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This article is primarily about effects during the 21st century. For longer-term effects, see .
Summary of climate change impacts.
Projected global warming in 2100 for a range of emission scenarios.
The effects of
are the environmental and social changes caused (directly or indirectly) by human emissions of . There is , and that human activities are the primary driver. Many impacts of climate change have already been observed, including , changes in the timing of seasonal events (e.g., earlier flowering of plants), and changes in agricultural productivity.
Future effects of climate change will vary depending on climate change policies and . The two main policies to address climate change are reducing human greenhouse gas emissions () and
to the impacts of climate change.
is another policy option.
Near-term climate change policies could significantly affect long-term climate change impacts. Stringent mitigation policies might be able to limit global warming (in 2100) to around 2 °C or below, relative to pre-industrial levels. Without mitigation, increased
and extensive use of
might lead to global warming of around 4 °C. Higher magnitudes of global warming would be more difficult to adapt to, and would increase the risk of negative impacts.
In this article, "" means a change in climate that persists over a sustained period of time. The
defines this time period as 30 years. Examples of climate change include increases in global surface temperature (global warming), changes in
patterns, and changes in the frequency of
events. Changes in climate may be due to natural causes, e.g., changes in the 's output, or due to human activities, e.g., changing the composition of the atmosphere. Any human-induced changes in climate will occur against a background of natural climatic variations and of variations in human activity such as population growth on shores or in arid areas which increase or decrease climate vulnerability.
Also, the term "anthropogenic forcing" refers to the influence exerted on a habitat or chemical environment by humans, as opposed to a natural process.
Global mean surface temperature difference from the average for .
The graph above shows the average of a set of temperature simulations for the 20th century (black line), followed by projected temperatures for the 21st century based on three greenhouse gas emissions scenarios (colored lines).
This article breaks down some of the impacts of climate change according to different levels of future global warming. This way of describing impacts has, for instance, been used in the IPCC () Assessment Reports on climate change. The instrumental
shows global warming of around 0.6 °C during the 20th century.
The future level of global warming is uncertain, but a wide range of estimates (projections) have been made. The IPCC's "" scenarios have been frequently used to make .:22–24 The SRES scenarios are "" (or "reference") scenarios, which means that they do not take into account any current or future measures to limit GHG emissions (e.g., the UNFCCC's
and the ). Emissions projections of the SRES scenarios are broadly comparable in range to the baseline emissions scenarios that have been developed by the scientific community.
In the , changes in future global mean temperature were projected using the six SRES "marker" emissions scenarios. Emissions projections for the six SRES "marker" scenarios are representative of the full set of forty SRES scenarios. For the lowest emissions SRES marker scenario ("B1" - see the
article for details on this scenario), the best estimate for global mean temperature is an increase of 1.8 °C (3.2 °F) by the end of the 21st century. This projection is relative to global temperatures at the end of the 20th century. The "likely" range (greater than 66% probability, based on expert judgement) for the SRES B1 marker scenario is 1.1–2.9 °C (2.0–5.2 °F). For the highest emissions SRES marker scenario (A1FI), the best estimate for global mean temperature increase is 4.0 °C (7.2 °F), with a "likely" range of 2.4–6.4 °C (4.3–11.5 °F).
The range in temperature projections partly reflects (1) the choice of , and (2) the "".:22–24 For (1), different scenarios make different assumptions of future social and economic development (e.g., , , ), which in turn affects projections of greenhouse gas (GHG) emissions.:22–24 The projected magnitude of warming by 2100 is closely related to the level of cumulative emissions over the 21st century (i.e. total emissions between ). The higher the cumulative emissions over this time period, the greater the level of warming is projected to occur.
(2) reflects uncertainty in the response of the climate system to past and future GHG emissions, which is measured by the ).:22–24 Higher estimates of climate sensitivity lead to greater projected warming, while lower estimates of climate sensitivity lead to less projected warming.
Over the next several millennia, projections suggest that global warming could be irreversible. Even if emissions were drastically reduced, global temperatures would remain close to their highest level for at least 1,000 years (see the later section on ).
Two millennia of mean surface temperatures according to different reconstructions from , each smoothed on a decadal scale, with the
overlaid in black.
Global surface temperature for the past 5.3 million years as inferred from cores of ocean
taken all around the global ocean. The last 800,000 years are expanded in the lower half of the figure (image credit: ).
Scientists have used various "proxy" data to assess past changes in Earth's climate (). Sources of proxy data include historical records (such as ' logs), , , , , and ocean and lake . Analysis of these data suggest that recent warming is unusual in the past 400 years, possibly longer. By the end of the 21st century, temperatures may increase to a level not experienced since the mid-, around 3 million years ago. At that time, models suggest that mean global temperatures were about 2–3 °C warmer than pre-industrial temperatures. Even a 2 °C rise above the pre-industrial level would be outside the range of temperatures experienced by human .
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Seven of these indicators would be expected to increase in a warming world and observations show that they are, in fact, increasing. Three would be expected to decrease and they are, in fact, decreasing.
This set of graphs show changes in climate indicators over several decades. Each of the different colored lines in each panel represents an independently analyzed set of data. The data come from many different technologies including , , ,
A broad range of evidence shows that the climate system has warmed. Evidence of global warming is shown in the graphs opposite. Some of the graphs show a positive , e.g., increasing temperature over land and the ocean, and . Other graphs show a negative trend, e.g., decreased
cover in the , and declining
extent. Evidence of warming is also apparent in living .
Human activities have contributed to a number of the observed changes in climate. This contribution has principally been through the burning of , which has led to an increase in the concentration of GHGs in the atmosphere. Another human influence on the climate are
emissions, which are a precursor to the formation of
in the atmosphere.
Human-induced warming could lead to
in physical systems. An example of this is the melting of , which contributes to sea level rise. The probability of warming having unforeseen consequences increases with the rate, magnitude, and duration of climate change.
Observations show that there have been changes in weather. As climate changes, the
of certain types of weather events are affected.
Projected change in annual average precipitation by the end of the 21st century, based on a medium emissions scenario ( A1B) (Credit: NOAA ).
Changes have been observed in the amount, intensity, frequency, and type of .:18 Widespread increases in heavy precipitation have occurred, even in places where total rain amounts have decreased. With medium confidence (see ), IPCC (2012) concluded that human influences had contributed to an increase in heavy precipitation events at the global scale.
