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Global mean surface temperature from 1880 to 2018, relative to the 1951–1980 mean. The black line is the global annual mean, and the red line is the five-year local regression line. The blue bars show a 95% confidence interval.
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Average global temperatures from 2014 to 2018 compared to a baseline average from 1951 to 1980, according to NASA's Goddard Institute for Space Studies.

Global warming is the long-term rise in the average temperature of the Earth's climate system, an aspect of current climate change shown by temperature measurements and by multiple effects of the warming.[1][2] The term commonly refers to the mainly human-caused increase in global surface temperatures and its projected continuation.[3][4] In this context, the terms global warming and climate change are often used interchangeably,[5] but climate change includes both global warming and its effects, such as changes in precipitation and impacts that differ by region.[6] There were prehistoric periods of global warming,[7] but observed changes since the mid-20th century have been much greater than those seen in previous records covering decades to thousands of years.[1][8]

In 2013, the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report concluded, "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century."[9] The largest human influence has been the emission of greenhouse gases such as carbon dioxide, methane, and nitrous oxide. Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 to 1.7 °C (0.5 to 3.1 °F) in a moderate scenario, or as much as 2.6 to 4.8 °C (4.7 to 8.6 °F) in an extreme scenario, depending on the rate of future greenhouse gas emissions and on climate feedback effects.[10] These findings have been recognized by the national science academies of the major industrialized nations[11] and are not disputed by any scientific body of national or international standing.[12][13]

The effects of global warming include rising sea levels, regional changes in precipitation, more frequent extreme weather events such as heat waves, and expansion of deserts.[14] Surface temperature increases are greatest in the Arctic, which has contributed to the retreat of glaciers, permafrost, and sea ice. Overall, higher temperatures bring more rain and snowfall, but for some regions droughts and wildfires increase instead.[15] Climate change threatens to diminish crop yields, harming food security, and rising sea levels may flood coastal infrastructure and force the abandonment of many coastal cities.[16][17] Environmental impacts include the extinction or relocation of many species as their ecosystems change, most immediately the environments of coral reefs,[18] mountains, and the Arctic.[19] Because the climate system has a large "inertia" and greenhouse gases persist in the atmosphere, climatic changes and their effects will continue for many centuries even if greenhouse gas emissions are stopped.[20]

Globally, a majority of people consider global warming a serious or very serious issue.[21] Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future climate engineering. Every country in the world is a party to the United Nations Framework Convention on Climate Change (UNFCCC),[22] whose ultimate objective is to prevent dangerous anthropogenic climate change.[23] Although the parties to the UNFCCC have agreed that deep cuts in emissions are required[24] and that global warming should be limited to well below 2 °C (3.6 °F) (with efforts made to limit warming to 1.5 °C (2.7 °F)[25]), the Earth's average surface temperature has already increased by about half this threshold.[26] Some scientists call into question the feasibility of the 2 °C (3.6 °F) temperature target,[27] and some question the feasibility, in higher emissions scenarios, of climate adaptation.[28]

Contents

Observed temperature changes

Annual temperature anomalies (thin lines) and five-year lowess smooths (thick lines) for average temperatures over the Earth's land area (red line) and sea surface over the part of the ocean that is free of ice at all times (blue line)
Two millennia of mean surface temperatures according to different reconstructions from climate proxies, each smoothed on a decadal scale, with the instrumental temperature record starting in 1856 in black

Climate proxy records show that natural variations offset the early effects of the Industrial Revolution, so there was little net warming between the 18th century and the mid-19th century,[29][30] when thermometer records began to provide global coverage.[31] The IPCC has adopted the baseline reference period 1850–1900 as an approximation of pre-industrial global mean surface temperature.[29]

Multiple independently produced instrumental datasets confirm that the 2009–2018 decade was 0.93 ± 0.07 °C warmer than the pre-industrial baseline (1850–1900).[32] Currently, surface temperatures are rising by about 0.2 °C per decade.[33] Since 1950, the number of cold days and nights have decreased, and the number of warm days and night have increased.[34] Historical patterns of warming and cooling, like the Medieval Climate Anomaly and the Little Ice Age, were not as synchronous as current warming, but may have reached temperatures as high as those of the late-20th century in a limited set of regions.[35]

Although the most common measure of global warming is the increase in the near-surface atmospheric temperature, over 90% of the additional energy stored in the climate system over the last 50 years has warmed ocean water.[36] The remainder of the additional energy has melted ice and warmed the continents and the atmosphere.[37]

The warming evident in the instrumental temperature record is consistent with a wide range of observations, documented by many independent scientific groups;[38] for example, in most continental regions the frequency and intensity of heavy precipitation has increased.[39] Further examples include sea level rise,[40] widespread melting of snow and land ice,[41] increased heat content of the oceans,[38] increased humidity,[38] and the earlier timing of spring events,[42] such as the flowering of plants.[43]

Regional trends

Above: Warming stripes graphics exhibit greater recent temperature anomalies for the Northern Hemisphere.[44] than for the Southern Hemisphere[45]
( blue=cool, red=warm,
1880 (left) — 2018 (right) )

Right: "Stacked" warming stripes[46] group countries by continent to show regional contrasts and global similarities.

Global warming refers to global averages, with the amount of warming varying by region. Since the pre-industrial period, global average land temperatures have increased almost twice as fast as global average temperatures.[47] This is due to the larger heat capacity of oceans and because oceans lose more heat by evaporation.[48] Patterns of warming are independent of the locations of greenhouse gas emissions because the gases persist long enough to diffuse across the planet; however, localized black carbon deposits on snow and ice do contribute to Arctic warming.[49]

The Northern Hemisphere and North Pole have warmed much faster than the South Pole and Southern Hemisphere. The Northern Hemisphere not only has much more land, but the arrangement of land masses around the Arctic Ocean has resulted in the maximum surface area flipping from reflective snow and ice cover to ocean and land surfaces that absorb more sunlight and thus more heat.[50] Arctic temperatures have increased and are predicted to continue to increase during this century at over twice the rate of the rest of the world.[51] As the temperature difference between the Arctic and the equator decreases, ocean currents that are driven by that temperature difference, like the Gulf Stream, are weakening.[52]

Short-term slowdowns and surges

Because the climate system has large thermal inertia, it can take centuries for the climate to fully adjust. While record-breaking years attract considerable public interest, individual years are less significant than the overall trend. Global surface temperature is subject to short-term fluctuations that overlie long-term trends, and can temporarily mask or magnify them.[53] An example of such an episode is the slower rate of surface temperature increase from 1998 to 2012, which was dubbed the global warming hiatus.[54] Throughout this period ocean heat storage continued to progress steadily upwards, and in subsequent years surface temperatures have spiked upwards. The slower pace of warming can be attributed to a combination of natural fluctuations, reduced solar activity, and increased volcanic activity.[55]

Physical drivers of recent climate change

 
Radiative forcing of different contributors to climate change in 2011, as reported in the fifth IPCC assessment report. For the gases and aerosols, the values represent both the effect they have themselves and the effect of any chemical compound they get converted into in the atmosphere.

By itself, the climate system experiences various cycles which can last for years (such as the El Niño–Southern Oscillation) to decades[56] or centuries.[57] Other changes are caused by external forcings. These forcings are "external" to the climate system, but not always external to the Earth.[58] Examples of external forcings include changes in the composition of the atmosphere (e.g., increased concentrations of greenhouse gases), solar luminosity, volcanic eruptions, and variations in the Earth's orbit around the Sun.[59]

Attributing detected temperature changes and extreme events to human-caused increases in greenhouse gases requires scientists to rule out known internal climate variability and natural external forcings. Therefore, a key approach is to use physically or statistically based computer modelling of the climate system to determine unique fingerprints for all potential causes. By comparing these fingerprints with observed patterns and evolution of climate change, and the observed evolution of the forcings, the causes of the observed changes can be determined.[60] Scientists have determined that the major factors in the current climate change are greenhouse gases, land use changes, and aerosols and soot.[61]

Greenhouse gases

 
Greenhouse effect schematic showing energy flows between space, the atmosphere, and the Earth's surface. Energy exchanges are expressed in watts per square meter (W/m2).
 
CO
2
concentrations over the last 800,000 years as measured from ice cores (blue/green) and directly (black)

Greenhouse gases trap heat radiating from the Earth to space.[62] This heat, in the form of infrared radiation, gets absorbed and emitted by these gases in the atmosphere, thus warming the lower atmosphere and the surface. Before the Industrial Revolution, naturally occurring amounts of greenhouse gases caused the air near the surface to be warmer by about 33 °C (59 °F) than it would be in their absence.[63] Without the Earth's atmosphere, the Earth's average temperature would be well below the freezing temperature of water.[64] The major greenhouse gases are water vapour, which causes about 36–70% of the greenhouse effect; carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone (O3), which causes 3–7%.[65][66][67]

Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs, and nitrous oxide. As of 2011, the concentrations of CO2 and methane had increased by about 40% and 150%, respectively, since pre-industrial times.[68] In 2013, CO2 readings taken at the world's primary benchmark site in Mauna Loa surpassing 400 ppm for the first time.[69] These levels are much higher than at any time during the last 800,000 years, the period for which reliable data have been collected from ice cores.[70] Less direct geological evidence indicates that CO2 values have not been this high for millions of years.[69]

Global anthropogenic greenhouse gas emissions in 2010 were equivalent to 49 billion tonnes of carbon dioxide (using the most recent global warming potentials over 100 years from the AR5 report). Of these emissions, 65% was carbon dioxide from fossil fuel burning and industry, 11% was carbon dioxide from land use change, which is primarily due to deforestation, 16% was from methane, 6.2% was from nitrous oxide, and 2.0% was from fluorinated gases.[71] Using life-cycle assessment to estimate emissions relating to final consumption, the dominant sources of 2010 emissions were: food (26–30% of emissions);[72] washing, heating, and lighting (26%); personal transport and freight (20%); and building construction (15%).[73]

Land use change

Changing the type of vegetation in a region impacts the local temperature by changing how much sunlight gets reflected back into space, called albedo, and how much heat is lost by evaporation. For instance, the change from a dark forest to grassland makes the surface lighter, and causes it to reflect more sunlight. Humans change the land surface mainly to create more agricultural land.[74] Since the pre-industrial era, albedo has increased due to land use change, which has a cooling effect on the planet. Other processes linked to land use change however have had the opposite effect, so that the net effect remains unclear.[75]

Aerosols and soot

 
Ship tracks can be seen as lines in these clouds over the Atlantic Ocean on the East Coast of the United States, an example of the Twomey effect.

