Open main menu
Global mean sea level evolution from different datasets (1993–2018).

At least since 1880, the average global sea level has been rising. This is due mostly to anthropogenic global warming that is driving the thermal expansion of seawater while melting land-based ice sheets and glaciers.[1] This trend is expected to accelerate during the 21st century.[2]:62

Projecting future sea level has always been challenging, due to our imperfect understanding of many aspects of the climate system. As climate research leads to improved computer models, projections have consistently increased. For example, in 2007 the high end of Intergovernmental Panel on Climate Change (IPCC) projections through 2099 was less than 2 feet (0.61 m),[3] but in their 2014 report the high end was considered to be about 3 feet (0.91 m).[4] A number of later studies have concluded that 2.0 to 2.7 metres (6 ft 7 in to 8 ft 10 in) rise this century is "physically plausible".[5] The contributions to sea level rise since 1993, based on 2018 figures, divide into ocean thermal expansion (42%), melting of temperate glaciers (21%), Greenland (15%) and Antarctica (8%).[6]

Sea level rise will not be the same at every location on earth, with some locations even getting a drop in sea levels. Local factors include tectonic effects, and subsidence of the land, tides, currents and storms. Sea level rise is expected to continue for centuries. Because of long response times for parts of the climate system, it has been estimated that we are committed to a sea-level rise of approximately 2.3 metres (7.5 ft) for each Celsius degree of temperature rise within the next 2,000 years.[7]

Sea level rises can considerably influence human populations in coastal and island regions and natural environments like marine ecosystems.[8] Widespread coastal flooding would be expected if several degrees of warming is sustained for millennia.[9] For example, sustained global warming of more than 2 C° relative to pre-industrial levels could lead to eventual sea level rise of about 1–4 metres (3.3–13 ft).[9]

Societies can respond to sea level rise in three different ways: retreat, accommodate and protect. Sometimes these adaptation strategies go hand in hand, but at other times choices have to be made between different strategies. Ecosystems that adapt to rising sea levels by moving inland might not always be able to do so, due to natural or man made barriers.

Contents

Past changes in sea levelEdit

 
Changes in sea level since the end of the last glacial episode

Understanding past sea level is important for the analysis of current and future changes. In the recent geological past changes in land ice and thermal expansion from increased temperatures are the dominant reasons of sea level rise. The last time the Earth was 2 °C warmer than the pre-industrial temperatures, sea levels were at least 5 metres (16 ft) higher than present. This was during the last interglacial, when the earth warming was caused by slow changes in the orbital forcing. The warming was sustained over a period of thousands of years and the magnitude of the rise in sea level implied a large contribution from the Antarctic and Greenland ice sheets.[10]:1139

Since the last glacial maximum about 20,000 years ago, the sea level has risen by more than 125 metres (410 ft), with rates varying from less than a mm/year to 40+ mm/year, as a result of melting ice sheets over Canada and Eurasia. Rapid disintegration of ice sheets led to so called 'meltwater pulses', periods during which sea level rose rapidly. The rate of rise started to slow down 8.2 thousand years before present; the sea level was almost constant in the last 2,500 years, before the recent rising trend starting approximately in 1850.[11]

Sea level measurementEdit

To get precise measurements for sea level, researchers studying the state of frozen water and the ocean on our planet factor in ongoing deformations of the solid Earth, in particular due to landmasses still rising from past ice masses retreating. Additionally, Earth gravitation and rotation have to be accounted for. These factors are dependent on the different layers which make up the Earth (lithosphere, asthenosphere), and the order in which land-based ice melts. Because the involved processes, which are collectively known as the Sea-level equation, change very slowly, on time scales of thousands of years, they are considered to be constant.[6]

SatellitesEdit

 
Jason-1 continued the sea surface measurements started by TOPEX/Poseidon. It was followed by the Ocean Surface Topography Mission on Jason-2, and by Jason-3
 
Satellite measurements of sea level, in millimeters, 1993–2018 (April).
 
Sea level trends from satellite altimetry (1993–2012)

Since the 1992 launch of TOPEX/Poseidon, altimetric satellites have been recording the change in sea level.[12] Those satellites can measure the hills and valleys in the sea caused by currents and detect trends in their height. To measure the distance to the sea surface, the satellite sends a microwave pulse to the ocean's surface and record the time it takes to return. A microwave radiometer corrects any delay that may be caused by water vapor in the atmosphere. Combining this data with the precise location of the spacecraft makes it possible to determine sea-surface height to within a few centimeters (about one inch).[13] Current rates of sea level rise from satellite altimetry have been estimated to be 3.0 ± 0.4 millimetres (0.118 ± 0.016 in) per year for the period 1993–2017.[14] Earlier satellite measurements were previously at odds with tide gauge measurements. A small calibration error for the Topex/Poseidon satellite discovered in 2015 was identified as the cause of this mismatch. It had caused a slight overestimation of the 1992–2005 sea levels, which masked the ongoing sea level rise acceleration.[15]

With satellites it is possible to capture regional variations in sea level rise well. In the 1993–2012 period for instance, sea level rose substantially in the western tropical Pacific. The sharp rise in this area has been linked to increasing trade winds, which occur when the Pacific Decadal Oscillation (PDO) and the El Niño–Southern Oscillation (ENSO) change from one state to the other.[16] The PDO is a basin-wide climate pattern consisting of two phases, each commonly lasting 10 to 30 years, while the ENSO has a shorter period of 2 to 7 years.[17]

Tide gaugesEdit

Another important source of sea-level observations comes from the global network of tide gauges. In contrast to the satellite record, this record has a lot of spatial and temporal gaps.[18] Coverage of tide gauges started primarily in the Northern Hemisphere, with data for the Southern Hemisphere remained scarce up to the 1970s.[18] The longest running sea-level measurements, NAP or Amsterdam Ordnance Datum established in 1675, are recorded in Amsterdam, the Netherlands.[19] In Australia, record collection is also quite extensive, including measurements by an amateur meteorologist beginning in 1837 and measurements taken from a sea-level benchmark struck on a small cliff on the Isle of the Dead[20] near the Port Arthur convict settlement in 1841.

This network was used, in combination with satellite altimeter data, to establish that global mean sea-level rose 19.5 cm (7.7 in) between 1870 and 2004 at an average rate of about 1.44 mm/yr (1.7 mm/yr during the 20th century).[21] This is an important confirmation of climate change simulations, predicting that SLR will accelerate in response to global warming. In Australia, data collected by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) show the current global mean sea level trend to be 3.2 mm (0.13 in) per year, a doubling of the rate during the 20th century.[22][23]

Some regional differences are also visible in the tide gauge data. Some of the recorded regional differences are due to differences in the actual sea level, while other are due to vertical land movements. In the United States for instance, considerable variation is found because some land areas are rising and some are sinking. Over the past 100 years, the rate of sea level rise varied from an increase of about 0.36 inches (9.1 mm) per year along the Louisiana Coast due to land sinking, to a drop of a few inches per decade in parts of Alaska due to post-glacial rebound. The rate of sea level rise increased during the 1993–2003 period compared with the longer-term average (1961–2003), although it is unclear whether the faster rate reflected a short-term variation or an increase in the long-term trend.[24]

ContributionsEdit

 
Close-up of Ross Ice Shelf, the largest ice shelf of Antarctica, about the size of France and up to several hundred metres thick.