Projections of future changes in precipitation show overall increases in the global average, but with substantial shifts in where and how precipitation falls.:24 Projections suggest a reduction in rainfall in the , and an increase in precipitation in subpolar latitudes and some . In other words, regions which are dry at present will in general become even drier, while regions that are currently wet will in general become even wetter. This projection does not apply to every locale, and in some cases can be modified by local conditions.
Over most land areas since the 1950s, it is very likely that there have been fewer or warmer cold days and nights. Hot days and nights have also very likely become warmer or more frequent. Human activities have very likely contributed to these trends. There may have been changes in other climate extremes (e.g., ,
and ) but these changes are more difficult to identify.
Projections suggest changes in the frequency and intensity of some extreme weather events. Confidence in projections varies over time.
Near-term projections ()
Some changes (e.g., more frequent hot days) will probably be evident in the near term, while other near-term changes (e.g., more intense droughts and tropical cyclones) are more uncertain.
Long-term projections ()
Future climate change will be associated with more very hot days and fewer very cold days. The frequency, length and intensity of
will very likely increase over most land areas. Higher growth in anthropogenic GHG emissions will be associated with larger increases in the frequency and severity of temperature extremes.
Assuming high growth in GHG emissions (IPCC scenario ), presently dry regions may be affected by an increase in the risk of drought and reductions in . Over most of the mid-latitude land masses and wet tropical regions, extreme precipitation events will very likely become more intense and frequent.
Tropical cyclones
At the global scale, the frequency of tropical cyclones will probably decrease or be unchanged. Global mean tropical cyclone maximum wind speed and precipitation rates will likely increase. Changes in tropical cyclones will probably vary by region, but these variations are uncertain.
Effects of climate extremes
The impacts of extreme events on the environment and human society will vary. Some impacts will be beneficial—e.g., fewer cold extremes will probably lead to fewer cold deaths. Overall, however, impacts will probably be mostly negative.
A map of the change in thickness of mountain glaciers since 1970. Thinning in orange and red, thickening in blue.
A map that shows ice concentration on 16 September 2012, along with the extent of the previous record low (yellow line) and the mid-September median extent (black line) setting a new record low that was 18 percent smaller than the previous record and nearly 50 percent smaller than the long-term () average.
is made up of areas of the Earth which are covered by snow or ice. Observed changes in the cryosphere include declines in
extent, the widespread retreat of , and reduced snow cover in the .
Solomon et al. (2007) assessed the potential impacts of climate change on
Arctic sea ice extent. Assuming high growth in greenhouse gas emissions (), some models projected that Arctic sea ice in the summer could largely disappear by the end of the 21st century. More recent projections suggest that the Arctic summers could be ice-free (defined as ice extent less than 1 million square km) as early as .
During the 21st century, glaciers and snow cover are projected to continue their widespread retreat. In the western mountains of , increasing temperatures and changes in precipitation are projected to lead to reduced . Snowpack is the seasonal accumulation of slow-melting snow. The melting of the
could contribute to sea level rise, especially over long time-scales (see the section on ).
Changes in the cryosphere are projected to have social impacts. For example, in some regions, glacier retreat could increase the risk of reductions in seasonal water availability. Barnett et al. (2005) estimated that more than one-sixth of the
rely on glaciers and snowpack for their water supply.
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The role of the oceans in global warming is complex. The oceans serve as a sink for carbon dioxide, taking up much that would otherwise remain in the atmosphere, but increased levels of CO
2 have led to . Furthermore, as the temperature of the oceans increases, they become less able to absorb excess CO
2. The ocean have also acted as a sink in absorbing extra heat from the atmosphere.:4 The increase in ocean
is much larger than any other store of
in the Earth’s heat balance over the two periods 1961 to 2003 and 1993 to 2003, and accounts for more than 90% of the possible increase in heat content of the Earth system during these periods.
Global warming is projected to have a number of effects on the oceans. Ongoing effects include rising sea levels due to thermal expansion and melting of glaciers and ice sheets, and warming of the ocean surface, leading to increased temperature stratification. Other possible effects include large-scale changes in ocean circulation.
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This map shows changes in the amount of
dissolved in
surface waters between the 1880s and the most recent decade (). Historical modeling suggests that since the 1880s, increased CO2 has led to lower
saturation levels (less availability of minerals) in the oceans around the world. The largest decreases in aragonite saturation have occurred in
waters. However, decreases in cold areas may be of greater concern because colder waters typically have lower aragonite levels to begin with.
About one-third of the carbon dioxide emitted by human activity has already been taken up by the oceans. As carbon dioxide dissolves in ,
is formed, which has the effect of acidifying the ocean, measured as a change in . The uptake of human carbon emissions since the year 1750 has led to an average decrease in pH of 0.1 units. Projections using the SRES emissions scenarios suggest a further reduction in average global surface ocean pH of between 0.14 and 0.35 units over the 21st century.
The effects of ocean acidification on the marine
have yet to be documented. Laboratory experiments suggest beneficial effects for a few species, with potentially highly detrimental effects for a substantial number of species. With medium confidence, Fischlin et al. (2007) projected that future ocean acidification and climate change would impair a wide range of
and shallow
marine organisms that use
to make their shells or skeletons, such as
and marine
(), with significant impacts particularly in the Southern Ocean.
The amount of oxygen dissolved in the oceans may decline, with adverse consequences for ocean life.
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Trends in global average absolute sea level, .
There is strong evidence that global sea level rose gradually over the 20th century. With high confidence, Bindoff et al. (2007) concluded that between the mid-19th and mid-20th centuries, the rate of sea level rise increased. Authors of the IPCC Fourth Assessment Synthesis Report (IPCC AR4 SYR, 2007) reported that between the years 1961 and 2003, global average sea level rose at an average rate of 1.8 mm per year (mm/yr), with a range of 1.3–2.3 mm/yr. Between 1993 and 2003, the rate increased above the previous period to 3.1 mm/yr (range of 2.4–3.8 mm/yr). Authors of IPCC AR4 SYR (2007) were uncertain whether the increase in rate from 1993 to 2003 was due to
in sea level over the time period, or whether it reflected an increase in the underlying long-term trend.
There are two main factors that have contributed to observed sea level rise. The first is : as ocean water warms, it expands. The second is from the contribution of land-based ice due to increased melting. The major store of water on land is found in glaciers and ice sheets. Anthropogenic forces very likely (greater than 90% probability, based on expert judgement) contributed to sea level rise during the latter half of the 20th century.