Solid and liquid particles known as aerosols – from volcanoes, plankton, and human-made pollutants – reflect incoming sunlight, cooling the climate.[76] From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed, a phenomenon popularly known as global dimming,[77] typically attributed to aerosols from biofuel and fossil fuel burning.[78] Aerosol removal by precipitation gives tropospheric aerosols an atmospheric lifetime of only about a week, while stratospheric aerosols can remain in the atmosphere for a few years.[79] Globally, aerosols have been declining since 1990, removing some of the masking of global warming that they had been providing.[80]

In addition to their direct effect by scattering and absorbing solar radiation, aerosols have indirect effects on the Earth's radiation budget. Sulfate aerosols act as cloud condensation nuclei and thus lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets, a phenomenon known as the Twomey effect.[81] This effect also causes droplets to be of more uniform size, which reduces the growth of raindrops and makes clouds more reflective to incoming sunlight, known as the Albrecht effect.[82] Indirect effects of aerosols are the largest uncertainty in radiative forcing.[83]

While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming. Not only does this increase the absorption of sunlight, it also increases melting and sea level rise.[84] Limiting new black carbon deposits in the Arctic could reduce global warming by 0.2 °C by 2050.[85] When soot is suspended in the atmosphere, it directly absorbs solar radiation, heating the atmosphere and cooling the surface. In areas with high soot production, such as rural India, as much as 50% of surface warming due to greenhouse gases may be masked by atmospheric brown clouds.[86] The influences of atmospheric particles, including black carbon, are most pronounced in the tropics and northern mid-latitudes, with the effects of greenhouse gases dominant in the other parts of the world.[87][88]

Minor forcings: the Sun and short-lived greenhouse gases

As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect the climate system.[89] Solar irradiance has been measured directly by satellites,[90] and indirect measurements are available beginning in the early 1600s.[89] There has been no upward trend in the amount of the Sun's energy reaching the Earth, so it cannot be responsible for the current warming.[91] Physical climate models are also unable to reproduce the rapid warming observed in recent decades when taking into account only variations in solar output and volcanic activity.[92] Another line of evidence for the warming not being due to the Sun is how temperature changes differ at different levels in the Earth's atmosphere.[93] According to basic physical principles, the greenhouse effect produces warming of the lower atmosphere (the troposphere), but cooling of the upper atmosphere (the stratosphere).[94] If solar variations were responsible for the observed warming, warming of both the troposphere and the stratosphere would be expected, but that has not been the case.[95]

Ozone in the lowest layer of the atmosphere, the troposphere, is itself a greenhouse gas. Furthermore, it is highly reactive and interacts with other greenhouse gases and aerosols.[96]

Climate change feedback

 
The dark ocean surface reflects only 6 percent of incoming solar radiation, whereas sea ice reflects 50 to 70 percent.[97]

The response of the climate system to an initial forcing is increased by positive feedbacks and reduced by negative feedbacks.[98] The main negative feedback to global temperature change is radiative cooling to space as infrared radiation, which increases strongly with increasing temperature.[99] The main positive feedbacks are the water vapour feedback, the ice–albedo feedback, and probably the net effect of clouds.[100] Uncertainty over feedbacks is the major reason why different climate models project different magnitudes of warming for a given amount of emissions.[101]

As air gets warmer, it can hold more moisture. After an initial warming due to emissions of greenhouse gases, the atmosphere will hold more water. As water is a potent greenhouse gas, this further heats the climate: the water vapour feedback.[100] The reduction of snow cover and sea ice in the Arctic reduces the albedo (reflectivity) of the Earth's surface.[102] More of the sun's energy is now absorbed in these regions, contributing to Arctic amplification, which has caused Arctic temperatures to increase at more than twice the rate of the rest of the world.[103] Arctic amplification also causes methane to be released as permafrost melts, which is expected to surpass land use changes as the second strongest anthropogenic source of greenhouse gases by the end of the century.[104]

Cloud cover may change in the future. If cloud cover increases, more sunlight will be reflected back into space, cooling the planet. Simultaneously, the clouds enhance the greenhouse effect, warming the planet. The opposite is true if cloud cover decreases. It depends on the cloud type and location which process is more important. Overall, the net feedback over the industrial era has probably been positive.[105] An analysis of satellite data between 1983 and 2009 reveals that cloud tops are reaching higher into the atmosphere and that cloudy storm tracks are shifting toward Earth's poles, suggesting clouds will be a positive feedback in the future.[106]

Carbon dioxide stimulates plant growth so the carbon cycle has been a negative feedback so far: roughly half of each year's CO2 emissions have been absorbed by plants on land and in oceans,[107] with an estimated 30% increase in plant growth from 2000 to 2017.[108] The limits and reversal point for this feedback are an area of uncertainty.[109] As more CO2 and heat are absorbed by the ocean it is acidifying and ocean circulation can change, changing the rate at which the ocean can absorb atmospheric carbon.[110] On land, greater plant growth will be constrained by nitrogen levels and can be reversed by plant heat stress, desertification, and the release of carbon from soil as the ground warms.[111]

A concern is that positive feedbacks will lead to a tipping point, where global temperatures transition to a hothouse climate state even if greenhouse gas emissions are reduced or eliminated. A 2018 study tried to identify such a planetary threshold for self-reinforcing feedbacks and found that even a 2 °C (3.6 °F) increase in temperature over pre-industrial levels may be enough to trigger such a hothouse Earth scenario.[112]

Climate models

 
Future CO2 projections, including all forcing agents' atmospheric CO2-equivalent concentrations in parts-per-million-by-volume (ppmv) according to four RCPs (Representative Concentration Pathways)
 
Projected change in annual mean surface air temperature from the late 20th century to the mid-21st century, based on a medium emissions scenario.[113] This scenario assumes that no future policies are adopted to limit greenhouse gas emissions. Image credit: NOAA GFDL.[114]

A climate model is a representation of the physical, chemical, and biological processes that affect the climate system.[115] Computer models are run on supercomputers to reproduce and predict the circulation of the oceans, the annual cycle of the seasons, and the flows of carbon between the land surface and the atmosphere.[116] There are more than two dozen scientific institutions that develop climate models.[116] Models not only project different future temperature with different emissions of greenhouse gases, but also because they don't fully agree on the strength of different feedbacks on climate sensitivity and the amount of inertia of the system.[117]

A subset of climate models add societal factors to a simple physical climate model. These models simulate how population, economic growth, and energy use affect – and interact with – the physical climate. With this information, scientists can produce scenarios of how greenhouse gas emissions may vary in the future. Scientists can then run these scenarios through physical climate models to generate climate change projections.[116]

Climate models include different external forcings for their models. For different greenhouse gas inputs four RCPs (Representative Concentration Pathways) are used: "a stringent mitigation scenario (RCP2.6), two intermediate scenarios (RCP4.5 and RCP6.0) and one scenario with very high GHG [greenhouse gas] emissions (RCP8.5)".[118] Models also include changes in the Earth's orbit, historical changes in the Sun's activity, and volcanic forcing.[116] RCPs only look at concentrations of greenhouse gases, factoring out uncertainty as to whether the carbon cycle will continue to remove about half of the carbon dioxide from the atmosphere each year.[119]

The physical realism of models is tested by examining their ability to simulate contemporary or past climates.[120] Past models have underestimated the rate of Arctic shrinkage[121] and underestimated the rate of precipitation increase.[122] Sea level rise since 1990 was underestimated in older models, but now agrees well with observations.[123] The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes".[124]

Effects

 
Historical sea level reconstruction and projections up to 2100 published in January 2017 by the U.S. Global Change Research Program for the Fourth National Climate Assessment.[125]
 
Map of the Earth with a six-meter sea level rise represented in red.

Physical environment

The environmental effects of global warming are broad and far-reaching. They include effects on the oceans, ice and weather and may occur gradually or rapidly.

Between 1993 and 2017, the global mean sea level rose on average by 3.1 ± 0.3 mm per year, with an acceleration detected as well.[126] Over the 21st century, the IPCC projects that in a high emissions scenario the sea level could rise by 52–98 cm.[127] The rate of ice loss from glaciers and ice sheets in the Antarctic is a key area of uncertainty since this source could account for 90% of the potential sea level rise.[128] Polar amplification and increased ocean warmth are undermining and threatening to unplug Antarctic glacier outlets, potentially resulting in more rapid sea level rise.[129]. The retreat of glaciers also contributes to sea level rise. Global warming has led to decades of shrinking and thinning of the Arctic sea ice, making it vulnerable to atmospheric anomalies.[130] Projections of declines in Arctic sea ice vary.[131] Recent projections suggest that Arctic summers could be ice-free (defined as an ice extent of less than 1 million square km) as early as 2025–2030.[132][needs update?]

