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This article is about the current change in Earth's climate. For general discussion of how the climate can change, see Climate change. For other uses, see Global warming (disambiguation).
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Global mean land-ocean temperature change from 1880–2013, relative to the 1951–1980 mean. The black line is the annual mean and the red line is the 5-year running mean. The green bars show uncertainty estimates. Source: NASA GISS. (click for larger image)
Map of temperature changes across the world
key to above map of temperature changes
The map shows the 10-year average (2000–2009) global mean temperature anomaly relative to the 1951–1980 mean. The largest temperature increases are in the Arctic and the Antarctic Peninsula. Source: NASA Earth Observatory
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Fossil fuel related carbon dioxide (CO2) emissions compared to five of the IPCC's "SRES" emissions scenarios. The dips are related to global recessions. Image source: Skeptical Science.
Global warming is the observed century-scale rise in the average temperature of Earth's climate system. Since 1971, 90% of the increased energy has been stored in the oceans, mostly in the 0 to 700m region. Despite the oceans' dominant role in energy storage, the term "global warming" is also used to refer to increases in average temperature of the air and sea at Earth's surface. Since the early 20th century, the global air and sea surface temperature has increased about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980. Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850.
Scientific understanding of the cause of global warming has been increasing. In its fourth assessment (AR4 2007) of the relevant scientific literature, the Intergovernmental Panel on Climate Change (IPCC) reported that scientists were more than 90% certain that most of global warming was being caused by increasing concentrations of greenhouse gases produced by human activities (anthropogenic). In 2010 that finding was recognized by the national science academies of all major industrialized nations.
Affirming these findings in 2013, the IPCC stated that the largest driver of global warming is carbon dioxide (CO2) emissions from fossil fuel combustion, cement production, and land use changes such as deforestation. Its 2013 report states:
Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since AR4. It is extremely likely (95-100%) that human influence has been the dominant cause of the observed warming since the mid-20th century. - IPCC AR5 WG1 Summary for Policymakers
Climate model projections were summarized in the 2013 Fifth Assessment Report (AR5) by the IPCC. They 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) for their lowest emissions scenario using stringent mitigation and 2.6 to 4.8 °C (4.7 to 8.6 °F) for their highest. The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations.
Future climate change and associated impacts will vary from region to region around the globe. The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well as a probable expansion of subtropical deserts. Warming is expected to be strongest in the Arctic, with the continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming include more frequent extreme weather events including heat waves, droughts and heavy rainfall; ocean acidification; and species extinctions due to shifting temperature regimes. Effects significant to humans include the threat to food security from decreasing crop yields and the loss of habitat from inundation.
Possible responses to global warming include mitigation by emissions reduction, adaptation to its effects, building systems resilient to its effects, and possible future climate engineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous anthropogenic climate change. Parties to the UNFCCC have adopted a range of policies designed to reduce greenhouse gas emissions and to assist in adaptation to global warming. Parties to the UNFCCC have agreed that deep cuts in emissions are required, and that future global warming should be limited to below 2.0 °C (3.6 °F) relative to the pre-industrial level. Reports published in 2011 by the United Nations Environment Programme and the International Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequate to meet the UNFCCC's 2 °C target.
Emissions of greenhouse gases grew 2.2% per year between 2000 and 2010, compared with 1.3% per year from 1970 to 2000. China currently leads the world in global CO
Observed temperature changes
Main article: Instrumental temperature record
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Two millennia of mean surface temperatures according to different reconstructions from climate proxies, each smoothed on a decadal scale, with the instrumental temperature record overlaid in black.
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NOAA graph of Global Annual Temperature Anomalies 1950–2012, showing the El Niño-Southern Oscillation
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Earth has been in radiative imbalance since at least the 1970s, where less energy leaves the atmosphere than enters it. Most of this extra energy has been absorbed by the oceans. It is very likely that human activities substantially contributed to this increase in ocean heat content.
The Earth's average surface temperature rose by 0.74±0.18 °C over the period 1906–2005. The rate of warming over the last half of that period was almost double that for the period as a whole (0.13±0.03 °C per decade, versus 0.07±0.02 °C per decade). The urban heat island effect is very small, estimated to account for less than 0.002 °C of warming per decade since 1900. Temperatures in the lower troposphere have increased between 0.13 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Climate proxies show the temperature to have been relatively stable over the one or two thousand years before 1850, with regionally varying fluctuations such as the Medieval Warm Period and the Little Ice Age.
The warming that is evident in the instrumental temperature record is consistent with a wide range of observations, as documented by many independent scientific groups. Examples include sea level rise (due to melting of snow and ice and because water above 3.98 °C expands as it warms), widespread melting of snow and ice, increased heat content of the oceans, increased humidity, and the earlier timing of spring events, e.g., the flowering of plants. The probability that these changes could have occurred by chance is virtually zero.
Recent estimates by NASA's Goddard Institute for Space Studies (GISS) and the National Climatic Data Center show that 2005 and 2010 tied for the planet's warmest year since reliable, widespread instrumental measurements became available in the late 19th century, exceeding 1998 by a few hundredths of a degree. Estimates by the Climatic Research Unit (CRU) show 2005 as the second warmest year, behind 1998 with 2003 and 2010 tied for third warmest year, however, "the error estimate for individual years ... is at least ten times larger than the differences between these three years." The World Meteorological Organization (WMO) WMO statement on the status of the global climate in 2010 explains that, "The 2010 nominal value of +0.53 °C ranks just ahead of those of 2005 (+0.52 °C) and 1998 (+0.51 °C), although the differences between the three years are not statistically significant..." Every year from 1986 to 2013 has seen annual average global land and ocean surface temperatures above the 1961–1990 average.
Surface temperatures in 1998 were unusually warm because global temperatures are affected by the El Niño-Southern Oscillation (ENSO), and the strongest El Niño in the past century occurred during that year. Global temperature is subject to short-term fluctuations that overlay long term trends and can temporarily mask them. The relative stability in surface temperature from 2002 to 2009—which has been dubbed the global warming hiatus by the media and some scientists— is consistent with such an episode. 2010 was also an El Niño year. On the low swing of the oscillation, 2011 as a La Niña year was cooler but it was still the 11th warmest year since records began in 1880. Of the 13 warmest years since 1880, 11 were the years from 2001 to 2011. Over the more recent record, 2011 was the warmest La Niña year in the period from 1950 to 2011, and was close to 1997 which was not at the lowest point of the cycle.
Temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade). Ocean temperatures increase more slowly than land temperatures because of the larger effective heat capacity of the oceans and because the ocean loses more heat by evaporation. The northern hemisphere is also naturally warmer than the southern hemisphere mainly because of meridional heat transport in the oceans which has a differential of about 0.9 petawatts northwards, with an additional contribution from the albedo differences between the polar regions. Since the beginning of industrialisation the temperature difference between the hemispheres has increased due to melting of sea ice and snow in the North. Average arctic temperatures have been increasing at almost twice the rate of the rest of the world in the past 100 years; however arctic temperatures are also highly variable. Although more greenhouse gases are emitted in the Northern than Southern Hemisphere this does not contribute to the difference in warming because the major greenhouse gases persist long enough to mix between hemispheres.