There is a widespread consensus that substantial long-term sea level rise will continue for centuries to come. In their Fourth Assessment Report, the IPCC projected sea level rise to the end of the 21st century using the SRES emissions scenarios. Across the six SRES marker scenarios, sea level was projected to rise by 18 to 59 cm (7.1 to 23.2 in), relative to sea level at the end of the 20th century. Thermal expansion is the largest component in these projections, contributing 70-75% of the central estimate for all scenarios. Due to a lack of scientific understanding, this sea level rise estimate does not include all of the possible contributions of ice sheets (see the section on ).
An assessment of the
on climate change was published in 2010 by the
(US NRC, 2010). NRC (2010) described the projections in AR4 (i.e. those cited in the above paragraph) as "conservative", and summarized the results of more recent studies. Cited studies suggested a great deal of uncertainty in projections. A range of projections suggested possible sea level rise by the end of the 21st century of between 0.56 and 2 m, relative to sea levels at the end of the 20th century.
Global ocean heat content from
From 1961 to 2003, the global ocean temperature has risen by 0.10 °C from the surface to a depth of 700 m. There is variability both year-to-year and over longer time scales, with global ocean heat content observations showing high rates of warming for , but some cooling from 2003 to 2007. The temperature of the Antarctic
rose by 0.17 °C (0.31 °F) between the 1950s and the 1980s, nearly twice the rate for the world's oceans as a whole. As well as having effects on ecosystems (e.g. by melting sea ice, affecting algae that grow on its underside), warming reduces the ocean's ability to absorb CO
2.[] It is likely (greater than 66% probability, based on expert judgement) that anthropogenic forcing contributed to the general warming observed in the upper several hundred metres of the ocean during the latter half of the 20th century.
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Temperatures across the world in the 1880s (left) and the 1980s (right), as compared to average temperatures from 1951 to 1980.
Projected changes in average temperatures across the world in the 2050s under three greenhouse gas (GHG) .
Regional effects of global warming vary in nature. Some are the result of a generalised global change, such as rising temperature, resulting in local effects, such as melting ice. In other cases, a change may be related to a change in a particular ocean current or weather system. In such cases, the regional effect may be disproportionate and will not necessarily follow the global trend.
There are three major ways in which global warming will make changes to regional climate: melting or forming ice, changing the
and ) and changing
and air flows in the atmosphere. The coast can also be considered a region, and will suffer severe impacts from .
With very high confidence, Rosenzweig et al. (2007) concluded that physical and biological systems on all continents and in most oceans had been affected by recent climate changes, particularly regional temperature increases. Impacts include earlier leafing of
an movements of species to higher latitudes and altitudes in the Northern H changes in
in Europe, North America and A and shifting of the oceans'
from cold- to warm-adapted communities.
The human influence on the climate can be seen in the geographical pattern of observed warming, with greater temperature increases over land and in
rather than over the oceans.:6 Using models, it is possible to identify the human "signal" of global warming over both land and ocean areas.:6
Projections of future climate changes at the regional scale do not hold as high a level of scientific confidence as projections made at the global scale.:9 It is, however, expected that future warming will follow a similar geographical pattern to that seen already, with greatest warming over land and high northern , and least over the
and parts of the . Nearly all land areas will very likely warm more than the global average.
The , , small islands and
are regions that are likely to be especially affected by climate change. ,
areas are at most risk of experiencing negative impacts due to climate change.
are also vulnerable to climate change. For example, developed countries will be negatively affected by increases in the severity and frequency of some
events, such as . In all regions, some people can be particularly at risk from climate change, such as the , young
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The impacts of climate change can be thought of in terms of sensitivity and vulnerability. "Sensitivity" is the degree to which a particular system or sector might be affected, positively or negatively, by climate change and/or . "Vulnerability" is the degree to which a particular system or sector might be adversely affected by climate change.
The sensitivity of human society to climate change varies. Sectors sensitive to climate change include water resources, coastal zones, human settlements, and human health. Industries sensitive to climate change include , , , , , , , , and .
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See also: ,
Climate change will impact agriculture and food production around the world due to: the effects of elevated CO2 in the atmosphere, higher temperatures, altered precipitation and
regimes, increased frequency of extreme events, and modified , , and
pressure. In general, low-latitude areas are at most risk of having decreased crop yields.
As of 2007, the effects of regional climate change on agriculture have been small. Changes in crop
provide important evidence of the response to recent regional climate change. Phenology is the study of natural phenomena that recur periodically, and how these phenomena relate to climate and seasonal changes. A significant advance in phenology has been observed for agriculture and forestry in large parts of the Northern Hemisphere.
Projected changes in crop yields at different latitudes with global warming. This graph is based on several studies.
Projected changes in yields of selected crops with global warming. This graph is based on several studies.
With low to medium confidence, Schneider et al. (2007) projected that for about a 1 to 3 °C increase in global mean temperature (by the years , relative to average temperatures in the years ), there would be productivity decreases for some
in low latitudes, and productivity increases in high latitudes. With medium confidence, global production potential was projected to:
increase up to around 3 °C,
very likely decrease above about 3 °C.
Most of the studies on global agriculture assessed by Schneider et al. (2007) had not incorporated a number of critical factors, including changes in extreme events, or the spread of pests and diseases. Studies had also not considered the development of specific practices or technologies to aid .
The graphs opposite show the projected effects of climate change on selected crop yields. Actual changes in yields may be above or below these central estimates.
The projections above can be expressed relative to pre-industrial (1750) temperatures. 0.6 °C of warming is estimated to have occurred between 1750 and . Add 0.6 °C to the above projections to convert them from a
to pre-industrial baseline.
Easterling et al. (2007) assessed studies that made quantitative projections of climate change impacts on . It was noted that these projections were highly uncertain and had limitations. However, the assessed studies suggested a number of fairly robust findings. The first was that climate change would likely increase the number of people at risk of
compared with reference scenarios with no climate change. Climate change impacts depended strongly on projected future social and economic development. Additionally, the magnitude of climate change impacts was projected to be smaller compared to the impact of social and economic development. In 2006, the global estimate for the number of people
was 820 million. Under the SRES A1, B1, and B2 scenarios (see the
for information on each scenario group), projections for the year 2080 showed a reduction in the number of people undernourished of about 560-700 million people, with a global total of undernourished people of 100-240 million in 2080. By contrast, the SRES A2 scenario showed only a small decrease in the risk of hunger from 2006 levels. The smaller reduction under A2 was attributed to the higher projected future population level in this scenario.