Extreme weather, extreme events, tropical cyclones: Many regions have probably already seen increases in warm spells and heat waves, and it is virtually certain that these changes will continue over the 21st century.[133] Since the 1950s, droughts and heat waves have appeared simultaneously with increasing frequency.[134] Extremely wet or dry events within the monsoon period have increased since 1980.[135][better source needed] Various mechanisms have been identified that might explain extreme weather in mid-latitudes from the rapidly warming Arctic, such as the jet stream becoming more erratic.[136] The maximum rainfall and wind speed from hurricanes and typhoons are likely increasing.[137]

Changes in ocean properties: Higher atmospheric CO2 concentrations have led to an increase in dissolved CO2, which causes ocean acidification.[138] Furthermore, oxygen levels decrease because oxygen is less soluble in warmer water, an effect known as ocean deoxygenation.[139]

Long-term effects of global warming: On the timescale of centuries to millennia, the magnitude of global warming will be determined primarily by anthropogenic CO2 emissions.[140] This is due to carbon dioxide's very long lifetime in the atmosphere.[140] Because the great mass of glaciers and ice caps depresses the Earth's crust, another long-term effect of ice melt and deglaciation will be the rising of landmasses, a process called post-glacial rebound. This could lead to landslides and increased seismic and volcanic activity. Tsunamis could be generated by submarine landslides caused by warmer ocean water thawing ocean-floor permafrost or releasing gas hydrates.[141] Sea level rise will continue over many centuries.[142]

Abrupt climate change, tipping points in the climate system: Climate change could result in global, large-scale changes.[143] Some large-scale changes could occur abruptly, i.e. over a short time period, and might also be irreversible. One potential source of abrupt climate change would be the rapid release of methane and carbon dioxide from permafrost, which would amplify global warming. Another example is the possibility for the Atlantic Meridional Overturning Circulation to slow or shut down (see also shutdown of thermohaline circulation).[144] This could trigger cooling in the North Atlantic, Europe, and North America.[145]

Biosphere

 
The U.S. Geological Survey projects that reduced sea ice from climate change will lower the population of polar bears by two-thirds by 2050.[146]

In terrestrial ecosystems, the earlier timing of spring events, as well as poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming.[147] It is expected that most ecosystems will be affected by higher atmospheric CO2 levels and higher global temperatures.[148] The expansion of deserts in the subtropics is probably linked to global warming.[149][needs update?] Without substantial actions to reduce the rate of global warming, land-based ecosystems risk major shifts in their composition and structure.[150] Overall, it is expected that climate change will result in the extinction of many species and reduced diversity of ecosystems.[151] Rising temperatures push bees to their physiological limits, and could cause the extinction of bee populations.[152]

The ocean has heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles as fast as or faster than species on land.[153] Just as on land, heat waves in the ocean occur more due to climate change, with harmful effects found on a wide range of organisms such as corals, kelp, and seabirds.[154] Ocean acidification threatens damage to coral reefs, fisheries, protected species, and other natural resources of value to society.[138][155] Higher oceanic CO2 may affect the brain and central nervous system of certain fish species, which reduces their ability to hear, smell, and evade predators.[156]

Humans

 
A helicopter drops water on a wildfire in California. Drought and higher temperatures linked to climate change are driving a trend towards larger fires.[157]

The effects of climate change on human systems, mostly due to warming and shifts in precipitation, have been detected worldwide. The future social impacts of climate change will be uneven across the world.[158] All regions are at risk of experiencing negative impacts,[159] with low-latitude, less developed areas facing the greatest risk.[160] Global warming has likely already increased global economic inequality, and is projected to do so in the future.[161] Regional impacts of climate change are now observable on all continents and across ocean regions.[162] The Arctic, Africa, small islands, and Asian megadeltas are regions that are likely to be especially affected by future climate change.[163] Many risks increase with higher magnitudes of global warming.[164]

Food and water

Crop production will probably be negatively affected in low-latitude countries, while effects at northern latitudes may be positive or negative.[165] Global warming of around 4 °C relative to late 20th century levels could pose a large risk to global and regional food security.[166] The impact of climate change on crop productivity for the four major crops was negative for wheat and maize, and neutral for soy and rice, in the years 1960–2013.[167] Climate variability and change is projected to severely compromise agricultural production, including access to food, across Africa.[168] By 2050, between 350 million and 600 million people are projected to experience increased water stress due to climate change in Africa.[168] Water availability will also become more limited in regions dependent on glacier water, regions with reductions in rainfall, and small islands.[168]

Health and security

 
Aerial view over southern Bangladesh after the passage of Cyclone Sidr. The combination rising sea levels and increased rainfall from cyclones makes countries more vulnerable to floods, impacting people's livelihoods and health.[169]

Generally, impacts on public health will be more negative than positive.[170] Impacts include the direct effects of extreme weather, leading to injury and loss of life;[171] and indirect effects, such as undernutrition brought on by crop failures.[172] There has been a shift from cold- to heat-related mortality in some regions as a result of warming.[162] Temperature rise has been connected to increased numbers of suicides.[173] Climate change has been linked to an increase in violent conflict by amplifying poverty and economic shocks, which are well-documented drivers of these conflicts.[174] Links have been made between a wide range of violent behaviour including fist fights, violent crimes, civil unrest, and wars.[175] Climate change may also lead to new human diseases. For example, while ordinary temperatures usually kill off the yeast Candida auris before it infects humans, three strains have recently appeared in widely separate regions, leading researchers to postulate that warmer temperatures are driving it to adapt to higher temperatures at which it can more readily infect humans.[176]

Livelihoods, industry, and infrastructure

In small islands and mega deltas, inundation from sea level rise is expected to threaten vital infrastructure and human settlements.[177] This could lead to homelessness in countries with low-lying areas such as Bangladesh, as well as statelessness for populations in island nations, such as the Maldives and Tuvalu.[178] Climate change can be an important driver of migration, both within and between countries.[179]

Africa is one of the most vulnerable continents to climate change because of multiple existing stresses and low adaptive capacity.[168] Existing stresses include poverty, political conflicts, and ecosystem degradation. Regions may even become uninhabitable, with humidity and temperatures reaching levels too high for humans to survive.[180]

Responses

Mitigation of and adaptation to climate change are two complementary responses to global warming. Successful adaptation is easier if there are substantial emission reductions. Many of the countries that have contributed least to global greenhouse gas emissions are among the most vulnerable to climate change, which raises questions about justice and fairness with regard to mitigation and adaptation.[181]

Mitigation

 
The graph on the right shows three "pathways" to meet the UNFCCC's 2 °C target, labelled "global technology", "decentralized solutions", and "consumption change". Each pathway shows how various measures (e.g. improved energy efficiency, increased use of renewable energy) could contribute to emissions reductions. Image credit: PBL Netherlands Environmental Assessment Agency.[182]
 
Annual greenhouse gas emissions attributed to different sectors as of 2010. Emissions are given as a percentage share of total emissions, measured in carbon dioxide-equivalents, using global warming potentials from the IPCC Fifth Assessment Report.

Climate change can be be mitigated through the reduction of greenhouse gas emissions or the enhancement of the capacity of carbon sinks to absorb greenhouse gases from the atmosphere.[183] There is a large potential for future reductions in emissions by a combination of activities, including energy conservation and increased energy efficiency; the use of low-carbon energy technologies, such as renewable energy, nuclear energy, and carbon capture and storage; decarbonizing buildings and transport; and enhancing carbon sinks through, for example, reforestation and preventing deforestation.[184][185] A 2015 report by Citibank concluded that transitioning to a low-carbon economy would yield a positive return on investments.[186]

 
Global carbon dioxide emissions by country in 2015

Drivers of greenhouse gas emissions

Over the last three decades of the twentieth century, gross domestic product per capita and population growth were the main drivers of increases in greenhouse gas emissions.[187] CO2 emissions are continuing to rise due to the burning of fossil fuels and land-use change.[188] Emissions can be attributed to different regions. The attribution of emissions from land-use change is subject to considerable uncertainty.[189]

Emissions scenarios, estimates of changes in future emission levels of greenhouse gases, depend upon uncertain economic, sociological, technological, and natural developments.[190] In some scenarios emissions continue to rise over the century, while others have reduced emissions.[191] Fossil fuel reserves are abundant, and will not limit carbon emissions in the 21st century.[192] Emission scenarios can be combined with modelling of the carbon cycle to predict how atmospheric concentrations of greenhouse gases might change in the future.[108] According to these combined models, by 2100 the atmospheric concentration of CO2 could be as low as 380 or as high as 1400 ppm, depending on the Shared Socioeconomic Pathway (SSP) the world takes and the mitigation scenario.[193]

Reducing greenhouse gases

Near- and long-term trends in the global energy system are inconsistent with limiting global warming to below 1.5 or 2 °C relative to pre-industrial levels.[194] Current pledges made as part of the Paris Agreement would lead to about 3.0 °C of warming at the end of the 21st century, relative to pre-industrial levels.[195] To keep warming below 2 °C, more stringent emission reductions in the near-term would allow for less rapid reductions after 2030,[196] and be cheaper overall.[197] To keep warming under 1.5°C, a far-reaching system change on an unprecedented scale is necessary in energy, land, cities, transport, buildings, and industry.[198]

Although low-level ozone is harmful, when in the stratosphere ozone is beneficial. As many of the substances which can cause stratospheric ozone depletion are also greenhouse gases, the Montreal Protocol against their emissions may have done more than any other measure, as of 2017, to mitigate climate change.[199]

Co-benefits of climate change mitigation may help society and individuals more quickly. For example, cycling reduces greenhouse gas emissions while reducing the effects of a sedentary lifestyle at the same time.[200] The development and scaling-up of clean technology, such as cement that produces less CO2,[201] is critical to achieve sufficient emission reductions for the Paris agreement goals.[202] Many integrated models are unable to meet the 2 °C target if pessimistic assumptions are made about the availability of mitigation technologies.[203]