The thermal inertia of the oceans and slow responses of other indirect effects mean that climate can take centuries or longer to adjust to changes in forcing. Climate commitment studies indicate that even if greenhouse gases were stabilized at year 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.
Initial causes of temperature changes (external forcings)
Main article: Attribution of recent climate change
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Greenhouse effect schematic showing energy flows between space, the atmosphere, and Earth's surface. Energy exchanges are expressed in watts per square meter (W/m).
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This graph, known as the Keeling Curve, shows the increase of atmospheric carbon dioxide (CO2) concentrations from 1958–2013. Monthly CO2 measurements display seasonal oscillations in an upward trend; each year's maximum occurs during the Northern Hemisphere's late spring, and declines during its growing season as plants remove some atmospheric CO2.
The climate system can respond to changes in external forcings. External forcings can "push" the climate in the direction of warming or cooling. Examples of external forcings include changes in atmospheric composition (e.g., increased concentrations of greenhouse gases), solar luminosity, volcanic eruptions, and variations in Earth's orbit around the Sun.Orbital cycles vary slowly over tens of thousands of years and at present are in an overall cooling trend which would be expected to lead towards a glacial period within the current ice age, but the 20th century instrumental temperature record shows a sudden rise in global temperatures.
Main articles: Greenhouse gas, Greenhouse effect, Radiative forcing and Carbon dioxide in Earth's atmosphere
See also: List of countries by carbon dioxide emissions
The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in a planet's atmosphere warm its lower atmosphere and surface. It was proposed by Joseph Fourier in 1824, discovered in 1860 by John Tyndall, was first investigated quantitatively by Svante Arrhenius in 1896, and was developed in the 1930s through 1960s by Guy Stewart Callendar.
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Annual world greenhouse gas emissions, in 2010, by sector.
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Percentage share of global cumulative energy-related CO
2 emissions between 1751 and 2012 across different regions.
On Earth, naturally occurring amounts of greenhouse gases have a mean warming effect of about 33 °C (59 °F). Without the Earth's atmosphere, the temperature across almost the entire surface of the Earth would be below freezing. The major greenhouse gases are water vapor, 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%. Clouds also affect the radiation balance through cloud forcings similar to greenhouse gases.
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. According to work published in 2007, the concentrations of CO2 and methane have increased by 36% and 148% respectively since 1750. These levels are much higher than at any time during the last 800,000 years, the period for which reliable data has been extracted from ice cores. Less direct geological evidence indicates that CO2 values higher than this were last seen about 20 million years ago.Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years. The rest of this increase is caused mostly by changes in land-use, particularly deforestation. Estimates of global CO2 emissions in 2011 from fossil fuel combustion, including cement production and gas flaring, was 34.8 billion tonnes (9.5 ± 0.5 PgC), an increase of 54% above emissions in 1990. Coal burning was responsible for 43% of the total emissions, oil 34%, gas 18%, cement 4.9% and gas flaring 0.7% In May 2013, it was reported that readings for CO2 taken at the world's primary benchmark site in Mauna Loa surpassed 400 ppm. According to professor Brian Hoskins, this is likely the first time CO2 levels have been this high for about 4.5 million years.
Over the last three decades of the 20th century, gross domestic product per capita and population growth were the main drivers of increases in greenhouse gas emissions. CO2 emissions are continuing to rise due to the burning of fossil fuels and land-use change. Emissions can be attributed to different regions, e.g., see the figure opposite. Attribution of emissions due to land-use change is a controversial issue.
Emissions scenarios, estimates of changes in future emission levels of greenhouse gases, have been projected that depend upon uncertain economic, sociological, technological, and natural developments. In most scenarios, emissions continue to rise over the century, while in a few, emissions are reduced. Fossil fuel reserves are abundant, and will not limit carbon emissions in the 21st century. Emission scenarios, combined with modelling of the carbon cycle, have been used to produce estimates of how atmospheric concentrations of greenhouse gases might change in the future. Using the six IPCC SRES "marker" scenarios, models suggest that by the year 2100, the atmospheric concentration of CO2 could range between 541 and 970 ppm. This is 90–250% above the concentration in the year 1750.
The popular media and the public often confuse global warming with ozone depletion, i.e., the destruction of stratospheric ozone by chlorofluorocarbons. Although there are a few areas of linkage, the relationship between the two is not strong. Reduced stratospheric ozone has had a slight cooling influence on surface temperatures, while increased tropospheric ozone has had a somewhat larger warming effect.
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Atmospheric CO2 concentration from 650,000 years ago to near present, using ice core proxy data and direct measurements
Particulates and soot
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Ship tracks can be seen as lines in these clouds over the Atlantic Ocean on the east coast of the United States. The climatic impacts from particulate forcing could have a large effect on climate through the indirect effect.
Global dimming, a gradual reduction in the amount of global direct irradiance at the Earth's surface, was observed from 1961 until at least 1990. The main cause of this dimming is particulates produced by volcanoes and human made pollutants, which exerts a cooling effect by increasing the reflection of incoming sunlight. The effects of the products of fossil fuel combustion – CO2 and aerosols – have partially offset one another in recent decades, so that net warming has been due to the increase in non-CO2 greenhouse gases such as methane. Radiative forcing due to particulates is temporally limited due to wet deposition which causes them to have an atmospheric lifetime of one week. Carbon dioxide has a lifetime of a century or more, and as such, changes in particulate concentrations will only delay climate changes due to carbon dioxide. Black carbon is second only to carbon dioxide for its contribution to global warming. In addition to their direct effect by scattering and absorbing solar radiation, particulates have indirect effects on the Earth's radiation budget. Sulfates 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, known as the Twomey effect. This effect also causes droplets to be of more uniform size, which reduces growth of raindrops and makes the cloud more reflective to incoming sunlight, known as the Albrecht effect. Indirect effects are most noticeable in marine stratiform clouds, and have very little radiative effect on convective clouds. Indirect effects of particulates represent the largest uncertainty in radiative forcing.
Soot may cool or warm the surface, depending on whether it is airborne or deposited. Atmospheric soot directly absorbs solar radiation, which heats the atmosphere and cools the surface. In isolated 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. When deposited, especially on glaciers or on ice in arctic regions, the lower surface albedo can also directly heat the surface. The influences of particulates, including black carbon, are most pronounced in the tropics and sub-tropics, particularly in Asia, while the effects of greenhouse gases are dominant in the extratropics and southern hemisphere.
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Satellite observations of Total Solar Irradiance from 1979–2006.
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Contribution of natural factors and human activities to radiative forcing of climate change. Radiative forcing values are for the year 2005, relative to the pre-industrial era (1750). The contribution of solar irradiance to radiative forcing is 5% the value of the combined radiative forcing due to increases in the atmospheric concentrations of carbon dioxide, methane and nitrous oxide.
Main articles: Solar variation and Solar wind
Since 1978, output from the Sun has been precisely measured by satellites. These measurements indicate that the Sun's output has not increased since 1978, so the warming during the past 30 years cannot be attributed to an increase in solar energy reaching the Earth.
Climate models have been used to examine the role of the sun in recent climate change. Models are unable to reproduce the rapid warming observed in recent decades when they only take into account variations in solar output and volcanic activity. Models are, however, able to simulate the observed 20th century changes in temperature when they include all of the most important external forcings, including human influences and natural forcings.