Some evidence suggests that droughts have been occurring more frequently because of global warming and they are expected to become more frequent and intense in Africa, southern Europe, the Middle East, most of the Americas, Australia, and Southeast Asia. However, other research suggests that there has been little change in drought over the past 60 years. Their impacts are aggravated because of increased water demand, population growth, urban expansion, and environmental protection efforts in many areas. Droughts result in crop failures and the loss of pasture grazing land for livestock.
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Human beings are exposed to climate change through changing weather patterns (temperature, precipitation, sea-level rise and more frequent extreme events) and indirectly through changes in water, air and food quality and changes in ecosystems, agriculture, industry and settlements and the economy (Confalonieri et al., ). According to an assessment of the scientific literature by Confalonieri et al. (), the effects of climate change to date have been small, but are projected to progressively increase in all countries and regions.
A study by the
(WHO, 2009) estimated the effect of climate change on human health. Not all of the effects of climate change were included in their estimates, for example, the effects of more frequent and extreme storms were excluded. Climate change was estimated to have been responsible for 3% of , 3% of , and 3.8% of
deaths worldwide in 2004. Total attributable mortality was about 0.2% of deaths in 2004; of these, 85% were child deaths.
With high confidence, authors of the IPCC AR4 Synthesis report:48 projected that climate change would bring some benefits in temperate areas, such as fewer deaths from cold exposure, and some mixed effects such as changes in range and transmission potential of
in . Benefits were projected to be outweighed by negative health effects of rising temperatures, especially in developing countries.
With very high confidence, Confalonieri et al. (2007):393 concluded that economic development was an important component of possible adaptation to climate change. Economic growth on its own, however, was not judged to be sufficient to insulate the world's population from disease and injury due to climate change. Future vulnerability to climate change will depend not only on the extent of social and economic change, but also on how the benefits and costs of change are distributed in society. For example, in the 19th century, rapid
lead to a plummeting in population health. Other factors important in determining the health of populations include , the availability of health services, and
Precipitation during the 20th century and up through 2008 during global warming, the
estimating an observed trend over that period of 1.87% global precipitation increase per century.
A number of climate-related trends have been observed that affect . These include changes in precipitation, the crysosphere and
(e.g., changes in ). Observed and projected impacts of climate change on
systems and their management are mainly due to changes in temperature, sea level and precipitation variability. Sea level rise will extend areas of
and , resulting in a decrease in freshwater availability for humans and ecosystems in coastal areas. In an assessment of the , Kundzewicz et al. (2007) concluded, with high confidence, that:
the negative impacts of climate change on freshwater systems outweigh the benefits. All of the regions assessed in the
and , , , ,
( and ), and small islands) showed an overall net negative impact of climate change on water resources and freshwater ecosystems.
areas are particularly exposed to the impacts of climate change on freshwater. With very high confidence, it was judged that many of these areas, e.g., the , , , and north-eastern , would suffer a decrease in water resources due to climate change.
project that the future climate change will bring wetter coasts, drier mid-continent areas, and further sea level rise. Such changes could result in the gravest effects of climate change through sudden . Millions might be displaced by , river and coastal , or severe .
Migration related to climate change is likely to be predominantly from
to towns and .:407 In the short term climate stress is likely to add incrementally to existing migration patterns rather than generating entirely new flows of people.:110
It has been argued that environmental degradation, loss of access to resources (e.g., water resources), and resulting human migration could become a source of political and even . Factors other than climate change may, however, be more important in affecting conflict. For example, Wilbanks et al. (2007) suggested that major environmentally influenced conflicts in Africa were more to do with the relative abundance of resources, e.g.,
and , than with resource scarcity. Scott et al. (2001) placed only low confidence in predictions of increased conflict due to climate change.
A 2013 study found that significant climatic changes were associated with a higher risk of conflict worldwide, and predicted that "amplified rates of human conflict could represent a large and critical social impact of anthropogenic climate change in both low- and high-income countries." Similarly, a 2014 study found that higher temperatures were associated with a greater likelihood of violent crime, and predicted that global warming would cause millions of such crimes in the United States alone during the 21st century.
Military planners are concerned that global warming is a "threat multiplier". "Whether it is poverty, food and water scarcity, diseases, economic instability, or threat of natural disasters, the broad range of changing climatic conditions may be far reaching. These challenges may threaten stability in much of the world".
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impacts adds up the total impact of climate change across sectors and/or regions. Examples of aggregate measures include
(e.g., changes in
(GDP) and the ), changes in ecosystems (e.g., changes over land area from one type of vegetation to another), human health impacts, and the number of people affected by climate change. Aggregate measures such as economic cost require researchers to make
over the importance of impacts occurring in different regions and at different times.
Global losses reveal rapidly rising costs due to extreme weather-related events since the 1970s.
factors have contributed to the observed trend of global losses, e.g., population growth, increased . Part of the growth is also related to regional climatic factors, e.g., changes in precipitation and flooding events. It is difficult to quantify the relative impact of socio-economic factors and climate change on the observed trend. The trend does, however, suggest increasing vulnerability of social systems to climate change.
The total economic impacts from climate change are highly uncertain. With medium confidence, Smith et al. (2001) concluded that world GDP would change by plus or minus a few percent for a small increase in global mean temperature (up to around 2 °C relative to the 1990 temperature level). Most studies assessed by Smith et al. (2001) projected losses in world GDP for a medium increase in global mean temperature (above 2-3 °C relative to the 1990 temperature level), with increasing losses for greater temperature increases. This assessment is consistent with the findings of more recent studies, as reviewed by Hitz and Smith (2004).
Economic impacts are expected to vary regionally. For a medium increase in global mean temperature (2-3 °C of warming, relative to the average temperature between ), market sectors in low-latitude and less-developed areas might experience net costs due to climate change. On the other hand, market sectors in high-latitude and developed regions might experience net benefits for this level of warming. A global mean temperature increase above about 2-3 °C (relative to ) would very likely result in market sectors across all regions experiencing either declines in net benefits or rises in net costs.
Aggregate impacts have also been quantified in non-economic terms. For example, climate change over the 21st century is likely to adversely affect hundreds of millions of people through increased coastal flooding, reductions in water supplies, increased malnutrition and increased health impacts.
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See also: , ,
A vast array of physical and biological systems across the Earth are being affected by human-induced global warming.
With very high confidence, Rosenzweig et al. (2007) concluded that recent warming had strongly affected natural biological systems. Hundreds of studies have documented responses of , , and
to the climate changes that have already occurred. For example, in the Northern Hemisphere, species are almost uniformly moving their ranges northward and up in elevation in search of cooler temperatures. Humans are very likely causing changes in regional temperatures to which plants and animals are responding.
