italian Alps. Evidence of middle Holocene timberline rise and glacier contraction". Quaternary Science Reviews. 185: 41. Bibcode:2018QSRv..185...41B. doi:10.1016/j.quascirev.2018.01.022. ISSN 0277-3791.
- Vahrenholt & Lüning 2019, p. 507.
- Greer, Lisa; Swart, Peter K. (2006). "Decadal cyclicity of regional mid-Holocene precipitation: Evidence from Dominican coral proxies". Paleoceanography. 21 (2): 2. Bibcode:2006PalOc..21.2020G. doi:10.1029/2005PA001166. ISSN 1944-9186. S2CID 17357948.
- Sbaffi, Laura; Wezel, Forese Carlo; Curzi, Giuseppe; Zoppi, Ugo (January 2004). "Millennial- to centennial-scale palaeoclimatic variations during Termination I and the Holocene in the central Mediterranean Sea". Global and Planetary Change. 40 (1–2): 203. Bibcode:2004GPC....40..201S. doi:10.1016/S0921-8181(03)00111-5. ISSN 0921-8181.
- Marshall et al. 2009, p. 124.
- Rolandone, F.; Lucazeau, F. (20 August 2012). "Heat-flow and subsurface temperature history at the site of Saraya (eastern Senegal)". Solid Earth. 3 (2): 216. Bibcode:2012SolE....3..213L. doi:10.5194/se-3-213-2012. ISSN 1869-9510.
- Liu et al. 2017, p. 123.
- Chiotis 2018, p. 17.
- Chiotis 2018, p. 20.
- Röhl et al. 2008, p. 671.
- Zerboni, Trombino & Cremaschi 2011, p. 331.
- Jones & Stewart 2016, p. 126.
- Krüger et al. 2017, pp. 12–13.
- Jones & Stewart 2016, p. 117.
- Timm et al. 2010, p. 2627.
- Hoelzmann & Holmes 2017, p. 10.
- Runge 2013, p. 65.
- Petraglia & Rose 2010, p. 45.
- Blümel 2002, p. 8.
- Adkins, Menocal & Eshel 2006, p. 1.
- Schefuß et al. 2017, p. 2.
- Coutros 2019, p. 4.
- Brooks et al. 2007, p. 255.
- Williams et al. 2010, p. 1131.
- Riemer 2006, pp. 554–555.
- Baumhauer & Runge 2009, p. 28.
- Muhs et al. 2013, p. 29.
- Kennett & Kennett 2007, p. 235.
- Pachur & Altmann 2006, p. 6.
- Brooks et al. 2007, pp. 258–259.
- Petraglia & Rose 2010, p. 197.
- Heine 2019, p. 514.
- Sangen 2012, p. 212.
- Krüger et al. 2017, p. 14.
- Haslett & Davies 2006, p. 43.
- Bard 2013, p. 808.
- Williams et al. 2010, p. 1129.
- Morrissey & Scholz 2014, p. 95.
- Williams et al. 2010, p. 1134.
- Castañeda et al. 2016, p. 54.
- Runge 2010, p. 237.
- Perego, Zerboni & Cremaschi 2011, p. 465.
- Muhs et al. 2013, pp. 42, 44.
- Gasse 2000, p. 195.
- Coutros 2019, p. 5.
- Brookes 2003, p. 164.
- Maley 2000, p. 133.
- Runge 2010, p. 234.
- Maley 2000, p. 122.
- Zerboni & Gatto 2015, p. 307.
- Maley 2000, p. 127.
- Moeyersons et al. 2006, p. 166.
- Pachur & Altmann 2006, p. 11.
- Pachur & Altmann 2006, p. 601.
- Junginger et al. 2014, p. 12.
- Talbot et al. 2007, p. 4.
- Williams et al. 2010, p. 1132.
- Hughes, Fenton & Gibbard 2011, pp. 1066–1068.
- Menocal et al. 2000, p. 354.
- Williams et al. 2006, p. 2652.
- Reid et al. 2019, p. 9.
- Battarbee, Gasse & Stickley 2004, p. 242.
- Bendaoud et al. 2019, p. 528.
- Peck et al. 2015, p. 142.
- Stokes, Martin; Gomes, Alberto; Carracedo-Plumed, Ana; Stuart, Fin (2019). Alluvial Fans And Their Relationship To African Humid Period Climate Dynamics. 20th Congress of the International Union for Quaternary Research (INQUA).
- Castilla-Beltrán, Alvaro; de Nascimento, Lea; Fernández-Palacios, José María; Fonville, Thierry; Whittaker, Robert J.; Edwards, Mary; Nogué, Sandra (15 June 2019). "Late Holocene environmental change and the anthropization of the highlands of Santo Antão Island, Cabo Verde". Palaeogeography, Palaeoclimatology, Palaeoecology. 524: 104. Bibcode:2019PPP...524..101C. doi:10.1016/j.palaeo.2019.03.033. ISSN 0031-0182.
- Petraglia & Rose 2010, p. 46.
- Neugebauer, Ina; Wulf, Sabine; Schwab, Markus J.; Serb, Johanna; Plessen, Birgit; Appelt, Oona; Brauer, Achim (August 2017). "Implications of S1 tephra findings in Dead Sea and Tayma palaeolake sediments for marine reservoir age estimation and palaeoclimate synchronisation". Quaternary Science Reviews. 170: 274. Bibcode:2017QSRv..170..269N. doi:10.1016/j.quascirev.2017.06.020. ISSN 0277-3791.
- Williams et al. 2010, p. 1127.
- Williams et al. 2006, p. 2664.
- Blanchet, Contoux & Leduc 2015, p. 225.
- Hamdan & Brook 2015, p. 184.
- Kuper 2006, p. 412.
- Revel et al. 2010, p. 1358.
- Barker et al. 2002, p. 302.
- Moeyersons et al. 2006, p. 177.
- Gasse 2000, p. 203.
- Guilderson et al. 2001, p. 196.
- Marshall et al. 2009, p. 125.
- Burrough & Thomas 2013, p. 29.
- Vermeersch, Linseele & Marinova 2008, p. 395.
- Röhl et al. 2008, p. 673.
- Mercuri et al. 2018, p. 219.
- Baumhauer 2004, p. 290.
- Menocal et al. 2000, p. 356.
- Renssen et al. 2003, p. 1.
- Renssen et al. 2003, p. 4.
- Shi & Liu 2009, p. 3721.
- Menocal 2015, p. 1.
- Hély et al. 2009, p. 672.
- Shi & Liu 2009, p. 3722.
- Tierney et al. 2011, p. 103.
- Renssen et al. 2006, p. 95.
- Phelps et al. 2020, p. 1119.
- Shi & Liu 2009, pp. 3720–3721.
- Shi & Liu 2009, p. 3723.
- Armitage, Bristow & Drake 2015, p. 8543.
- Beer et al. 2002, p. 591.
- Martin, Damodaran & D'Souza 2019, p. 53.
- Thompson et al. 2019, p. 3917.
- Battarbee, Gasse & Stickley 2004, p. 243.
- Timm et al. 2010, p. 2613.
- Donnelly et al. 2017, p. 6222.
- Gaetani et al. 2017, p. 7622.
- Thompson et al. 2019, p. 3918.
- Sha et al. 2019, p. 6.
- Chandan & Peltier 2020, p. 9.
- Thompson et al. 2019, p. 3923.
- Servant, Buchet & Vincens 2010, p. 290.
- Menocal et al. 2000, p. 357.
- Heine 2019, p. 45.
- The Hadley circulation : present, past and future. Advances in Global Change Research. 21. Kluwer academic Publishers. 2004. p. 339. doi:10.1007/978-1-4020-2944-8. ISBN 978-1-4020-2944-8.
- Tierney et al. 2011, p. 110.
- Cohen et al. 2008, p. 254.
- Vahrenholt & Lüning 2019, p. 529.
- Burrough & Thomas 2013, pp. 29–30.
- Tierney et al. 2011, p. 109.
- Wang et al. 2019, p. 150.
- Burrough & Thomas 2013, p. 30.
- Junginger et al. 2014, p. 13.
- Costa et al. 2014, p. 64.
- Costa et al. 2014, p. 59.
- Castañeda et al. 2016, p. 53.
- Liu et al. 2017, p. 130.
- Reid et al. 2019, p. 10.
- Yang, Deming; Uno, Kevin T.; Souron, Antoine; McGrath, Kate; Pubert, Éric; Cerling, Thure E. (5 November 2020). "Intra-tooth stable isotope profiles in warthog canines and third molars: Implications for paleoenvironmental reconstructions". Chemical Geology. 554: 11–12. Bibcode:2020ChGeo.554k9799Y. doi:10.1016/j.chemgeo.2020.119799. ISSN 0009-2541.
- Reid et al. 2019, p. 1.
- Liu et al. 2017, p. 131.
- Johnson, Thomas C.; Werne, Josef P.; Castañeda, Isla S. (1 September 2007). "Wet and arid phases in the southeast African tropics since the Last Glacial Maximum". Geology. 35 (9): 825. Bibcode:2007Geo....35..823C. doi:10.1130/G23916A.1. ISSN 0091-7613.
- Hoelzmann & Holmes 2017, p. 31.
- Barker et al. 2002, p. 295.
- Barker et al. 2002, p. 296.
- Timm et al. 2010, p. 2629.
- Hoelzmann & Holmes 2017, p. 26.
- Hamdan & Brook 2015, p. 185.
- Phillipps et al. 2012, p. 72.
- Petit-Maire 1989, p. 648.
- Hamdan et al. 2020, p. 468.
- Williams et al. 2010, p. 1133.
- Baumhauer & Runge 2009, p. 6.
- Prasad & Negendank 2004, pp. 219–220.
- Linstädter & Kröpelin 2004, p. 763.
- Marks, Leszek; Welc, Fabian; Milecka, Krystyna; Zalat, Abdelfattah; Chen, Zhongyuan; Majecka, Aleksandra; Nitychoruk, Jerzy; Salem, Alaa; Sun, Qianli; Szymanek, Marcin; Gałecka, Izabela; Tołoczko-Pasek, Anna (15 August 2019). "Cyclonic activity over northeastern Africa at 8.5–6.7 cal kyr B.P., based on lacustrine records in the Faiyum Oasis, Egypt". Palaeogeography, Palaeoclimatology, Palaeoecology. 528: 121. Bibcode:2019PPP...528..120M. doi:10.1016/j.palaeo.2019.04.032. ISSN 0031-0182.
- Skinner & Poulsen 2016, pp. 355–356.
- Bowman, D.; Nyamweru, C. K. (1 January 1989). "Climatic changes in the Chalbi Desert, North Kenya". Journal of Quaternary Science. 4 (2): 137. Bibcode:1989JQS.....4..131N. doi:10.1002/jqs.3390040204. ISSN 1099-1417.
- Pachur & Altmann 2006, p. 276.
- Reimer et al. 2010, p. 42.
- Schefuß et al. 2017, p. 7.
- Pachur & Altmann 2006, p. 556.
- Heine 2019, p. 518.
- Schefuß et al. 2017, p. 3.
- Hoelzmann & Holmes 2017, pp. 25–26.
- Schefuß et al. 2017, p. 5.
- Mercuri et al. 2018, p. 225.
- Prasad & Negendank 2004, p. 221.
- Hopcroft et al. 2017, p. 6804.
- Dixit et al. 2018, p. 234.
- Bendaoud et al. 2019, p. 529.
- Pachur & Altmann 2006, p. 9.
- Dixit et al. 2018, p. 247.
- Russell & Ivory 2018, p. 1.
- Huang et al. 2008, p. 1459.
- Engel et al. 2012, p. 131.
- Piao et al. 2020, p. 1.
- Heine 2019, p. 586.
- He, Wei; Liu, Jianguo; Huang, Yun; Cao, Li (2020). "Sea Level Change Controlled the Sedimentary Processes at the Makran Continental Margin Over the Past 13,000 yr". Journal of Geophysical Research: Oceans. 125 (3): 9. Bibcode:2020JGRC..12515703H. doi:10.1029/2019JC015703. ISSN 2169-9291.
- Hiner, Christine A.; Silveira, Emily; Arevalo, Andrea; Murrieta, Rosa; Lucero, Ricardo; Eeg, Holly; Palermo, Jennifer; Lachniet, Matthew S.; Anderson, William T.; Knell, Edward J.; Kirby, Matthew E. (2015). "Evidence for insolation and Pacific forcing of late glacial through Holocene climate in the Central Mojave Desert (Silver Lake, CA)". Quaternary Research. 84 (2): 9. Bibcode:2015QuRes..84..174K. doi:10.1016/j.yqres.2015.07.003. ISSN 1096-0287.
- Huang et al. 2008, p. 1461.
- Flögel, S.; Beckmann, B.; Hofmann, P.; Bornemann, A.; Westerhold, T.; Norris, R.D.; Dullo, C.; Wagner, T. (September 2008). "Evolution of tropical watersheds and continental hydrology during the Late Cretaceous greenhouse; impact on marine carbon burial and possible implications for the future". Earth and Planetary Science Letters. 274 (1–2): 10. Bibcode:2008E&PSL.274....1F. doi:10.1016/j.epsl.2008.06.011. ISSN 0012-821X.
- Usai, Donatella (2 June 2016). A Picture of Prehistoric Sudan. 1. Oxford University Press. doi:10.1093/oxfordhb/9780199935413.013.56.
- Liu et al. 2017, p. 127.
- Coussin, Vincent; Penaud, Aurelie; Combourieu-Nebout, Nathalie; Peyron, Odile; Miras, Yannick; Sicre, Marie-Alexandrine; Babonneau, Nathalie; Cattaneo, Antonio (1 May 2020). Holocene Paleoenvironments in the Western Mediterranean Sea: palynological evidences on the Algerian coast and climatic reconstructions. 22nd EGU General Assembly. Egu General Assembly Conference Abstracts. 22. p. 17688. Bibcode:2020EGUGA..2217688C.
- Wu et al. 2017, p. 95.
- Stojanowski, Carver & Miller 2014, p. 80.
- Chiotis 2018, p. 187.
- Phelps et al. 2020, p. 1120.
- Bristow et al. 2018, p. 182.
- Hély et al. 2009, p. 685.
- Sylvestre et al. 2013, p. 224 (lower estimate).
- Lézine 2017, p. 4 (upper estimate).
- Baumhauer 2004, p. 291.
- Watrin, Lézine & Hély 2009, p. 663.