Another line of evidence against the sun having caused recent climate change comes from looking at how temperatures at different levels in the Earth's atmosphere have changed. Models and observations show that greenhouse warming results in warming of the lower atmosphere (called the troposphere) but cooling of the upper atmosphere (called the stratosphere).Depletion of the ozone layer by chemical refrigerants has also resulted in a strong cooling effect in the stratosphere. If the sun were responsible for observed warming, warming of both the troposphere and stratosphere would be expected.
Main articles: Climate change feedback and Climate sensitivity
Sea ice, shown here in Nunavut, in northern Canada, reflects more sunshine, while open ocean absorbs more, accelerating melting.
The climate system includes a range of feedbacks, which alter the response of the system to changes in external forcings. Positive feedbacks increase the response of the climate system to an initial forcing, while negative feedbacks reduce the response of the climate system to an initial forcing.
There are a range of feedbacks in the climate system, including water vapor, changes in ice-albedo (snow and ice cover affect how much the Earth's surface absorbs or reflects incoming sunlight), clouds, and changes in the Earth's carbon cycle (e.g., the release of carbon from soil). The main negative feedback is the energy which the Earth's surface radiates into space as infrared radiation. According to the Stefan-Boltzmann law, if the absolute temperature (as measured in kelvin) doubles, radiated energy increases by a factor of 16 (2 to the 4th power).
Feedbacks are an important factor in determining the sensitivity of the climate system to increased atmospheric greenhouse gas concentrations. Other factors being equal, a higher climate sensitivity means that more warming will occur for a given increase in greenhouse gas forcing. Uncertainty over the effect of feedbacks is a major reason why different climate models project different magnitudes of warming for a given forcing scenario. More research is needed to understand the role of clouds and carbon cycle feedbacks in climate projections.
The IPCC projections given in the lede span the "likely" range (greater than 66% probability, based on expert judgement) for the selected emissions scenarios. However, the IPCC's projections do not reflect the full range of uncertainty. The lower end of the "likely" range appears to be better constrained than the upper end of the "likely" range.
Main article: Global climate model
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Calculations of global warming prepared in or before 2001 from a range of climate models under the SRES A2 emissions scenario, which assumes no action is taken to reduce emissions and regionally divided economic development.
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Projected change in annual mean surface air temperature from the late 20th century to the middle 21st century, based on a medium emissions scenario (SRES A1B). This scenario assumes that no future policies are adopted to limit greenhouse gas emissions. Image credit: NOAA GFDL.
A climate model is a computerized representation of the five components of the climate system: Atmosphere, hydrosphere, cryosphere, land surface, and biosphere. Such models are based on scientific disciplines such as fluid dynamics, thermodynamics as well as physical processes such as radiative transfer. The models take into account various components, such as local air movement, temperature, clouds, and other atmospheric properties; ocean temperature, salt content, and circulation; ice cover on land and sea; the transfer of heat and moisture from soil and vegetation to the atmosphere; chemical and biological processes; solar variability and others.
Although researchers attempt to include as many processes as possible, simplifications of the actual climate system are inevitable because of the constraints of available computer power and limitations in knowledge of the climate system. Results from models can also vary due to different greenhouse gas inputs and the model's climate sensitivity. For example, the uncertainty in IPCC's 2007 projections is caused by (1) the use of multiple models with differing sensitivity to greenhouse gas concentrations, (2) the use of differing estimates of humanities' future greenhouse gas emissions, (3) any additional emissions from climate feedbacks that were not included in the models IPCC used to prepare its report, i.e., greenhouse gas releases from permafrost.
The models do not assume the climate will warm due to increasing levels of greenhouse gases. Instead the models predict how greenhouse gases will interact with radiative transfer and other physical processes. One of the mathematical results of these complex equations is a prediction whether warming or cooling will occur.
Recent research has called special attention to the need to refine models with respect to the effect of clouds and the carbon cycle.
Models are also used to help investigate the causes of recent climate change by comparing the observed changes to those that the models project from various natural and human-derived causes. Although these models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects, they do indicate that the warming since 1970 is dominated by man-made greenhouse gas emissions.
The physical realism of models is tested by examining their ability to simulate contemporary or past climates. Climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate. Not all effects of global warming are accurately predicted by the climate models used by the IPCC. Observed Arctic shrinkage has been faster than that predicted. Precipitation increased proportional to atmospheric humidity, and hence significantly faster than global climate models predict. Since 1990, sea level has also risen considerably faster than models predicted it would.
Observed and expected environmental effects
Main article: Effects of global warming
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Projections of global mean sea level rise by Parris and others. Probabilities have not been assigned to these projections. Therefore, none of these projections should be interpreted as a "best estimate" of future sea level rise. Image credit: NOAA.
"Detection" is the process of demonstrating that climate has changed in some defined statistical sense, without providing a reason for that change. Detection does not imply attribution of the detected change to a particular cause. "Attribution" of causes of climate change is the process of establishing the most likely causes for the detected change with some defined level of confidence. Detection and attribution may also be applied to observed changes in physical, ecological and social systems.
Main article: Physical impacts of climate change
Global warming has been detected in a number of natural systems. Some of these changes are described in the section on observed temperature changes, e.g., sea level rise and widespread decreases in snow and ice extent. Anthropogenic forcing has likely contributed to some of the observed changes, including sea level rise, changes in climate extremes (such as the number of warm and cold days), declines in Arctic sea ice extent, and to glacier retreat.
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Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s measurements began that allow the monitoring of glacial mass balance, reported to the World Glacier Monitoring Service (WGMS) and the National Snow and Ice Data Center (NSIDC)
Over the 21st century, the IPCC projects that global mean sea level could rise by 0.18–0.59 m. The IPCC do not provide a best estimate of global mean sea level rise, and their upper estimate of 59 cm is not an upper-bound, i.e., global mean sea level could rise by more than 59 cm by 2100. The IPCC's projections are conservative, and may underestimate future sea level rise. Over the 21st century, Parris and others suggest that global mean sea level could rise by 0.2 to 2.0 m (0.7–6.6 ft), relative to mean sea level in 1992.
Widespread coastal flooding would be expected if several degrees of warming is sustained for millennia. For example, sustained global warming of more than 2 °C (relative to pre-industrial levels) could lead to eventual sea level rise of around 1 to 4 m due to thermal expansion of sea water and the melting of glaciers and small ice caps. Melting of the Greenland ice sheet could contribute an additional 4 to 7.5 m over many thousands of years.
Changes in regional climate are expected to include greater warming over land, with most warming at high northern latitudes, and least warming over the Southern Ocean and parts of the North Atlantic Ocean. During the 21st century, glaciers and snow cover are projected to continue their widespread retreat. Projections of declines in Arctic sea ice vary. Recent projections suggest that Arctic summers could be ice-free (defined as ice extent less than 1 million square km) as early as 2025-2030.
Future changes in precipitation are expected to follow existing trends, with reduced precipitation over subtropical land areas, and increased precipitation at subpolar latitudes and some equatorial regions. Projections suggest a probable increase in the frequency and severity of some extreme weather events, such as heat waves.