There are three main contributions to sea level rise. Oceans expand if they are warming, glaciers at high altitudes melt and the total mass of ice sheets decreases. Sea level rise in the last 150 years was dominated by retreat of glaciers and expansion of the ocean, but the contributions of the two large ice sheets (Greenland and Antarctica) is expected to increase in the 21st century.[1] The ice sheets store most of the land ice (∼99.5%), with a sea-level equivalent (SLE) of 7.4 m (24 ft) for Greenland and 58.3 m (191 ft) for Antarctica.[6]

Each year about 8 mm (0.31 in) of precipitation (liquid equivalent) falls on the ice sheets in Antarctica and Greenland, mostly as snow, which accumulates and over time forms glacial ice. Much of this precipitation began as water vapor evaporated from the ocean surface. To a first approximation, the same amount of water appeared to return to the ocean in icebergs and from ice melting at the edges. Scientists previously had estimated which is greater, ice going in or coming out, called the glacier mass balance, important because a nonzero balance causes changes in global sea level. The rate of ice loss is accelerating.[25]

Ocean heatingEdit

 
Ocean heat content (OHC), NOAA 2012

In terms of heat content, it is the world ocean that dominates the atmospheric climate. The oceans store more than 90% of the heat in Earth's climate system and act as a buffer against the effects of climate change. For instance, an average temperature increase of the entire world ocean by 0.01 °C may seem small, but in fact it represents a very large increase in heat content. If all the heat associated with this anomaly was instantaneously transferred to the entire global atmosphere it would increase the average temperature of the atmosphere by approximately 10 °C.[26] Thus, a small change in the mean temperature of the ocean represents a very large change in the total heat content of the climate system. Of course, when the ocean gains heat the water expands and this represents a component of global sea-level rise.

The thermal expansion of water increases with temperature and pressure of the water. Hence, cold Arctic Ocean water will expand less for a given increase in temperature compared to warm tropical water. Because different climate models have slightly different patterns of ocean heating, they do not agree fully on the predictions for the contribution of ocean heating on sea level rise.[27]

AntarcticaEdit

 
Processes around an Antarctic ice shelf

The large volume of ice on the Antarctic continent stores around 70% of the world's fresh water.[28] The Antarctic ice sheet mass balance is affected by snowfall accumulations, and ice discharge along the periphery. Under the influence of global warming, melt at the base of the ice sheet increases. Simultaneously, the capacity of the atmosphere to carry precipitation increases with temperature so that precipitation, in the form of snowfall, increases. Furthermore, the additional snowfall causes increased ice flow which leads to further loss of ice.[29]

Different satellite methods for measuring ice mass and change are in good agreement, and combining methods leads to more certainty how the East Antarctic Ice Sheet, the West Antarctic Ice Sheet, and the Antarctic Peninsula evolve.[30] A 2018 systematic review study estimated that ice loss across the entire continent was 43 gigatons (Gt) per year on average during the period from 1992 to 2002, but has accelerated to an average of 220 Gt per year during the five years from 2012 to 2017. Most of the melt comes from the West Antarctic Ice Sheet, but the Antarctic Peninsula also positively contributes. The East Antarctic Ice Sheet does not contribute much and scientists are not able to determine whether it gains or loses mass.[31] The sea-level budget from Antarctica has been estimated to be 0.25 mm (0.0098 in) per year from 1993–2005, and 0.42 mm (0.017 in) per year from 2005 to 2015. All datasets generally show an acceleration of mass loss from the Antarctic ice-sheet, but with year-to-year variations.[6]

East AntarcticaEdit

The world's largest potential source of sea level rise is the East Antarctic Ice Sheet, which holds enough ice to raise global sea levels by 53.3 m.[32] Satellite observations suggest the overall mass balance of the East Antarctic Ice Sheet was relatively steady or slightly positive for much of the period from 1992–2017,[33] with the notable exception of Totten Glacier, which has steadily lost mass in recent decades [34] in response to ocean warming[35][36] and possibly a reduction in local sea ice cover.[37] Totten Glacier is the primary outlet of the Aurora Sublgacial Basin, which together with the Wilkes Basin are the two major ice reservoirs in East Antarctica which are subject to potential rapid collapse through marine ice sheet instability.

West AntarcticaEdit

West Antarctica is currently experiencing a net outflow of glacial ice, which will increase global sea level over time. A review of the scientific studies looking at data from 1992 to 2017 suggests an increase in the melt from around 53 ± 29 Gt of ice per year to 159 ± 26 Gt.[31] Significant acceleration of outflow glaciers in the Amundsen Sea Embayment may have contributed to this increase.[38] The data showed that the Amundsen Sea sector of the West Antarctic Ice Sheet was discharging 250 cubic kilometres (60 cu mi) of ice every year, which was 60% more than the precipitation accumulation in the catchment areas. This alone was sufficient to raise the sea level at 0.24 mm (0.0094 in) per year. Further, thinning rates for the glaciers studied in 2002–2003 had increased over the values measured in the early 1990s.

Annual temperatures based on Byrd Station (central West Antarctica) from 1958 to 2010 increased linear by 2.4 ± 1.2 °C, the study authors note, "West Antarctica as one of the fastest-warming regions globally. In contrast to previous studies, we report statistically significant warming [...] particularly in December–January, the peak of the melting season. A continued rise in summer temperatures could lead to more frequent and extensive episodes of surface melting of the West Antarctic Ice Sheet."[39]

A graphical representation of how warm waters, and the Marine Ice Sheet Instability and Marine Ice Cliff Instability processes are affecting the West Antarctic Ice Sheet

Two types of instability are at play in West Antarctica. The first one is the Marine Ice Sheet Instability, the bedrock on which parts of the ice sheet rest is moving deeper inland. This means that when a part of the ice sheet melts, a thicker part of the ice sheet is exposed, which may lead to additional ice loss. Secondly, melting of the ice shelfs, the floating extensions of the ice sheet, leads to a process named the Marine Ice Cliff Instability. Because they function as a buttress to the ice sheet, their melt leads to additional ice flow. Melt of ice shelfs is accelerated when surface melt creates crevasses and these crevasses cause fracturing.[40]

Since most of the bedrock underlying the West Antarctic Ice Sheet lies well below sea level and ocean waters are warming, the ice sheet is becoming less stable.[41] A rapid collapse of West Antarctic Ice Sheet could raise sea level by 3.3 metres (11 ft) at an unknown rate.[42][43]

The Thwaites and Pine Island glaciers have been identified to be potentially prone to these processes, since both glaciers bedrock topography gets deeper farther inland, exposing them to more warm water intrusion at the grounding line, and with the continued melt, retreat, eventually raising global sea levels.[44][45]

GreenlandEdit

 
Greenland 2007 melt anomaly, measured as the difference between the number of days on which melting occurred in 2007 compared to the average annual melting days from 1988–2006[46]

Most ice on Greenland is part of the Greenland ice sheet which rises to an average of 2.135 kilometres (1.327 mi). The rest of the ice on Greenland is part of isolated glaciers and ice caps.

The sources contributing to sea level rise from Greenland are from ice sheet melting (70%) and from glacier calving (30%). Dust, soot, and microbes and algae living on parts of the ice sheet further enhance melting by darkening its surface and thus absorbing more thermal radiation; these regions grew by 12% between 2000 and 2012, and are likely to expand further. Estimates on future contribution to sea level rise from Greenland range from 0.3 to 3 metres (1 ft 0 in to 9 ft 10 in), for the year 2100.[47]

Some of Greenland's largest outlet glaciers, such as Jakobshavn Isbræ and Kangerlussuaq Glacier have seen an acceleration in how fast they are flowing into the ocean.[48][49] It was shown that this acceleration of outlet glaciers had mostly taken place on the Southern part of Greenland (66 N in 1996), but had spread further north (70 N) in 2005.[50]

The contribution of the Greenland ice sheet on sea level over the next couple of centuries can be very high due to a self-reinforcing cycle (a so-called positive feedback). After an initial period of melting, the height of the ice sheet will have lowered. As air temperature increases closer to the sea surface, more melt starts to occur. This melting may further be accelerated because the color of ice is darker while it is melting. There is a threshold in surface warming beyond which a partial or near-complete melting of the Greenland ice sheet occurs. Different research has put this threshold value as low as 1.0 °C, and definitely 4.0 °C, above pre-industrial temperatures.[51][10]:1170