- Castañeda, Isla S.; Mulitza, Stefan; Schefuß, Enno; Santos, Raquel A. Lopes dos; Damsté, Jaap S. Sinninghe; Schouten, Stefan (1 December 2009). "Wet phases in the Sahara/Sahel region and human migration patterns in North Africa". Proceedings of the National Academy of Sciences. 106 (48): 20160. Bibcode:2009PNAS..10620159C. doi:10.1073/pnas.0905771106. ISSN 0027-8424. PMC 2776605. PMID 19910531.
- Ruan, Y.; Mohtadi, M.; Dupont, L. M.; Hebbeln, D.; Kaars, S.; Hopmans, E. C.; Schouten, S.; Hyer, E. J.; Schefuß, E. (November 2020). "Interaction of Fire, Vegetation, and Climate in Tropical Ecosystems: A Multiproxy Study Over the Past 22,000 Years". Global Biogeochemical Cycles. 34 (11): 11. Bibcode:2020GBioC..3406677R. doi:10.1029/2020GB006677.
- Watrin, Lézine & Hély 2009, p. 668.
- Lézine 2017, p. 5.
- Watrin, Lézine & Hély 2009, p. 667.
- Ewédjè, Eben-Ezer Baba Kayode; Jansen, Simon; Koffi, Guillaume Kouame; Staquet, Adrien; Piñeiro, Rosalia; Essaba, Rodolphe Abessole; Obiang, Nestor Laurier Engone; Daïnou, Kasso; Biwolé, Achille Bernand; Doucet, Jean-Louis; Hardy, Olivier J. (June 2020). "Species delimitation in the African tree genus Lophira (Ochnaceae) reveals cryptic genetic variation" (PDF). Conservation Genetics. 21 (3): 502. doi:10.1007/s10592-020-01265-7. S2CID 212732469.
- Sochor, M.; Manning, J. C.; Šarhanová, P.; van Herwijnen, Z.; Lebeda, A.; Doležalová, I. (1 August 2020). "Lactuca dregeana DC. (Asteraceae: Chicorieae) – A South African crop relative under threat from hybridization and climate change". South African Journal of Botany. 132: 153. doi:10.1016/j.sajb.2020.04.012. ISSN 0254-6299.
- Linstädter & Kröpelin 2004, p. 762.
- Brookes 2003, p. 163.
- White et al. 2011, p. 458.
- Sha et al. 2019, p. 2.
- Prasad & Negendank 2004, p. 225.
- White et al. 2011, p. 460.
- Hopcroft et al. 2017, p. 6808.
- Cole et al. 2009, p. 257.
- Neer et al. 2020, pp. 18–19.
- Stivers et al. 2008, p. 4.
- Neer et al. 2020, p. 23.
- Stivers et al. 2008, p. 11.
- Neer et al. 2020, pp. 16–17.
- Metcalfe & Nash 2012, p. 100.
- Neer et al. 2020, p. 15.
- Petit-Maire 1989, p. 641.
- Mercuri et al. 2018, p. 221.
- Neer et al. 2020, p. 16.
- Pachur & Altmann 2006, p. 528.
- Gross et al. 2014, p. 14472.
- Neer et al. 2020, p. 17.
- Blanchet, Contoux & Leduc 2015, p. 222.
- Cooper, Alan; Llamas, Bastien; Breen, James; Burns, James A.; Kosintsev, Pavel; Jahren, A. Hope; Shute, Elen; Zazula, Grant D.; Wooller, Matthew J.; Rabanus-Wallace, M. Timothy (May 2017). "Megafaunal isotopes reveal role of increased moisture on rangeland during late Pleistocene extinctions". Nature Ecology & Evolution. 1 (5): 4. doi:10.1038/s41559-017-0125. ISSN 2397-334X. PMID 28812683. S2CID 4473573.
- Mouline, Karine; Granjon, Laurent; Galan, Maxime; Tatard, Caroline; Abdoullaye, Doukary; Atteyine, Solimane Ag; Duplantier, Jean-Marc; Cosson, Jean-François (2008). "Phylogeography of a Sahelian rodent species Mastomys huberti: a Plio-Pleistocene story of emergence and colonization of humid habitats". Molecular Ecology. 17 (4): 1036–1053. doi:10.1111/j.1365-294X.2007.03610.x. ISSN 1365-294X. PMID 18261047. S2CID 24332384.
- Bard 2013, p. 809.
- Bristow et al. 2018, p. 183.
- Armitage, Bristow & Drake 2015, p. 8544.
- Drake & Bristow 2006, p. 906.
- Sepulchre et al. 2008, p. 43.
- Pachur & Altmann 2006, p. 26.
- Jewell, Amy M.; Drake, Nick; Crocker, Anya J.; Bakker, Natalie L.; Kunkelova, Tereza; Bristow, Charlie S.; Cooper, Matthew J.; Milton, J. Andrew; Breeze, Paul S.; Wilson, Paul A. (15 January 2021). "Three North African dust source areas and their geochemical fingerprint". Earth and Planetary Science Letters. 554: 8. Bibcode:2021E&PSL.55416645J. doi:10.1016/j.epsl.2020.116645. ISSN 0012-821X.
- Sylvestre et al. 2013, pp. 232–233.
- Heine 2019, p. 515.
- Pachur & Altmann 2006, p. 23.
- Runge 2010, p. 239.
- Lézine, Duplessy & Cazet 2005, p. 234.
- Martin, Damodaran & D'Souza 2019, p. 102.
- Quade et al. 2018, p. 2.
- Runge 2010, p. 238.
- Duringer, Philippe; Marsaleix, Patrick; Moussa, Abderamane; Roquin, Claude; Denamiel, Cléa; Ghienne, Jean-François; Schuster, Mathieu; Bouchette, Frédéric (2010). "Hydrodynamics in Holocene Lake Mega-Chad". Quaternary Research. 73 (2): 226. Bibcode:2010QuRes..73..226B. doi:10.1016/j.yqres.2009.10.010. ISSN 1096-0287.
- Quade et al. 2018, p. 19.
- Pachur & Altmann 2006, p. 83.
- Vahrenholt & Lüning 2019, pp. 518–519.
- Petit-Maire 1989, p. 645.
- Wendorf, Karlén & Schild 2007, p. 196.
- Hillaire-Marcel, Claude; Casanova, Joël; Lézine, Anne-Marie (1 March 1990). "Across an early Holocene humid phase in western Sahara:Pollen and isotope stratigraphy". Geology. 18 (3): 264. Bibcode:1990Geo....18..264L. doi:10.1130/0091-7613(1990)018<0264:AAEHHP>2.3.CO;2. ISSN 0091-7613.
- Gasse 2000, p. 204.
- Gasse & Van Campo 1994, p. 447.
- Baumhauer & Runge 2009, p. 152.
- Pachur & Altmann 2006, p. 246.
- Jahns 1995, p. 23.
- McCool 2019, p. 6.
- Wendorf, Karlén & Schild 2007, p. 206.
- McGee & deMenocal 2017, p. 11.
- McGee & deMenocal 2017, p. 12.
- Wendorf, Karlén & Schild 2007, pp. 206–207.
- Wendorf, Karlén & Schild 2007, p. 215.
- Wendorf, Karlén & Schild 2007, p. 216.
- Bubenzer, Olaf; Bolten, Andreas (December 2008). "The use of new elevation data (SRTM/ASTER) for the detection and morphometric quantification of Pleistocene megadunes (draa) in the eastern Sahara and the southern Namib". Geomorphology. 102 (2): 225. Bibcode:2008Geomo.102..221B. doi:10.1016/j.geomorph.2008.05.003. ISSN 0169-555X.
- Pachur & Altmann 2006, p. 80.
- Heine 2019, p. 516.
- Colin et al. 2020, p. 44.
- Franz, Gerhard; Breitkreuz, Christoph; Coyle, David A.; El Hur, Bushra; Heinrich, Wilhelm; Paulick, Holger; Pudlo, Dieter; Smith, Robyn; Steiner, Gesine (August 1997). "The alkaline Meidob volcanic field (Late Cenozoic, northwest Sudan)". Journal of African Earth Sciences. 25 (2): 7. Bibcode:1997JAfES..25..263F. doi:10.1016/S0899-5362(97)00103-6. ISSN 1464-343X.
- Wendorf, Karlén & Schild 2007, p. 204.
- Lenhardt, Nils; Borah, Suranjana B.; Lenhardt, Sukanya Z.; Bumby, Adam J.; Ibinoof, Montasir A.; Salih, Salih A. (May 2018). "The monogenetic Bayuda Volcanic Field, Sudan – New insights into geology and volcanic morphology". Journal of Volcanology and Geothermal Research. 356: 222. Bibcode:2018JVGR..356..211L. doi:10.1016/j.jvolgeores.2018.03.010. ISSN 0377-0273.
- Armitage, S.J.; Pinder, R.C. (April 2017). "Testing the applicability of optically stimulated luminescence dating to Ocean Drilling Program cores". Quaternary Geochronology. 39: 125. doi:10.1016/j.quageo.2017.02.008. ISSN 1871-1014.
- Heine 2019, p. 381.
- Lecomte, Frédéric; Dodson, Julian J.; Guinand, Bruno; Durand, Jean-Dominique (9 October 2013). "Pelagic Life and Depth: Coastal Physical Features in West Africa Shape the Genetic Structure of the Bonga Shad, Ethmalosa fimbriata". PLOS ONE. 8 (10): 2. Bibcode:2013PLoSO...877483D. doi:10.1371/journal.pone.0077483. ISSN 1932-6203. PMC 3793960. PMID 24130890.
- Lewin, John; Ashworth, Philip J.; Strick, Robert J. P. (February 2017). "Spillage sedimentation on large river floodplains: Spillage sedimentation on large river floodplains". Earth Surface Processes and Landforms. 42 (2): 301. doi:10.1002/esp.3996. S2CID 53535390.
- Wu et al. 2017, p. 96.
- Ramos, Ramil & Sanz 2017, p. 95.
- Bendaoud et al. 2019, p. 514.
- Ramos, Ramil & Sanz 2017, p. 101.
- Wu et al. 2017, p. 106.
- White et al. 2011, p. 459.
- Quade et al. 2018, p. 18.
- Kindermann & Classen 2010, p. 27.
- Perego, Zerboni & Cremaschi 2011, p. 472.
- Zerboni & Gatto 2015, p. 309.
- Neer et al. 2020, p. 5.
- Maley 2000, p. 125.
- Drake & Bristow 2006, p. 909.
- Neer et al. 2020, p. 28.
- Sparavigna, Amelia Carolina (9 January 2013). "Neolithic Mounds of Tassili and Amguid in the Satellite Google Maps". Archaeogate. Social Science Research Network: 3. SSRN 2776906.
- Zaki, Abdallah S.; King, Georgina E.; Haghipour, Negar; Herman, Frédéric; Giegengack, Robert; Schuster, Mathieu; Gupta, Sanjeev; Watkins, Stephen E.; Khairy, Hossam; Ahmed, Salah; Eltayeb, Saleh A.; El-wakil, Mostafa; Castelltort, Sébastien (1 May 2020). New palaeoclimate record from ancient river channels in the eastern Sahara: Implications for climate impact on human dispersals during the late Quaternary. 22nd EGU General Assembly. Egu General Assembly Conference Abstracts. 22. p. 12189. Bibcode:2020EGUGA..2212189Z.
- Maslin, Manning & Brierley 2018, p. 1.
- Lernia et al. 2017, p. 1.
- Riemer 2006, p. 555.
- Stojanowski, Carver & Miller 2014, pp. 80–82.
- Coutros 2019, p. 6.
- Mercuri, Anna Maria; Sadori, Laura (2014), Goffredo, Stefano; Dubinsky, Zvy (eds.), "Mediterranean Culture and Climatic Change: Past Patterns and Future Trends", The Mediterranean Sea, Springer Netherlands, p. 519, doi:10.1007/978-94-007-6704-1_30, ISBN 9789400767034
- Cremaschi et al. 2010, p. 88.
- Cremaschi et al. 2010, p. 91.
- Lernia et al. 2013, p. 122.
- Chiotis 2018, p. 16.
- Hoelzmann et al. 2001, p. 210.
- Smith 2018, p. 243.
- Phillipps et al. 2012, p. 71.
- McCool 2019, p. 17.
- White et al. 2011, pp. 460–461.
- Tafuri et al. 2006, p. 390.
- Riemer 2006, p. 556.
- Brooks et al. 2007, p. 260.
- Phelps et al. 2020, p. 1121.
- Zerboni & Nicoll 2019, p. 24.
- Lernia et al. 2012, pp. 391–392.
- Lernia et al. 2013, p. 121.
- Breunig, Neumann & Van Neer 1996, p. 116.
- Breunig, Neumann & Van Neer 1996, p. 117.
- McDonald, Mary M. A. (1 September 2020). "The Mid-Holocene bifacial projectile points from Dakhleh Oasis, Egypt: Implications concerning origins of the knapping tradition, changing hunting patterns, the local neolithic, and African cultural independence". Journal of Anthropological Archaeology. 59: 6. doi:10.1016/j.jaa.2020.101199. ISSN 0278-4165.
- Lernia et al. 2013, pp. 123–124.
- Stojanowski, Christopher M. (30 November 2018), "Persistence or Pastoralism: The Challenges of Studying Hunter-Gatherer Resilience in Africa", in Temple, Daniel H.; Stojanowski, Christopher M. (eds.), Hunter-Gatherer Adaptation and Resilience (1 ed.), Cambridge University Press, p. 195, doi:10.1017/9781316941256.009, ISBN 9781316941256, retrieved 22 July 2019
- Lézine 2017, p. 3.
- Lernia et al. 2017, p. 5.
- Scarcelli, Nora; Cubry, Philippe; Akakpo, Roland; Thuillet, Anne-Céline; Obidiegwu, Jude; Baco, Mohamed N.; Otoo, Emmanuel; Sonké, Bonaventure; Dansi, Alexandre; Djedatin, Gustave; Mariac, Cédric; Couderc, Marie; Causse, Sandrine; Alix, Karine; Chaïr, Hâna; François, Olivier; Vigouroux, Yves (1 May 2019). "Yam genomics supports West Africa as a major cradle of crop domestication". Science Advances. 5 (5): 4. Bibcode:2019SciA....5.1947S. doi:10.1126/sciadv.aaw1947. ISSN 2375-2548. PMC 6527260. PMID 31114806.