Main article: Climate change and ecosystems
In terrestrial ecosystems, the earlier timing of spring events, and poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming. Future climate change is expected to particularly affect certain ecosystems, including tundra, mangroves, and coral reefs. It is expected that most ecosystems will be affected by higher atmospheric CO2 levels, combined with higher global temperatures. Overall, it is expected that climate change will result in the extinction of many species and reduced diversity of ecosystems.
Increases in atmospheric CO2 concentrations have led to an increase in ocean acidity. Dissolved CO2 increases ocean acidity, which is measured by lower pH values. Between 1750 to 2000, surface-ocean pH has decreased by ≈0.1, from ≈8.2 to ≈8.1. Surface-ocean pH has probably not been below ≈8.1 during the past 2 million years. Projections suggest that surface-ocean pH could decrease by an additional 0.3–0.4 units by 2100. Future ocean acidification could threaten coral reefs, fisheries, protected species, and other natural resources of value to society.
Main article: 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. This is due to carbon dioxide's very long lifetime in the atmosphere.
Stabilizing global average temperature would require reductions in anthropogenic CO2 emissions. Reductions in emissions of non-CO2 anthropogenic GHGs (e.g., methane and nitrous oxide) would also be necessary. For CO2, anthropogenic emissions would need to be reduced by more than 80% relative to their peak level. Even if this were to be achieved, global average temperatures would remain close to their highest level for many centuries.
Large-scale and abrupt impacts
Main article: Abrupt climate change
Climate change could result in global, large-scale changes in natural and social systems. Two examples are ocean acidification caused by increased atmospheric concentrations of carbon dioxide, and the long-term melting of ice sheets, which contributes to sea level rise.
Some large-scale changes could occur abruptly, i.e., over a short time period, and might also be irreversible. An example of abrupt climate change is the rapid release of methane and carbon dioxide from permafrost, which would lead to amplified global warming. Scientific understanding of abrupt climate change is generally poor. The probability of abrupt change for some climate related feedbacks may be low. Factors that may increase the probability of abrupt climate change include higher magnitudes of global warming, warming that occurs more rapidly, and warming that is sustained over longer time periods.
Observed and expected effects on social systems
Further information: Effects of global warming § Social systems and Regional effects of global warming § Regional impacts
The effects of climate change on human systems, mostly due to warming or shifts in precipitation patterns, or both, have been detected worldwide. Production of wheat and maize globally has been impacted by climate change. While crop production has increased in some mid-latitude regions such as the UK and Northeast China, economic losses due to extreme weather events have increased globally. There has been a shift from cold- to heat-related mortality in some regions as a result of warming. Livelihoods of indigenous peoples of the Arctic have been altered by climate change, and there is emerging evidence of climate change impacts on livelihoods of indigenous peoples in other regions. Regional impacts of climate change are now observable at more locations than before, on all continents and across ocean regions.
The future social impacts of climate change will be uneven. Many risks are expected to increase with higher magnitudes of global warming. All regions are at risk of experiencing negative impacts. Low-latitude, less developed areas face the greatest risk. Examples of impacts include:
Food: Crop production will probably be negatively affected in low latitude countries, while effects at northern latitudes may be positive or negative. Global warming of around 4.6 °C relative to pre-industrial levels could pose a large risk to global and regional food security.
Health: Generally impacts will be more negative than positive. Impacts include: the effects of extreme weather, leading to injury and loss of life; and indirect effects, such as undernutrition brought on by crop failures.
Map showing where natural disasters caused/aggravated by global warming may occur.
Further information: Effects of climate change on humans § Displacement/migration
See also: Climate refugee
In small islands and mega deltas, inundation as a result of sea level rise is expected to threaten vital infrastructure and human settlements. This could lead to issues of homelessness in countries with low lying areas such as Bangladesh, as well as statelessness for populations in countries such as the Maldives and Tuvalu.
Possible responses to global warming
Main article: Climate change mitigation
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The graph on the right shows three "pathways" to meet the UNFCCC's 2 °C target, labelled "global technology", "decentralised 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.
Reducing the amount of future climate change is called mitigation of climate change. The IPCC defines mitigation as activities that reduce greenhouse gas (GHG) emissions, or enhance the capacity of carbon sinks to absorb GHGs from the atmosphere. Studies indicate substantial potential for future reductions in emissions by a combination of emission-reducing activities such as energy conservation, increased energy efficiency, and satisfying more of society's power demands with renewable energy and nuclear energy sources. Climate mitigation also includes acts to enhance natural sinks, such as reforestation.
In order to limit warming to within the lower range described in the IPCC's "Summary Report for Policymakers" it will be necessary to adopt policies that will limit greenhouse gas emissions to one of several significantly different scenarios described in the full report. This will become more and more difficult with each year of increasing volumes of emissions and even more drastic measures will be required in later years to stabilize a desired atmospheric concentration of greenhouse gases. Energy-related carbon-dioxide (CO2) emissions in 2010 were the highest in history, breaking the prior record set in 2008.
Main article: Adaptation to global warming
Other policy responses include adaptation to climate change. Adaptation to climate change may be planned, either in reaction to or anticipation of climate change, or spontaneous, i.e., without government intervention. Planned adaptation is already occurring on a limited basis. The barriers, limits, and costs of future adaptation are not fully understood.
A concept related to adaptation is "adaptive capacity", which is the ability of a system (human, natural or managed) to adjust to climate change (including climate variability and extremes) to moderate potential damages, to take advantage of opportunities, or to cope with consequences. Unmitigated climate change (i.e., future climate change without efforts to limit greenhouse gas emissions) would, in the long term, be likely to exceed the capacity of natural, managed and human systems to adapt.
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.
Main article: Climate engineering
Climate engineering (sometimes called by the more expansive term 'geoengineering'), is the deliberate modification of the climate. It has been investigated as a possible response to global warming, e.g. by NASA and the Royal Society. Techniques under research fall generally into the categories 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 they are either ineffective or have potentially severe side effects and cannot be stopped without causing rapid climate change.
Discourse about global warming
Main article: Politics of global warming
Further information: 2011 United Nations Climate Change Conference, 2012 United Nations Climate Change Conference and 2013 United Nations Climate Change Conference
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Article 2 of the UN Framework Convention refers explicitly to "stabilization of greenhouse gas concentrations." In order to stabilize the atmospheric concentration of CO
2, emissions worldwide would need to be dramatically reduced from their present level.
Most countries are Parties to the United Nations Framework Convention on Climate Change (UNFCCC). The ultimate objective of the Convention is to prevent dangerous human interference of the climate system. As is stated in the Convention, this requires that GHG 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 proceed in a sustainable fashion. The Framework Convention was agreed in 1992, but since then, global emissions have risen. During negotiations, the G77 (a lobbying group in the United Nations representing 133 developing nations) pushed for a mandate requiring developed countries to "[take] the lead" in reducing their emissions. This was justified on the basis that: the developed world's emissions had contributed most to the stock of GHGs in the atmosphere; per-capita emissions (i.e., emissions per head of population) were still relatively low in developing countries; and the emissions of developing countries would grow to meet their development needs. This mandate was sustained in the Kyoto Protocol to the Framework Convention, which entered into legal effect in 2005.