It has been suggested that the most effective and comprehensive policy to reduce carbon emissions is a carbon tax[204] or the closely related emissions trading.[205]

There are diverse opinions on how people could mitigate their carbon footprint. One suggestion is that the best approach is having fewer children, and to a lesser extent living car-free, forgoing air travel, and adopting a plant-based diet.[206] Some disagree with encouraging people to stop having children, saying that children "embody a profound hope for the future", and that more emphasis should be placed on overconsumption, lifestyle choices of the world's wealthy, fossil fuel companies, and government inaction.[207]

Adaptation

Climate change adaptation is the process of adjusting to actual or expected climate change and its effects.[208] Humans can strive to moderate or avoid harm due to climate change and exploit opportunities.[208] Examples of adaptation are improved coastline protection, better disaster management, and the development of more resistant crops.[209] The adaptation may be planned, either in reaction to or anticipation of global warming, or spontaneous, i.e. without government intervention.[210]

The public sector, private sector, and communities are all gaining experience with adaptation, and adaptation is becoming embedded within certain planning processes.[211] While some adaptation responses call for trade-offs, others bring synergies and co-benefits.[211] Environmental organizations and public figures have emphasized changes in the climate and the risks they entail, while promoting adaptation to changes in infrastructural needs and emissions reductions.[212]

Adaptation is especially important in developing countries since they are predicted to bear the brunt of the effects of global warming.[213] The capacity and potential for humans to adapt, called adaptive capacity, is unevenly distributed across different regions and populations, and developing countries generally have less capacity to adapt.[214] In June 2019, U.N. special rapporteur Philip Alston warned of a "climate apartheid" situation developing, where global warming "could push more than 120 million more people into poverty by 2030 and will have the most severe impact in poor countries, regions, and the places poor people live and work".[215]

Climate engineering

Climate engineering (sometimes called geoengineering or climate intervention) is the deliberate modification of the climate. It has been investigated as a possible response to global warming by groups including NASA[216] and the Royal Society.[217] Techniques studied fall generally into the categories of solar radiation management and carbon dioxide removal, although various other schemes have been suggested. A study from 2014 investigated the most common climate engineering methods and concluded that they are either ineffective or have potentially severe side effects and cannot be stopped without causing rapid climate change.[218]

Society and culture

Political response

 
Article 2 of the UN Framework Convention refers explicitly to "stabilization of greenhouse gas concentrations".[219] To stabilize the atmospheric concentration of CO
2
, emissions worldwide would need to be dramatically reduced from their present level.[220]

As of 2019 all countries in the world are parties to the United Nations Framework Convention on Climate Change (UNFCCC), but 12 countries have not ratified it,[221] which means they are not legally bound by the agreement.[222] The objective of the Convention is to prevent dangerous human interference with the climate system.[223] As stated in the Convention, this requires that greenhouse gas concentrations are stabilized in the atmosphere at a level where ecosystems can adapt naturally to climate change, food production is not threatened, and economic development can be sustained.[224] The Framework Convention was agreed on in 1992, but global emissions have risen since then.[225] Its yearly conferences are the stage of global negotiations.[226]

During these negotiations, the G77 (a lobbying group in the United Nations representing developing countries)[227] pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions.[228] This was justified on the basis that the developed countries' emissions had contributed most to the accumulation of greenhouse gases in the atmosphere, per-capita emissions were still relatively low in developing countries, and the emissions of developing countries would grow to meet their development needs.[229]

This mandate was sustained in the 2005 Kyoto Protocol to the Framework Convention.[230] In ratifying the Kyoto Protocol, most developed countries accepted legally binding commitments to limit their emissions. These first-round commitments expired in 2012.[231] United States President George W. Bush rejected the treaty on the basis that "it exempts 80% of the world, including major population centres such as China and India, from compliance, and would cause serious harm to the US economy".[232] In 2009 several UNFCCC Parties produced the Copenhagen Accord,[233] which has been widely portrayed as disappointing because of its low goals, leading poor nations to reject it.[234] Parties associated with the Accord aim to limit the future increase in global mean temperature to below 2 °C.[235]

In 2015 all UN countries negotiated the Paris Agreement, which aims to keep climate change well below 2 °C. The agreement replaced the Kyoto Protocol. Unlike Kyoto, no binding emission targets are set in the Paris Agreement. Instead, the procedure of regularly setting ever more ambitious goals and reevaluating these goals every five years has been made binding.[236] The Paris Agreement reiterated that developing countries must be financially supported.[236]

Scientific discussion

In the scientific literature, there is an overwhelming consensus that global surface temperatures have increased in recent decades and that the trend is caused mainly by human-induced emissions of greenhouse gases.[237] No scientific body of national or international standing disagrees with this view.[238] Scientific discussion takes place in journal articles that are peer-reviewed, which scientists subject to assessment every couple of years in the Intergovernmental Panel on Climate Change reports.[239] The scientific consensus as of 2013, as stated in the IPCC Fifth Assessment Report, is that it "is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century".[240]

National science academies have called on world leaders for policies to cut global emissions.[241] In November 2017, a second warning to humanity signed by 15,364 scientists from 184 countries stated that "the current trajectory of potentially catastrophic climate change due to rising greenhouse gases from burning fossil fuels, deforestation, and agricultural production – particularly from farming ruminants for meat consumption" is "especially troubling".[242] In 2018 the IPCC published a Special Report on Global Warming of 1.5 °C which warned that, if the current rate of greenhouse gas emissions is not mitigated, global warming is likely to reach 1.5 °C (2.7 °F) between 2030 and 2052, risking major crises. The report said that preventing such crises will require a swift transformation of the global economy that has "no documented historic precedent".[243]

Public opinion and disputes

 
Global warming was the cover story in this 2007 issue of Ms. magazine

The global warming problem came to international public attention in the late 1980s.[244] Significant regional differences exist in how concerned people are about climate change and how much they understand the issue.[21] In 2010, just a little over half the US population viewed it as a serious concern for either themselves or their families, while 73% of people in Latin America and 74% in developed Asia felt this way.[245] Similarly, in 2015 a median of 54% of respondents considered it "a very serious problem", but Americans and Chinese (whose economies are responsible for the greatest annual CO2 emissions) were among the least concerned.[21] Worldwide in 2011, people were more likely to attribute global warming to human activities than to natural causes, except in the US where nearly half of the population attributed global warming to natural causes.[246] Public reactions to global warming and concern about its effects have been increasing, with many perceiving it as the worst global threat.[247]

Due to confusing media coverage in the early 1990s, issues such as ozone depletion and climate change were often mixed up, affecting public understanding of these issues.[248] Although there are a few areas of linkage, the relationship between the two is weak.[249]

Controversy

From about 1990 onward, American conservative think tanks had begun challenging the legitimacy of global warming as a social problem. They challenged the scientific evidence, argued that global warming would have benefits, feared that concern for global warming was some kind of socialist plot to undermine American capitalism,[250] and asserted that proposed solutions would do more harm than good.[251] Organizations such as the libertarian Competitive Enterprise Institute, as well as conservative commentators, have challenged IPCC climate change scenarios, funded scientists who disagree with the scientific consensus, and provided their own projections of the economic cost of stricter controls.[252]

Global warming has been the subject of controversy, substantially more pronounced in the popular media than in the scientific literature,[253] with disputes regarding the nature, causes, and consequences of global warming. The disputed issues include the causes of increased global average air temperature, especially since the mid-20th century, whether this warming trend is unprecedented or within normal climatic variations, whether humankind has contributed significantly to it, and whether the increase is completely or partially an artifact of poor measurements. Additional disputes concern estimates of climate sensitivity, predictions of additional warming, what the consequences of global warming will be, and what to do about it.[254]

In the 20th century and early 2000s some companies, such as ExxonMobil, challenged IPCC climate change scenarios, funded scientists who disagreed with the scientific consensus, and provided their own projections of the economic cost of stricter controls.[255] In general, since the 2010s, global oil companies do not dispute that climate change exists and is caused by the burning of fossil fuels.[256] As of 2019, however, some are lobbying against a carbon tax and plan to increase production of oil and gas,[257] but others are in favour of a carbon tax in exchange for immunity from lawsuits which seek climate change compensation.[258]

The climate movement

In response to perceived inaction on climate change, a climate movement is protesting in various ways, such as by fossil fuel divestment,[259] worldwide demonstrations,[260] and a school strike for climate.[261] Mass civil disobedience actions by Extinction Rebellion and Ende Gelände have ended in police intervention and large-scale arrests.[262]

History of the science

 
Scientific American description of Eunice Newton Foote's 1856 experiments which found that carbonic acid (CO2) causes warming

The history of climate change science began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect was identified.[263] In the late 19th century, scientists first argued that human emissions of greenhouse gases could change the climate. In the 1960s, the warming effect of carbon dioxide gas became increasingly convincing.[264] By the 1990s, as a result of the improving fidelity of computer models and observational work confirming the Milankovitch theory of the ice ages, a consensus position formed: greenhouse gases were deeply involved in most climate changes, and human-caused emissions were bringing discernible global warming. Since then, scientific research on climate change has expanded.[265] The Intergovernmental Panel on Climate Change, set up in the 1990s to provide formal advice to the world's governments, spurred unprecedented levels of exchange between different scientific disciplines.[266]

The greenhouse effect was proposed by Joseph Fourier in 1824, discovered in 1856 by Eunice Newton Foote,[267] expanded upon by John Tyndall,[268] investigated quantitatively by Svante Arrhenius in 1896,[263] and the hypothesis was reported in the popular press as early as 1912.[269] The scientific description of global warming was further developed in the 1930s through the 1960s by Guy Stewart Callendar.[270]