- Lernia et al. 2012, p. 390.
- Marinova, Margarita M.; Meckler, A. Nele; McKay, Christopher P. (January 2014). "Holocene freshwater carbonate structures in the hyper-arid Gebel Uweinat region of the Sahara Desert (Southwestern Egypt)". Journal of African Earth Sciences. 89: 54. Bibcode:2014JAfES..89...50M. doi:10.1016/j.jafrearsci.2013.10.003. ISSN 1464-343X.
- Olsen 2017, p. 107.
- Olsen 2017, p. 93.
- Pachur & Altmann 2006, p. 533.
- Soriano et al. 2009, p. 8.
- Grillo, Katherine M.; McKeeby, Zachary; Hildebrand, Elisabeth A. (12 November 2020). ""Nderit Ware" and the origins of pastoralist pottery in eastern Africa". Quaternary International: 2. doi:10.1016/j.quaint.2020.06.032. ISSN 1040-6182.
- Cremaschi & Zerboni 2009, p. 690.
- Pirie et al. 2009, p. 930.
- Brooks et al. 2007, p. 259.
- Calderón, Rosario; Pereira, Luisa; Baali, Abdellatif; Melhaoui, Mohammed; Oliveira, Marisa; Rito, Teresa; Rodríguez, Juan N.; Novelletto, Andrea; Dugoujon, Jean M.; Soares, Pedro; Hernández, Candela L. (28 October 2015). "Early Holocenic and Historic mtDNA African Signatures in the Iberian Peninsula: The Andalusian Region as a Paradigm". PLOS ONE. 10 (10): 16. Bibcode:2015PLoSO..1039784H. doi:10.1371/journal.pone.0139784. ISSN 1932-6203. PMC 4624789. PMID 26509580.
- Haber, Marc; Mezzavilla, Massimo; Bergström, Anders; Prado-Martinez, Javier; Hallast, Pille; Saif-Ali, Riyadh; Al-Habori, Molham; Dedoussis, George; Zeggini, Eleftheria; Blue-Smith, Jason; Wells, R. Spencer; Xue, Yali; Zalloua, Pierre A.; Tyler-Smith, Chris (1 December 2016). "Chad Genetic Diversity Reveals an African History Marked by Multiple Holocene Eurasian Migrations". The American Journal of Human Genetics. 99 (6): 1316–1324. doi:10.1016/j.ajhg.2016.10.012. ISSN 0002-9297. PMC 5142112. PMID 27889059.
- Blümel 2002, p. 12.
- Lancaster 2020, p. 116.
- Martin, Damodaran & D'Souza 2019, p. 103.
- Zerboni, Trombino & Cremaschi 2011, p. 321.
- Zerboni, Trombino & Cremaschi 2011, p. 332.
- Sponholz, Baumhauer & Felix-Henningsen 1993, pp. 97–98.
- Baumhauer 2004, p. 296.
- Kendall 2020, p. 182.
- Heine 2019, p. 118.
- Sponholz, Baumhauer & Felix-Henningsen 1993, p. 103.
- Perego, Zerboni & Cremaschi 2011, p. 466.
- Eggermont et al. 2008, p. 2411.
- Cremaschi et al. 2010, p. 87.
- Pachur & Altmann 2006, p. 153.
- Bouchez, Camille; Deschamps, Pierre; Goncalves, Julio; Hamelin, Bruno; Mahamat Nour, Abdallah; Vallet-Coulomb, Christine; Sylvestre, Florence (16 May 2019). "Water transit time and active recharge in the Sahel inferred by bomb-produced 36 Cl". Scientific Reports. 9 (1): 3. Bibcode:2019NatSR...9.7465B. doi:10.1038/s41598-019-43514-x. ISSN 2045-2322. PMC 6522497. PMID 31097734.
- Pachur & Altmann 2006, p. 2.
- McCool 2019, p. 8.
- Hély et al. 2009, p. 680.
- Goudie, Andrew S.; Middleton, Nicholas J. (2006), "Quaternary Dust Loadings", Desert Dust in the Global System, Springer Berlin Heidelberg, p. 202, doi:10.1007/3-540-32355-4_9, ISBN 9783540323549
- Muhs et al. 2013, p. 43.
- Kohn, Marion; Steinke, Stephan; Baumann, Karl-Heinz; Donner, Barbara; Meggers, Helge; Zonneveld, Karin A.F. (March 2011). "Stable oxygen isotopes from the calcareous-walled dinoflagellate Thoracosphaera heimii as a proxy for changes in mixed layer temperatures off NW Africa during the last 45,000yr". Palaeogeography, Palaeoclimatology, Palaeoecology. 302 (3–4): 319. Bibcode:2011PPP...302..311K. doi:10.1016/j.palaeo.2011.01.019. ISSN 0031-0182.
- Zarriess, Michelle; Mackensen, Andreas (September 2010). "The tropical rainbelt and productivity changes off northwest Africa: A 31,000-year high-resolution record". Marine Micropaleontology. 76 (3–4): 87. Bibcode:2010MarMP..76...76Z. doi:10.1016/j.marmicro.2010.06.001. ISSN 0377-8398.
- Haslett, Simon K.; Smart, Christopher W. (2006). "Late Quaternary upwelling off tropical NW Africa: new micropalaeontological evidence from ODP Hole 658C". Journal of Quaternary Science. 21 (3): 267. Bibcode:2006JQS....21..259H. doi:10.1002/jqs.970. ISSN 1099-1417.
- Haslett & Davies 2006, p. 37.
- Matter et al. 2016, p. 88.
- Radies et al. 2005, p. 111.
- Damme, Kay Van; Benda, Petr; Damme, Dirk Van; Geest, Peter De; Hajdas, Irka (26 August 2018). "The first vertebrate fossil from Socotra Island (Yemen) is an early Holocene Egyptian fruit bat". Journal of Natural History. 52 (31–32): 2017. doi:10.1080/00222933.2018.1510996. ISSN 0022-2933. S2CID 92040903.
- Engel, Max; Rückmann, Stefanie; Drechsler, Philipp; Brill, Dominik; Opitz, Stephan; Fassbinder, Jörg W.; Pint, Anna; Peis, Kim; Wolf, Dennis; Gerber, Christoph; Pfeiffer, Kristina; Eichmann, Ricardo; Brückner, Helmut (9 January 2020). "Sediment-filled karst depressions and riyad – key archaeological environments of south Qatar". E&G Quaternary Science Journal. 68 (2): 229. Bibcode:2020EGQSJ..68..215E. doi:10.5194/egqsj-68-215-2020. ISSN 0424-7116.
- Vahrenholt & Lüning 2019, p. 524.
- Radies et al. 2005, p. 122.
- Kocurek et al. 2020, p. 4.
- Vahrenholt & Lüning 2019, p. 527.
- Matter et al. 2016, p. 99.
- Petraglia & Rose 2010, p. 28.
- Matter et al. 2016, p. 89.
- Kennett & Kennett 2007, p. 236.
- Kocurek et al. 2020, p. 11.
- Kendall 2020, p. 24.
- Petraglia & Rose 2010, p. 219.
- Vahrenholt & Lüning 2019, pp. 525–527.
- Lézine et al. 2010, p. 427.
- Renaud et al. 2010, p. 230.
- Kennett & Kennett 2007, p. 237.
- Groucutt et al. 2020, p. 1768.
- Heine 2019, p. 566.
- Matter et al. 2016, p. 98.
- Lézine et al. 2010, p. 426.
- Rojas et al. 2019, p. 146.
- Prasad & Negendank 2004, p. 213.
- Groucutt et al. 2020, p. 1776.
- Rojas et al. 2019, p. 145.
- Renaud et al. 2010, p. 228.
- Matter et al. 2016, pp. 89, 98.
- Hamdan et al. 2020, p. 16.
- Hamdan et al. 2020, p. 473.
- Hamdan et al. 2020, p. 15.
- Hamdan et al. 2020, p. 14.
- Ullmann, Tobias; Nill, Leon; Schiestl, Robert; Trappe, Julian; Lange-Athinodorou, Eva; Baumhauer, Roland; Meister, Julia (9 December 2020). "Mapping buried paleogeographical features of the Nile Delta (Egypt) using the Landsat archive". E&G Quaternary Science Journal. 69 (2): 227. doi:10.5194/egqsj-69-225-2020. ISSN 0424-7116.
- Gasse, Françoise (January 2005). "Continental palaeohydrology and palaeoclimate during the Holocene". Comptes Rendus Geoscience. 337 (1–2): 81. Bibcode:2005CRGeo.337...79G. doi:10.1016/j.crte.2004.10.006. ISSN 1631-0713.
- Mercuri et al. 2018, p. 226.
- Morrissey & Scholz 2014, p. 98.
- Graham, Angus; Strutt, Kristian D.; Peeters, Jan; Toonen, Willem H. J.; Pennington, Benjamin T.; Emery, Virginia L.; Barker, Dominic S.; Johansson, Carolin (30 June 2017). "Theban Harbours and Waterscapes Survey, Spring 2016". The Journal of Egyptian Archaeology. 102 (1): 19. doi:10.1177/030751331610200103. S2CID 194765922.
- Wendorf, Karlén & Schild 2007, p. 205.
- Hoelzmann et al. 2001, p. 212.
- Morrissey & Scholz 2014, p. 96.
- Blanchet et al. 2013, p. 105.
- Gasse 2000, p. 189.
- Garcin et al. 2017, p. 60.
- Junginger et al. 2014, p. 2.
- van der Lubbe et al. 2017, p. 8.
- Nutz, A.; Schuster, M.; Barboni, D.; Gassier, G.; Van Bocxlaer, B.; Robin, C.; Ragon, T.; Ghienne, J. -F.; Rubino, J. -L. (1 December 2020). "Plio-Pleistocene sedimentation in West Turkana (Turkana Depression, Kenya, East African Rift System): Paleolake fluctuations, paleolandscapes and controlling factors". Earth-Science Reviews. 211: 22. Bibcode:2020ESRv..21103415N. doi:10.1016/j.earscirev.2020.103415. ISSN 0012-8252.
- Beck et al. 2019, p. 20.
- Bloszies, Forman & Wright 2015, p. 66.
- van der Lubbe et al. 2017, p. 3.
- Smith 2018, p. 249.
- Khalidi et al. 2020, p. 1.
- Khalidi et al. 2020, p. 4.
- Khalidi et al. 2020, p. 3.
- Khalidi et al. 2020, p. 17.
- Awaleh, Mohamed Osman; Boschetti, Tiziano; Adaneh, Abdillahi Elmi; Daoud, Mohamed Ahmed; Ahmed, Moussa Mahdi; Dabar, Omar Assowe; Soubaneh, Youssouf Djibril; Kawalieh, Ali Dirir; Kadieh, Ibrahim Houssein (1 July 2020). "Hydrochemistry and multi-isotope study of the waters from Hanlé-Gaggadé grabens (Republic of Djibouti, East African Rift System): A low-enthalpy geothermal resource from a transboundary aquifer". Geothermics. 86: 15. doi:10.1016/j.geothermics.2020.101805. ISSN 0375-6505.
- Khalidi et al. 2020, p. 2.
- Khalidi et al. 2020, p. 18.
- Khalidi et al. 2020, p. 19.
- Roubeix & Chalié 2018, p. 100.
- Gasse & Van Campo 1994, p. 445.
- Hamdan et al. 2020, p. 471.
- Loakes, Katie (2 January 2017). "Late Quaternary palaeolimnology and environmental change in the South Wollo Highlands". Azania: Archaeological Research in Africa. 52 (1): 131. doi:10.1080/0067270X.2016.1259821. ISSN 0067-270X. S2CID 163784238.
- Hoelzmann & Holmes 2017, p. 17.
- Riedl, Simon; Melnick, Daniel; Mibei, Geoffrey K.; Njue, Lucy; Strecker, Manfred R. (2020). "Continental rifting at magmatic centres: structural implications from the Late Quaternary Menengai Caldera, central Kenya Rift". Journal of the Geological Society. 177 (1): 12. Bibcode:2020JGSoc.177..153R. doi:10.1144/jgs2019-021. S2CID 202898410.
- Dommain, René; Riedl, Simon; Olaka, Lydia; deMenocal, Peter; Deino, Alan; Potts, Richard; Strecker, Manfred (1 May 2020). Hydrological basin connectivity in a low-latitude rift: the impact of the Holocene African Humid Period (AHP) on fluvial activity and species dispersal in the Kenya Rift, East African Rift System (EARS). 22nd EGU General Assembly. Egu General Assembly Conference Abstracts. 22. p. 9323. Bibcode:2020EGUGA..22.9323D.
- Runge, Jürgen (12 October 2017). Runge, Jürgen; Eisenberg, Joachim (eds.). The African Neogene – Climate, Environments and People (1 ed.). CRC Press. p. 145. doi:10.1201/9781315161808. ISBN 9781315161808.
- Jackson, M. S.; Kelly, M. A.; Russell, J. M.; Doughty, A. M.; Howley, J. A.; Chipman, J. W.; Cavagnaro, D. A.; Baber, M. B.; Zimmerman, S. R. H.; Nakileza, B. (1 September 2020). "Glacial fluctuations in tropical Africa during the last glacial termination and implications for tropical climate following the Last Glacial Maximum". Quaternary Science Reviews. 243: 51. Bibcode:2020QSRv..24306455J. doi:10.1016/j.quascirev.2020.106455. ISSN 0277-3791.
- Beer et al. 2002, p. 593.
- Gabrielli, P.; Hardy, D.R.; Kehrwald, N.; Davis, M.; Cozzi, G.; Turetta, C.; Barbante, C.; Thompson, L.G. (June 2014). "Deglaciated areas of Kilimanjaro as a source of volcanic trace elements deposited on the ice cap during the late Holocene". Quaternary Science Reviews. 93: 3. Bibcode:2014QSRv...93....1G. doi:10.1016/j.quascirev.2014.03.007. ISSN 0277-3791.
- Zech, Michael (December 2006). "Evidence for Late Pleistocene climate changes from buried soils on the southern slopes of Mt. Kilimanjaro, Tanzania". Palaeogeography, Palaeoclimatology, Palaeoecology. 242 (3–4): 310. Bibcode:2006PPP...242..303Z. doi:10.1016/j.palaeo.2006.06.008. ISSN 0031-0182.