In ratifying the Kyoto Protocol, most developed countries accepted legally binding commitments to limit their emissions. These first-round commitments expired in 2012. US President George W. Bush rejected the treaty on the basis that "it exempts 80% of the world, including major population centers such as China and India, from compliance, and would cause serious harm to the US economy."
At the 15th UNFCCC Conference of the Parties, held in 2009 at Copenhagen, several UNFCCC Parties produced the Copenhagen Accord. Parties associated with the Accord (140 countries, as of November 2010) aim to limit the future increase in global mean temperature to below 2 °C. A preliminary assessment published in November 2010 by the United Nations Environment Programme (UNEP) suggests a possible "emissions gap" between the voluntary pledges made in the Accord and the emissions cuts necessary to have a "likely" (greater than 66% probability) chance of meeting the 2 °C objective. The UNEP assessment takes the 2 °C objective as being measured against the pre-industrial global mean temperature level. To having a likely chance of meeting the 2 °C objective, assessed studies generally indicated the need for global emissions to peak before 2020, with substantial declines in emissions thereafter.
The 16th Conference of the Parties (COP16) was held at Cancún in 2010. It produced an agreement, not a binding treaty, that the Parties should take urgent action to reduce greenhouse gas emissions to meet a goal of limiting global warming to 2 °C above pre-industrial temperatures. It also recognized the need to consider strengthening the goal to a global average rise of 1.5 °C.
See also: Scientific opinion on climate change and Surveys of scientists' views on climate change
Most scientists agree that humans are contributing to observed climate change. A meta study of academic papers concerning global warming, published between 1991 and 2011 and accessible from Web of Knowledge, found that among those whose abstracts expressed a position on the cause of global warming, 97.2% supported the consensus view that it is man made. In an October 2011 paper published in the International Journal of Public Opinion Research, researchers from George Mason University analyzed the results of a survey of 489 American scientists working in academia, government, and industry. Of those surveyed, 97% agreed that that global temperatures have risen over the past century and 84% agreed that "human-induced greenhouse warming" is now occurring, only 5% disagreeing that human activity is a significant cause of global warming. National science academies have called on world leaders for policies to cut global emissions.
In the scientific literature, there is a strong consensus that global surface temperatures have increased in recent decades and that the trend is caused mainly by human-induced emissions of greenhouse gases. No scientific body of national or international standing disagrees with this view.
Discussion by the public and in popular media
Main articles: climate change denial, global warming controversy and media coverage of climate change
The global warming controversy refers to a variety of disputes, substantially more pronounced in the popular media than in the scientific literature, 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 wholly or partially an artifact of poor measurements. Additional disputes concern estimates of climate sensitivity, predictions of additional warming, and what the consequences of global warming will be.
From 1990–1997 in the United States, conservative think tanks mobilized to challenge the legitimacy of global warming as a social problem. They challenged the scientific evidence, argued that global warming will have benefits, and asserted that proposed solutions would do more harm than good.
Some people dispute aspects of climate change science. Organizations such as the libertarian Competitive Enterprise Institute, conservative commentators, and some companies such as ExxonMobil 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. Some fossil fuel companies have scaled back their efforts in recent years, or called for policies to reduce global warming.
Surveys of public opinion
Main article: Public opinion on climate change
Researchers at the University of Michigan have found that the public's belief as to the causes of global warming depends on the wording choice used in the polls.
In 2007–2008 Gallup Polls surveyed 127 countries. Over a third of the world's population was unaware of global warming, with people in developing countries less aware than those in developed, and those in Africa the least aware. Of those aware, Latin America leads in belief that temperature changes are a result of human activities while Africa, parts of Asia and the Middle East, and a few countries from the Former Soviet Union lead in the opposite belief. There is a significant contrast of the opinions of the concept and the appropriate response between Europe and the United States. Nick Pidgeon of Cardiff University said that "results show the different stages of engagement about global warming on each side of the Atlantic", adding, "The debate in Europe is about what action needs to be taken, while many in the US still debate whether climate change is happening." A 2010 poll by the Office for National Statistics found that 75% of UK respondents were at least "fairly convinced" that the world's climate is changing, compared to 87% in a similar survey in 2006. A January 2011 ICM poll in the UK found 83% of respondents viewed climate change as a current or imminent threat, while 14% said it was no threat. Opinion was unchanged from an August 2009 poll asking the same question, though there had been a slight polarisation of opposing views.
By 2010, with 111 countries surveyed, Gallup determined that there was a substantial decrease in the number of Americans and Europeans who viewed global warming as a serious threat. In the US, a little over half the population (53%) now viewed it as a serious concern for either themselves or their families; this was 10% below the 2008 poll (63%). Latin America had the biggest rise in concern, with 73% saying global warming was a serious threat to their families. That global poll also found that people are more likely to attribute global warming to human activities than to natural causes, except in the USA where nearly half (47%) of the population attributed global warming to natural causes.
A March–May 2013 survey by Pew Research Center for the People & the Press polled 39 countries about global threats. According to 54% of those questioned, global warming featured top of the perceived global threats. In a January 2013 survey, Pew found that 69% of Americans say there is solid evidence that the Earth's average temperature has been getting warmer over the past few decades, up six points since November 2011 and 12 points since 2009.
According to Erik M. Conway, global warming became the dominant popular term after June 1988, when NASA climate scientist James Hansen used the term in a testimony to Congress when 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." Conway claims that this testimony was widely reported in the media and subsequently global warming became the commonly used term by both the press and in public discourse. However, he also points out that "global climate change" is the more scientifically accurate term, because changes in Earth systems are not limited to surface temperatures.
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^ The 2001 joint statement was signed by the national academies of science of Australia, Belgium, Brazil, Canada, the Caribbean, the People's Republic of China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, New Zealand, Sweden, and the UK. The 2005 statement added Japan, Russia, and the U.S. The 2007 statement added Mexico and South Africa. The Network of African Science Academies, and the Polish Academy of Sciences have issued separate statements. Professional scientific societies include American Astronomical Society, American Chemical Society, American Geophysical Union, American Institute of Physics, American Meteorological Society, American Physical Society, American Quaternary Association, Australian Meteorological and Oceanographic Society, Canadian Foundation for Climate and Atmospheric Sciences, Canadian Meteorological and Oceanographic Society, European Academy of Sciences and Arts, European Geosciences Union, European Science Foundation, Geological Society of America, Geological Society of Australia, Geological Society of London-Stratigraphy Commission, InterAcademy Council, International Union of Geodesy and Geophysics, International Union for Quaternary Research, National Association of Geoscience Teachers, National Research Council (US), Royal Meteorological Society, and World Meteorological Organization.
^ Earth has already experienced almost 1/2 of the 2.0 °C (3.6 °F) described in the Cancún Agreement. In the last 100 years, Earth's average surface temperature increased by about 0.8 °C (1.4 °F) with about two thirds of the increase occurring over just the last three decades.
^ The greenhouse effect produces an average worldwide temperature increase of about 33 °C (59 °F) compared to black body predictions without the greenhouse effect, not an average surface temperature of 33 °C (91 °F). The average worldwide surface temperature is about 14 °C (57 °F).