By the year 2100, ecosystems will be exposed to atmospheric CO
2 levels substantially higher than in the past 650,000 years, and global temperatures at least among the highest of those experienced in the past 740,000 years. Significant disruptions of ecosystems are projected to increase with future climate change. Examples of disruptions include disturbances such as fire, drought, pest , invasion of species, storms, and
events. The stresses caused by climate change, added to other stresses on ecological systems (e.g., land conversion, , , and ), threaten substantial damage to or complete loss of some unique ecosystems, and
of some critically endangered species.
Climate change has been estimated to be a major driver of
loss in cool
forests, ,
systems, , in the , and in . In other ecosystems,
change may be a stronger driver of biodiversity loss at least in the near-term. Beyond the year 2050, climate change may be the major driver for biodiversity loss globally.
A literature assessment by Fischlin et al. (2007) included a quantitative estimate of the number of species at increased risk of extinction due to climate change. With medium confidence, it was projected that approximately 20 to 30% of plant and animal species assessed so far (in an unbiased ) would likely be at increasingly high risk of extinction should global mean temperatures exceed a warming of 2 to 3 °C above pre-industrial temperature levels. The uncertainties in this estimate, however, are large: for a rise of about 2 °C the percentage may be as low as 10%, or for about 3 °C, as high as 40%, and depending on
(all living
of an area, the
considered as a unit) the range is between 1% and 80%. As global average temperature exceeds
above pre-industrial levels, model projections suggested that there could be significant extinctions (40-70% of species that were assessed) around the globe.
Assessing whether future changes in ecosystems will be beneficial or detrimental is largely based on how ecosystems are valued by human society. For increases in global average temperature exceeding 1.5 to 2.5 °C (relative to global temperatures over the years ) and in concomitant atmospheric CO
2 concentrations, projected changes in ecosystems will have predominantly negative consequences for biodiversity and ecosystems goods and , e.g., water and food supply.
Physical, ecological and social systems may respond in an abrupt,
or irregular way to climate change. This is as opposed to a smooth or regular response. A quantitative entity behaves "irregularly" when its
(i.e., not smooth), nondifferentiable, unbounded, wildly varying, or otherwise ill-defined. Such behaviour is often termed "". Irregular behaviour in Earth systems may give rise to certain thresholds, which, when crossed, may lead to a large change in the system.
Some singularities could potentially lead to severe impacts at regional or global scales. Examples of "large-scale" singularities are discussed in the articles on ,
and . It is possible that human-induced climate change could trigger large-scale singularities, but the probabilities of triggering such events are, for the most part, poorly understood.
With low to medium confidence, Smith et al. (2001) concluded that a rapid warming of more than 3 °C above 1990 levels would exceed thresholds that would lead to large-scale discontinuities in the climate system. Since the assessment by Smith et al. (2001), improved scientific understanding provides more guidance for two large-scale singularities: the role of
feedbacks in future climate change (discussed below in the section on biogeochemical cycles) and the melting of the
Climate change may have an effect on the
in an interactive "feedback" process. A feedback exists where an initial process triggers changes in a second process that in turn influences the initial process. A positive feedback intensifies the original process, and a negative feedback reduces it.:78 Models suggest that the interaction of the climate system and the carbon cycle is one where the feedback effect is positive.:792
Using the A2 SRES emissions scenario, Schneider et al. (2007):789 found that this effect led to additional warming by the years
(relative to the ) of 0.1–1.5 °C. This estimate was made with high confidence. The climate projections made in the IPCC Fourth Assessment Report summarized earlier of 1.1–6.4 °C account for this feedback effect. On the other hand, with medium confidence, Schneider et al. (2007):789 commented that additional releases of GHGs were possible from permafrost, peat lands, wetlands, and large stores of marine hydrates at high latitudes.
With medium confidence, authors of AR4 concluded that with a global average temperature increase of 1–4 °C (relative to temperatures over the years ), at least a partial deglaciation of the , and possibly the
would occur. The estimated timescale for partial deglaciation was centuries to millennia, and would contribute 4 to 6 metres (13 to 20 ft) or more to sea level rise over this period.
This map shows the general location and direction of the warm surface (red) and cold deep water (blue) currents of the .
is represented by color in units of the Practical Salinity Scale. Low values (blue) are less saline, while high values (orange) are more saline.
The Atlantic Meridional Overturning Circulation (AMOC) is an important component of the Earth's climate system, characterized by a northward flow of warm, salty water in the upper layers of the
and a southward flow of colder water in the deep Atlantic.:5 The AMOC is equivalently known as the
(THC). Potential impacts associated with MOC changes include reduced warming or (in the case of abrupt change) absolute cooling of northern high-latitude areas near
and north-western Europe, an increased warming of
high-latitudes, tropical drying, as well as changes to , terrestrial vegetation, oceanic CO
2 uptake, oceanic oxygen concentrations, and shifts in fisheries. According to an assessment by the US
(CCSP, 2008b),:5 it is very likely (greater than 90% probability, based on expert judgement):12 that the strength of the AMOC will decrease over the course of the 21st century. Warming is still expected to occur over most of the European region downstream of the
in response to increasing GHGs, as well as over . Although it is very unlikely (less than 10% probability, based on expert judgement):12 that the AMOC will collapse in the 21st century, the potential consequences of such a collapse could be severe.:5
Emissions of GHGs are a potentially irreversible commitment to sustained
in the future. The contribution of a GHG to radiative forcing depends on the gas's ability to trap
(heat) radiation, the concentration of the gas in the atmosphere, and the length of time the gas resides in the atmosphere.
2 is the most important anthropogenic GHG. While more than half of the CO
2 emitted is currently removed from the atmosphere within a century, some fraction (about 20%) of emitted CO
2 remains in the atmosphere for many thousands of years. Consequently, CO
2 emitted today is potentially an irreversible commitment to sustained radiative forcing over thousands of years.
This commitment may not be truly irreversible should techniques be developed to remove CO
2 or other GHGs directly from the atmosphere, or to block sunlight to induce cooling. Techniques of this sort are referred to as . Little is known about the effectiveness, costs or potential
of geoengineering options. Some geoengineering options, such as blocking sunlight, would not prevent further .