- Kervyn, M.; Macheyeki, A.; Kwelwa, S.; Delvaux, D.; Delcamp, A. (1 January 2016). "Sector collapse events at volcanoes in the North Tanzanian divergence zone and their implications for regional tectonics". GSA Bulletin. 128 (1–2): 15. doi:10.1130/B31119.1. ISSN 0016-7606.
- Garcin et al. 2017, p. 67.
- Garcin et al. 2017, p. 68.
- Bastian, Luc; Vigier, Nathalie; Revel, Marie; Yirgu, Gezahegn; Ayalew, Dereje; Pik, Raphaël (20 July 2019). "Chemical erosion rates in the upper Blue Nile Basin and related atmospheric CO2 consumption". Chemical Geology. 518: 29. Bibcode:2019ChGeo.518...19B. doi:10.1016/j.chemgeo.2019.03.033. ISSN 0009-2541.
- Barker et al. 2002, p. 303.
- Wang et al. 2019, p. 146.
- Russell & Ivory 2018, p. 7.
- Russell & Ivory 2018, p. 8.
- Jahns 1995, p. 28.
- Beck et al. 2019, p. 31.
- Russell & Ivory 2018, p. 12.
- Rojas et al. 2019, p. 147.
- Kuzmicheva et al. 2017, p. 80.
- Russell & Ivory 2018, p. 9.
- Tierney et al. 2011, p. 106.
- Stinchcomb, Gary; Quade, Jay; Levin, Naomi; Iverson, Nels; Dunbar, Nelia; McIntosh, William; Arnold, Lee J.; Duval, Mathieu; Grün, Rainer; Bynum, Kevin; White, Marie; Gilbert, Henry; Rogers, Michael J.; Semaw, Sileshi (2020). FLUVIAL RESPONSE AND ITS IMPLICATIONS FOR HUMAN-ENVIRONMENT INTERACTIONS DURING THE MIDDLE TO LATE PLEISTOCENE AND AFRICAN HUMID PERIOD IN ETHIOPIA (Report). Geological Society of America Abstracts with Programs. p. 357299. doi:10.1130/abs/2020AM-357299.
- Junginger & Trauth 2013, p. 186.
- Junginger & Trauth 2013, p. 174.
- White et al. 2011, p. 461.
- Müller, Ulrich C.; Pross, Jörg; Tzedakis, Polychronis C.; Gamble, Clive; Kotthoff, Ulrich; Schmiedl, Gerhard; Wulf, Sabine; Christanis, Kimon (February 2011). "The role of climate in the spread of modern humans into Europe". Quaternary Science Reviews. 30 (3–4): 273–279. Bibcode:2011QSRv...30..273M. doi:10.1016/j.quascirev.2010.11.016. ISSN 0277-3791.
- Hoelzmann & Holmes 2017, p. 12.
- McGee & deMenocal 2017, p. 10.
- McGee & deMenocal 2017, p. 19.
- Daniau et al. 2019, p. 23.
- Nguetsop, Victor François; Bentaleb, Ilham; Favier, Charly; Bietrix, Sophie; Martin, Céline; Servant-Vildary, Simone; Servant, Michel (July 2013). "A late Holocene palaeoenvironmental record from Lake Tizong, northern Cameroon using diatom and carbon stable isotope analyses". Quaternary Science Reviews. 72: 50. Bibcode:2013QSRv...72...49N. doi:10.1016/j.quascirev.2013.04.005. ISSN 0277-3791.
- Lézine, Anne-Marie; Izumi, Kenji; Kageyama, Masa; Achoundong, Gaston (11 January 2019). "A 90,000-year record of Afromontane forest responses to climate change" (PDF). Science. 363 (6423): 177–181. Bibcode:2019Sci...363..177L. doi:10.1126/science.aav6821. ISSN 0036-8075. PMID 30630932. S2CID 57825928.
- Hély et al. 2009, p. 683.
- Tropical rainforest responses to climatic change. Environmental Sciences (2nd ed.). Springer. 2011. p. 166. ISBN 978-3-642-05383-2.
- Ifo, Suspense A.; Bocko, Yannick E.; Page, Susan E.; Mitchard, Edward T. A.; Lawson, Ian T.; Lewis, Simon L.; Dargie, Greta C. (February 2017). "Age, extent and carbon storage of the central Congo Basin peatland complex" (PDF). Nature. 542 (7639): 86–90. Bibcode:2017Natur.542...86D. doi:10.1038/nature21048. ISSN 1476-4687. PMID 28077869. S2CID 205253362.
- Dargie, Greta C.; Lawson, Ian T.; Rayden, Tim J.; Miles, Lera; Mitchard, Edward T. A.; Page, Susan E.; Bocko, Yannick E.; Ifo, Suspense A.; Lewis, Simon L. (1 April 2019). "Congo Basin peatlands: threats and conservation priorities". Mitigation and Adaptation Strategies for Global Change. 24 (4): 673. doi:10.1007/s11027-017-9774-8. ISSN 1573-1596. S2CID 21705940.
- La Roche, Francisco; Genise, Jorge F.; Castillo, Carolina; Quesada, María Luisa; García-Gotera, Cristo M.; De la Nuez, Julio (September 2014). "Fossil bee cells from the Canary Islands. Ichnotaxonomy, palaeobiology and palaeoenvironments of Palmiraichnus castellanosi". Palaeogeography, Palaeoclimatology, Palaeoecology. 409: 262. Bibcode:2014PPP...409..249L. doi:10.1016/j.palaeo.2014.05.012. ISSN 0031-0182.
- Rodríguez-Berriguete, Álvaro; Alonso-Zarza, Ana María (1 March 2019). "Controlling factors and implications for travertine and tufa deposition in a volcanic setting". Sedimentary Geology. 381: 25–26. Bibcode:2019SedG..381...13R. doi:10.1016/j.sedgeo.2018.12.001. ISSN 0037-0738.
- Morinha, Francisco; Milá, Borja; Dávila, José A.; Fargallo, Juan A.; Potti, Jaime; Blanco, Guillermo (December 2020). "The ghost of connections past: A role for mainland vicariance in the isolation of an insular population of the red‐billed chough (Aves: Corvidae)". Journal of Biogeography. 47 (12): 2578. doi:10.1111/jbi.13977.
- Sha et al. 2019, p. 8.
- Bendaoud et al. 2019, p. 515.
- Zielhofer, Christoph; Faust, Dominik (March 2008). "Mid- and Late Holocene fluvial chronology of Tunisia". Quaternary Science Reviews. 27 (5–6): 586. Bibcode:2008QSRv...27..580Z. doi:10.1016/j.quascirev.2007.11.019. ISSN 0277-3791.
- Stoetzel, Emmanuelle (1 December 2017). "Adaptations and Dispersals of Anatomically Modern Humans in the Changing Environments of North Africa: the Contribution of Microvertebrates". African Archaeological Review. 34 (4): 9. doi:10.1007/s10437-017-9272-0. ISSN 1572-9842. S2CID 165916003.
- Zielhofer et al. 2016, p. 858.
- Zielhofer, Christoph; Köhler, Anne; Mischke, Steffen; Benkaddour, Abdelfattah; Mikdad, Abdeslam; Fletcher, William J. (20 March 2019). "Western Mediterranean hydro-climatic consequences of Holocene ice-rafted debris (Bond) events". Climate of the Past. 15 (2): 471. Bibcode:2019CliPa..15..463Z. doi:10.5194/cp-15-463-2019. ISSN 1814-9324.
- Yanes, Yurena; Romanek, Christopher S.; Molina, Fernando; Cámara, Juan Antonio; Delgado, Antonio (November 2011). "Holocene paleoenvironment (∼7200–4000 cal BP) of the Los Castillejos archaeological site (SE Spain) inferred from the stable isotopes of land snail shells". Quaternary International. 244 (1): 73–74. Bibcode:2011QuInt.244...67Y. doi:10.1016/j.quaint.2011.04.031. ISSN 1040-6182.
- Censi, P.; Incarbona, A.; Oliveri, E.; Bonomo, S.; Tranchida, G. (June 2010). "Yttrium and REE signature recognized in Central Mediterranean Sea (ODP Site 963) during the MIS 6–MIS 5 transition". Palaeogeography, Palaeoclimatology, Palaeoecology. 292 (1–2): 206. Bibcode:2010PPP...292..201C. doi:10.1016/j.palaeo.2010.03.045. ISSN 0031-0182.
- Spötl, Christoph; Nicolussi, Kurt; Patzelt, Gernot; Boch, Ronny (April 2010). "Humid climate during deposition of sapropel 1 in the Mediterranean Sea: Assessing the influence on the Alps". Global and Planetary Change. 71 (3–4): 242. Bibcode:2010GPC....71..242S. doi:10.1016/j.gloplacha.2009.10.003. ISSN 0921-8181.
- Segadelli, Stefano; Grazzini, Federico; Rossi, Veronica; Aguzzi, Margherita; Marvelli, Silvia; Marchesini, Marco; Chelli, Alessandro; Francese, Roberto; De Nardo, Maria Teresa; Nanni, Sandro (19 August 2020). "Changes in high-intensity precipitation on the northern Apennines (Italy) as revealed by multidisciplinary data over the last 9000 years". Climate of the Past. 16 (4): 1555. Bibcode:2020CliPa..16.1547S. doi:10.5194/cp-16-1547-2020. ISSN 1814-9324.
- Incarbona, Alessandro; Zarcone, Giuseppe; Agate, Mauro; Bonomo, Sergio; Stefano, Enrico; Masini, Federico; Russo, Fabio; Sineo, Luca (2010). "A multidisciplinary approach to reveal the Sicily Climate and Environment over the last 20 000 years". Open Geosciences. 2 (2): 71. Bibcode:2010CEJG....2...71I. doi:10.2478/v10085-010-0005-8. ISSN 2391-5447. S2CID 128477875.
- Jiménez-Moreno, Gonzalo; Anderson, R. Scott; Ramos-Román, María J.; Camuera, Jon; Mesa-Fernández, Jose Manuel; García-Alix, Antonio; Jiménez-Espejo, Francisco J.; Carrión, José S.; López-Avilés, Alejandro (15 August 2020). "The Holocene Cedrus pollen record from Sierra Nevada (S Spain), a proxy for climate change in N Africa". Quaternary Science Reviews. 242: 13. Bibcode:2020QSRv..24206468J. doi:10.1016/j.quascirev.2020.106468. ISSN 0277-3791.
- Hamann et al. 2017, p. 453.
- Williams et al. 2010, p. 1117.
- Hamann et al. 2017, p. 461.
- Fontaine, M.C. (1 January 2016). Harbour Porpoises, Phocoena phocoena, in the Mediterranean Sea and Adjacent Regions: Biogeographic Relicts of the Last Glacial Period. Advances in Marine Biology. 75. pp. 333–358. doi:10.1016/bs.amb.2016.08.006. ISBN 9780128051528. ISSN 0065-2881. PMID 27770989.
- Rüggeberg, Andres; Foubert, Anneleen (2019), Orejas, Covadonga; Jiménez, Carlos (eds.), "25 Cold-Water Corals and Mud Volcanoes: Life on a Dynamic Substrate", Mediterranean Cold-Water Corals: Past, Present and Future: Understanding the Deep-Sea Realms of Coral, Coral Reefs of the World, Springer International Publishing, p. 267, doi:10.1007/978-3-319-91608-8_25, ISBN 978-3-319-91608-8
- Vahrenholt & Lüning 2019, p. 522.
- Kiro, Yael; Goldstein, Steven L.; Garcia-Veigas, Javier; Levy, Elan; Kushnir, Yochanan; Stein, Mordechai; Lazar, Boaz (April 2017). "Relationships between lake-level changes and water and salt budgets in the Dead Sea during extreme aridities in the Eastern Mediterranean". Earth and Planetary Science Letters. 464: 221. Bibcode:2017E&PSL.464..211K. doi:10.1016/j.epsl.2017.01.043. ISSN 0012-821X.
- Reimer et al. 2010, p. 36.
- Sletten, Hillary R.; Railsback, L. Bruce; Liang, Fuyuan; Brook, George A.; Marais, Eugene; Hardt, Benjamin F.; Cheng, Hai; Edwards, R. Lawrence (April 2013). "A petrographic and geochemical record of climate change over the last 4600 years from a northern Namibia stalagmite, with evidence of abruptly wetter climate at the beginning of southern Africa's Iron Age". Palaeogeography, Palaeoclimatology, Palaeoecology. 376: 158. Bibcode:2013PPP...376..149S. doi:10.1016/j.palaeo.2013.02.030. ISSN 0031-0182.
- Reimer et al. 2010, p. 40.
- Ramisch, Arne; Bens, Oliver; Buylaert, Jan-Pieter; Eden, Marie; Heine, Klaus; Hürkamp, Kerstin; Schwindt, Daniel; Völkel, Jörg (March 2017). "Fluvial landscape development in the southwestern Kalahari during the Holocene – Chronology and provenance of fluvial deposits in the Molopo Canyon" (PDF). Geomorphology. 281: 104. Bibcode:2017Geomo.281...94R. doi:10.1016/j.geomorph.2016.12.021. ISSN 0169-555X.
- Bäumle, Roland; Himmelsbach, Thomas (1 March 2018). "Erkundung tiefer, bislang unbekannter semi-fossiler Grundwasserleiter im Kalahari-Becken (südliches Afrika)". Grundwasser (in German). 23 (1): 34. Bibcode:2018Grund..23...29B. doi:10.1007/s00767-017-0378-8. ISSN 1432-1165. S2CID 133707017.
- Lubbe, H. J. L. van der; Frank, Martin; Tjallingii, Rik; Schneider, Ralph R. (2016). "Neodymium isotope constraints on provenance, dispersal, and climate-driven supply of Zambezi sediments along the Mozambique Margin during the past ∼45,000 years" (PDF). Geochemistry, Geophysics, Geosystems. 17 (1): 195. Bibcode:2016GGG....17..181V. doi:10.1002/2015GC006080. ISSN 1525-2027.
- Heine 2019, p. 441.
- Wang et al. 2019, p. 151.
- Burrough & Thomas 2013, p. 43.
- Battarbee, Gasse & Stickley 2004, p. 572.
- Heine 2019, p. 528.
- Fitchett, Jennifer M.; Grab, Stefan W.; Bamford, Marion K.; Mackay, Anson W. (2 September 2017). "Late Quaternary research in southern Africa: progress, challenges and future trajectories" (PDF). Transactions of the Royal Society of South Africa. 72 (3): 284. doi:10.1080/0035919X.2017.1297966. ISSN 0035-919X. S2CID 131918185.