Accounting for the Greenland ice sheet, its peripheral glaciers and ice caps, contributions to current sea level rise have been estimated to be 43%. A study published in 2017, concluded that Greenland’s glaciers and ice caps crossed an irreversible tipping point in 1997, and will continue to melt.[52][53] Results based on the existing literature found estimates for the Greenland ice sheet and its glaciers and ice caps, they were the largest contributor to the observed sea level rise from land ice sources (excluding thermal expansion), combined accounting for 71 percent, or 1.32 mm per year during the 2012–2016 period.[54]

GlaciersEdit

Mountain glaciers include only a minor fraction of all water bound up in glaciers ice (<1%), compared to a bigger portion in Greenland and Antarctica (99%). Still, mountain glaciers have contributed appreciably to historical sea level rise and are set to contribute a smaller, but still significant fraction of sea level rise in the 21st century.[55] The roughly 200,000 glaciers on earth are spread out across all continents.[56] Different glaciers respond differently to increasing temperatures. For instance, valley glaciers that have a shallow slope already retreat under mild warming. Every glacier has a height above which there is net gain in mass and under which the glacier loses mass. If that height changes a bit, this has large consequences for glaciers with a shallow slope.[57]:345 A large set of glaciers drain into the ocean and ice loss can therefore increase when ocean temperatures increase.[56]

Observational and modelling studies of mass loss from glaciers and ice caps indicate a contribution to sea-level rise of 0.2–0.4 mm/yr, averaged over the 20th century.[58] Over the 21st century, this is expected to rise, with glaciers contributing 7 to 24 centimetres (3 to 9 in) to global sea levels.[10]:1165 Glaciers contributed around 40% to sea-level rise during the 20th century, with estimates for the 21st century of around 30%.[6]

Sea iceEdit

Sea ice melt has a very small contribution to global sea level rise. According to Archimedes' principle, sea ice that melts does not take up more volume than it had in the form of sea ice or icebergs. However, this only holds true in the case that the salinity of the sea ice and sea water are equal. This assumption is not valid in the case of melting sea ice, where the sea ice contains less salt than sea water. Fresh water has a larger volume compared to salt water, and as such there can be a small contribution of sea ice melt. In the case that all floating ice shelves and icebergs melt, the sea levels would rise only by about 4 cm (1.6 in).[59]

Land water storageEdit

 
Trends in land water storage from GRACE observations in gigatons per year, April 2002 to November 2014 (glaciers and ice sheets are excluded).

Humans impact how much water is stored on land. Building dams prevents large masses of water from flowing into the sea and therefore increases the storage of water on land. On the other hand humans extract water from lakes, wetlands and underground reservoirs for food production leading to rising seas. Furthermore, the hydrological cycle is influenced by climate change and deforestation, which can lead to further positive and negative contributions to sea level rise. In the 20th century, these processes roughly balanced, but dam building has slowed down and is expected to stay low for the 21st century.[60][10]:1155

ModelsEdit

There are broadly two ways of modelling sea level rise and making future projections. On the one hand, scientist use process-based modelling, where all relevant and well-understood physical processes are included in a physical model. An ice-sheet model is used to calculate the contributions of ice sheets and a general circulation model is used to compute the rising sea temperature and its expansion. A disadvantage of this method is that not all relevant processes might be understood to a sufficient level. Alternatively, some scientist use semi-empirical techniques that use geological data from the past to determine likely sea level responses to a warming world in addition to some basic physical modelling. Semi-empiral modelling relies on sophisticated statistical techniques.[1] This type of modelling was partially motivated by the fact that in the 2007 IPCC report, most physical models underestimated the amount of sea level rise compared to observations.[10]

ProjectionsEdit

 
This graph shows the minimum projected change in global sea level rise if atmospheric carbon dioxide (CO2) concentrations were to either quadruple or double. [61] The projection is based on several multi-century integrations of a GFDL global coupled ocean-atmosphere model. These projections are the expected changes due to thermal expansion of sea water alone, and do not include the effect of melted continental ice sheets. With the effect of ice sheets included the total rise will be larger, by an uncertain but possibly substantial factor.[61] Image credit: NOAA GFDL.

21st centuryEdit

The Intergovernmental Panel on Climate Change (IPCC) has made predictions of sea level changes to the year 2100, using the available scientific literature. Their projections are based on the contributors to sea level rise, but do exclude some processes that are less understood. In the case of rapid cuts in emission (the so-called RCP2.6 scenario), the IPCC deem it likely that the sea level will rise to 26–55 cm (10–22 in) with a 67% confidence interval. The higher value should thus not be read as an upper limit, which can be substantially higher. For a scenario with very high emissions, the IPCC project the sea level to rise to 52–98 cm (20–39 in).[10] Compared to the previous IPCC estimate, more sea level rise is expected for similar scenarios.[62]

Projections assessed by the US National Research Council (2010)[63] suggest possible sea level rise over the 21st century of between 56 and 200 cm (22 and 79 in). The NRC describes the IPCC projections as "conservative".[63] In 2011, Rignot and others projected a rise of 32 centimetres (13 in) by 2050. Their projection included increased contributions from the Antarctic and Greenland ice sheets. Use of two completely different approaches reinforced the Rignot projection.[64][65] Other estimates suggest that for the same period, global mean sea level could rise by 0.2 to 2.0 m (8 in to 6 ft 7 in), relative to the mean sea level in 1992.[66]

The Third National Climate Assessment (NCA), released May 6, 2014, projected a sea level rise of 1 to 4 feet (0.3 to 1 m) by 2100. Decision makers who are particularly susceptible to risk may wish to use a wider range of scenarios from 20 to 200 cm (8 to 80 in) by 2100.[67]

A 2016 study concluded that based on past climate change data, sea level rise could accelerate exponentially in the coming decades, with a doubling time of 10, 20 or 40 years, respectively, raising the ocean by several meters, in 50, 100 or 200 years.[68] However, Greg Holland from the National Center for Atmospheric Research, who reviewed the study, noted: “There is no doubt that the sea level rise, within the IPCC, is a very conservative number, so the truth lies somewhere between IPCC and Jim.[69]

One 2017 study's scenario, assuming high fossil fuel use for combustion and strong economic growth during this century, projects sea level rise of up to 1.32 metres (4.3 ft) on average — and an extreme scenario with as much as 1.89 metres (6.2 ft), by 2100. This could mean rapid sea level rise of up to 19 millimeters per year by the end of the century. The study also concluded that the Paris climate agreement emissions scenario, if met, would result in a median 0.52 metres (1.7 ft) of sea level rise by 2100.[70][71]

Estimates of future sea level were also produced in the 20th century. For instance, Hansen et al. 1981, published the study Climate impact of increasing atmospheric carbon dioxide, and predicted that anthropogenic carbon dioxide warming and its potential effects on climate in the 21st century could cause a sea level rise of 5 to 6 m (16 to 20 ft), from melting of the West Antarctic ice-sheet alone.[72]

After 2100Edit

 
Map of the Earth with a long-term 6-metre (20 ft) sea level rise represented in red (uniform distribution, actual sea level rise will vary regionally).

There is a widespread consensus that substantial long-term sea-level rise will continue for centuries to come even if the temperature stabilizes.[73] IPCC AR4 estimated that at least a partial deglaciation of the Greenland ice sheet, and possibly the West Antarctic ice sheet, would occur given a global average temperature increase of 1–4 °C (relative to temperatures over the years 1990–2000).[74] This estimate was given about a 50% chance of being correct.[75] The estimated timescale was centuries to millennia, and would contribute 4 to 6 metres (13 to 20 ft) or more to sea levels over this period.