Human-induced climate change may lead to irreversible impacts on physical, biological, and social systems. There are a number of examples of climate change impacts that may be irreversible, at least over the timescale of many human generations. These include the large-scale singularities described above – changes in carbon cycle feedbacks, the melting of the Greenland and West Antarctic ice sheets, and changes to the AMOC. In biological systems, the extinction of species would be an irreversible impact. In social systems, unique
may be lost due to climate change. For example, humans living on
islands face risks due to sea-level rise, sea-surface warming, and increased frequency and intensity of extreme weather events.
(IPCC) has published several major assessments on the effects of global warming. Its most recent comprehensive impact assessment was published in 2014. Publications describing the effects of climate change have also been produced by the following organizations:
A report by the , the , and
UK AVOID research programme
A report by the UK
Climate Change Research Centre
A report by Molina et al. (no date) states:
The overwhelming evidence of human-caused climate change documents both current impacts with significant costs and extraordinary future risks to society and natural systems
(United States)
1 The TAR and AR4 that are referred to in this article use specific and quantitative language to describe uncertainty. This language is intended to provide an indication of the level of confidence that IPCC authors have about a particular finding. The qualitative language used to describe uncertainty has a quantitative scale associated with it. The quantitative values for qualitative terms are intended to ensure that confidence levels are interpreted correctly. The is because qualitative statements, e.g., using the word "likely", can be interpreted differently in quantitative terms.:44
Confidence levels used in the TAR:
Very High = 95% or greater
High = 67-95%
Medium = 33-67%
Low = 5-33%
Very Low = 5% or less
Confidence statements made in AR4 are listed below:
Very high confidence: At least 9 out of 10 chance of being correct
High confidence: About 8 out of 10 chance " " "
Medium confidence: About 5 out of 10 chance " " "
Low confidence: About 2 out of 10 chance " " "
Very low confidence: Less than a 1 out of 10 chance " " "
IPCC (2012) uses the following terms: "very low", "low", "medium", "high", and "very high confidence". Unlike the TAR and AR4, the scale is qualitative rather than quantitative.
The quantitative values used by IPCC authors are "subjective" probabilities, also known as "personalist" or "" probabilities, and reflect the expert judgement of IPCC authors. In this formulation, probability is not only a function of an event, but also the state of information that is available to the person making the assessment. In this framework, assigned probabilities may change as more or different information becomes available.
The IPCC also uses another scale to describe the likelihood of a particular event occurring. This is different from the confidence scales described above, and it is possible to assign confidence values to statements of likelihood. For example, the judgement that an event is improbable (e.g., rolling a
twice and getting a six both times) may be assigned a high level of scientific confidence. Also, the probability that an event has an even chance of occurring (e.g., a tossed
coming up heads) may also be assigned a high level of confidence.
, Washington DC, USA: American Association for the Advancement of Science. Archived .
Cramer, W., et al., Executive summary, in:
(archived ), pp.982-984, in
Settele, J., et al., Section 4.3.2.1: Phenology, in:
(archived ), p.291, in
Oppenheimer, M., et al., Section 19.7.1: Relationship between Adaptation Efforts, Mitigation Efforts, and Residual Impacts, in:
(archived ), pp., in
Oppenheimer, M., et al., Section 19.6.2.2. The Role of Adaptation and Alternative Development Pathways, in:
(archived ), pp., in
Denton, F., et al., Section 20.3. Contributions to Resilience through Climate Change Responses, in:
(archived ), pp., in
Field, C.B., et al., Section A-3. The Decision-making Context, in:
(archived ), p.55, in
SPM.4.1 Long‐ erm mitigation pathways, in: , pp.11-15 (archived , in
Clarke, L., et al., Section 6.3.1.3 Baseline emissions projections from fossil fuels and industry (pp.17-18 of final draft), in:
(archived ), in:
Greenhouse Gas Concentrations and Climate Implications, p.14, in . The range given by Prinn and Reilly is 3.3 to 5.5 °C, with a median of 3.9 °C.
SPM.3 Trends in stocks and flows of greenhouse gases and their drivers, in: , p.8 (archived , in . The range given by the Intergovernmental Panel on Climate Change is 3.7 to 4.8 °C, relative to pre-industrial levels (2.5 to 7.8 °C including climate uncertainty).
Field, C.B., et al., Box TS.8: Adaptation Limits and Transformation, in:
(archived ), p.89, in
Field, C.B., et al., Section B-1. Key Risks across Sectors and Regions, in:
(archived ), p.62, in
IPCC, , in
US Environmental Protection Agency (US EPA) (14 June 2012), , US EPA, Click on the image to open a pop-up that explains the differences between climate change and global warming.
Albritton et al., ,
Pielke, R Gwyn Prins, Steve Rayner and Daniel Sarewitz ().
(PDF). Nature 445: 597–8. :.
Herring, D. (March 6, 2012). . NOAA Climate Portal.
Schneider et al., ,
, p. 5, in .
Fisher et al., ,
(ed.). "Global Climate Change". (PDF) .
Morita et al., ,
Morita et al., ,
Temperature change in years
relative to years
Solomon et al., ,
United Nations Environment Programme (UNEP) (November 2010), "Ch 2: Which emissions pathways are consistent with a 2 °C or a 1.5 °C temperature limit?: Sec 2.2 What determines long-term temperature?",
(PDF), UNEP, p.28. This publication is also available in
, in , p. 195
Solomon, S. et al. (January 28, 2009).
(PDF). Proceedings of the National Academy of Sciences of the United States of America (PNAS) (US National Academy of Sciences) 106 (6): 1704–9. :. :.  .  .
"Question 5",
, in , p. 89
Meehl, G.A. et al., "Ch 10: Global Climate Projections",
Hansen, J.E. and M. Sato (July 2011), , New York City, New York, USA: NASA GISS
Overpeck, J.T. (20 August 2008), , NOAA Paleoclimatology Program - NCDC Paleoclimatology Branch
Jansen et al., ,
Smith, J.B. et al., "Ch 19. Vulnerability to Climate Change and Reasons for Concern: A Synthesis",
, in , p. 957
, p. 2
, p. 3
Solomon et al., ,
Rosenzweig et al., ,
Hegerl et al., ,
Committee on the Science of Climate Change, US National Research Council (2001). "3. Human Caused Forcings". . Washington, D.C., USA: . p. 12.  .
ESRL web team (26 January 2009).
(Press release). US Department of Commerce, NOAA, Earth System Research Laboratory (ESRL).