^ A rise in temperature from 10 °C to 20 °C is not a doubling of absolute temperature; a rise from (273 + 10) K = 283 K to (273 + 20) K = 293 K is an increase of (293 − 283)/283 = 3.5 %.
^ 2009 Ends Warmest Decade on Record. NASA Earth Observatory Image of the Day, 22 January 2010.
^ "Warming of the climate system is unequivocal" p.2, IPCC, Climate Change 2013: The Physical Science Basis - Summary for Policymakers, Observed Changes in the Climate System, p. 2, in IPCC AR5 WG1 2013.
^ "Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010." p.6,IPCC, Climate Change 2013: The Physical Science Basis - Summary for Policymakers, Observed Changes in the Climate System, p. 6, in IPCC AR5 WG1 2013.
^ Riebeek, H. (June 3, 2010). "Global Warming: Feature Articles". Earth Observatory, part of the EOS Project Science Office located at NASA Goddard Space Flight Center."Global warming is the unusually rapid increase in Earth's average surface temperature over the past century primarily due to the greenhouse gases released as people burn fossil fuels."
^ America's Climate Choices. Washington, D.C.: The National Academies Press. 2011. p. 15. ISBN 978-0-309-14585-5. "The average temperature of the Earth's surface increased by about 1.4 °F (0.8 °C) over the past 100 years, with about 1.0 °F (0.6 °C) of this warming occurring over just the past three decades."
^ "Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850." p.3, IPCC, Climate Change 2013: The Physical Science Basis - Summary for Policymakers, Observed Changes in the Climate System, p. 3, in IPCC AR5 WG1 2013.
^ "Three different approaches are used to describe uncertainties each with a distinct form of language. * * * Where uncertainty in specific outcomes is assessed using expert judgment and statistical analysis of a body of evidence (e.g. observations or model results), then the following likelihood ranges are used to express the assessed probability of occurrence: virtually certain >99%; extremely likely >95%; very likely >90%; likely >66%;......" IPCC, Synthesis Report, Treatment of Uncertainty, in IPCC AR4 SYR 2007.
^ "Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations. This is an advance since the TAR's conclusion that 'most of the observed warming over the last 50 years is likely to have been due to the increase in GHG concentrations'."IPCC, Synthesis Report, Section 2.4: Attribution of climate change, in IPCC AR4 SYR 2007.
^ America's Climate Choices: Panel on Advancing the Science of Climate Change; National Research Council (2010). Advancing the Science of Climate Change. Washington, D.C.: The National Academies Press. ISBN 0-309-14588-0. "(p1) ... there is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by human activities. While much remains to be learned, the core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious scientific debate and careful evaluation of alternative explanations. * * * (p21-22) Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities."
^ "Joint Science Academies' Statement" (PDF). Retrieved 6 January 2014.
^ Kirby, Alex (17 May 2001). "Science academies back Kyoto". BBC News. Retrieved 27 July 2011.
^ "Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750." (p 11) "From 1750 to 2011, CO2 emissions from fossil fuel combustion and cement production have released 375 [345 to 405] GtC to the atmosphere, while deforestation and other land use change are estimated to have released 180 [100 to 260] GtC." (p 10), IPCC, Climate Change 2013: The Physical Science Basis - Summary for Policymakers, Observed Changes in the Climate System, p. 10&11, in IPCC AR5 WG1 2013.
^ IPCC, Climate Change 2013: The Physical Science Basis - Summary for Policymakers, Observed Changes in the Climate System, p. 15, in IPCC AR5 WG1 2013. "Extremely likely" is defined as a 95-100% likelihood on p 2.
^ Stocker et al., Technical Summary, in IPCC AR5 WG1 2013.
^ Schneider Von Deimling, Thomas; Held, Ganopolski, Rahmstorf (2006). "Climate sensitivity estimated from ensemble simulations of glacial climate". Climate Dynamics 27 (2–3): 149. Bibcode:2006ClDy...27..149S. doi:10.1007/s00382-006-0126-8. CiteSeerX: 10.1.1.172.3264.
^ Meehl et al., Chap. 10: Global Climate Projections, Section 10.5: Quantifying the Range of Climate Change, in IPCC AR4 WG1 2007.
^ Parry, M.L., et al., "Technical summary", Box TS.6. The main projected impacts for regions, in IPCC AR4 WG2 2007, pp. 59–63
^ Solomon et al., Technical Summary, Section TS.5.3: Regional-Scale Projections, in IPCC AR4 WG1 2007.
^ Lu, Jian; Vechhi, Gabriel A.; Reichler, Thomas (2007). "Expansion of the Hadley cell under global warming" (PDF). Geophysical Research Letters 34 (6): L06805. Bibcode:2007GeoRL..3406805L. doi:10.1029/2006GL028443.
^ Battisti, David; Naylor (2009). "Historical warnings of future food insecurity with unprecedented seasonal heat". Science 323 (5911): 240–4. doi:10.1126/science.1164363. PMID 19131626. Retrieved 13 April 2012.
^ US NRC 2012, p. 31
^ United Nations Framework Convention on Climate Change (UNFCCC) (2011). "Status of Ratification of the Convention". UNFCCC Secretariat: Bonn, Germany: UNFCCC.. Most countries in the world are Parties to the United Nations Framework Convention on Climate Change (UNFCCC), which has adopted the 2 °C target. As of 25 November 2011, there are 195 parties (194 states and 1 regional economic integration organization (the European Union)) to the UNFCCC.
^ "Article 2". The United Nations Framework Convention on Climate Change. "The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner", excerpt from the founding international treaty which entered into force on 21 March 1994.
^ United Nations Framework Convention on Climate Change (UNFCCC) (2005). "Sixth compilation and synthesis of initial national communications from Parties not included in Annex I to the Convention. Note by the secretariat. Executive summary" (PDF). Geneva (Switzerland): United Nations Office at Geneva.
^ Gupta, S. et al. 13.2 Climate change and other related policies, in IPCC AR4 WG3 2007.
^ Ch 4: Climate change and the energy outlook., in IEA 2009, pp. 173–184 (pp.175-186 of PDF)
^ United Nations Framework Convention on Climate Change (UNFCCC) (2011). "Compilation and synthesis of fifth national communications. Executive summary. Note by the secretariat" (PDF). Geneva (Switzerland): United Nations Office at Geneva.
^ Adger, et al., Chapter 17: Assessment of adaptation practices, options, constraints and capacity, Executive summary, in IPCC AR4 WG2 2007.
^ 6. Generating the funding needed for mitigation and adaptation (PDF), in World Bank (2010). "World Development Report 2010: Development and Climate Change". Washington, D.C., USA: The International Bank for Reconstruction and Development / The World Bank. pp. 262–263.
^ United Nations Framework Convention on Climate Change (UNFCCC) (2011). "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: UNFCCC. p. 3. "(...) 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"
^ United Nations Environment Programme (UNEP) (November 2011). "Executive Summary" (PDF). Bridging the Emissions Gap: A UNEP Synthesis Report. Nairobi, Kenya: UNEP. p. 8. ISBN 978-92-807-3229-0. UNEP Stock Number: DEW/1470/NA
^ International Energy Agency (IEA) (2011). "Executive Summary (English)" (PDF). World Energy Outlook 2011. Paris, France: IEA. p. 2.