- Pausata et al. 2020, p. 238.
- Dixit et al. 2018, p. 233.
- Lézine, Duplessy & Cazet 2005, pp. 226–227.
- Pachur & Altmann 2006, p. 564.
- Heine 2019, p. 520.
- Quade et al. 2018, p. 16.
- Hoelzmann & Holmes 2017, p. 15.
- Hoelzmann & Holmes 2017, pp. 16–18.
- Junginger & Trauth 2013, p. 178.
- Baumhauer & Runge 2009, p. 29.
- Baumhauer & Runge 2009, p. 11.
- Engel et al. 2012, p. 139.
- Radies et al. 2005, p. 123.
- Donnelly et al. 2017, p. 6223.
- Gaetani et al. 2017, p. 7639.
- Pausata et al. 2020, p. 242.
- Donnelly et al. 2017, p. 6225.
- Hayes & Wallace 2019, p. 6.
- Toomey et al. 2013, p. 31.
- Gaetani et al. 2017, p. 7640.
- Donnelly et al. 2017, p. 6224.
- Hayes & Wallace 2019, p. 5.
- Hayes & Wallace 2019, p. 7.
- Toomey et al. 2013, p. 39.
- Liu et al. 2017, p. 2.
- Piao et al. 2020, p. 2.
- Liu et al. 2017, p. 3.
- Pausata et al. 2020, p. 241.
- Liu et al. 2017, p. 9.
- Piao et al. 2020, p. 5.
- Sun et al. 2019, p. 9877.
- Sun et al. 2019, pp. 9874–9875.
- Piao et al. 2020, p. 6.
- Sun et al. 2019, p. 9873.
- Piao et al. 2020, p. 7.
- Sun et al. 2019, p. 9871.
- Sun et al. 2020, p. 239.
- Sun et al. 2020, p. 234.
- Sun et al. 2020, p. 236.
- Sun et al. 2020, p. 233.
- Sun et al. 2020, p. 229.
- Sun et al. 2020, p. 238.
- Niedermeyer et al. 2010, p. 3003.
- Menocal et al. 2000, pp. 354–355.
- Cohen et al. 2008, p. 252.
- Junginger et al. 2014, p. 14.
- Wendorf, Karlén & Schild 2007, p. 191.
- Bloszies, Forman & Wright 2015, p. 65.
- Talbot et al. 2007, pp. 9–10.
- Zielhofer et al. 2016, p. 857.
- Muhs et al. 2013, p. 34.
- Talbot et al. 2007, p. 10.
- Morrill, Overpeck & Cole 2016, p. 469.
- Ghosh, Sambit; Sanyal, Prasanta; Roy, Sohom; Bhushan, Ravi; Sati, SP; Philippe, Anne; Juyal, Navin (1 July 2020). "Early Holocene Indian summer monsoon and its impact on vegetation in the Central Himalaya: Insight from δD and δ13C values of leaf wax lipid". The Holocene. 30 (7): 1070. Bibcode:2020Holoc..30.1063G. doi:10.1177/0959683620908639. ISSN 0959-6836. S2CID 219020685.
- Zerboni & Gatto 2015, p. 310.
- Zerboni & Nicoll 2019, p. 31.
- Menocal et al. 2000, p. 355.
- Zielhofer et al. 2016, p. 851.
- Caballero, Margarita; Zawisza, Edyta; Hernández, Martín; Lozano-García, Socorro; Ruiz-Córdova, Juan Pablo; Waters, Matthew N; Ortega Guerrero, Beatriz (1 June 2020). "The Holocene history of a tropical high-altitude lake in central Mexico". The Holocene. 30 (6): 866. Bibcode:2020Holoc..30..865C. doi:10.1177/0959683620902226. ISSN 0959-6836. S2CID 213398634.
- Lubell, David; Jackes, Mary (1 June 2008). "Early and Middle Holocene Environments and Capsian Cultural Change: Evidence from the Télidjène Basin, Eastern Algeria". African Archaeological Review. 25 (1–2): 53. CiteSeerX 10.1.1.518.2283. doi:10.1007/s10437-008-9024-2. ISSN 1572-9842. S2CID 53678760.
- Stivers et al. 2008, p. 1.
- Cremaschi et al. 2010, p. 89.
- Blanchet et al. 2013, p. 108.
- Peck et al. 2015, p. 141.
- Zielhofer et al. 2017, p. 131.
- Garcin, Yannick; Vincens, Annie; Williamson, David; Guiot, Joël; Buchet, Guillaume (2006). "Wet phases in tropical southern Africa during the last glacial period". Geophysical Research Letters. 33 (7): 3. Bibcode:2006GeoRL..33.7703G. doi:10.1029/2005GL025531. ISSN 1944-8007.
- Lézine, Duplessy & Cazet 2005, p. 236.
- Schuster & Nutz 2016, p. 1615.
- Junginger et al. 2014, pp. 98–99.
- Beck et al. 2019, p. 28.
- Nickolaus, Peter; Markowska, Monika; Vonhof, Hubert; Bocherens, Hervé; Martin, Ashley; Zinaye, Bahru; Fischer, Markus; Asrat, Asfawossen; Junginger, Annett (1 May 2020). Insights into the African Humid Period from fossil stromatolites and Etheria elliptica shells from the Chew Bahir Basin, southern Ethiopia. 22nd EGU General Assembly. Egu General Assembly Conference Abstracts. 22. p. 18611. Bibcode:2020EGUGA..2218611N.
- Schuster & Nutz 2016, pp. 1614–1615.
- Sylvestre et al. 2013, p. 237.
- Wendorf, Karlén & Schild 2007, p. 197.
- Wendorf, Karlén & Schild 2007, p. 203.
- Said 1993, p. 131.
- Lézine, A. -M.; Izumi, K.; Achoundong, G. (13 December 2020). "Mbi Crater (Cameroon) illustrates the relations between mountain and lowland forests over the past 15,000 years in western equatorial Africa". Quaternary International: 8. doi:10.1016/j.quaint.2020.12.014. ISSN 1040-6182.
- Heine 2019, p. 624.
- Chiotis 2018, p. 18.
- Coutros 2019, pp. 7–8.
- Zerboni & Gatto 2015, p. 312.
- Huang et al. 2008, p. 1460.
- Dawelbeit, Jaillard & Eisawi 2019, p. 13.
- Krüger et al. 2017, p. 10.
- Armitage, Bristow & Drake 2015, p. 8547.
- Sylvestre et al. 2013, p. 223.
- Nogué, Sandra; Nascimento, Lea de; Fernández‐Palacios, José María; Whittaker, Robert J.; Willis, Kathy J. (2013). "The ancient forests of La Gomera, Canary Islands, and their sensitivity to environmental change". Journal of Ecology. 101 (2): 374. doi:10.1111/1365-2745.12051. ISSN 1365-2745.
- Vaezi, Alireza; Ghazban, Fereydoun; Tavakoli, Vahid; Routh, Joyanto; Beni, Abdolmajid Naderi; Bianchi, Thomas S.; Curtis, Jason H.; Kylin, Henrik (15 January 2019). "A Late Pleistocene-Holocene multi-proxy record of climate variability in the Jazmurian playa, southeastern Iran". Palaeogeography, Palaeoclimatology, Palaeoecology. 514: 763–764. Bibcode:2019PPP...514..754V. doi:10.1016/j.palaeo.2018.09.026. ISSN 0031-0182.
- Castilla-Beltrán, Alvaro; Duarte, Ivani; de Nascimento, Lea; Fernández-Palacios, José María; Romeiras, Maria; Whittaker, Robert J.; Jambrina-Enríquez, Margarita; Mallol, Carolina; Cundy, Andrew B.; Edwards, Mary; Nogué, Sandra (1 February 2020). "Using multiple palaeoecological indicators to guide biodiversity conservation in tropical dry islands: The case of São Nicolau, Cabo Verde". Biological Conservation. 242: 6. doi:10.1016/j.biocon.2019.108397. ISSN 0006-3207.
- Blümel 2002, p. 11.
- Magny & Haas 2004, p. 425.
- Hou & Wu 2020, p. 13.
- Mooney, Scott D.; Black, Manu P. (1 March 2006). "Holocene fire history from the Greater Blue Mountains World Heritage Area, New South Wales, Australia: the climate, humans and fire nexus". Regional Environmental Change. 6 (1–2): 48–49. Bibcode:2013REC..2013....1J. doi:10.1007/s10113-005-0003-8. ISSN 1436-378X. S2CID 154477236.
- Wu, Jiaying; Porinchu, David F.; Campbell, Nicole L.; Mordecai, Taylor M.; Alden, Evan C. (15 March 2019). "Holocene hydroclimate and environmental change inferred from a high-resolution multi-proxy record from Lago Ditkebi, Chirripó National Park, Costa Rica". Palaeogeography, Palaeoclimatology, Palaeoecology. 518: 184. Bibcode:2019PPP...518..172W. doi:10.1016/j.palaeo.2019.01.004. ISSN 0031-0182.
- Zolitschka, Bernd; Fey, Michael; Janssen, Stephanie; Maidana, Nora I; Mayr, Christoph; Wulf, Sabine; Haberzettl, Torsten; Corbella, Hugo; Lücke, Andreas; Ohlendorf, Christian; Schäbitz, Frank (20 December 2018). "Southern Hemispheric Westerlies control sedimentary processes of Laguna Azul (south-eastern Patagonia, Argentina)". The Holocene. 29 (3): 414. doi:10.1177/0959683618816446. S2CID 134667787.
- Hou & Wu 2020, pp. 1–2.
- Lebamba et al. 2016, p. 130.
- Beer et al. 2002, p. 592.
- Wendorf, Karlén & Schild 2007, p. 201.
- Liu et al. 2014, p. 2024.
- Sylvestre et al. 2013, p. 224.
- Zielhofer et al. 2017, p. 120.
- Hély et al. 2009, p. 673.
- Pausata et al. 2020, pp. 238–239.
- Heine 2019, p. 512.
- Metcalfe & Nash 2012, p. 101.
- Roubeix & Chalié 2018, p. 99.
- Roubeix & Chalié 2018, p. 3.
- Wong 2020, p. 1.
- Jung et al. 2004, p. 35.
- Claussen et al. 1999, p. 2037.
- Jung et al. 2004, pp. 34–35.
- Metcalfe & Nash 2012, p. 112.
- Roubeix & Chalié 2018, pp. 11–12.
- Colin et al. 2020, p. 1.
- Colin et al. 2020, p. 20.
- Bristow et al. 2018, p. 194.
- Schefuß et al. 2017, p. 6.
- Bristow et al. 2018, p. 186.
- Hoelzmann & Holmes 2017, pp. 26–27.
- Drake & Bristow 2006, p. 908.
- Kindermann & Classen 2010, p. 21.
- McGee & deMenocal 2017, p. 15.
- Mercuri et al. 2018, p. 222.
- Lézine 2009, p. 751.
- Petit-Maire 1989, p. 649.
- Zerboni, Andrea; Mori, Lucia; Bosi, Giovanna; Buldrini, Fabrizio; Bernasconi, Andrea; Gatto, Maria Carmela; Mercuri, Anna Maria (September 2017). "Domestic firing activities and fuel consumption in a Saharan oasis: Micromorphological and archaeobotanical evidence from the Garamantian site of Fewet (Central Sahara, SW Libya)". Journal of Arid Environments. 144: 124. Bibcode:2017JArEn.144..123Z. doi:10.1016/j.jaridenv.2017.03.012. hdl:11380/1135660. ISSN 0140-1963.
- Pachur & Altmann 2006, p. 34.
- Pennington et al. 2019, p. 116.
- Eggermont et al. 2008, p. 2423.
- Lézine 2009, p. 753.
- Cole et al. 2009, p. 264.
- Krinner et al. 2012, p. 2.
- Zerboni & Nicoll 2019, pp. 24–25.
- Olsen 2017, p. 91.
- Roubeix & Chalié 2018, p. 13.
- Kennett & Kennett 2007, p. 240.
- Kuzmicheva et al. 2017, pp. 81–82.
- Russell & Ivory 2018, p. 10.
- Junginger et al. 2014, pp. 14–15.
- Pennington et al. 2019, p. 115.
- van der Lubbe et al. 2017, p. 1.
- Berke et al. 2012, p. 99.
- Berke et al. 2012, p. 100.
- Berke et al. 2012, p. 103.
- Morrissey & Scholz 2014, p. 89.
- Santisteban et al. 2019, p. 13.
- Costas, Susana; Jerez, Sonia; Trigo, Ricardo M.; Goble, Ronald; Rebêlo, Luís (May 2012). "Sand invasion along the Portuguese coast forced by westerly shifts during cold climate events" (PDF). Quaternary Science Reviews. 42: 24. Bibcode:2012QSRv...42...15C. doi:10.1016/j.quascirev.2012.03.008. hdl:10400.9/1848. ISSN 0277-3791.
- Santisteban et al. 2019, p. 12.
- Zielhofer et al. 2017, p. 132.
- Sangen 2012, p. 215.
- Servant, Buchet & Vincens 2010, p. 291.
- Lebamba et al. 2016, p. 136.
- Pirie et al. 2009, p. 924.
- Niedermeyer et al. 2010, p. 3002.
- Lézine et al. 2013, p. 329.
- Lézine et al. 2013, p. 328.
- Lézine 2017, p. 20.
- Hipondoka, M.H.T.; Mauz, B.; Kempf, J.; Packman, S.; Chiverrell, R.C.; Bloemendal, J. (January 2014). "Chronology of sand ridges and the Late Quaternary evolution of the Etosha Pan, Namibia". Geomorphology. 204: 561–562. Bibcode:2014Geomo.204..553H. doi:10.1016/j.geomorph.2013.08.034. ISSN 0169-555X.
- Forman, Wright & Bloszies 2014, p. 85.
- Meeker, L. David; Cumming, Brian F.; Stager, J. Curt (2003). "A 10,000-year high-resolution diatom record from Pilkington Bay, Lake Victoria, East Africa". Quaternary Research. 59 (2): 180. Bibcode:2003QuRes..59..172S. doi:10.1016/S0033-5894(03)00008-5. ISSN 1096-0287.
- Krinner et al. 2012, pp. 1–2.
- Servant, Buchet & Vincens 2010, p. 282.
- Brooks et al. 2007, p. 257.