Terminology

Research in the 1950s suggested that temperatures were increasing, and a 1952 newspaper used the term "climate change". This phrase next appeared in a November 1957 report in The Hammond Times which described Roger Revelle's research into the effects of increasing human-caused CO
2
emissions on the greenhouse effect: "a large scale global warming, with radical climate changes may result". A 1971 MIT report referred to the human impact as "inadvertent climate modification", identifying many possible causes.[271]

Both the terms global warming and climate change were used only occasionally until 1975, when Wallace Smith Broecker published a scientific paper on the topic, "Climatic Change: Are We on the Brink of a Pronounced Global Warming?". The phrase began to come into common use, and in 1976 Mikhail Budyko's statement that "a global warming up has started" was widely reported.[264] An influential 1979 National Academy of Sciences study headed by Jule Charney followed Broecker in using global warming to refer to rising surface temperatures, while describing the wider effects of increased CO
2
as climate change.[272]

There were increasing heatwaves and drought problems in the summer of 1988, and NASA climate scientist James Hansen's testimony in the U.S. Senate sparked worldwide interest.[265] He said "global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming".[273] Public attention increased over the summer, and global warming became the dominant popular term, commonly used both by the press and in public discourse.[272] In the 2000s, the term climate change increased in popularity.[274]

People who regard climate change as catastrophic, irreversible, or rapid might label climate change as a climate crisis or a climate emergency.[275] Some major newspapers, such as The Guardian, have taken up the use of this terminology, as well as the term global heating, in order to emphasize its seriousness and urgency.[276] Since 2016, some city councils have issued climate emergency declarations.[277][278] In 2019, the British Parliament became the first national government in the world to officially declare a climate emergency.[279]