Melting of the Greenland ice sheet could contribute an additional 4 to 7.5 m (10 to 20 ft) over many thousands of years.[9] It has been estimated that we are already committed to a sea-level rise of approximately 2.3 m (7 ft 7 in) for each degree of temperature rise within the next 2,000 years.[76] Warming beyond the 2 °C target would potentially lead to rates of sea-level rise dominated by ice loss from Antarctica. Continued carbon dioxide emissions from fossil fuel sources could cause additional tens of metres of sea level rise, over the next millennia, and ultimately melt the entire Antarctic ice sheet, causing about 58 m (190 ft) of sea level rise.[77]

After 500 years, sea-level rise from thermal expansion alone may have reached only half of its eventual level, which models suggest may lie within ranges of 0.5 to 2 m (1 ft 8 in to 6 ft 7 in).[78]

Rising sea levels will cause flooding and may erase entire cities. In a study published by Nature, the entire state of Delaware could be completely wiped out by 2500.[79]

Regional sea level riseEdit

Subsidence, isostatic rebound, gravitational effects of changing ice masses, and spatially varying patterns of warming lead to differences in sea level rise around the globe.[80]

Many ports, urban conglomerations, and agricultural regions are built on river deltas, where subsidence of land contributes to a substantially increased effective sea level rise. This is caused by both unsustainable extraction of groundwater (in some places also by extraction of oil and gas), and by levees and other flood management practices that prevent accumulation of sediments from compensating for the natural settling of deltaic soils.[81] In many deltas, this results in subsidence ranging from several millimeters per year up to possibly 25 centimeters per year in parts of the Ciliwung delta (Jakarta).[82] Total anthropogenic-caused subsidence in the Rhine-Meuse-Scheldt delta (Netherlands) is estimated at 3 to 4 m (9.8 to 13.1 ft), over 3 m (9.8 ft) in urban areas of the Mississippi River Delta (New Orleans), and over 9 m (30 ft) in the Sacramento-San Joaquin River Delta.[83]

The Atlantic is set to warm at a faster pace than the Pacific. This has consequences for Europe and the U.S. East Coast, which may receive a sea level rise 3–4 times the global average.[84] The downturn of the Atlantic meridional overturning circulation (AMOC) has been also tied to extreme regional sea level rise on the US Northeast Coast.[85]

EffectsEdit

 
Map of major cities of the world most vulnerable to sea level rise

Current and future climate change is set to have a number of impacts, particularly on coastal systems. Such impacts include increased coastal erosion, higher storm-surge flooding, inhibition of primary production processes, more extensive coastal inundation, changes in surface water quality and groundwater characteristics, increased loss of property and coastal habitats, increased flood risk and potential loss of life, loss of non-monetary cultural resources and values, impacts on agriculture and aquaculture through decline in soil and water quality, and loss of tourism, recreation, and transportation functions.[86]:356

Many of these impacts are detrimental — especially for the three-quarters of the world's poor who depend on agriculture systems.[87] The report does, however, note that owing to the great diversity of coastal environments; regional and local differences in projected relative sea level and climate changes; and differences in the resilience and adaptive capacity of ecosystems, sectors, and countries, the impacts will be highly variable in time and space. River deltas and small island states are particularly vulnerable to sea-level rise.

Globally tens of millions of people will be displaced in the latter decades of the century if greenhouse gases are not reduced drastically. Many coastal areas have large population growth, which results in more people at risk from sea level rise. The rising seas pose both a direct risk: unprotected homes can be flooded, and indirect threats of higher storm surges, tsunamis and king tides. Asia has the largest population at risk from sea level with countries such as Bangladesh, China, India, Indonesia, and Vietnam having very densely populated coastal areas.[88] The effects of displacement are very dependent on how successful governments will be in implementing defenses against the rising sea, with concerns for the poorerst countries such as sub-Saharan countries and island nations.[89]

Coastal areasEdit

Ten per cent of the world's population live in coastal areas that are less than 10 metres (33 ft) above sea level. Furthermore, two thirds of the world's cities with over five million people are located in these low-lying coastal areas.[90] Future sea level rise could lead to potentially catastrophic difficulties for shore-based communities in the next centuries: for example, many major cities such as Venice, London, New Orleans, and New York City already need storm-surge defenses, and will need more if the sea level rises; they also face issues such as subsidence.[91][citation needed] The Egyptian city Alexandria faces a similar situation, where hundreds of thousands people living in the low-lying areas may already have to be relocated in the coming decade. The nearby farmland in the Nile Delta is also affected by salt water flooding.[92] However, modest increases in sea level are likely to be offset when cities adapt by constructing sea walls or through relocating.[93]

The impacts of sea level rise are strong in the eastern coast of United States.[94] Miami has been listed as "the number-one most vulnerable city worldwide" in terms of potential damage to property from storm-related flooding and sea-level rise.[95] According to a 2011 study conducted by the U.S. Geological Survey, 68 percent of beaches in New England and the mid-Atlantic states observe coastal erosion, with some barrier beaches in Louisiana recording twenty or more meters of eroding coastlines per year. However, the rate of coastal erosion is partially related to human developments, eg, bulldozing dunes.[96]

Rising seas has also been tied to an increased risk from tsunamis, potentially affecting coastal cities in the Pacific and Atlantic Oceans.[97]

Island nationsEdit

Atolls and low-lying coastal areas on islands are particularly vulnerable to sea level rise. Possible impacts include coastal erosion, floodings and salt intrusion into soils and freshwater. It is difficult to assess how much of past erosion and floods have been caused by sea level change, compared to other environmental events such as hurricanes. Adaptation to sea level rise is costly for small island nation as a large portion of their population lives in areas that are at risk.[98]

 
Schematic animation of projected sea level rise around Taiwan

Maldives, Tuvalu, and other low-lying countries are among the areas that are at the highest level of risk. At current rates, sea level would be high enough to make the Maldives uninhabitable by 2100.[99][100] Geomorphological events such as storms tend to have larger impacts on reef island than sea level rise, for instance at one of the Marshall Islands. These effects include the immediate erosion and subsequent regrowth process that may vary in length from decades to centuries, even resulting in land areas larger than pre-storm values. With an expected rise in the frequency and intensity of storms, they may become more significant in determining island shape and size than sea level rise.[101] Five of the Solomon Islands have disappeared due to the combined effects of sea level rise and stronger trade winds that were pushing water into the Western Pacific.[102]

In the case all islands of an island nation become uninhabitable or completely submerged by the sea, the states themselves would also become dissolved. Once this happens, all rights on the surrounding area (sea) are removed. This area can be huge as rights extend to a radius of 224 nautical miles (415 km; 258 mi) around the entire island state. Any resources, such as fossil oil, minerals and metals, within this area can be freely dug up by anyone and sold without needing to pay any commission to the (now dissolved) island state.[103]

EcosystemsEdit

Coastal ecosystems are facing drastic changes as a consequence of rising sea levels. Many systems might ultimately be lost when sea levels rise too much or too fast. Some ecosystems can move land inward with the high-water mark, but many are prevented from migrating due to natural or man-made barriers. This 'coastal squeeze' could result in the loss of habitats such as mudflats and marshes.[104] Human activities, such as dam building, may restrict sediment supplies to wetlands, and thereby prevent natural adaptation processes. The loss of some tidal marshes is unavoidable as a consequence.[105] Mangroves, among the most widely studied ecosystems in the world, adjust to rising sea levels by building vertically using accumulated sediment and organic matter. If sea level rise is too rapid, they will not be able to keep up and will instead be submerged.[106] As mangroves protect against storm surges, waves and tsunamis, losing them makes the effects of sea level rise worse.[107]

When seawater approaches inland, problems related to contaminated soils and flooded wetlands may occur. Also, fish, birds, and coastal plants could lose parts of their habitat.[108] Coral, important for bird and fish life, needs to grow vertically to remain close to the sea surface in order to get enough energy from sunlight. It has so far been able to keep up the vertical growth with the rising seas, but might not be able to do so in the future.[109] In 2016, it was reported that the Bramble Cay melomys, which lived on a Great Barrier Reef island, had probably become extinct because of inundation due to sea level rises.[110]

AdaptationEdit

 
Beach nourishment in progress in Barcelona.