(). Abrupt Climate Change: Inevitable Surprises (). June 2002.[]
Le Treut et al., ,
NOAA Geophysical Fluid Dynamics Laboratory (GFDL) (9 October 2012), , NOAA GFDL
NOAA (February 2007),
(PDF), GFDL Climate Modeling Research Highlights (Princeton, NJ, USA: National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL)) 1 (5). Revision 10/15/:16 PM.
"Summary for policymakers",
, in , p. 8
IPCC (2013), Table SPM.1, in
Stocker, T.F., et al. (2013), Temperature Extremes, Heat Waves and Warm Spells, in: TFE.9, in:
Stocker, T.F., et al. (2013), Floods and Droughts, in: TFE.9, in:
Christensen, J.H.,et al. (2013), Cyclones, in: Executive Summary, in:
Confalonieri et al., ,
IPCC, "Summary for Policymakers",
, p.14, in .
, pp. 64–65, in .
Solomon, S. et al., ,
Met Office, , Exeter, UK: Met Office
Meehl, G.A. et al., ,
, in , p. 776
Meehl, G.A. et al., ,
, in , pp. 770, 772
Field, C.B. et al., ,
, in , p. 627
Some of these impacts are included in table SPM.2: ,
, in , pp. 11–12
, in , p. 187
Barnett, T.P. et al. (17 November 2005),
(PDF), Nature 438: 303, :, :,  
. Website of the US National Oceanic and Atmospheric Administration: National Climatic Data Center. July 2010.
Bindoff, N.L. et al., ,
, in , referred to by: , Skeptical Science, Components of global warming for the period 1993 to 2003 calculated from IPCC AR4 5.2.2.3
 This article incorporates  from the  document: , US Environmental Protection Agency (EPA)
"Introduction". . p. 8., in
Fischlin et al., , Executive summary [??]
Crowley, T. J.;
(May 1988). "Abrupt Climate Change and Extinction Events in Earth History".
240 (4855): 996–1002. :. :.  .
Shaffer, G. .; Olsen, S. M.; Pedersen, J. O. P. (2009). "Long-term ocean oxygen depletion in response to carbon dioxide emissions from fossil fuels". Nature Geoscience 2 (2): 105–109. :. :.
US Environmental Protection Agency (US EPA) (2010). . US EPA.
Bindoff et al., ,
Bindoff et al., ,
Albritton et al., ,
"7 Sea Level Rise and the Coastal Environment",
, in , p. 245.
change in sea level by 2090–99, relative to 1980–99
Meehl et al., ,
"7 Sea Level Rise and the Coastal Environment", pp. 243–245
Bindoff et al., ,
Gille, Sarah T. (February 15, 2002). .
295 (5558): 1275–7. :. :.  .
US Environmental Protection Agency (14 June 2012). . US EPA.
Rosenzweig, C. (December 2008). . Website of the US National Aeronautics and Space Administration, Goddard Institute for Space Studies.
US NRC (2008).
(PDF). Washington DC, USA: , National Academy of Sciences.
Schneider, S.H. et al., ,
, in , p. 796
Schneider, S.H. et al., ,
, in , p. 792
Wilbanks, T.J. et al., ,
, in , pp. 373–376
IPCC, , in .
Schneider et al., ,
Easterling et al., ,
, in , p. 282.
Schneider et al., ,
, in , p. 790.
Rosenzweig et al., ,
IPCC, , in .
, p.161, in: Sec 5.1 FOOD PRODUCTION, PRICES, AND HUNGER, in: Ch 5: Impacts in the Next Few Decades and Coming Centuries, in:
Sec 5.1 FOOD PRODUCTION, PRICES, AND HUNGER, , in: Ch 5: Impacts in the Next Few Decades and Coming Centuries, in
Schneider, S.H. et al., ,
, in , p. 783.
Easterling et al., ,
. Food and Agriculture Organization (FAO) Newsroom. 30 October 2006.
Dai, A. (2011). "Drought under global warming: A review". Wiley Interdisciplinary Reviews: Climate Change 2: 45–65. :.
Sheffield, J.; Wood, E. F.; Roderick, M. L. (2012). "Little change in global drought over the past 60 years". Nature 491 (7424): 435. :.
Mishra, A. K.; Singh, V. P. (2011). "Drought modeling – A review". Journal of Hydrology 403: 157. :.
Ding, Y.; Hayes, M. J.; Widhalm, M. (2011). "Measuring economic impacts of drought: A review and discussion". Disaster Prevention and Management 20 (4): 434. :.
WHO (2009).
(PDF). Geneva, Switzerland: WHO Press. p. 24.  .
Confalonieri et al., ,
Kundzewicz et al., ,
Kundzewicz et al., ,
, p. 175, in .
Scott et al., "Chapter 12: Human settlements in a changing climate: impacts and adaptation", Sec. 12.3.1 Population Migration
, pp. 406—407, in .
The World Bank,
(PDF), Managing social risks: Empower communities to protect themselves, p. 109, .
Desanker et al., ,
Scott et al., ,
Wilbanks et al., ,
Hsiang SM, Burke M, Miguel E (September 2013). "Quantifying the influence of climate on human conflict". Science 341 (6151): 1235367. :.  .
Ranson, M. (2014). "Crime, weather, and climate change". Journal of Environmental Economics and Management. :.
Spaner, J S; LeBali, H (October 2013). "The Next Security Frontier". Proceedings of the US Naval Institute 139 (10): 30–35 2013.
, in , p. 76
Smith et al., ,
Smith et al., ,
Rosenzweig et al., ,
, p. 55, .
Schneider et al., ,
, p. 790, in .
Smith et al., ,
Smith et al., ,
. "Introduction". . p. 14.
. "Introduction". . p. 16.
Fischlin et al., ,
IPCC, "Synthesis Report, Question 3",
Van Riper, Charles. (2014)
Reston, Va.: , .
Fischlin et al., ,
IPCC, , in .
NRC, "Introduction", , p. 16, in .
Smith et al., ,
White et al., ,
"[F]or the most part" refers to improved scientific understanding of singularities since the assessment by White et al. (2001). See: Schneider et al., ,
Schneider et al., , Sec. ???
Riebeek, H.. design by R. Simmon (May 9, 2006). . NASA Earth Observatory.
CCSP (2008b). . Reston, VA: US Geological Survey.
Schneider et al., ,
Albritton et al., ,
, p. 38, in .
, p. 5, in .
Meehl et al. . . , in .
Barker et al., ,
IPCC, "5.14", Question 5
Schneider et al., ,
Barnett, J and WN Adger (2003).