See also

Notes

  1. ^ a b IPCC AR5 WG1 Summary for Policymakers 2013, p. 4: Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased
  2. ^ "Myths vs. Facts: Denial of Petitions for Reconsideration of the Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act". U.S. Environmental Protection Agency. Retrieved 7 August 2017. The U.S. Global Change Research Program, the National Academy of Sciences, and the Intergovernmental Panel on Climate Change (IPCC) have each independently concluded that warming of the climate system in recent decades is "unequivocal". This conclusion is not drawn from any one source of data but is based on multiple lines of evidence, including three worldwide temperature datasets showing nearly identical warming trends as well as numerous other independent indicators of global warming (e.g. rising sea levels, shrinking Arctic sea ice).
  3. ^ IPCC AR5 SYR Glossary 2014, p. 124: Global warming refers to the gradual increase, observed or projected, in global surface temperature, as one of the consequences of radiative forcing caused by anthropogenic emissions. {WGIII}
  4. ^ IPCC SR15 Ch1 2018, p. 51: Global warming is defined in this report as an increase in combined surface air and sea surface temperatures averaged over the globe and over a 30-year period. Unless otherwise specified, warming is expressed relative to the period 1850–1900, used as an approximation of pre-industrial temperatures in AR5.
  5. ^ Shaftel 2016: "'Climate change' and 'global warming' are often used interchangeably but have distinct meanings. .... Global warming refers to the upward temperature trend across the entire Earth since the early 20th century .... Climate change refers to a broad range of global phenomena ...[which] include the increased temperature trends described by global warming."
  6. ^ NOAA, 17 June 2015; IPCC AR5 SYR Glossary 2014, p. 120: "Climate change refers to a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use. .... {WGI, II, III}"
  7. ^ IPCC AR5 WG1 Ch5 2013, pp. 389, 399–400: "5: Information from Paleoclimate Archives: The PETM [around 55.5–55.3 million years ago] was marked by ... global warming of 4°C to 7°C ..... Deglacial global warming occurred in two main steps from 17.5 to 14.5 ka [thousand years ago] and 13.0 to 10.0 ka.
  8. ^ IPCC AR5 SYR Summary for Policymakers 2014, p. 2: SPM 1.1 .... Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. The period from 1983 to 2012 was likely the warmest 30-year period of the last 1400 years in the Northern Hemisphere, where such assessment is possible (medium confidence).
  9. ^ IPCC AR5 WG1 Summary for Policymakers 2013, p. 17: "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century."
  10. ^ IPCC AR5 WG1 Technical Summary 2013, p. 57.
  11. ^ "Joint Science Academies' Statement" (PDF). Archived (PDF) from the original on 9 September 2013. Retrieved 6 January 2014.
  12. ^ "Scientific consensus: Earth's climate is warming". Climate Change: Vital Signs of the Planet. NASA. Archived from the original on 28 June 2018. Retrieved 7 August 2017.
  13. ^ "List of Organizations". The Governor's Office of Planning & Research, State of California. Archived from the original on 7 August 2017. Retrieved 7 August 2017.
  14. ^ IPCC AR5 WG2 Technical Summary 2014, pp. 44–46; D'Odorico et al. 2013
  15. ^ National Geographic 2019; NPR 2010
  16. ^ Campbella et al. 2016.
  17. ^ US NRC 2012, pp. 26–27
  18. ^ Knowlton 2001.
  19. ^ EPA (19 January 2017). "Climate Impacts on Ecosystems". Archived from the original on 27 January 2018. Retrieved 5 February 2019.
  20. ^ Clark et al. 2016.
  21. ^ a b c Stokes, Wike & Carle 2015.
  22. ^ "Status of Ratification of the Convention". United Nations Framework Convention on Climate Change. 2019. Archived from the original on 19 May 2019. Retrieved 19 May 2019. As of May 2019 12 parties have not ratified the convention. Non-ratification means they are not legally bound by it.
  23. ^ "First steps to a safer future: Introducing The United Nations Framework Convention on Climate Change". United Nations Framework Convention on Climate Change. Archived from the original on 8 January 2014. Retrieved 7 August 2017. Preventing "dangerous" human interference with the climate system is the ultimate aim of the UNFCCC.
  24. ^ "Conference of the Parties – Sixteenth Session: Decision 1/CP.16: The Cancun Agreements: Outcome of the work of the Ad Hoc Working Group on Long-term Cooperative Action under the Convention (English): Paragraph 4" (PDF). UNFCCC Secretariat: Bonn, Germany: United Nations Framework Convention on Climate Change. 2011. p. 3. Archived (PDF) from the original on 17 November 2011. Retrieved 28 October 2011. (...) deep cuts in global greenhouse gas emissions are required according to science, and as documented in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, with a view to reducing global greenhouse gas emissions so as to hold the increase in global average temperature below 2 °C above preindustrial levels
  25. ^ CNN, 12 December 2015; Vaughan 2015.
  26. ^ IPCC SR15 Ch1 2018, p. 51
  27. ^ Steffen et al. 2018
  28. ^ Hansen et al. 2013.
  29. ^ a b IPCC SR15 Ch1 2018, p. 57: This report adopts the 51-year reference period, 1850–1900 inclusive, assessed as an approximation of pre-industrial levels in AR5 .... Temperatures rose by 0.0°C–0.2°C from 1720–1800 to 1850–1900 (Hawkins et al., 2017)
  30. ^ Hawkins, Ed; Ortega, Pablo; Suckling, Emma; Schurer, Andrew; Hegerl, Gabi; Jones, Phil; Joshi, Manoj; Osborn, Timothy J.; Masson-Delmotte, Valérie; Mignot, Juliette; Thorne, Peter; van Oldenborgh, Geert Jan (2017). "Estimating Changes in Global Temperature since the Preindustrial Period". Bulletin of the American Meteorological Society. American Meteorological Society. 98 (9): 1841–1856. doi:10.1175/bams-d-16-0007.1. ISSN 0003-0007. The period after 1800 is influenced by the Dalton Minimum in solar activity and the large eruptions of an unlocated volcano in 1808/09, Tambora (1815; Raible et al. 2016), and several others in the 1820s and 1830s. In addition, greenhouse gas concentrations had already increased slightly by this time .... The 1720–1800 period is most suitable to be defined as preindustrial in physical terms ... The 1850–1900 period is a reasonable pragmatic surrogate for preindustrial global mean temperature.
  31. ^ IPCC AR5 WG1 Summary for Policymakers 2013, pp. 4–5: Global-scale observations from the instrumental era began in the mid-19th century for temperature and other variables ... the period 1880 to 2012 ... multiple independently produced datasets exist.
  32. ^ IPCC SR15 Summary for Policymakers 2018, p. 4; WMO 2019, p. 6
  33. ^ IPCC SR15 Ch1 2018, p. 81
  34. ^ IPCC AR5 WG1 Ch2 2013, p. 162.
  35. ^ IPCC AR5 WG1 Ch5 2013, p. 386; Neukom et al. 2019
  36. ^ "Climate Change: Ocean Heat Content". NOAA. 2018. Archived from the original on 12 February 2019. Retrieved 20 February 2019.
  37. ^ IPCC AR5 WG1 Ch3 2013, p. 257: "Ocean warming dominates the global energy change inventory. Warming of the ocean accounts for about 93% of the increase in the Earth's energy inventory between 1971 and 2010 (high confidence), with warming of the upper (0 to 700 m) ocean accounting for about 64% of the total.
  38. ^ a b c Kennedy et al. 2010
  39. ^ USGCRP Chapter 1 2017, p. 35
  40. ^ Cazenave et al. 2014
  41. ^ IPCC AR4 WG1 Summary for Policymakers 2007.
  42. ^ IPCC AR4 WG2 Summary for Policymakers 2007, Part B: "Current knowledge about observed impacts of climate change on the natural and human environment".
  43. ^ IPCC AR4 WG2 Ch1 2007, Sec. 1.3.5.1: "Changes in phenology", p. 99.
  44. ^ "Climate at a Glance / Global Time Series". ncdc.noaa.gov. NOAA (National Centers for Environmental Information; National Climatic Data Center). December 2018. Archived from the original on 26 July 2019. Retrieved 26 July 2019. Choose 12-Month timescale, December, 1880-2019, Northern Hemisphere, Land and Ocean, Plot.
  45. ^ "Climate at a Glance / Global Time Series". ncdc.noaa.gov. NOAA (National Centers for Environmental Information; National Climatic Data Center). December 2018. Archived from the original on 26 July 2019. Retrieved 26 July 2019. Choose 12-Month timescale, December, 1880-2019, Southern Hemisphere, Land and Ocean, Plot.
  46. ^ Hawkins, Ed (21 July 2019). "#ShowYourStripes / Temperature changes around the world (1901-2018)". Climate Lab Book. Archived from the original on 2 August 2019. (Direct link to image).
  47. ^ IPCC SRCCL Summary for Policymaker 2019, p. 5
  48. ^ Sutton, Dong & Gregory 2007.
  49. ^ United States Environmental Protection Agency 2016, p. 5: "Black carbon that is deposited on snow and ice darkens those surfaces and decreases their reflectivity (albedo). This is known as the snow/ice albedo effect. This effect results in the increased absorption of radiation that accelerates melting."
  50. ^ NOAA (10 July 2011). "Polar Opposites: the Arctic and Antarctic". Archived from the original on 22 February 2019. Retrieved 20 February 2019.
  51. ^ IPCC AR5 WG1 Ch12 2013, p. 1062; Cohen et al. 2014
  52. ^ NASA, 12 September 2018: "We are seeing a major shift in the circulation in the North Atlantic, likely related to a weakening Atlantic Meridional Overturning Circulation (AMOC)", said Pershing. "One of the side effects of a weaker AMOC is that the Gulf Stream shifts northward and the cold current flowing into the Gulf of Maine gets weaker. This means we get more warmer water pushing into the Gulf."
  53. ^ Sévellec & Drijfhout 2018; Mooney 2018
  54. ^ England et al. 2014; Knight et al. 2009.
  55. ^ Lindsey 2018.
  56. ^ Delworth & Mann 2000, p. 661
  57. ^ Delworth & Zeng 2012, p. 5
  58. ^ US NRC 2012, p. 9
  59. ^ IPCC AR4 WG1 Ch9 2007, p. 690: "Recent estimates indicate a relatively small combined effect of natural forcings on the global mean temperature evolution of the second half of the 20th century, with a small net cooling from the combined effects of solar and volcanic forcings."
  60. ^ Knutson 2017, p. 443; IPCC AR5 WG1 Ch10 2013, pp. 875–876.
  61. ^ IPCC AR5 WG1 Summary for Policymakers 2013, pp. 13-14
  62. ^ NASA. "The Causes of Climate Change". Climate Change: Vital Signs of the Planet. Archived from the original on 8 May 2019. Retrieved 8 May 2019.
  63. ^ IPCC AR4 WG1 Ch1 2007, FAQ1.1: "To emit 240 W m–2, a surface would have to have a temperature of around −19 °C. This is much colder than the conditions that actually exist at the Earth's surface (the global mean surface temperature is about 14 °C). Instead, the necessary −19 °C is found at an altitude about 5 km above the surface."
  64. ^ ACS. "What Is the Greenhouse Effect?". Archived from the original on 26 May 2019. Retrieved 26 May 2019.
  65. ^ Kiehl & Trenberth 1997
  66. ^ Schmidt, Gavin (6 April 2005). "Water vapour: feedback or forcing?". RealClimate. Archived from the original on 18 April 2009. Retrieved 21 April 2009.
  67. ^ Russell, Randy (16 May 2007). "The Greenhouse Effect & Greenhouse Gases". University Corporation for Atmospheric Research Windows to the Universe. Archived from the original on 28 March 2010. Retrieved 27 December 2009.
  68. ^ IPCC AR5 WG1 Summary for Policymakers 2013, p. 11.
  69. ^ a b Amos 2013; Schiermeier 2015.
  70. ^ Siegenthaler et al. 2005; Lüthi et al. 2008
  71. ^ IPCC AR5 WG3 Summary for Policymakers 2014, pp. 6–7.
  72. ^ Poore & Nemecek 2018
  73. ^ Bajzelj, Allwood & Cullen 2013
  74. ^ Duveiller, Hooker & Cescatti 2018
  75. ^ Andrews et al. 2016; IPCC AR5 WG1 Technical Summary 2013
  76. ^ Haywood 2016
  77. ^ IPCC AR5 WG1 Ch2 2013, p. 183
  78. ^ He et al. 2018; Storelvmo et al. 2016
  79. ^ Ramanathan & Carmichael 2008
  80. ^ Wild et al. 2005; Pinker, Zhang & Dutton 2005; Storelvmo et al. 2016
  81. ^ Twomey 1977
  82. ^ Albrecht 1989
  83. ^ USGCRP Chapter 2 2017, p. 78
  84. ^ Ramanathan & Carmichael 2008; RIVM 2016
  85. ^ Sand et al. 2015
  86. ^ Ramanathan et al. 2008; Ramanathan et al. 2005
  87. ^ Ramanathan, V.; et al. (2008). "Part III: Global and Future Implications" (PDF). Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia. United Nations Environment Programme. Archived from the original (PDF) on 18 July 2011.
  88. ^ Wang & Xie 2016; Zhang et al. 2019
  89. ^ a b USGCRP Chapter 2 2017, p. 78
  90. ^ US NRC 2008, p. 6
  91. ^ "Is the Sun causing global warming?". Climate Change: Vital Signs of the Planet. Archived from the original on 5 May 2019. Retrieved 10 May 2019.
  92. ^ Schmidt, Shindell & Tsigaridis 2014; Fyfe et al. 2016
  93. ^ IPCC AR4 WG1 Ch9 2007, pp. 702–703
  94. ^ IPCC AR4 WG1 Ch9 2007, pp. 702–703; Randel et al. 2009
  95. ^ USGCRP 2009, p. 20
  96. ^ Wang, Shugart & Lerdau 2017
  97. ^ "Thermodynamics: Albedo". NSIDC. Archived from the original on 11 October 2017. Retrieved 10 October 2017.
  98. ^ "The study of Earth as an integrated system". Vitals Signs of the Planet. Earth Science Communications Team at NASA's Jet Propulsion Laboratory / California Institute of Technology. 2013. Archived from the original on 26 February 2019.
  99. ^ Lindsey, R. (14 January 2009). "Earth's Energy Budget, in: Climate and Earth's Energy Budget: Feature Articles". Earth Observatory, part of the EOS Project Science Office, located at NASA Goddard Space Flight Center. Archived from the original on 2 September 2018. The amount of heat a surface radiates is proportional to the fourth power of its temperature (in Kelvin).
  100. ^ a b Met Office 2016
  101. ^ Wolff et al. 2015: "the nature and magnitude of these feedbacks are the principal cause of uncertainty in the response of Earth's climate (over multi-decadal and longer periods) to a particular emissions scenario or greenhouse gas concentration pathway."
  102. ^ NASA, 28 May 2013
  103. ^ Cohen et al. 2014
  104. ^ Farquharson et al. 2019; NASA, 20 August 2018; The Guardian, 18 June 2019
  105. ^ USGCRP Chapter 2 2017, p. 90
  106. ^ Witze 2016: "By 2009, the team found that there were fewer clouds over the mid-latitudes than there had been in 1983. That finding meshes with climate predictions that dry zones will expand out of the subtropics and push storms towards the poles. The team also found that cloud tops rose higher in the atmosphere by the end of the 2000s, again as predicted for a warming atmosphere."
  107. ^ NASA, 16 June 2011: "So far, land plants and the ocean have taken up about 55 percent of the extra carbon people have put into the atmosphere while about 45 percent has stayed in the atmosphere. Eventually, the land and oceans will take up most of the extra carbon dioxide, but as much as 20 percent may remain in the atmosphere for many thousands of years."
  108. ^ a b NOAA, 20 April 2017
  109. ^ Scientific American, 23 January 2018: "Climate change's negative effects on plants will likely outweigh any gains from elevated atmospheric carbon dioxide levels"
  110. ^ "How the oceans absorb carbon dioxide is critical for predicting climate change". Archived from the original on 29 March 2019. Retrieved 24 February 2019. increasing CO2 modifies the climate which in turn impacts ocean circulation and therefore ocean CO2 uptake. Changes in marine ecosystems resulting from rising CO2 and/or changing climate can also result in changes in air-sea CO2 exchange. These feedbacks can change the role of the oceans in taking up atmospheric CO2 making it very difficult to predict how the ocean carbon cycle will operate in the future.
  111. ^ Melillo et al. 2017: "Our first-order estimate of a warming-induced loss of 190 Pg of soil carbon over the 21st century is equivalent to the past two decades of carbon emissions from fossil fuel burning and is comparable in magnitude to the cumulative carbon losses to the atmosphere due to human-driven land use change during the past two centuries."