Adaptation options to sea level rise can be broadly classified into retreat, accommodate and protect. Retreating is moving people and infrastructure to less exposed areas and preventing further development in areas that are at risk. This type of adaptation is potentially disruptive, as displacement of people might lead to tensions. Accommodation options are measurements that make societies more flexible to sea level rise. Examples are the cultivation of food crops that tolerate a high salt content in the soil and making new building standards which require building to be built higher and have less damage in the case a flood does occur. Finally, areas can be protected by the construction of dams, dikes and by improving natural defenses.[111][112]

These adaptation options can be further divided into hard and soft. Hard adaptation relies mostly on capital-intensive human-built infrastructure and involves large-scale changes to human societies and ecological systems. Because of its large scale, it is often not flexible. Soft adaptation involves strengthening natural defenses and adaptation strategies in local communities and the use of simple and modular technology, which can be locally owned. The two types of adaptation might be complementary or mutually exclusive. The building of a dike (hard adaptation) for instance destroys the natural dune system and dune nourishment will not be possible anymore.[112][113]

Many countries are developing concrete plans for adaptation. An example is the extension of the Dutch Delta Works. In 2008, the Dutch Delta Commission, advised in a report that the Netherlands would need a massive new building program to strengthen the country's water defenses against the anticipated effects of global warming for the next 190 years. This included drawing up worst-case plans for evacuations. The plan also included more than €100 billion (US$113 billion) in new spending through to the year 2100 to implement precautionary measures, such as broadening coastal dunes and strengthening sea and river dikes. The commission said the country must plan for a rise in the North Sea up to 1.3 metres (4 ft 3 in) by 2100 and plan for a 2-4 m rise by 2200.[114] About a quarter of the Netherlands lies beneath sea level, while more than 50% of the nation's area would be inundated by tidal floods if it did not have an extensive levee system.

The New York City Panel on Climate Change (NPCC) is an effort to prepare the New York City area for climate change. Miami Beach is spending $500 million from 2015 to 2020 to address sea-level rise. Actions include a pump drainage system, and raising of roadways and sidewalks.[115] U.S. coastal cities also conduct so called beach nourishment, also known as beach replenishment, where new beach sand is trucked in and added.[96]

Options that have been proposed to assist island nations to adapt to rising sea level include abandoning islands, building dikes, and "building upwards."[116]