- Ganopolski et al. 2009, p. 458.
- Ganopolski et al. 2009, p. 466.
- Menocal 2015, p. 2.
- Guilderson et al. 2001, p. 197.
- Vincenzo & Massimo 2015, p. 15.
- Vincenzo & Massimo 2015, p. 13.
- Schefuß et al. 2017, p. 9.
- Schuster & Nutz 2016, p. 1616.
- Russell & Ivory 2018, p. 11.
- Lebamba et al. 2016, p. 137.
- Lézine et al. 2013, p. 334.
- Sachse et al. 2018, p. 3261.
- Daniau et al. 2019, p. 24.
- Lézine 2017, p. 19.
- Sachse et al. 2018, p. 3262.
- Claussen et al. 1999, p. 2040.
- Maslin, Manning & Brierley 2018, p. 4.
- Maslin, Manning & Brierley 2018, p. 5.
- Coutros 2019, p. 8.
- Zerboni & Nicoll 2019, p. 32.
- Pausata et al. 2020, p. 239.
- Reimer et al. 2010, p. 41.
- Morrill, Overpeck & Cole 2016, p. 473.
- Fedotov, A.P; Chebykin, E.P; Yu, Semenov M; Vorobyova, S.S; Yu, Osipov E; Golobokova, L.P; Pogodaeva, T.V; Zheleznyakova, T.O; Grachev, M.A; Tomurhuu, D; Oyunchimeg, Ts; Narantsetseg, Ts; Tomurtogoo, O; Dolgikh, P.T; Arsenyuk, M.I; De Batist, M (July 2004). "Changes in the volume and salinity of Lake Khubsugul (Mongolia) in response to global climate changes in the upper Pleistocene and the Holocene". Palaeogeography, Palaeoclimatology, Palaeoecology. 209 (1–4): 256. doi:10.1016/j.palaeo.2003.12.022. ISSN 0031-0182.
- Marsicek et al. 2013, p. 130.
- Aharon, Paul; Dhungana, Rajesh (August 2017). "Ocean-atmosphere interactions as drivers of mid-to-late Holocene rapid climate changes: Evidence from high-resolution stalagmite records at DeSoto Caverns, Southeast USA". Quaternary Science Reviews. 170: 78. Bibcode:2017QSRv..170...69A. doi:10.1016/j.quascirev.2017.06.023. ISSN 0277-3791.
- Wahl, David; Byrne, Roger; Anderson, Lysanna (November 2014). "An 8700 year paleoclimate reconstruction from the southern Maya lowlands". Quaternary Science Reviews. 103: 21. Bibcode:2014QSRv..103...19W. doi:10.1016/j.quascirev.2014.08.004. ISSN 0277-3791.
- Rowe, Harold D; Guilderson, Thomas P; Dunbar, Robert B; Southon, John R; Seltzer, Geoffrey O; Mucciarone, David A; Fritz, Sherilyn C; Baker, Paul A (September 2003). "Late Quaternary lake-level changes constrained by radiocarbon and stable isotope studies on sediment cores from Lake Titicaca, South America". Global and Planetary Change. 38 (3–4): 287. Bibcode:2003GPC....38..273R. doi:10.1016/S0921-8181(03)00031-6. ISSN 0921-8181.
- Shuman, Bryan N.; Serravezza, Marc (October 2017). "Patterns of hydroclimatic change in the Rocky Mountains and surrounding regions since the last glacial maximum". Quaternary Science Reviews. 173: 74. Bibcode:2017QSRv..173...58S. doi:10.1016/j.quascirev.2017.08.012. ISSN 0277-3791.
- Shinker, Jacqueline J.; Powers, Kristine; Hougardy, Devin D.; Carter, Grace E.; Shuman, Bryan N. (1 March 2014). "A north–south moisture dipole at multi-century scales in the Central and Southern Rocky Mountains, U.S.A., during the late Holocene". Rocky Mountain Geology. 49 (1): 45. doi:10.2113/gsrocky.49.1.33. ISSN 1555-7332.
- McGee & deMenocal 2017, p. 26.
- Pirie et al. 2009, p. 931.
- Lernia et al. 2013, p. 120.
- Andersen, Gidske L.; Krzywinski, Knut; Talib, Mohamed; Saadallah, Ahmed E.M.; Hobbs, Joseph J.; Pierce, Richard H. (July 2014). "Traditional nomadic tending of trees in the Red Sea Hills". Journal of Arid Environments. 106: 36. Bibcode:2014JArEn.106...36A. doi:10.1016/j.jaridenv.2014.02.009. ISSN 0140-1963.
- Tafuri et al. 2006, p. 392.
- Schuster & Nutz 2016, p. 1609.
- Junginger & Trauth 2013, p. 176.
- Junginger & Trauth 2013, p. 175.
- Redford, Donald B. (1992). Egypt, Canaan, and Israel in ancient times. Internet Archive. Princeton University Press. p. 17. ISBN 978-0-691-03606-9.
- Kuper 2006, p. 415.
- Linstädter & Kröpelin 2004, p. 764.
- Mercuri et al. 2018, p. 228.
- Brooks et al. 2007, pp. 262–263.
- Magny & Haas 2004, p. 428.
- Cremaschi & Zerboni 2009, p. 700.
- Pennington et al. 2019, pp. 115–116.
- Castañeda et al. 2016, p. 47.
- Wong 2020, p. 2.
- Bar-Matthews, Miryam; Ayalon, Avner; Gilmour, Mabs; Matthews, Alan; Hawkesworth, Chris J. (September 2003). "Sea–land oxygen isotopic relationships from planktonic foraminifera and speleothems in the Eastern Mediterranean region and their implication for paleorainfall during interglacial intervals". Geochimica et Cosmochimica Acta. 67 (17): 3195. Bibcode:2003GeCoA..67.3181B. doi:10.1016/S0016-7037(02)01031-1. ISSN 0016-7037.
- Cremaschi & Zerboni 2009, p. 699.
- Sachse et al. 2018, p. 3264.
- Brooks et al. 2007, p. 261.
- Tafuri et al. 2006, p. 399.
- Brooks et al. 2007, p. 262.
- Miller, Jennifer M.; Sawchuk, Elizabeth A. (27 November 2019). "Ostrich eggshell bead diameter in the Holocene: Regional variation with the spread of herding in eastern and southern Africa". PLOS ONE. 14 (11): 2. Bibcode:2019PLoSO..1425143M. doi:10.1371/journal.pone.0225143. ISSN 1932-6203. PMC 6880992. PMID 31774851.
- Sawchuk, Elizabeth A.; Pfeiffer, Susan; Klehm, Carla E.; Cameron, Michelle E.; Hill, Austin C.; Janzen, Anneke; Grillo, Katherine M.; Hildebrand, Elisabeth A. (1 November 2019). "The bioarchaeology of mid-Holocene pastoralist cemeteries west of Lake Turkana, Kenya". Archaeological and Anthropological Sciences. 11 (11): 6222. doi:10.1007/s12520-019-00914-4. ISSN 1866-9565. PMC 6941650. PMID 31956376.
- Smith, Alison J. (27 July 2016). "Century-scale Holocene processes as a source of natural selection pressure in human evolution: Holocene climate and the Human Genome Project". The Holocene. 17 (5): 692–693. Bibcode:2007Holoc..17..689S. doi:10.1177/0959683607079003. S2CID 85435419.
- Spinage 2012, p. 58.
- Médail et al. 2013, p. 2.
- Boratyński, Adam; Ok, Tolga; Boratyńska, Krystyna; Dagher-Kharrat, Magda Bou; Romo, Angel; Dering, Monika; Sękiewicz, Katarzyna (28 September 2018). "Phylogenetic and biogeographic insights into long-lived Mediterranean Cupressus taxa with a schizo-endemic distribution and Tertiary origin". Botanical Journal of the Linnean Society. 188 (2): 15. doi:10.1093/botlinnean/boy049. ISSN 0024-4074.
- Escoriza, Daniel; Bakhouche, Badis (2017). "11. Genus Malpolon: New distribution area in Algeria". The Herpetological Bulletin (140): 35.
- Blick, Theo; Seiter, Michael (7 September 2016). "Whip spiders (Amblypygi, Arachnida) of the Western Palaearctic—a review". Zootaxa. 4161 (4): 588–589. doi:10.11646/zootaxa.4161.4.11. ISSN 1175-5334. PMID 27615955 – via ResearchGate.
- Faith, J. Tyler (January 2014). "Late Pleistocene and Holocene mammal extinctions on continental Africa". Earth-Science Reviews. 128: 115. Bibcode:2014ESRv..128..105F. doi:10.1016/j.earscirev.2013.10.009. ISSN 0012-8252.
- Vilhelmsen, Lars (7 March 2005). "Chalinus albitibialis, a new species of Orussidae (Insecta, Hymenoptera) from Morocco". Zootaxa. 880 (1): 6. doi:10.11646/zootaxa.880.1.1. ISSN 1175-5334.
- Hassanin, Alexandre; Ropiquet, Anne; Gourmand, Anne-Laure; Chardonnet, Bertrand; Rigoulet, Jacques (March 2007). "Mitochondrial DNA variability in Giraffa camelopardalis: consequences for taxonomy, phylogeography and conservation of giraffes in West and central Africa". Comptes Rendus Biologies. 330 (3): 265–74. doi:10.1016/j.crvi.2007.02.008. ISSN 1631-0691. PMID 17434121.
- Gross et al. 2014, p. 14473.
- Holl, Augustin F. C. (1 September 2020). "Dark Side Archaeology: Climate Change and Mid-Holocene Saharan Pastoral Adaptation". African Archaeological Review. 37 (3): 491–495. doi:10.1007/s10437-020-09406-6. ISSN 1572-9842. PMC 7445821. PMID 32863519.
- Lyam, Paul T.; Duque-Lazo, Joaquin; Schnitzler, Jan; Hauenschild, Frank; Muellner-Riehl, Alexandra N. (2020). "Testing the forest refuge hypothesis in sub-Saharan Africa using species distribution modeling for a key savannah tree species, Senegalia senegal (L.) Britton". Frontiers of Biogeography. 12 (4): 10. doi:10.21425/F5FBG48689.
- Salzmann, Ulrich; Hoelzmann, Philipp (1 February 2005). "The Dahomey Gap: an abrupt climatically induced rain forest fragmentation in West Africa during the late Holocene". The Holocene. 15 (2): 190. Bibcode:2005Holoc..15..190S. doi:10.1191/0959683605hl799rp. ISSN 0959-6836. S2CID 129839236.
- Hély et al. 2009, p. 684.
- White et al. 2011, p. 472.
- Heine 2019, p. 654.
- Adkins, Menocal & Eshel 2006, p. 2.
- Lancaster 2020, p. 115.
- Zielhofer et al. 2017, p. 119.
- D'Odorico, Paolo; Porporato, Amilcare, eds. (2006). Dryland Ecohydrology. Dordrecht: Kluwer Academic Publishers. p. 589. doi:10.1007/1-4020-4260-4. ISBN 978-1-4020-4259-1.
- Muschitiello et al. 2015, p. 93.
- Muschitiello et al. 2015, pp. 94–95.
- Muschitiello et al. 2015, p. 96.
- Hoelzmann & Holmes 2017, p. 5.
- Baumhauer & Runge 2009, p. 25.
- Gasse 2000, p. 190.
- Lézine, Duplessy & Cazet 2005, p. 225.
- Pausata et al. 2020, p. 235.
- Pausata et al. 2020, p. 236.
- Pausata et al. 2020, p. 240.
- Junginger et al. 2014, p. 4.
- Forman, Wright & Bloszies 2014, p. 88.
- Lézine et al. 2017, p. 69.
- Spinage 2012, p. 60.
- Brooks et al. 2007, p. 267.
- Donnelly et al. 2017, p. 6221.
- IPCC 2014, pp. 16–17.
- IPCC 2014, p. 11.
- "Impacts of 1.5°C of Global Warming on Natural and Human Systems". IPCC. 23 May 2019. p. 197. Retrieved 29 December 2018.
- Petoukhov et al. 2003, p. 100.
- Pausata et al. 2020, p. 244.
- Petoukhov et al. 2003, p. 114.
- Petoukhov et al. 2003, p. 113.
- Pausata et al. 2020, p. 245.
- Lu, Zhengyao; Zhang, Qiong; Miller, Paul A.; Zhang, Qiang; Berntell, Ellen; Smith, Benjamin (11 December 2020). "Impacts of large‐scale Sahara solar farms on global climate and vegetation cover". Geophysical Research Letters. 48 (2): 2–3. doi:10.1029/2020GL090789. ISSN 1944-8007.
- Brooks et al. 2007, p. 268.
- Brooks et al. 2007, p. 269.
- Adkins, Jess; Menocal, Peter de; Eshel, Gidon (1 December 2006). "The "African humid period" and the record of marine upwelling from excess 230Th in Ocean Drilling Program Hole 658C" (PDF). Paleoceanography. 21 (4): PA4203. Bibcode:2006PalOc..21.4203A. doi:10.1029/2005PA001200. ISSN 1944-9186.
- Armitage, Simon J.; Bristow, Charlie S.; Drake, Nick A. (29 June 2015). "West African monsoon dynamics inferred from abrupt fluctuations of Lake Mega-Chad". Proceedings of the National Academy of Sciences. 112 (28): 8543–8548. Bibcode:2015PNAS..112.8543A. doi:10.1073/pnas.1417655112. ISSN 0027-8424. PMC 4507243. PMID 26124133.
- Bard, Edouard (15 November 2013). "Out of the African Humid Period". Science. 342 (6160): 808–809. Bibcode:2013Sci...342..808B. doi:10.1126/science.1246519. ISSN 1095-9203. PMID 24233711. S2CID 206552609.
- Barker, Philip; Telford, Richard; Gasse, Françoise; Thevenon, Florian (November 2002). "Late Pleistocene and Holocene palaeohydrology of Lake Rukwa, Tanzania, inferred from diatom analysis". Palaeogeography, Palaeoclimatology, Palaeoecology. 187 (3–4): 295–305. Bibcode:2002PPP...187..295B. doi:10.1016/S0031-0182(02)00482-0.
- Battarbee, Richard W.; Gasse, Françoise; Stickley, Catherine E. (2004). Past climate variability through Europe and Africa. Springer. ISBN 978-1-4020-2121-3.