(PDF). Climatic Change (Kluwer Academic Publishers) 61: 321. :. This paper was published in 2001 as
, pp. 4-7
For example: ). Refer to ) for other AVOID publications.
, p. 3
Moss, R.; Schneider, S. (July 2000), "Uncertainties", in R. Pachuari, T. Taniguchi and K. Tanaka, (eds.),
(PDF), 2-1-1 Toranomon, Minato-ku, 1050001 Tokyo, Japan: Global Industrial and Social Progress Research Institute (GISPRI),  
White et al., ,
"Summary for policymakers",
, in , p. 19
Ahmad et al., ,
Granger Morgan, M. (Lead Author), H. Dowlatabadi, M. Henrion, D. Keith, R. Lempert, S. McBride, M. Small and T. Wilbanks (Contributing Authors) (2009). . Washington D.C., USA.: National Oceanic and Atmospheric Administration. pp. 19–20; 27–28. Tables 2.1 and 2.2 on pages 27-28 show two quantitative scales of uncertainty which are used in the TAR and AR4.
Allison, I. et al. (2009), , Sydney, Australia: The University of New South Wales Climate Change Research Centre (CCRC) 2014 . .
Good, P. et al. (2010),
(PDF), London, UK: Committee on Climate Change . Archived
Committee on Ecological Impacts of Climate Change, US National Research Council (NRC) (2008). . 500 Fifth Street, NW Washington, DC 20001, USA: The National Academies Press.  .
IPCC (November 2010),
(PDF), IPCC 2014.
(1996), Watson, R.T.; Zinyowera, M.C.; and Moss, R.H., ed., , Contribution of Working Group II to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb:
(2001), Houghton, J.T.; Ding, Y.; Griggs, D.J.; Noguer, M.; van der Linden, P.J.; Dai, X.; Maskell, K.; and Johnson, C.A., ed., , Contribution of Working Group I to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb: ).
(2001), McCarthy, J. J.; Canziani, O. F.; Leary, N. A.; Dokken, D. J.; and White, K. S., ed., , Contribution of Working Group II to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb: ).
(2001), Metz, B.; Davidson, O.; Swart, R.; and Pan, J., ed., , Contribution of Working Group III to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb: ).
(2001), Watson, R. T.; and the Core Writing Team, ed., , Contribution of Working Groups I, II, and III to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb: ).
(2007), Solomon, S.; Qin, D.; Manning, M.; Chen, Z.; Marquis, M.; Averyt, K.B.; Tignor, M.; and Miller, H.L., ed., , Contribution of Working Group I to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb: ).
(2007), Parry, M.L.; Canziani, O.F.; Palutikof, J.P.; van der Linden, P.J.; and Hanson, C.E., ed., , Contribution of Working Group II to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb: ).
(2007), Metz, B.; Davidson, O.R.; Bosch, P.R.; Dave, R.; and Meyer, L.A., ed., , Contribution of Working Group III to the
of the Intergovernmental Panel on Climate Change, Cambridge University Press,   (pb: ).
(2007), Core Writing T Pachauri, R.K; and Reisinger, A., ed., , Contribution of Working Groups I, II and III to the
of the Intergovernmental Panel on Climate Change, , : IPCC,  .
IPCC SREX (2012), Field, C.B., et al., ed., , Cambridge University Press . Summary for Policymakers
in Arabic, Chinese, French, Russian, and Spanish.
IPCC AR5 WG1 (2013), Stocker, T.F. et al., eds., , Cambridge University Press .
IPCC AR5 WG2 A (2014), Field, C.B. et al., eds., , Cambridge University Press . Archived
IPCC AR5 WG3 (2014), Edenhofer, O. et al., eds., , Cambridge University Press . Archived
IPCC press release (31 March 2014),
(PDF), IPCC 2014. . Also
in Arabic, Chinese, French, Russian and Spanish.
; Melillo, Jerry M.; Peterson, Thomas C., eds. (2009).
(PDF). New York: Cambridge University Press.  .
 This article incorporates  from the  document: NOAA (July 2010), , US National Oceanic and Atmospheric Administration (NOAA): National Climatic Data Center
 This article incorporates  from the  document: Kennedy, C.H. (10 July 2012), , NOAA
Molina, M. et al. (n.d.),
(PDF), AAAS 2014 . . Report
(archived ).
PBL et al. (November 2009),
(PDF), Bilthoven, Netherlands: PBL . . Report
Prinn, R.G. and J.M. Reilly (2014),
(PDF), Cambridge, MA, USA: MIT Joint Program on the Science and Policy of Global Change. Archived . Report
(archived ).
Stern, N. (2006), , London, UK: HM Treasury
UKMO (18 September 2013), , UK Meteorological Office (UKMO) 2014. .
UK Royal Society and US National Academy of Sciences (2014),
(PDF) 2014. . Report
(archived .
 This article incorporates  from the  document: , US Environmental Protection Agency (EPA) Climate Change Division, 14 June 2012
Staff of the International Bank for Reconstruction and Development / The World Bank (2010). . 1818 H Street NW, Washington DC 20433, USA: International Bank for Reconstruction and Development / The World Bank. :.  .
US NRC (2010). . Washington, D.C., USA: National Academies Press.  .. Archived
US NRC (2011), , Washington, D.C., USA: National Academies Press Archived
Watkins, K. et al. (2007), Ugaz, C., ed., , Basingstoke, UK: Palgrave Macmillian,  
Physical impacts
. This body assesses the physical scientific aspects of the climate system and climate change.
Social, economic and ecological impacts
on the United Nations Economic and Social Development (UNESD) Division for Sustainable Development website.
– This body assesses the vulnerability of socio-economic and natural systems to climate change, negative and positive consequences of climate change, and options for adapting to it.
, the humanitarian news and analysis service of the UN Office for the Coordination of Humanitarian Affairs: , , and
. Panel discussion with James J. McCarthy, Professor at Harvard University, and A Paul R. Epstein, M.D., instructor in medicine at Harvard Medical S and Ross Gelbspan, Pulitzer Prize–winning journalist and author. Massachusetts School of Law.
. Interviews with Christopher Field and Michael MacCracken. Christopher Field is the director of the Department of Global Ecology at the Carnegie Institution of Washington, professor of biology and environmental earth system science at Stanford University, and the Working Group II Co-Chair for the Intergovernmental Panel on Climate Change. Michael MacCracken is the chief scientist for Climate Change Programs at the Climate Institute and a co-author and contributing author for various chapters in the IPCC assessment reports. Climate Progress website, February 5, 2010.
— (October 11, 2014)
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