See alsoEdit

NotesEdit

  1. ^ a b c Mengel, Matthias; Levermann, Anders; Frieler, Katja; Robinson, Alexander; Marzeion, Ben; Winkelmann, Ricarda (2016-02-18). "Future sea level rise constrained by observations and long-term commitment". Proceedings of the National Academy of Sciences. 113 (10): 2597–602. doi:10.1073/pnas.1500515113. ISSN 0027-8424. PMC 4791025. PMID 26903648.
  2. ^ Climate Change 2014 Synthesis Report Fifth Assessment Report, AR5 (Report). Intergovernmental Panel on Climate Change. 2014. Under all RCP scenarios, the rate of sea level rise will very likely exceed the rate of 2.0 [1.7–2.3] mm/yr observed during 1971–2010
  3. ^ IPCC, "Summary for Policymakers", Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007, page 13-14"Models used to date do not include uncertainties in climate-carbon cycle feedback nor do they include the full effects of changes in ice sheet flow, because a basis in published literature is lacking."
  4. ^ Mooney, Chris. "Scientists keep upping their projections for how much the oceans will rise this century". Washington Post.
  5. ^ Global and Regional Sea Level Rise Scenarios for the United States (PDF) (Report) (NOAA Technical Report NOS CO-OPS 083 ed.). National Oceanic and Atmospheric Administration. January 2017. p. vi. Retrieved 24 August 2018."The projections and results presented in several peer-reviewed publications provide evidence to support a physically plausible GMSL rise in the range of 2.0 meters (m) to 2.7 m, and recent results regarding Antarctic ice-sheet instability indicate that such outcomes may be more likely than previously thought."
  6. ^ a b c d e WCRP Global Sea Level Budget Group (2018). "Global sea-level budget 1993–present". Earth System Science Data. doi:10.5194/essd-10-1551-2018.
  7. ^ Anders Levermann, Peter U. Clark, Ben Marzeion, Glenn A. Milne, David Pollard, Valentina Radic, and Alexander Robinson (13 June 2013). "The multimillennial sea-level commitment of global warming". PNAS. 110 (34): 13745–13750. Bibcode:2013PNAS..11013745L. doi:10.1073/pnas.1219414110. PMC 3752235. PMID 23858443.
  8. ^ Bindoff, N.L., J. Willebrand, V. Artale, A, Cazenave, J. Gregory, S. Gulev, K. Hanawa, C. Le Quéré, S. Levitus, Y. Nojiri, C.K. Shum, L.D. Talley and A. Unnikrishnan (2007), "Section 5.5.1: Introductory Remarks", in IPCC AR4 WG1 2007, Chapter 5: Observations: Ocean Climate Change and Sea Level, ISBN 978-0-521-88009-1, retrieved 25 January 2017
  9. ^ a b c Box SYN-1: Sustained warming could lead to severe impacts, p. 5, in: Synopsis, in National Research Council 2011
  10. ^ a b c d e f Church, J.A.; Clark, P.U. (2013). "Sea Level Change". In Stocker, T.F.; et al. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
  11. ^ Lambeck, Kurt; Rouby, Hélène; Purcell, Anthony; Sun, Yiying; Sambridge, Malcolm (2014-10-28). "Sea level and global ice volumes from the Last Glacial Maximum to the Holocene". Proceedings of the National Academy of Sciences. 111 (43): 15296–15303. doi:10.1073/pnas.1411762111. ISSN 0027-8424. PMC 4217469. PMID 25313072.
  12. ^ "Ocean Surface Topography from Space". NASA/JPL.
  13. ^ "Jason-3 Satellite - Mission". www.nesdis.noaa.gov. Retrieved 2018-08-22.
  14. ^ Nerem, R. S.; Beckley, B. D.; Fasullo, J. T.; Hamlington, B. D.; Masters, D.; Mitchum, G. T. (2018-02-07). "Climate-change–driven accelerated sea-level rise detected in the altimeter era". Proceedings of the National Academy of Sciences. 115 (9): 2022–2025. doi:10.1073/pnas.1717312115. ISSN 0027-8424. PMC 5834701. PMID 29440401.
  15. ^ Michael Le Page (11 May 2015). "Apparent slowing of sea level rise is artefact of satellite data".
  16. ^ Merrifield, Mark A.; Thompson, Philip R.; Lander, Mark (2012). "Multidecadal sea level anomalies and trends in the western tropical Pacific". Geophysical Research Letters. 39 (13): n/a. doi:10.1029/2012gl052032. ISSN 0094-8276.
  17. ^ Mantua, N.J., Hare, S.R., Zhang, Y., Wallace, J.M., Francis, R.C.; Hare; Zhang; Wallace; Francis (1997). "A Pacific interdecadal climate oscillation with impacts on salmon production". Bulletin of the American Meteorological Society. 78 (6): 1069–79. Bibcode:1997BAMS...78.1069M. doi:10.1175/1520-0477(1997)078<1069:APICOW>2.0.CO;2. ISSN 1520-0477.
  18. ^ a b Rhein, Monika; Rintoul, Stephan (2013). "Observations: Ocean". IPCC AR5 WGI (PDF). New York: Cambridge University Press. p. 285.
  19. ^ "Other Long Records not in the PSMSL Data Set". PSMSL. Retrieved 11 May 2015.
  20. ^ Hunter, John; R. Coleman; D. Pugh (April 2003). "The Sea Level at Port Arthur, Tasmania, from 1841 to the Present". Geophysical Research Letters. 30 (7): 1401. Bibcode:2003GeoRL..30.1401H. doi:10.1029/2002GL016813.
  21. ^ Church, J. A., White, N.J.; White (2006). "20th century acceleration in global sea-level rise". Geophysical Research Letters. 33 (1): L01602. Bibcode:2006GeoRL..33.1602C. doi:10.1029/2005GL024826.
  22. ^ "Historical sea level changes: Last decades". www.cmar.csiro.au. Retrieved 2018-08-26.
  23. ^ Neil, White. "Historical Sea Level Changes". CSIRO. Retrieved 25 April 2013.
  24. ^ "Sea Level Changes". United States Environmental Protection Agency. Retrieved Jan 5, 2012.
  25. ^ Sea level rise overflowing estimates; Feedback mechanisms are speeding up ice melt November 8, 2012 Science News
  26. ^ Levitus, S., Boyer, T., Antonov, J., Garcia, H., and Locarnini, R. (2005) Ocean Warming 1955–2003 Archived 17 July 2009 at the Wayback Machine.. Poster presented at the U.S. Climate Change Science Program Workshop, 14–16 November 2005, Arlington VA, Climate Science in Support of Decision-Making; Last viewed 22 May 2009 .
  27. ^ Kuhlbrodt, T; Gregory, J.M. (2012). "Ocean heat uptake and its consequences for the magnitude of sea level rise and climate change". Geophysical Research Letters. 39 (18). doi:10.1029/2012GL052952.
  28. ^ "How Stuff Works: polar ice caps". howstuffworks.com. Retrieved 2006-02-12.
  29. ^ Winkelmann, R.; Levermann, A.; Martin, M. A.; Frieler, K. (2012-12-12). "Increased future ice discharge from Antarctica owing to higher snowfall". Nature. 492 (7428): 239–242. doi:10.1038/nature11616. ISSN 0028-0836. PMID 23235878.
  30. ^ Shepherd, Andrew; Ivins, Erik; et al. (IMBIE team) (2012-11-30). "A Reconciled Estimate of Ice-Sheet Mass Balance". Science. 338 (6111): 1183–1189. Bibcode:2012Sci...338.1183S. doi:10.1126/science.1228102. hdl:2060/20140006608. PMID 23197528.
  31. ^ a b Shepherd, Andrew; Ivins, Erik; et al. (IMBIE team) (2018-06-13). "Mass balance of the Antarctic Ice Sheet from 1992 to 2017". Nature. 558 (7709): 219–222. doi:10.1038/s41586-018-0179-y. PMID 29899482. Lay summaryArs Technica (2018-06-13).
  32. ^ Fretwell, P.; Pritchard, H. D.; Vaughan, D. G.; Bamber, J. L.; Barrand, N. E.; Bell, R.; Bianchi, C.; Bingham, R. G.; Blankenship, D. D. (2013-02-28). "Bedmap2: improved ice bed, surface and thickness datasets for Antarctica". The Cryosphere. 7 (1): 375–393. doi:10.5194/tc-7-375-2013. ISSN 1994-0424.
  33. ^ "Mass balance of the Antarctic Ice Sheet from 1992 to 2017". Nature. 558 (7709): 219–222. 2018. doi:10.1038/s41586-018-0179-y. ISSN 0028-0836.
  34. ^ Chen, J. L.; Wilson, C. R.; Tapley, B. D.; Blankenship, D.; Young, D. (2008). "Antarctic regional ice loss rates from GRACE". Earth and Planetary Science Letters. 266 (1–2): 140–148. Bibcode:2008E&PSL.266..140C. doi:10.1016/j.epsl.2007.10.057.
  35. ^ Greene, Chad A.; Blankenship, Donald D.; Gwyther, David E.; Silvano, Alessandro; Wijk, Esmee van (2017-11-01). "Wind causes Totten Ice Shelf melt and acceleration". Science Advances. 3 (11): e1701681. doi:10.1126/sciadv.1701681. ISSN 2375-2548. PMC 5665591. PMID 29109976.
  36. ^ Roberts, Jason; Galton-Fenzi, Benjamin K.; Paolo, Fernando S.; Donnelly, Claire; Gwyther, David E.; Padman, Laurie; Young, Duncan; Warner, Roland; Greenbaum, Jamin (2017-08-23). "Ocean forced variability of Totten Glacier mass loss". Geological Society, London, Special Publications. 461 (1): 175–186. doi:10.1144/sp461.6. ISSN 0305-8719.
  37. ^ Greene, Chad A.; Young, Duncan A.; Gwyther, David E.; Galton-Fenzi, Benjamin K.; Blankenship, Donald D. (2018-09-06). "Seasonal dynamics of Totten Ice Shelf controlled by sea ice buttressing". The Cryosphere. 12 (9): 2869–2882. doi:10.5194/tc-12-2869-2018. ISSN 1994-0416.