- Baumhauer, Roland (2004). "Die spätpleistozänen und holozänen Paläoseen in der zentralen Sahara - neue Ergebnisse aus der Téneré, dem Erg de Téneré und dem Erg de Fachi-Bilma, NE-Niger". Die Erde (in German). 135 (Heft 3–4): 289–313.
- Baumhauer, Roland; Runge, Jörgen, eds. (27 February 2009). Holocene Palaeoenvironmental History of the Central Sahara: Palaeoecology of Africa. An International Yearbook of Landscape Evolution and Palaeoenvironments. 29 (1 ed.). CRC Press. doi:10.1201/9780203874899. ISBN 9780429206788.
- Beck, Catherine C.; Allen, Mary Margaret; Feibel, Craig S.; Beverly, Emily J.; Stone, Jeffery R.; Wegter, Bruce; Wilson, Charles L. (1 June 2019). "Living in a swampy paradise: Paleoenvironmental reconstruction of an African Humid Period lacustrine margin, West Turkana, Kenya". Journal of African Earth Sciences. 154: 20–34. Bibcode:2019JAfES.154...20B. doi:10.1016/j.jafrearsci.2019.03.007. ISSN 1464-343X.
- Beer, Jürg; Hardy, Douglas R.; Mikhalenko, Vladimir N.; Lin, Ping-Nan; Mashiotta, Tracy A.; Zagorodnov, Victor S.; Brecher, Henry H.; Henderson, Keith A.; Davis, Mary E.; Mosley-Thompson, Ellen; Thompson, Lonnie G. (18 October 2002). "Kilimanjaro Ice Core Records: Evidence of Holocene Climate Change in Tropical Africa". Science. 298 (5593): 589–593. Bibcode:2002Sci...298..589T. doi:10.1126/science.1073198. ISSN 1095-9203. PMID 12386332. S2CID 32880316.
- Bendaoud, Abderrahmane; Hamimi, Zakaria; Hamoudi, Mohamed; Djemai, Safouane; Zoheir, Basem, eds. (2019). The Geology of the Arab World---An Overview. Springer Geology. Cham: Springer International Publishing. doi:10.1007/978-3-319-96794-3. ISBN 978-3-319-96793-6. S2CID 199493195.
- Berke, Melissa A.; Johnson, Thomas C.; Werne, Josef P.; Schouten, Stefan; Sinninghe Damsté, Jaap S. (October 2012). "A mid-Holocene thermal maximum at the end of the African Humid Period". Earth and Planetary Science Letters. 351–352: 95–104. Bibcode:2012E&PSL.351...95B. doi:10.1016/j.epsl.2012.07.008. ISSN 0012-821X.
- Blanchet, C. L.; Contoux, C.; Leduc, G. (15 December 2015). "Runoff and precipitation dynamics in the Blue and White Nile catchments during the mid-Holocene: A data-model comparison". Quaternary Science Reviews. 130: 222–230. Bibcode:2015QSRv..130..222B. doi:10.1016/j.quascirev.2015.07.014. ISSN 0277-3791.
- Blanchet, Cécile L.; Tjallingii, Rik; Frank, Martin; Lorenzen, Janne; Reitz, Anja; Brown, Kevin; Feseker, Tomas; Brückmann, Warner (February 2013). "High- and low-latitude forcing of the Nile River regime during the Holocene inferred from laminated sediments of the Nile deep-sea fan". Earth and Planetary Science Letters. 364: 98–110. Bibcode:2013E&PSL.364...98B. doi:10.1016/j.epsl.2013.01.009. ISSN 0012-821X.
- Bloszies, C.; Forman, S.L.; Wright, D.K. (September 2015). "Water level history for Lake Turkana, Kenya in the past 15,000 years and a variable transition from the African Humid Period to Holocene aridity". Global and Planetary Change. 132: 64–76. doi:10.1016/j.gloplacha.2015.06.006. ISSN 0921-8181.
- Blümel, Wolf Dieter (2002). "20000 Jahre Klimawandel und Kulturgeschichte – von der Eiszeit in die Gegenwart". Wechselwirkungen, Jahrbuch aus Lehre und Forschung der Universität Stuttgart (in German). doi:10.18419/opus-1619.
- Breunig, Peter; Neumann, Katharina; Van Neer, Wim (June 1996). "New research on the Holocene settlement and environment of the Chad Basin in Nigeria". African Archaeological Review. 13 (2): 111–145. doi:10.1007/BF01956304. S2CID 162196033.
- Bristow, Charlie S.; Holmes, Jonathan A.; Mattey, Dave; Salzmann, Ulrich; Sloane, Hilary J. (December 2018). "A late Holocene palaeoenvironmental 'snapshot' of the Angamma Delta, Lake Megachad at the end of the African Humid Period" (PDF). Quaternary Science Reviews. 202: 182–196. Bibcode:2018QSRv..202..182B. doi:10.1016/j.quascirev.2018.04.025. ISSN 0277-3791.
- Brookes, Ian A. (November 2003). "Geomorphic indicators of Holocene winds in Egypt's Western Desert". Geomorphology. 56 (1–2): 155–166. Bibcode:2003Geomo..56..155B. doi:10.1016/S0169-555X(03)00076-X. ISSN 0169-555X.
- Brooks, Nick; Chiapello, Isabelle; Lernia, Savino Di; Drake, Nick; Legrand, Michel; Moulin, Cyril; Prospero, Joseph (24 January 2007). "The climate-environment-society nexus in the Sahara from prehistoric times to the present day". The Journal of North African Studies. 10 (3–4): 253–292. doi:10.1080/13629380500336680. S2CID 145727673.
- IPCC (2014). "IPCC's Fifth Assessment Report: What's in it for Africa?" (PDF). CDKN.
- Burrough, S.L.; Thomas, D.S.G. (November 2013). "Central southern Africa at the time of the African Humid Period: a new analysis of Holocene palaeoenvironmental and palaeoclimate data". Quaternary Science Reviews. 80: 29–46. Bibcode:2013QSRv...80...29B. doi:10.1016/j.quascirev.2013.08.001. ISSN 0277-3791.
- Castañeda, Isla S.; Schouten, Stefan; Pätzold, Jürgen; Lucassen, Friedrich; Kasemann, Simone; Kuhlmann, Holger; Schefuß, Enno (March 2016). "Hydroclimate variability in the Nile River Basin during the past 28,000 years" (PDF). Earth and Planetary Science Letters. 438: 47–56. Bibcode:2016E&PSL.438...47C. doi:10.1016/j.epsl.2015.12.014. ISSN 0012-821X.
- Chandan, Deepak; Peltier, W. Richard (16 November 2020). "African Humid Period Precipitation Sustained by Robust Vegetation, Soil, and Lake Feedbacks". Geophysical Research Letters. 47 (21): e88728. Bibcode:2020GeoRL..4788728C. doi:10.1029/2020GL088728.
- Chiotis, Eustathios (15 November 2018). Chiotis, Eustathios (ed.). Climate Changes in the Holocene: Impacts and Human Adaptation (1 ed.). Boca Raton: CRC Press. doi:10.1201/9781351260244. ISBN 9781351260244.
- Claussen, Martin; Kubatzki, Claudia; Brovkin, Victor; Ganopolski, Andrey; Hoelzmann, Philipp; Pachur, Hans-Joachim (1999). "Simulation of an abrupt change in Saharan vegetation in the Mid-Holocene" (PDF). Geophysical Research Letters. 26 (14): 2037–2040. Bibcode:1999GeoRL..26.2037C. doi:10.1029/1999GL900494. ISSN 1944-8007.
- Cohen, Andrew S.; Hopmans, Ellen C.; Damsté, Jaap S. Sinninghe; Huang, Yongsong; Russell, James M.; Tierney, Jessica E. (10 October 2008). "Northern Hemisphere Controls on Tropical Southeast African Climate During the Past 60,000 Years". Science. 322 (5899): 252–255. Bibcode:2008Sci...322..252T. doi:10.1126/science.1160485. ISSN 1095-9203. PMID 18787132. S2CID 7364713.
- Cole, Jennifer M.; Goldstein, Steven L.; Menocal, Peter B. de; Hemming, Sidney R.; Grousset, Francis E. (February 2009). "Contrasting compositions of Saharan dust in the eastern Atlantic Ocean during the last deglaciation and African Humid Period". Earth and Planetary Science Letters. 278 (3–4): 257–266. Bibcode:2009E&PSL.278..257C. doi:10.1016/j.epsl.2008.12.011. ISSN 0012-821X.
- Colin, Frédéric; Quiles, Anita; Schuster, Mathieu; Schwartz, Dominique; Duvette, Catherine; Marchand, Sylvie; Dorry, Mennat-Allah El; Heesch, Johan van (2020). "The End of the "green Oasis": Chronological Bayesian Modeling of Human and Environmental Dynamics in the Bahariya Area (Egyptian Sahara) from Pharaonic Third Intermediate Period to Medieval Times". Radiocarbon. 62: 25–49. doi:10.1017/RDC.2019.106. ISSN 0033-8222.
- Costa, Kassandra; Russell, James; Konecky, Bronwen; Lamb, Henry (January 2014). "Isotopic reconstruction of the African Humid Period and Congo Air Boundary migration at Lake Tana, Ethiopia". Quaternary Science Reviews. 83: 58–67. Bibcode:2014QSRv...83...58C. doi:10.1016/j.quascirev.2013.10.031. ISSN 0277-3791.
- Coutros, Peter R. (2019). "A fluid past: Socio-hydrological systems of the West African Sahel across the long durée". WIREs Water. 6 (5). doi:10.1002/wat2.1365. ISSN 2049-1948.
- Cremaschi, Mauro; Zerboni, Andrea (August 2009). "Early to Middle Holocene landscape exploitation in a drying environment: Two case studies compared from the central Sahara (SW Fezzan, Libya)". Comptes Rendus Geoscience. 341 (8–9): 689–702. Bibcode:2009CRGeo.341..689C. doi:10.1016/j.crte.2009.05.001. ISSN 1631-0713.
- Cremaschi, Mauro; Zerboni, Andrea; Spötl, Christoph; Felletti, Fabrizio (March 2010). "The calcareous tufa in the Tadrart Acacus Mt. (SW Fezzan, Libya)". Palaeogeography, Palaeoclimatology, Palaeoecology. 287 (1–4): 81–94. Bibcode:2010PPP...287...81C. doi:10.1016/j.palaeo.2010.01.019. ISSN 0031-0182.
- Daniau, Anne-Laure; Desprat, Stéphanie; Aleman, Julie C.; Bremond, Laurent; Davis, Basil; Fletcher, William; Marlon, Jennifer R.; Marquer, Laurent; Montade, Vincent; Morales-Molino, César; Naughton, Filipa; Rius, Damien; Urrego, Dunia H. (1 June 2019). "Terrestrial plant microfossils in palaeoenvironmental studies, pollen, microcharcoal and phytolith. Towards a comprehensive understanding of vegetation, fire and climate changes over the past one million years" (PDF). Revue de Micropaléontologie. 63: 1–35. doi:10.1016/j.revmic.2019.02.001. hdl:10871/36362. ISSN 0035-1598.
- Dawelbeit, Ahmed; Jaillard, Etienne; Eisawi, Ali (1 December 2019). "Sedimentary and paleobiological records of the latest Pleistocene-Holocene climate evolution in the Kordofan region, Sudan". Journal of African Earth Sciences. 160: 103605. Bibcode:2019JAfES.16003605D. doi:10.1016/j.jafrearsci.2019.103605. ISSN 1464-343X.
- Dixit, Vishal; Sherwood, Steven; Geoffroy, Olivier; Mantsis, Damianos (January 2018). "The Role of Nonlinear Drying above the Boundary Layer in the Mid-Holocene African Monsoon". Journal of Climate. 31 (1): 233–249. Bibcode:2018JCli...31..233D. doi:10.1175/jcli-d-17-0234.1.
- Donnelly, Jeffrey P.; Stager, J. Curt; Sushama, Laxmi; Zhang, Qiong; Diro, Gulilat T.; Chiacchio, Marc; Emanuel, Kerry A.; Pausata, Francesco S. R. (13 June 2017). "Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period". Proceedings of the National Academy of Sciences. 114 (24): 6221–6226. Bibcode:2017PNAS..114.6221P. doi:10.1073/pnas.1619111114. ISSN 1091-6490. PMC 5474772. PMID 28559352.
- Drake, N.; Bristow, C. (1 September 2006). "Shorelines in the Sahara: geomorphological evidence for an enhanced monsoon from palaeolake Megachad". The Holocene. 16 (6): 901–911. Bibcode:2006Holoc..16..901D. doi:10.1191/0959683606hol981rr. S2CID 128565786.
- Eggermont, Hilde; Verschuren, Dirk; Fagot, Maureen; Rumes, Bob; Van Bocxlaer, Bert; Kröpelin, Stefan (December 2008). "Aquatic community response in a groundwater-fed desert lake to Holocene desiccation of the Sahara". Quaternary Science Reviews. 27 (25–26): 2411–2425. Bibcode:2008QSRv...27.2411E. doi:10.1016/j.quascirev.2008.08.028. ISSN 0277-3791.
- Engel, Max; Brückner, Helmut; Pint, Anna; Wellbrock, Kai; Ginau, Andreas; Voss, Peter; Grottker, Matthias; Klasen, Nicole; Frenzel, Peter (July 2012). "The early Holocene humid period in NW Saudi Arabia – Sediments, microfossils and palaeo-hydrological modelling". Quaternary International. 266: 131–141. Bibcode:2012QuInt.266..131E. doi:10.1016/j.quaint.2011.04.028. ISSN 1040-6182.ar
- Forman, Steven L.; Wright, David K.; Bloszies, Christopher (August 2014). "Variations in water level for Lake Turkana in the past 8500 years near Mt. Porr, Kenya and the transition from the African Humid Period to Holocene aridity". Quaternary Science Reviews. 97: 84–101. Bibcode:2014QSRv...97...84F. doi:10.1016/j.quascirev.2014.05.005. ISSN 0277-3791.
- Gaetani, Marco; Messori, Gabriele; Zhang, Qiong; Flamant, Cyrille; Pausata, Francesco S. R. (October 2017). "Understanding the Mechanisms behind the Northward Extension of the West African Monsoon during the Mid-Holocene" (PDF). Journal of Climate. 30 (19): 7621–7642. Bibcode:2017JCli...30.7621G. doi:10.1175/jcli-d-16-0299.1.