^ IPCC, Climate Change 2014: Mitigation of Climate Change - Summary for Policymakers, Trends in stocks and flows of greenhouse gases and their drivers, p.6, in IPCC AR5 WG3 2014.
^ Rhein, M., et al. (7 June 2013): Box 3.1, in: Chapter 3: Observations: Ocean (final draft accepted by IPCC Working Group I), pp.11-12 (pp.14-15 of PDF chapter), in: IPCC AR5 WG1 2013
^ IPCC (11 November 2013): D.3 Detection and Attribution of Climate Change, in: Summary for Policymakers (finalized version), p.15, in: IPCC AR5 WG1 2013
^ Trenberth et al., Ch. 3, Observations: Atmospheric Surface and Climate Change, Section 184.108.40.206: Urban Heat Islands and Land Use Effects, p. 244, in IPCC AR4 WG1 2007.
^ Jansen et al., Ch. 6, Palaeoclimate, Section 220.127.116.11: What Do Reconstructions Based on Palaeoclimatic Proxies Show?, pp. 466–478, in IPCC AR4 WG1 2007.
^ Kennedy, J.J., et al. (2010). "How do we know the world has warmed? in: 2. Global Climate, in: State of the Climate in 2009". Bull.Amer.Meteor.Soc. 91 (7): 26.
^ Kennedy, C. (10 July 2012). "ClimateWatch Magazine >> State of the Climate: 2011 Global Sea Level". NOAA Climate Services Portal.
^ "Summary for Policymakers". Direct Observations of Recent Climate Change., in IPCC AR4 WG1 2007
^ "Summary for Policymakers". B. Current knowledge about observed impacts of climate change on the natural and human environment., in IPCC AR4 WG2 2007
^ Rosenzweig, C., et al. "Ch 1: Assessment of Observed Changes and Responses in Natural and Managed Systems". Sec 18.104.22.168 Changes in phenology., in IPCC AR4 WG2 2007, p. 99
^ Cole, Steve; Leslie McCarthy. "NASA – NASA Research Finds 2010 Tied for Warmest Year on Record" (Feature). NASA. Retrieved 3 March 2011.
^ Hansen, James E.; et al. (12 January 2006). "Goddard Institute for Space Studies, GISS Surface Temperature Analysis". NASA Goddard Institute for Space Studies. Retrieved 17 January 2007.
^ "State of the Climate: Global Analysis for Annual 2009". 15 January 2010. Retrieved 3 May 2011.
^ Jones, Phil. "CRU Information Sheet no. 1: Global Temperature Record". Climatic Research Unit, School of Environmental Sciences, University of East Anglia. Retrieved 3 May 2011.
^ World Meteorological Organization (2011). "WMO statement on the status of the global climate in 2010" (PDF). World Meteorological Organization. p. 2. ISBN 978-92-63-11074-9.
^ "Press release no. 972: WMO annual climate statement confirms 2012 as among top ten warmest years". WMO media centre (Press release). Geneva: World Meteorological Organization. 2 May 2013. Retrieved 16 February 2014.
^ "Press release no. 983: 2013 among top ten warmest on record". WMO media centre (Press release). Geneva: World Meteorological Organization. 5 February 2014. Retrieved 16 February 2014.
^ Changnon, Stanley A.; Bell, Gerald D. (2000). El Niño, 1997–1998: The Climate Event of the Century. London: Oxford University Press. ISBN 0-19-513552-0.
^ England, Matthew (February 2014). "Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus". Nature Climate Change. doi:10.1038/nclimate2106.
^ Knight, J.; Kenney, J.J.; Folland, C.; Harris, G.; Jones, G.S.; Palmer, M.; Parker, D.; Scaife, A.; Stott, P. (August 2009). "Do Global Temperature Trends Over the Last Decade Falsify Climate Predictions? [in "State of the Climate in 2008"]" (PDF). Bull.Amer.Meteor.Soc. 90 (8): S75–S79. Retrieved 13 August 2011.
^ Global temperature slowdown – not an end to climate change. UK Met Office. Retrieved 20 March 2011.
^ "NOAA National Climatic Data Center, State of the Climate: Global Analysis for Annual 2011". NOAA. 19 January 2012. Retrieved 31 January 2012.
^ Trenberth et al., Chap 3, Observations: Atmospheric Surface and Climate Change, Executive Summary, p. 237, in IPCC AR4 WG1 2007.
^ Rowan T. Sutton, Buwen Dong, Jonathan M. Gregory (2007). "Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations". Geophysical Research Letters 34 (2): L02701. Bibcode:2007GeoRL..3402701S. doi:10.1029/2006GL028164. Retrieved 19 September 2007.
^ Carl, Wunsch (November 2005). "The Total Meridional Heat Flux and Its Oceanic and Atmospheric Partition". Journal of Climate 18 (21): 4374–4380. Bibcode:2005JCli...18.4374W. doi:10.1175/JCLI3539.1. Retrieved 25 April 2013.
^ Feulner, Georg; Stefan Rahmstorf, Anders Levermann, and Silvia Volkwardt (March 2013). "On the Origin of the Surface Air Temperature Difference Between the Hemispheres in Earth's Present-Day Climate". Journal of Climate: 130325101629005. doi:10.1175/JCLI-D-12-00636.1. Retrieved 25 April 2013.
^ TS.3.1.2 Spatial Distribution of Changes in Temperature, Circulation and Related Variables - AR4 WGI Technical Summary
^ Ehhalt et al., Chapter 4: Atmospheric Chemistry and Greenhouse Gases, Section 22.214.171.124: Carbon monoxide (CO) and hydrogen (H2), p. 256, in IPCC TAR WG1 2001.
^ Meehl, Gerald A.; et al. (18 March 2005). "How Much More Global Warming and Sea Level Rise" (PDF). Science 307 (5716): 1769–1772. Bibcode:2005Sci...307.1769M. doi:10.1126/science.1106663. PMID 15774757. Retrieved 11 February 2007.
^ Group (28 November 2004). "Forcings (filed under: Glossary)". RealClimate.
^ Pew Center on Global Climate Change / Center for Climate and Energy Solutions (September 2006). "Science Brief 1: The Causes of Global Climate Change". Arlington, Virginia, USA: Center for Climate and Energy Solutions., p.2
^ US NRC 2012, p. 9
^ Hegerl et al., Chapter 9: Understanding and Attributing Climate Change, Section 126.96.36.199: The Influence of Other Anthropogenic and Natural Forcings, in IPCC AR4 WG1 2007, pp. 690–691. "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." p. 690
^ Kaufman, D. S.; Schneider, D. P.; McKay, N. P.; Ammann, C. M.; Bradley, R. S.; Briffa, K. R.; Miller, G. H.; Otto-Bliesner, B. L.; Overpeck, J. T.; Vinther, B. M.; Abbott, M.; Axford, M.; Bird, Y.; Birks, B.; Bjune, H. J. B.; Briner, A. E.; Cook, J.; Chipman, T.; Francus, M.; Gajewski, P.; Geirsdottir, K.; Hu, A.; Kutchko, F. S.; Lamoureux, B.; Loso, S.; MacDonald, M.; Peros, G.; Porinchu, M.; Schiff, D.; Seppa, C.; Seppa, H.; Arctic Lakes 2k Project Members (2009). "Recent Warming Reverses Long-Term Arctic Cooling". Science 325 (5945): 1236–1239. doi:10.1126/science.1173983. PMID 19729653. edit
"Arctic Warming Overtakes 2,000 Years of Natural Cooling". UCAR. 3 September 2009. Retrieved 8 June 2011.