  38. ^ Rignot, E.; Bamber, J. L.; Van Den Broeke, M. R.; Davis, C.; Li, Y.; Van De Berg, W. J.; Van Meijgaard, E. (2008). "Recent Antarctic ice mass loss from radar interferometry and regional climate modelling". Nature Geoscience. 1 (2): 106–110. Bibcode:2008NatGe...1..106R. doi:10.1038/ngeo102. PMC 4032514. PMID 24891394.
  39. ^ Bromwhich et al. (2013). "Central West Antarctica among the most rapidly warming regions on Earth". Nature. doi:10.1038/ngeo1671.
  40. ^ Pattyn, Frank (2018). "The paradigm shift in Antarctic ice sheet modelling". Nature Communications. 9 (1). doi:10.1038/s41467-018-05003-z. ISSN 2041-1723.
  41. ^ Pollard et al. (2015). "Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure". Nature. doi:10.1016/j.epsl.2014.12.035.
  42. ^ Bamber J.L.; Riva R.E.M.; Vermeersen B.L.A.; LeBroq A.M. (2009). "Reassessment of the potential sea-level rise from a collapse of the West Antarctic Ice Sheet". Science. 324 (5929): 901–3. Bibcode:2009Sci...324..901B. doi:10.1126/science.1169335. PMID 19443778.
  43. ^ Joughin, Ian; Alley, Richard B. (2011). "Stability of the West Antarctic ice sheet in a warming world". Nature Geoscience. 4 (8): 506–513. doi:10.1038/ngeo1194. ISSN 1752-0894.
  44. ^ "After Decades of Losing Ice, Antarctica Is Now Hemorrhaging It". The Atlantic. 2018.
  45. ^ "Marine ice sheet instability". AntarcticGlaciers.org. 2014.
  46. ^ Earth Observatory (2009) Melting Anomalies in Greenland in 2007
  47. ^ Bob Berwyn (2018). "What's Eating Away at the Greenland Ice Sheet?". Inside Climate News.
  48. ^ Joughin, I; et al. (December 2004). "Large fluctuations in speed on Greenland's Jakobshavn Isbræ glacier". Nature. 432 (7017): 608–610. Bibcode:2004Natur.432..608J. doi:10.1038/nature03130. PMID 15577906.
  49. ^ Connor, Steve (2005-07-25). "Melting Greenland glacier may hasten rise in sea level". The Independent. London. Retrieved 2010-04-30.
  50. ^ Rignot, E; Kanagaratnam, P (2006). "Changes in the Velocity Structure of the Greenland Ice Sheet". Science. 311 (5763): 986–90. Bibcode:2006Sci...311..986R. doi:10.1126/science.1121381. PMID 16484490.
  51. ^ Robinson, Alexander; Calov, Reinhard; Ganopolski, Andrey (2012). "Multistability and critical thresholds of the Greenland ice sheet". Nature Climate Change. 2 (6): 429–432. doi:10.1038/nclimate1449. ISSN 1758-678X.
  52. ^ Noël et al. (2017). "A tipping point in refreezing accelerates mass loss of Greenland's glaciers and ice caps". Nature Communications. 8: 14730. doi:10.1038/ncomms14730. PMC 5380968. PMID 28361871.
  53. ^ "Greenland's Coastal Ice Caps Have Melted Past The Point Of No Return". HuffPost. 2017.
  54. ^ Bamber; et al. (2018). "The land ice contribution to sea level during the satellite era". Environmental Research Letters. 13 (6): 063008. Bibcode:2018ERL....13f3008B. doi:10.1088/1748-9326/aac2f0.
  55. ^ Radić, Valentina; Hock, Regine (2011-01-09). "Regionally differentiated contribution of mountain glaciers and ice caps to future sea-level rise". Nature Geoscience. 4 (2): 91–94. doi:10.1038/ngeo1052. ISSN 1752-0894.
  56. ^ a b Huss, Matthias; Hock, Regine (2015). "A new model for global glacier change and sea-level rise". Frontiers in Earth Science. 3. doi:10.3389/feart.2015.00054. ISSN 2296-6463.
  57. ^ Vaughan, David G.; Comiso, Josefino C (2013). "Observations: Cryosphere". IPCC AR5 WGI (PDF). New York: Cambridge University Press.
  58. ^ Dyurgerov, Mark. 2002. Glacier Mass Balance and Regime: Data of Measurements and Analysis. INSTAAR Occasional Paper No. 55, ed. M. Meier and R. Armstrong. Boulder, CO: Institute of Arctic and Alpine Research, University of Colorado. Distributed by National Snow and Ice Data Center, Boulder, CO. A shorter discussion is at [1]
  59. ^ Noerdlinger, P.D. and Brower, K.R., 2007. The melting of floating ice raises the ocean level. Geophysical Journal International, 170(1), pp. 145-150.
  60. ^ Wada, Yoshihide; Reager, John T.; Chao, Benjamin F.; Wang, Jida; Lo, Min-Hui; Song, Chunqiao; Li, Yuwen; Gardner, Alex S. (2016). "Recent Changes in Land Water Storage and its Contribution to Sea Level Variations". Surveys in Geophysics. 38 (1): 131–152. doi:10.1007/s10712-016-9399-6.
  61. ^ a b   This article incorporates public domain material from the NOAA document: NOAA GFDL, Geophysical Fluid Dynamics Laboratory – Climate Impact of Quadrupling CO2, Princeton, NJ, USA: NOAA GFDL
  62. ^ Karl, TR; et al., eds. (2009). Global Climate Change Impacts in the United States. 32 Avenue of the Americas, New York, NY 10013-2473, USA: Cambridge University Press. pp. 22–24. ISBN 978-0-521-14407-0. Retrieved 2011-04-28.
  63. ^ a b America's Climate Choices: Panel on Advancing the Science of Climate Change, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES (2010). "7 Sea Level Rise and the Coastal Environment". Advancing the Science of Climate Change. Washington, D.C.: The National Academies Press. pp. 243–250. ISBN 978-0-309-14588-6. Retrieved 2011-06-17. (From pg 250) Even if sea-level rise were to remain in the conservative range projected by the IPCC (0.6–1.9 feet [0.18–0.59 m])—not considering potentially much larger increases due to rapid decay of the Greenland or West Antarctic ice sheets—tens of millions of people worldwide would become vulnerable to flooding due to sea-level rise over the next 50 years (Nicholls, 2004; Nicholls and Tol, 2006). This is especially true in densely populated, low-lying areas with limited ability to erect or establish protective measures. In the United States, the high end of the conservative IPCC estimate would result in the loss of a large portion of the nation's remaining coastal wetlands. The impact on the east and Gulf coasts of the United States of 3.3 feet (1 m) of sea-level rise, which is well within the range of more recent projections for the 21st century (e.g., Pfeffer et al., 2008; Vermeer and Rahmstorf, 2009), is shown in pink in Figure 7.7. Also shown, in red, is the effect of 19.8 feet (6 m) of sea-level rise, which could occur over the next several centuries if warming were to continue unabated.
  64. ^ Rignot E.; I. Velicogna; M. R. van den Broeke; A. Monaghan; J. Lenaerts (2011). "Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise". Geophysical Research Letters. 38 (5): n/a. Bibcode:2011GeoRL..3805503R. doi:10.1029/2011GL046583. Considerable disparity remains between these estimates due to the inherent uncertainties of each method, the lack of detailed comparison between independent estimates, and the effect of temporal modulations in ice sheet surface mass balance. Here, we present a consistent record of mass balance for the Greenland and Antarctic ice sheets over the past two decades, validated by the comparison of two independent techniques over the past eight years: one differencing perimeter loss from net accumulation, and one using a dense time series of timevariable gravity. We find excellent agreement between the two techniques for absolute mass loss and acceleration of mass loss.
  65. ^ Romm, Joe (10 Mar 2011). "JPL bombshell: Polar ice sheet mass loss is speeding up, on pace for 1 foot sea level rise by 2050". Climate Progress. Center for American Progress Action Fund. Retrieved 16 April 2012.
  66. ^ 4. Global Mean Sea Level Rise Scenarios, in: Main Report, in Parris & others 2012, p. 12
  67. ^ "Sea Level Rise Key Message Third National Climate Assessment". National Climate Assessment. Retrieved 25 June 2014.
  68. ^ J. Hansen; M. Sato; P. Hearty; R. Ruedy; M. Kelley; V. Masson-Delmotte; G. Russell; G. Tselioudis; J. Cao; E. Rignot; I. Velicogna; E. Kandiano; K. von Schuckmann; P. Kharecha; A. N. Legrande; M. Bauer; K.-W. Lo (2016). "Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous". Atmospheric Chemistry and Physics (ACP). 16: 3761–3812. doi:10.5194/acp-16-3761-2016.
  69. ^ "James Hansen's controversial sea level rise paper has now been published online". The Washington Post. 2015.
  70. ^ Chris Mooney (October 26, 2017). "New science suggests the ocean could rise more — and faster — than we thought". The Chicago Tribune.
  71. ^ Alexander Nauels; Joeri Rogelj; Carl-Friedrich Schleussner; Malte Meinshausen; Matthias Mengel (26 October 2017). "Linking sea level rise and socioeconomic indicators under the Shared Socioeconomic Pathways". Environmental Research Letters. 12 (11): 114002. Bibcode:2017ERL....12k4002N. doi:10.1088/1748-9326/aa92b6.