  112. ^ & Phys.org, 6 August 2018: "Hothouse Earth is likely to be uncontrollable and dangerous to many ... global average temperatures would exceed those of any interglacial period—meaning warmer eras that come in between Ice Ages—of the past 1.2 million years."; Steffen et al. 2018: "A Hothouse Earth trajectory would almost certainly flood deltaic environments, increase the risk of damage from coastal storms, and eliminate coral reefs (and all of the benefits that they provide for societies) by the end of this century or earlier".; The Guardian, 7 August 2018
  113. ^ "Patterns of greenhouse warming" (PDF). GFDL Climate Modeling Research Highlights. Princeton, New Jersey: The National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL). 1 (6). January 2007. Archived from the original (PDF) on 14 October 2012. Retrieved 1 December 2012.
  114. ^ "NOAA GFDL Climate Research Highlights Image Gallery: Patterns of Greenhouse Warming". NOAA Geophysical Fluid Dynamics Laboratory (GFDL). 9 October 2012. Archived from the original on 14 October 2012. Retrieved 1 December 2012.
  115. ^ IPCC AR4 SYR Glossary 2007, "Climate Model Archived 23 December 2018 at the Wayback Machine".
  116. ^ a b c d Carbon Brief, 15 January 2018
  117. ^ Stott & Kettleborough 2002
  118. ^ IPCC AR5 SYR Summary for Policymakers 2014, Sec. 2.1.
  119. ^ IPCC AR5 WG1 Technical Summary 2013.
  120. ^ IPCC AR4 WG1 Ch8 2007, Sec. FAQ 8.1.
  121. ^ Stroeve et al. 2007.
  122. ^ Liepert & Previdi 2009.
  123. ^ Rahmstorf et al. 2007; Mitchum et al. 2018.
  124. ^ USGCRP Chapter 15 2017
  125. ^ NOAA 2017
  126. ^ WCRP Global Sea Level Budget Group 2018
  127. ^ IPCC AR5 WG1 Ch13 2013.
  128. ^ U.S. Geological Survey, 18 June 2018
  129. ^ NOAA. "Climate Change: Global Sea Level". Archived from the original on 28 February 2019. Retrieved 27 February 2019. In 2017, global mean sea level was 3 inches (77 millimeters) above the 1993 average—the highest annual average in the satellite record (1993–present). It was the sixth consecutive year, and the 22nd out of the last 24 years in which global mean sea level increased relative to the previous year.
  130. ^ Zhang et al. 2008
  131. ^ IPCC AR5 WG1 Ch11 2013, p. 995; Wang & Overland 2009.
  132. ^ "Arctic sea ice 2012". Exeter, UK: Met Office. Archived from the original on 15 May 2013. Retrieved 29 March 2013.
  133. ^ IPCC SREX Summary for Policymakers 2012, section D ("Future Climate Extremes, Impacts, and Disaster Losses"), pp. 9-13.
  134. ^ USGCRP Chapter 15 2017, p. 415
  135. ^ Scientific American, 29 April 2014
  136. ^ Francis & Vavrus 2012; Sun, Perlwitz & Hoerling 2016; Carbon Brief, 31 January 2019
  137. ^ USGCRP Chapter 9 2017, p. 260
  138. ^ a b Ocean Acidification, in: Ch. 2. Our Changing Climate Archived 11 September 2013 at the Wayback Machine, in NCADAC 2013, pp. 69–70
  139. ^ Deutsch et al. 2011
  140. ^ a b National Research Council 2011, p. 14, Summary; IPCC AR5 WG1 Ch12 2013, pp. 88–89, FAQ 12.3.
  141. ^ McGuire 2010
  142. ^ Smith et al. 2009
  143. ^ IPCC TAR WG2 Ch19 2001, Section 19.6: Extreme and Irreversible Effects Archived 28 June 2019 at the Wayback Machine.
  144. ^ Clark et al. 2008; BBC, 22 February 2013
  145. ^ ScienceDaily, 20 December 2004; Liu et al. 2017
  146. ^ "Global Warming and Polar Bears – National Wildlife Federation". Archived from the original on 17 October 2017. Retrieved 16 October 2017. As climate change melts sea ice, the U.S. Geological Survey projects that two thirds of polar bears will disappear by 2050.Amstrup, Marcot & Douglas 2013, p. 213
  147. ^ IPCC AR4 SYR 2007, Section 1: Observed changes in climate and their effects Archived 23 December 2018 at the Wayback Machine.
  148. ^ IPCC AR4 WG2 Ch4 2007, Executive Summary Archived 27 June 2019 at the Wayback Machine, p. 213.
  149. ^ Zeng & Yoon 2009
  150. ^ The Washington Post, 30 August 2018
  151. ^ IPCC AR4 WG2 Ch19 2007, Section 19.3.4: Ecosystems and biodiversity Archived 23 December 2018 at the Wayback Machine.
  152. ^ ScienceDaily, 28 June 2018
  153. ^ Poloczanska et al. 2013
  154. ^ Smale et al. 2019
  155. ^ UNEP 2010, pp. 73–81
  156. ^ ScienceDaily, 21 January 2012
  157. ^ National Geographic 15 November 2018; Barbero et al. 2015
  158. ^ IPCC AR5 WG2 Technical Summary 2014, pp. 93–94, FAQ 7 and 8.
  159. ^ IPCC AR5 WG2 Technical Summary 2014, Section B-3: "Regional Risks and Potential for Adaptation", pp. 27–30.
  160. ^ IPCC AR5 WG2 Ch19 2014, p. 1077.
  161. ^ Diffenbaugh & Burke 2019; The Guardian, 26 January 2015; Burke, Davis & Diffenbaugh 2018
  162. ^ a b IPCC AR5 WG2 Ch18 2014, p. 983.
  163. ^ IPCC AR4 SYR 2007, Section 3.3.3: Especially affected systems, sectors and regions Archived 23 December 2018 at the Wayback Machine.
  164. ^ IPCC AR5 WG2 Ch19 2014, pp. 1073–1080.
  165. ^ IPCC AR5 WG2 Ch7 2014, p. 488.
  166. ^ IPCC AR5 WG2 Summary for Policymakers 2014, p. 18.
  167. ^ IPCC AR5 WG2 Ch7 2014, pp. 491–492.
  168. ^ a b c d   This article incorporates public domain material from the US Environmental Protection Agency document: International Impacts & Adaptation: Climate Change: US EPA. US Environmental Protection Agency. 14 June 2012. Archived from the original on 29 August 2015. Retrieved 18 May 2018.
  169. ^ Kabir et al. 2016
  170. ^ IPCC AR5 WG2 Ch11 2014, p. 742; Costello et al. 2009; Watts et al. 2015.
  171. ^ IPCC AR5 WG2 Ch11 2014, pp. 720–723.
  172. ^ Costello et al. 2009; Watts et al. 2015; IPCC AR5 WG2 Ch11 2014, p. 713.
  173. ^ USA Today, 13 July 2018
  174. ^ IPCC AR5 WG2 Summary for Policymakers 2014, p. 20.
  175. ^ The Washington Post, 22 October 2014; Ranson 2014; Marshall, Hsiang & Edward 2014; National Review, 27 February 2014
  176. ^ American Society for Microbiology (23 July 2019). "Rise of Candida auris blamed on global warming". Science Daily. Retrieved 25 July 2019.
  177. ^ IPCC AR4 SYR 2007, Section 3.3.3: "Especially affected systems, sectors and regions" Archived 23 December 2018 at the Wayback Machine; IPCC AR4 WG2 Ch16 2007, Executive Summary Archived 23 December 2018 at the Wayback Machine.
  178. ^ UNHCR 2011
  179. ^ UN Environment, 25 October 2018; UNFCCC, 17 October 2017
  180. ^ Sherwood & Huber 2010
  181. ^ IPCC AR5 SYR Summary for Policymakers 2014, p. 17, Section 3.
  182. ^ PBL Netherlands Environment Agency 2012
  183. ^ Mitigation Archived 21 January 2015 at the Wayback Machine, in USGCRP 2015.
  184. ^ IPCC AR4 SYR 2007, Section 4: Adaptation and mitigation options Archived 1 May 2010 at the Wayback Machine; Table TS.3, in IPCC AR5 WG3 Technical Summary 2014, p. 68.
  185. ^ Carrington, Damian (4 July 2019). "Tree planting 'has mind-blowing potential' to tackle climate crisis". The Guardian. ISSN 0261-3077. Archived from the original on 5 July 2019. Retrieved 5 July 2019.
  186. ^ The Guardian, 31 August 2015.
  187. ^ IPCC AR4 WG3 Ch1 2007, Section 1.3.1.2: Intensities Archived 23 December 2018 at the Wayback Machine.
  188. ^ NRC 2008; World Bank 2010, p. 71.
  189. ^ Liverman 2009, p. 289.
  190. ^ IPCC AR4 WG3 Ch3 2007, Section 3.1: Emissions scenarios: Issues related to mitigation in the long term context Archived 23 December 2018 at the Wayback Machine
  191. ^ Riahi et al. 2017; Carbon Brief, 19 April 2018
  192. ^ IPCC TAR WG3 Summary for Policymakers 2001, Introduction, paragraph 6 Archived 11 March 2006 at the Wayback Machine.
  193. ^ Carbon Brief, 19 April 2018; Meinshausen 2019, p. 462
  194. ^ IPCC AR5 WG3 Ch6 2014, p. 418; IPCC AR5 WG3 Summary for Policymakers 2014, pp. 10–13.
  195. ^ "The CAT Thermometer". Climate Action Tracker. 11 December 2018. Archived from the original on 14 April 2019. Retrieved 14 April 2019.
  196. ^ IPCC AR5 WG3 Technical Summary 2014, pp. 55–56.
  197. ^ UNFCCC SYN 2016 p.10-11 Archived 14 April 2019 at the Wayback Machine
  198. ^ IPCC SR15 Summary for Policymakers 2018, p. 15
  199. ^ "The Montreal Protocol: triumph by treaty". UN Environment. 20 November 2017. Archived from the original on 12 April 2019. Retrieved 12 April 2019.
  200. ^ Quam et al. 2017
  201. ^ BBC, 17 December 2018
  202. ^ United Nations Development Program. "Reducing emissions, promoting clean energy and protecting forests". Archived from the original on 17 April 2019. Retrieved 17 April 2019.
  203. ^ IPCC AR5 WG3 Technical Summary 2014, p. 58.
  204. ^ The Economist, 7 February 2019.
  205. ^ Hagmann, Ho & Loewenstein 2019.
  206. ^ Science, 11 July 2017; Wynes & Nicholas 2017.
  207. ^ The Guardian, 27 February 2019; Vox, 15 October 2018.
  208. ^ a b IPCC AR4 WG2 Summary for Policymakers 2007, p. 5.
  209. ^ NASA's Global Climate Change. "Global climate change adaptation and mitigation". Climate Change: Vital Signs of the Planet. Archived from the original on 3 April 2019. Retrieved 12 April 2019.
  210. ^ IPCC TAR WG2 Ch18 2001, Section 18.2.3: Adaptation Types and Forms.
  211. ^ a b IPCC AR5 SYR Summary for Policymakers 2014, Section 4.2, p. 26.
  212. ^ "New Report Provides Authoritative Assessment of National, Regional Impacts of Global Climate Change" (Press release). U.S. Global Change Research Program. 16 June 2009. Archived from the original on 13 April 2016. Retrieved 14 January 2016.
  213. ^ Cole 2008
  214. ^ IPCC AR4 WG2 Ch19 2007, p. 796.
  215. ^ "UN expert condemns failure to address impact of climate change on poverty". OHCHR. 25 June 2019. Archived from the original on 10 July 2019. Retrieved 9 July 2019.
  216. ^ Lane, Lee; Caldeira, Ken (April 2007). Workshop on managing solar radiation (PDF) (Report). NASA. Archived from the original (PDF) on 31 May 2009. Retrieved 23 May 2009.
  217. ^ "Stop emitting CO2 or geoengineering could be our only hope" (Press release). The Royal Society. 28 August 2009. Archived from the original on 24 June 2011. Retrieved 14 June 2011.
  218. ^ Keller, Feng & Oschlies 2014: We find that even when applied continuously and at scales as large as currently deemed possible, all methods are, individually, either relatively ineffective with limited (<8%) warming reductions, or they have potentially severe side effects and cannot be stopped without causing rapid climate change.
  219. ^ UN General Assembly 1992, article 2
  220. ^ Morgan et al. 2009, p. 11
  221. ^ "Paris Agreement - Status of Ratification". United Nations Framework Convention on Climate Change. n.d. Archived from the original on 16 May 2019. Retrieved 18 May 2019.
  222. ^ "Ratification Tracker". climateanalytics.org. Archived from the original on 24 July 2018. Retrieved 19 May 2019.
  223. ^ UN General Assembly 1992, Article 2
  224. ^ IPCC AR4 WG3 Ch1 2007, Executive summary Archived 23 December 2018 at the Wayback Machine.
  225. ^ US EPA 2016
  226. ^ UNFCCC. "What are United Nations Climate Change Conferences?". Archived from the original on 12 May 2019. Retrieved 12 May 2019.
  227. ^ Dessai 2001, p. 4
  228. ^ Grubb 2003
  229. ^ Liverman 2009, p. 290
  230. ^ UNFCC 1997; Liverman 2009, p. 290
  231. ^ UNFCC 1997
  232. ^ Dessai 2001, p. 5
  233. ^ Müller 2010; The New York Times, 25 May 2015
  234. ^ openDemocracy, 12 January 2010; EUobserver, 20 December 2009
  235. ^ UNFCCC 2010
  236. ^ a b "The Paris Agreement: Summary. Climate Focus Client Brief on the Paris Agreement III" (PDF). Climate Focus. December 2015. Archived (PDF) from the original on 5 October 2018. Retrieved 12 April 2019.
  237. ^ Cook et al. 2016
  238. ^ NRC 2008, p. 2; DiMento & Doughman 2007, p. 68; Brigham-Grette et al. 2006: "The AAPG stands alone among scientific societies in its denial of human-induced effects on global warming."
  239. ^ Royal Society 2011
  240. ^ IPCC AR5 WG1 Summary for Policymakers 2013: "It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century" (page 15) and "In this Summary for Policymakers, the following terms have been used to indicate the assessed likelihood of an outcome or a result: (...) extremely likely: 95–100%" (page 2).
  241. ^ Academia Brasileira de Ciéncias (Brazil); Royal Society of Canada; Chinese Academy of Sciences; Académie des Sciences (France); Deutsche Akademie der Naturforscher Leopoldina (Germany); Indian National Science Academy; Accademia Nazionale dei Lincei (Italy); Science Council of Japan, Academia Mexicana de Ciencias; Russian Academy of Sciences; Academy of Science of South Africa; Royal Society (United Kingdom); National Academy of Sciences (United States of America) (May 2009). "G8+5 Academies' joint statement: Climate change and the transformation of energy technologies for a low carbon future" (PDF). The National Academies of Sciences, Engineering, and Medicine. Archived (PDF) from the original on 15 February 2010. Retrieved 5 May 2010.
  242. ^ Ripple et al. 2017
  243. ^ IPCC SR15 Ch4 2018, p. 317; The New York Times, 7 October 2018
  244. ^ Weart 2015
  245. ^ Gallup, 20 April 2011
  246. ^ Gallup, 22 April 2011
  247. ^ Pew Research, 24 June 2013
  248. ^ Newell 2006, p. 80; Yale Climate Connections, 2 November 2010
  249. ^ Shindell et al. 2006
  250. ^ Montlake, Simon (2019). "What does climate change have to do with socialism". The Christian Science Monitor. ISSN 0882-7729. Retrieved 16 August 2019. For many climate skeptics, climate change has little to do with science. One of the most vocal strains of opposition to mainstream climate science appears to be rooted in fears of socialism.
  251. ^ McCright & Dunlap 2000
  252. ^ Newsweek, 13 August 2007
  253. ^ Boykoff & Boykoff 2004; Oreskes & Conway 2010
  254. ^ Poortinga et al. 2018, p. 15.
  255. ^ Newsweek, 13 August 2007; Adams 2006; MSNBC, 12 January 2007; ABC, 3 January 2007.
  256. ^ "Oil Company Positions on the Reality and Risk of Climate Change". Environmental Studies, University of Oshkosh – Wisconsin. Archived from the original on 16 April 2016. Retrieved 27 March 2016.
  257. ^ The Economist, 9 February 2009
  258. ^ Milman 2019
  259. ^ Gunningham 2018.
  260. ^ The New York Times, 29 April 2017.
  261. ^ The Guardian, 19 March 2019.
  262. ^ BBC, 16 April 2019; Euronews, 22 June 2019; Deutsche Welle, 22 June 2019
  263. ^ a b Weart, Spencer (2008). "The Carbon Dioxide Greenhouse Effect". The Discovery of Global Warming. American Institute of Physics. Archived from the original on 11 November 2016. Retrieved 21 April 2009.
  264. ^ a b Weart, Spencer R. (February 2014). "The Discovery of Global Warming; The Public and Climate Change: Suspicions of a Human-Caused Greenhouse (1956–1969)". American Institute of Physics. Archived from the original on 11 November 2016. Retrieved 12 May 2015. Also footnote 27 Archived 16 May 2015 at the Wayback Machine Archived 16 May 2015 at the Wayback Machine
  265. ^ a b Weart, Spencer R. (February 2014). "The Discovery of Global Warming; The Public and Climate Change: The Summer of 1988". American Institute of Physics. Archived from the original on 11 November 2016. Retrieved 12 May 2015.
  266. ^ Weart 2013
  267. ^ Sorenson 2011; Foote 1856
  268. ^ Tyndall 1861
  269. ^ Popular Mechanics, March 1912; The Braidwood Dispatch and Mining Journal, 17 July 1912
  270. ^ Callendar 1938; Fleming 2007
  271. ^ Bhargava 2002, p. 211
  272. ^ a b Conway, Erik M. (5 December 2008). "What's in a Name? Global Warming vs. Climate Change". NASA. Archived from the original on 9 August 2010.
  273. ^ U.S. Senate, Committee on Energy and Natural Resources, 100th Cong. 1st sess. (23 June 1988). Greenhouse Effect and Global Climate Change, part 2. p. 44.
  274. ^ Joo et al. 2015
  275. ^ Hodder & Martin 2009
  276. ^ The Guardian, 17 May 2019
  277. ^ "Minutes of the Council Meeting". Meetings. City of Darebin. 24 August 2017 [2017-08-21]. Archived from the original on 16 June 2019. Retrieved 11 May 2019.
  278. ^ "Darebin Climate Emergency Plan". Agendas and minutes of Council. City of Darebin. 21 August 2017. Archived from the original on 10 June 2019. Retrieved 11 May 2019.
  279. ^ BBC, 1 May 2019; Vice, 2 May 2019