- Ganopolski, A.; Chen, F.; Peng, Y.; Jin, L. (21 August 2009). "Modeling sensitivity study of the possible impact of snow and glaciers developing over Tibetan Plateau on Holocene African-Asian summer monsoon climate". Climate of the Past. 5 (3): 457–469. Bibcode:2009CliPa...5..457J. doi:10.5194/cp-5-457-2009. ISSN 1814-9324.
- Garcin, Yannick; Schildgen, Taylor F.; Torres Acosta, Verónica; Melnick, Daniel; Guillemoteau, Julien; Willenbring, Jane; Strecker, Manfred R. (February 2017). "Short-lived increase in erosion during the African Humid Period: Evidence from the northern Kenya Rift". Earth and Planetary Science Letters. 459: 58–69. Bibcode:2017E&PSL.459...58G. doi:10.1016/j.epsl.2016.11.017. ISSN 0012-821X.
- Gasse, Françoise (January 2000). "Hydrological changes in the African tropics since the Last Glacial Maximum". Quaternary Science Reviews. 19 (1–5): 189–211. Bibcode:2000QSRv...19..189G. doi:10.1016/S0277-3791(99)00061-X.
- Gasse, Françoise; Van Campo, Elise (September 1994). "Abrupt post-glacial climate events in West Asia and North Africa monsoon domains". Earth and Planetary Science Letters. 126 (4): 435–456. Bibcode:1994E&PSL.126..435G. doi:10.1016/0012-821X(94)90123-6.
- Gross, Thilo; Guimarães, Paulo R.; Koch, Paul L.; Dominy, Nathaniel J.; Rudolf, Lars; Pires, Mathias M.; Yeakel, Justin D. (7 October 2014). "Collapse of an ecological network in Ancient Egypt". Proceedings of the National Academy of Sciences. 111 (40): 14472–14477. arXiv:1409.7006. Bibcode:2014PNAS..11114472Y. doi:10.1073/pnas.1408471111. ISSN 1091-6490. PMC 4210013. PMID 25201967.
- Groucutt, Huw S; Breeze, Paul S; Guagnin, Maria; Stewart, Mathew; Drake, Nick; Shipton, Ceri; Zahrani, Badr; Omarfi, Abdulaziz Al; Alsharekh, Abdullah M; Petraglia, Michael D (December 2020). "Monumental landscapes of the Holocene humid period in Northern Arabia: The mustatil phenomenon". The Holocene. 30 (12): 1767–1779. Bibcode:2020Holoc..30.1767G. doi:10.1177/0959683620950449. PMC 7575307. PMID 33132543.
- Guilderson, Thomas P.; Charles, Christopher D.; Crosta, Xavier; Shemesh, Aldo; Kanfoush, Sharon L.; Hodell, David A. (2001). "Abrupt Cooling of Antarctic Surface Waters and Sea Ice Expansion in the South Atlantic Sector of the Southern Ocean at 5000 cal yr B.P.". Quaternary Research. 56 (2): 191–198. Bibcode:2001QuRes..56..191H. doi:10.1006/qres.2001.2252. ISSN 1096-0287.
- Hamann, Yvonne; Ehrmann, Werner; Schmiedl, Gerhard; Kuhnt, Tanja (20 January 2017). "Modern and late Quaternary clay mineral distribution in the area of the SE Mediterranean Sea". Quaternary Research. 71 (3): 453–464. Bibcode:2009QuRes..71..453H. doi:10.1016/j.yqres.2009.01.001. ISSN 0033-5894.
- Hamdan, Mohamed A.; Brook, George A. (December 2015). "Timing and characteristics of Late Pleistocene and Holocene wetter periods in the Eastern Desert and Sinai of Egypt, based on 14 C dating and stable isotope analysis of spring tufa deposits". Quaternary Science Reviews. 130: 168–188. Bibcode:2015QSRv..130..168H. doi:10.1016/j.quascirev.2015.09.011. ISSN 0277-3791.
- Hamdan, M. A.; Flower, R. J.; Hassan, F. A.; Hassan, S. M. (1 June 2020). "The Holocene history of the Faiyum Lake (Egypt) based on sediment characteristics, diatoms and ostracods contents". Journal of Great Lakes Research. 46 (3): 456–475. doi:10.1016/j.jglr.2020.03.016. ISSN 0380-1330.
- Hamdan, M. A.; Flower, R. J.; Hassan, F. A.; Leroy, S. A. G. (1 July 2020). "Geochemical and palynological analysis of Faiyum Lake sediments, Egypt: Implications for holocene paleoclimate". Journal of African Earth Sciences. 167: 103864. Bibcode:2020JAfES.16703864H. doi:10.1016/j.jafrearsci.2020.103864. ISSN 1464-343X.
- Haslett, Simon K; Davies, Catherine F C (1 March 2006). "Late Quaternary climate–ocean changes in western North Africa: offshore geochemical evidence". Transactions of the Institute of British Geographers. 31 (1): 34–52. doi:10.1111/j.1475-5661.2006.00193.x. ISSN 0020-2754.
- Hayes, Christopher T.; Wallace, Davin J. (1 February 2019). "Exploring records of Saharan dust transport and hurricanes in the western North Atlantic over the Holocene". Quaternary Science Reviews. 205: 1–9. Bibcode:2019QSRv..205....1H. doi:10.1016/j.quascirev.2018.11.018. ISSN 0277-3791.
- Heine, Klaus (2019). Das Quartär in den Tropen: Eine Rekonstruktion des Paläoklimas (in German). Berlin, Heidelberg: Springer Berlin Heidelberg. doi:10.1007/978-3-662-57384-6. ISBN 978-3-662-57383-9.
- Hély, Christelle; Braconnot, Pascale; Watrin, Julie; Zheng, Weipeng (August 2009). "Climate and vegetation: Simulating the African humid period". Comptes Rendus Geoscience. 341 (8–9): 671–688. Bibcode:2009CRGeo.341..671H. doi:10.1016/j.crte.2009.07.002. ISSN 1631-0713.
- Hoelzmann, Philipp; Keding, Birgit; Berke, Hubert; Kröpelin, Stefan; Kruse, Hans-Joachim (May 2001). "Environmental change and archaeology: lake evolution and human occupation in the Eastern Sahara during the Holocene". Palaeogeography, Palaeoclimatology, Palaeoecology. 169 (3–4): 193–217. Bibcode:2001PPP...169..193H. doi:10.1016/S0031-0182(01)00211-5.
- Hoelzmann, Philipp; Holmes, Jonathan (26 April 2017). "The Late Pleistocene-Holocene African Humid Period as Evident in Lakes". Oxford Research Encyclopedia of Climate Science. 1. doi:10.1093/acrefore/9780190228620.013.531.
- Hopcroft, Peter O.; Valdes, Paul J.; Harper, Anna B.; Beerling, David J. (16 July 2017). "Multi vegetation model evaluation of the Green Sahara climate regime: RAINFALL SUPPORTING A GREEN SAHARA". Geophysical Research Letters. 44 (13): 6804–6813. doi:10.1002/2017GL073740.
- Hou, Mei; Wu, Wen Xiang (5 December 2020). "A review of 6000-5000 cal BP climatic anomalies in China". Quaternary International. 571: 58–72. doi:10.1016/j.quaint.2020.12.004. ISSN 1040-6182.
- Huang, Jianbin; Wang, Shaowu; Wen, Xinyu; Yang, Bao (December 2008). "Progress in studies of the climate of humid period and the impacts of changing precession in early-mid Holocene". Progress in Natural Science. 18 (12): 1459–1464. doi:10.1016/j.pnsc.2008.05.011. ISSN 1002-0071.
- Hughes, Philip D.; Fenton, C.R.; Gibbard, Philip L. (1 January 2011). Quaternary Glaciations of the Atlas Mountains, North Africa. Developments in Quaternary Sciences. 15. pp. 1065–1074. doi:10.1016/B978-0-444-53447-7.00076-3. ISBN 9780444534477. ISSN 1571-0866.
- Jahns, Susanne (1 February 1995). "A holocene pollen diagram from El Atrun, northern Sudan". Vegetation History and Archaeobotany. 4 (1): 23–30. doi:10.1007/BF00198612. ISSN 1617-6278. S2CID 129636065.
- Jones, Sacha C.; Stewart, Brian A., eds. (2016). Africa from MIS 6-2: Population Dynamics and Paleoenvironments. Vertebrate Paleobiology and Paleoanthropology. Dordrecht: Springer Netherlands. doi:10.1007/978-94-017-7520-5. ISBN 9789401775199. S2CID 12509903.
- Jung, S.J.A.; Davies, G.R.; Ganssen, G.M.; Kroon, D. (30 April 2004). "Stepwise Holocene aridification in NE Africa deduced from dust-borne radiogenic isotope records". Earth and Planetary Science Letters. 221 (1–4): 27–37. Bibcode:2004E&PSL.221...27J. doi:10.1016/S0012-821X(04)00095-0. ISSN 0012-821X.
- Junginger, Annett; Roller, Sybille; Olaka, Lydia A.; Trauth, Martin H. (February 2014). "The effects of solar irradiation changes on the migration of the Congo Air Boundary and water levels of paleo-Lake Suguta, Northern Kenya Rift, during the African Humid Period (15–5ka BP)". Palaeogeography, Palaeoclimatology, Palaeoecology. 396: 1–16. Bibcode:2014PPP...396....1J. doi:10.1016/j.palaeo.2013.12.007. ISSN 0031-0182.
- Junginger, Annett; Trauth, Martin H. (December 2013). "Hydrological constraints of paleo-Lake Suguta in the Northern Kenya Rift during the African Humid Period (15–5kaBP)". Global and Planetary Change. 111: 174–188. Bibcode:2013GPC...111..174J. doi:10.1016/j.gloplacha.2013.09.005. ISSN 0921-8181.
- Kendall, C. G. C. (26 August 2020). Alsharhan, A.S; Glennie, K.W; Whittle, G.L; Kendall, C.G.C (eds.). Quaternary Deserts and Climatic Change. CRC Press. doi:10.1201/9781003077862. ISBN 978-1-003-07786-2.
- Kennett, Douglas J.; Kennett, James P. (1 January 2007). Influence of Holocene marine transgression and climate change on cultural evolution in southern Mesopotamia. Climate Change and Cultural Dynamics. pp. 229–264. doi:10.1016/B978-012088390-5.50012-1. ISBN 9780120883905.
- Khalidi, Lamya; Mologni, Carlo; Ménard, Clément; Coudert, Lucie; Gabriele, Marzia; Davtian, Gourguen; Cauliez, Jessie; Lesur, Joséphine; Bruxelles, Laurent; Chesnaux, Lorène; Redae, Blade Engda; Hainsworth, Emily; Doubre, Cécile; Revel, Marie; Schuster, Mathieu; Zazzo, Antoine (1 September 2020). "9000 years of human lakeside adaptation in the Ethiopian Afar: Fisher-foragers and the first pastoralists in the Lake Abhe basin during the African Humid Period". Quaternary Science Reviews. 243: 106459. Bibcode:2020QSRv..24306459K. doi:10.1016/j.quascirev.2020.106459. ISSN 0277-3791.
- Kindermann, Karin; Classen, Erich (2010). Djara: zur mittelholozänen Besiedlungsgeschichte zwischen Niltal und Oasen, Abu-Muharik-Plateau, Ägypten (in German). Köln: Heinrich-Barth-Instut. ISBN 978-3-927688-35-3. OCLC 641458909.
- Kocurek, Gary; Westerman, Robin; Hern, Caroline; Tatum, Dominic; Rajapara, H. M.; Singhvi, Ashok K. (1 April 2020). "Aeolian dune accommodation space for Holocene Wadi Channel Avulsion Strata, Wahiba Dune Field, Oman". Sedimentary Geology. 399: 105612. Bibcode:2020SedG..39905612K. doi:10.1016/j.sedgeo.2020.105612. ISSN 0037-0738.
- Krinner, G.; Lézine, A.-M.; Braconnot, P.; Sepulchre, P.; Ramstein, G.; Grenier, C.; Gouttevin, I. (2012). "A reassessment of lake and wetland feedbacks on the North African Holocene climate". Geophysical Research Letters. 39 (7). Bibcode:2012GeoRL..39.7701K. doi:10.1029/2012GL050992. ISSN 1944-8007.
- Krüger, Stefan; Beuscher, Sarah; Schmiedl, Gerhard; Ehrmann, Werner (27 January 2017). "Intensity of African Humid Periods Estimated from Saharan Dust Fluxes". PLOS ONE. 12 (1): e0170989. Bibcode:2017PLoSO..1270989E. doi:10.1371/journal.pone.0170989. ISSN 1932-6203. PMC 5271358. PMID 28129378.
- Kuper, Rudolph (January 2006). "After 5000 BC: The Libyan desert in transition". Comptes Rendus Palevol. 5 (1–2): 409–419. doi:10.1016/j.crpv.2005.10.013.
- Kuzmicheva, Evgeniya A.; Debella, Habte Jebessa; Khasanov, Bulat F.; Krylovich, Olga A.; Girmay, Wondwossen; Vasyukov, Dmitry D.; Yirga, Solomon; Savinetsky, Arkady B. (14 November 2017). "ECOSYSTEM HISTORY OF THE BALE MOUNTAINS". Ethiopian Journal of Biological Sciences. 16 (1): 61–93. ISSN 1819-8678.
- Lancaster, Nicholas (2020). "On the formation of desert loess". Quaternary Research. 96: 105–122. Bibcode:2020QuRes..96..105L. doi:10.1017/qua.2020.33. ISSN 0033-5894.
- Lebamba, Judicaël; Vincens, Annie; Lézine, Anne-Marie; Marchant, Rob; Buchet, Guillaume (December 2016). "Forest-savannah dynamics on the Adamawa plateau (Central Cameroon) during the "African humid period" termination: A new high-resolution pollen record from Lake Tizong". Review of Palaeobotany and Palynology. 235: 129–139. doi:10.1016/j.revpalbo.2016.10.001. ISSN 0034-6667.
- Lernia, Savino di; Biagetti, Stefano; Ryan, Kathleen; Bruni, Silvia; Cramp, Lucy; Salque, Mélanie; Evershed, Richard P.; Dunne, Julie (June 2012). "First dairying in green Saharan Africa in the fifth millennium bc". Nature. 486 (7403): 390–394. Bibcode:2012Natur.486..390D. doi:10.1038/nature11186. ISSN 1476-4687. PMID 22722200. S2CID 39800.