  72. ^ Hansen, J.; et al. (1981). "Climate impact of increasing atmospheric carbon dioxide". Science. 231 (4511): 957–966. Bibcode:1981Sci...213..957H. doi:10.1126/science.213.4511.957. PMID 17789014.
  73. ^ America's Climate Choices: Panel on Advancing the Science of Climate Change, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, NATIONAL RESEARCH COUNCIL OF THE NATIONAL ACADEMIES (2010). "7 Sea Level Rise and the Coastal Environment". Advancing the Science of Climate Change. Washington, D.C.: The National Academies Press. p. 245. ISBN 978-0-309-14588-6. Retrieved 2011-06-17.
  74. ^ IPCC AR4, Summary for Policymakers, Section C. Current knowledge about future impacts – Magnitudes of impact in IPCC AR4 WG2 2007
  75. ^ IPCC AR4, Summary for Policymakers, Endbox 2. Communication of Uncertainty, in IPCC AR4 WG2 2007
  76. ^ Anders Levermann; Peter U. Clark; Ben Marzeion; Glenn A. Milne; David Pollard; Valentina Radic; Alexander Robinson (13 June 2013). "The multimillennial sea-level commitment of global warming". PNAS. 110 (34): 13745–50. Bibcode:2013PNAS..11013745L. doi:10.1073/pnas.1219414110. PMC 3752235. PMID 23858443.
  77. ^ Ricarda Winkelmann; Anders Levermann; Andy Ridgwell; Ken Caldeira (11 September 2015). "Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet". Science Advances. 1 (8): e1500589. Bibcode:2015SciA....1E0589W. doi:10.1126/sciadv.1500589. PMC 4643791. PMID 26601273.
  78. ^ Solomon, S., Plattner, G.K., Knutti, R., Friedlingstein, P.; Plattner; Knutti; Friedlingstein (2009). "Irreversible climate change due to carbon dioxide emissions". Proc. Natl. Acad. Sci. U.S.A. 106 (6): 1704–9. Bibcode:2009PNAS..106.1704S. doi:10.1073/pnas.0812721106. PMC 2632717. PMID 19179281.
  79. ^ "Scientists say Antarctic melting could double sea level rise. Here's what that looks like".
  80. ^ Katsman, Caroline A.; Sterl, A.; Beersma, J. J.; van den Brink, H. W.; Church, J. A.; Hazeleger, W.; Kopp, R. E.; Kroon, D.; Kwadijk, J. (2011-02-24). "Exploring high-end scenarios for local sea level rise to develop flood protection strategies for a low-lying delta—the Netherlands as an example". Climatic Change. 109 (3–4): 617–645. doi:10.1007/s10584-011-0037-5. ISSN 0165-0009.
  81. ^ Bucx et al. 2010, p. 88;Tessler et al. 2015, p. 638
  82. ^ Bucx et al. 2010, p. 81
  83. ^ Bucx et al. 2010, pp. 81, 88,90
  84. ^ "Why the U.S. East Coast could be a major 'hotspot' for rising seas". The Washington Post. 2016.
  85. ^ Jianjun Yin & Stephen Griffies (March 25, 2015). "Extreme sea level rise event linked to AMOC downturn". CLIVAR.
  86. ^ IPCC TAR WG1 2001.
  87. ^ Watkins, Kevin; Program, United Nations Development (2009). "Climate Shocks: Risk and Vulnerability in an Unequal World". Human Development Report 2007/2008. United Nations Development Programme. pp. 71–107. doi:10.1057/9780230598508_3. ISBN 978-0-230-54704-9.
  88. ^ McLeman, Robert (2018). "Migration and displacement risks due to mean sea-level rise". Bulletin of the Atomic Scientists. 74 (3): 148–154. doi:10.1080/00963402.2018.1461951. ISSN 0096-3402.
  89. ^ Nicholls, Robert J.; Marinova, Natasha; Lowe, Jason A.; Brown, Sally; Vellinga, Pier; Gusmão, Diogo de; Hinkel, Jochen; Tol, Richard S. J. (2011). "Sea-level rise and its possible impacts given a 'beyond 4°C world' in the twenty-first century". Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 369 (1934): 161–181. doi:10.1098/rsta.2010.0291. ISSN 1364-503X. PMID 21115518.
  90. ^ McGranahan, Gordon; Balk, Deborah; Anderson, Bridget (2007). "The rising tide: assessing the risks of climate change and human settlements in low elevation coastal zones". Environment and Urbanization. 19 (1): 17–37. doi:10.1177/0956247807076960. ISSN 0956-2478.
  91. ^ Jacobson, Rebecca. "Engineers Consider Barriers to Protect New York From Another Sandy". PBS. Retrieved 26 November 2012.
  92. ^ Michaelson, Ruth (25 August 2018). "Houses claimed by the canal: life on Egypt's climate change frontline". The Guardian. Retrieved 30 August 2018.
  93. ^ "IPCC's New Estimates for Increased Sea-Level Rise". Yale. 2013.
  94. ^ "Climate Change Indicators: Coastal Flooding". United States Environmental Protection Agency. Retrieved 30 September 2018.
  95. ^ Jeff Goodell (June 20, 2013). "Goodbye, Miami". Rolling Stone. Retrieved June 21, 2013. The Organization for Economic Co-operation and Development lists Miami as the number-one most vulnerable city worldwide in terms of property damage, with more than $416 billion in assets at risk to storm-related flooding and sea-level rise.
  96. ^ a b "Climate Change, Sea Level Rise Spurring Beach Erosion". Climate Central. 2012.
  97. ^ "Sea level to increase risk of deadly tsunamis". UPI. 2018.
  98. ^ Nurse, Leonard A.; McLean, Roger (2014). "29: Small Islands". In Barros, VR; Field. AR5 WGII (PDF). Cambridge University Press.
  99. ^ Megan Angelo (1 May 2009). "Honey, I Sunk the Maldives: Environmental changes could wipe out some of the world's most well-known travel destinations".
  100. ^ Kristina Stefanova (19 April 2009). "Climate refugees in Pacific flee rising sea".
  101. ^ Ford, Murray R.; Kench, Paul S. (2016). "Spatiotemporal variability of typhoon impacts and relaxation intervals on Jaluit Atoll, Marshall Islands". Geology. 44 (2): 159–162. Bibcode:2016Geo....44..159F. doi:10.1130/g37402.1.
  102. ^ Klein, Alice. "Five Pacific islands vanish from sight as sea levels rise". New Scientist. Retrieved 2016-05-09.
  103. ^ Alfred Henry Adriaan Soons (1989). Zeegrenzen en zeespiegelrijzing : volkenrechtelijke beschouwingen over de effecten van het stijgen van de zeespiegel op grenzen in zee : rede, uitgesproken bij de aanvaarding van het ambt van hoogleraar in het volkenrecht aan de Rijksuniversiteit te Utrecht op donderdag 13 april 1989 [Sea borders and rising sea levels: international law considerations about the effects of rising sea levels on borders at sea: speech, pronounced with the acceptance of the post of professor in international law at the University of Utrecht on 13 April 1989] (in Dutch). Kluwers. ISBN 978-90-268-1925-4.
  104. ^ "Sea level rise poses a major threat to coastal ecosystems and the biota they support". birdlife.org. Birdlife International. 2015.
  105. ^ Weston, Nathaniel B. (2013-07-16). "Declining Sediments and Rising Seas: an Unfortunate Convergence for Tidal Wetlands". Estuaries and Coasts. 37 (1): 1–23. doi:10.1007/s12237-013-9654-8. ISSN 1559-2723.
  106. ^ Krauss, Ken W.; McKee, Karen L.; Lovelock, Catherine E.; Cahoon, Donald R.; Saintilan, Neil; Reef, Ruth; Chen, Luzhen (2013-11-19). "How mangrove forests adjust to rising sea level". New Phytologist. 202 (1): 19–34. doi:10.1111/nph.12605. ISSN 0028-646X.
  107. ^ Spalding M.; McIvor A.; Tonneijck F.H.; Tol S.; van Eijk P. (2014). "Mangroves for coastal defence. Guidelines for coastal managers & policy makers" (PDF). Wetlands International and The Nature Conservancy.
  108. ^ "Sea Level Rise" National Geographic.
  109. ^ Wong, Poh Poh; Losado, I.J.; Gattuso, J.-P.; Hinkel, Jochen (2014). "Coastal Systems and Low-Lying Areas" (PDF). Climate Change 2014: Impacts, Adaptation, and Vulnerability. New York: Cambridge University Press.
  110. ^ Smith, Lauren (2016-06-15). "Extinct: Bramble Cay melomys". Australian Geographic. Retrieved 2016-06-17.
  111. ^ Thomsen, Dana C.; Smith, Timothy F.; Keys, Noni (2012). "Adaptation or Manipulation? Unpacking Climate Change Response Strategies". Ecology and Society. 17 (3). JSTOR 26269087.
  112. ^ a b Fletcher, Cameron; Taylor, BM; Rambaldi, AN; Harman, BP; Heyenga, S; Ganegodage, KR; Lipkin, F; McAllister, RRJ (2013). Costs and coasts: an empirical assessment of physical and institutional climate adaptation pathways (PDF). Cold Coast: the National Climate Change Adaptation Research Facility.
  113. ^ Sovacool, Benjamin K. (2011). "Hard and soft paths for climate change adaptation" (PDF). Climate policy. 11.
  114. ^ "Dutch draw up drastic measures to defend coast against rising seas". New York Times. 3 September 2008.
  115. ^ "$500 million, 5-year plan to help Miami Beach withstand sea-level rise". 6 April 2015.
  116. ^ "Policy Implications of Sea Level Rise: The Case of the Maldives". Proceedings of the Small Island States Conference on Sea Level Rise. November 14–18, 1989. Malé, Republic of Maldives. Edited by Hussein Shihab. Retrieved 2007-01-12.

ReferencesEdit

Further readingEdit

External linksEdit