Sources

IPCC reports

TAR Working Group II Report

TAR Working Group III Report

AR4 Working Group I Report

AR4 Working Group II Report

AR4 Working Group III Report

AR4 Synthesis Report

AR5 Working Group I Report

AR5 Working Group II Report

AR5 Working Group III Report

AR5 Synthesis Report

Special Report: SREX

Special Report: SR15

Special report: Climate change and Land


Other peer-reviewed sources

Books, reports and legal documents

Non-technical sources

ABC

American Institute of Physics

BBC

Carbon Brief

CNN

Deutsche Welle

The Economist

EPA

EUobserver

Euronews

Gallup

The Guardian

MSNBC

Met Office

NASA

National Geographic

National Review

Nature

Newsweek

NOAA

NPR

OpenDemocracy

Pew Research

Phys.org

Popular Mechanics

RIVM

  • Documentary Sea Blind (Dutch Television) (in Dutch). RIVM: Netherlands National Institute for Public Health and the Environment. 11 October 2016. Archived from the original on 17 August 2018. Retrieved 26 February 2019.

Science

ScienceDaily

Scientific American

The Braidwood Dispatch and Mining Journal

The New York Times

The Washington Post

U.S. Geological Survey

UN Environment

UNFCCC

USA Today

Vice

Vox

Yale Climate Connections

External links

Research

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