Bello, David (4 September 2009). "Global Warming Reverses Long-Term Arctic Cooling". Scientific American. Retrieved 8 June 2011.
Mann, M. E.; Zhang, Z.; Hughes, M. K.; Bradley, R. S.; Miller, S. K.; Rutherford, S.; Ni, F. (2008). "Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia". Proceedings of the National Academy of Sciences 105 (36): 13252–7. doi:10.1073/pnas.0805721105. PMC 2527990. PMID 18765811. edit
^ Tyndall, John (1861). "On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connection of Radiation, Absorption, and Conduction". Philosophical Magazine. 4 22: 169–94, 273–85. Retrieved 8 May 2013.
^ Weart, Spencer (2008). "The Carbon Dioxide Greenhouse Effect". The Discovery of Global Warming. American Institute of Physics. Retrieved 21 April 2009.
^ The Callendar Effect: the life and work of Guy Stewart Callendar (1898–1964) Amer Meteor Soc., Boston. ISBN 978-1-878220-76-9
^ Le Treut et al. "Chapter 1: Historical Overview of Climate Change Science". FAQ 1.1., p. 97, in IPCC AR4 WG1 2007: "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."
^ Blue, Jessica. "What is the Natural Greenhouse Effect?". National Geographic (magazine). Retrieved 27 May 2013.
^ Kiehl, J.T.; Trenberth, K.E. (1997). "Earth's Annual Global Mean Energy Budget" (PDF). Bulletin of the American Meteorological Society 78 (2): 197–208. Bibcode:1997BAMS...78..197K. doi:10.1175/1520-0477(1997)078<0197:EAGMEB>2.0.CO;2. ISSN 1520-0477. Archived from the original on 24 June 2008. Retrieved 21 April 2009.
^ Schmidt, Gavin (6 April 2005). "Water vapour: feedback or forcing?". RealClimate. Retrieved 21 April 2009.
^ Russell, Randy (16 May 2007). "The Greenhouse Effect & Greenhouse Gases". University Corporation for Atmospheric Research Windows to the Universe. Retrieved 27 December 2009.
^ EPA (2007). "Recent Climate Change: Atmosphere Changes". Climate Change Science Program. United States Environmental Protection Agency. Retrieved 21 April 2009.
^ Spahni, Renato; et al. (November 2005). "Atmospheric Methane and Nitrous Oxide of the Late Pleistocene from Antarctic Ice Cores". Science 310 (5752): 1317–1321. Bibcode:2005Sci...310.1317S. doi:10.1126/science.1120132. PMID 16311333.
^ Siegenthaler, Urs; et al. (November 2005). "Stable Carbon Cycle–Climate Relationship During the Late Pleistocene" (PDF). Science 310 (5752): 1313–1317. Bibcode:2005Sci...310.1313S. doi:10.1126/science.1120130. PMID 16311332. Retrieved 25 August 2010.
^ Petit, J. R.; et al. (3 June 1999). "Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica" (PDF). Nature 399 (6735): 429–436. Bibcode:1999Natur.399..429P. doi:10.1038/20859. Retrieved 27 December 2009.
^ Lüthi, D.; Le Floch, M.; Bereiter, B.; Blunier, T.; Barnola, J. M.; Siegenthaler, U.; Raynaud, D.; Jouzel, J.; Fischer, H.; Kawamura, K.; Stocker, T. F. (2008). "High-resolution carbon dioxide concentration record 650,000–800,000 years before present". Nature 453 (7193): 379–382. doi:10.1038/nature06949. PMID 18480821. edit
^ Pearson, PN; Palmer, MR (2000). "Atmospheric carbon dioxide concentrations over the past 60 million years". Nature 406 (6797): 695–699. doi:10.1038/35021000. PMID 10963587.
^ IPCC, Summary for Policymakers, Concentrations of atmospheric greenhouse gases ..., p. 7, in IPCC TAR WG1 2001.
^ Le Quéré, C.; Andres, R. J.; Boden, T.; Conway, T.; Houghton, R. A.; House, J. I.; Marland, G.; Peters, G. P.; van der Werf, G.; Ahlström, A.; Andrew, R. M.; Bopp, L.; Canadell, J. G.; Ciais, P.; Doney, S. C.; Enright, C.; Friedlingstein, P.; Huntingford, C.; Jain, A. K.; Jourdain, C.; Kato, E.; Keeling, R. F.; Klein Goldewijk, K.; Levis, S.; Levy, P.; Lomas, M.; Poulter, B.; Raupach, M. R.; Schwinger, J.; Sitch, S.; Stocker, B. D.; Viovy, N.; Zaehle, S.; Zeng, N. (2 December 2012). "The global carbon budget 1959–2011". Earth System Science Data Discussions 5 (2): 1107–1157. Bibcode:2012ESSDD...5.1107L. doi:10.5194/essdd-5-1107-2012.
^ "Carbon dioxide passes symbolic mark". BBC. 2013-05-10. Retrieved 2013-05-27.
^ Pilita Clark (2013-05-10). "CO2 at highest level for millions of years" ((registration required)). The Financial Times. Retrieved 2013-05-27.
^ Rogner, H.-H., et al., Chap. 1, Introduction, Section 188.8.131.52: Intensities, in IPCC AR4 WG3 2007.
^ NRC (2008). "Understanding and Responding to Climate Change". Board on Atmospheric Sciences and Climate, US National Academy of Sciences. p. 2. Retrieved 9 November 2010.
^ World Bank (2010). World Development Report 2010: Development and Climate Change. The International Bank for Reconstruction and Development / The World Bank, 1818 H Street NW, Washington, D.C. 20433. doi:10.1596/978-0-8213-7987-5. ISBN 978-0-8213-7987-5. Archived from the original on 5 March 2010. Retrieved 6 April 2010.
^ Banuri et al., Chapter 3: Equity and Social Considerations, Section 3.3.3: Patterns of greenhouse gas emissions, and Box 3.1, pp. 92–93 in IPCC SAR WG3 1996.
^ Liverman, D.M. (2008). "Conventions of climate change: constructions of danger and the dispossession of the atmosphere" (PDF). Journal of Historical Geography 35 (2): 279–296. doi:10.1016/j.jhg.2008.08.008. Retrieved 10 May 2011.
^ Fisher et al., Chapter 3: Issues related to mitigation in the long-term context, Section 3.1: Emissions scenarios: Issues related to mitigation in the long term context in IPCC AR4 WG3 2007.
^ Morita, Chapter 2: Greenhouse Gas Emission Mitigation Scenarios and Implications, Section 184.108.40.206: Emissions and Other Results of the SRES Scenarios, in IPCC TAR WG3 2001.
^ Rogner et al., Ch. 1: Introduction, Figure 1.7, in IPCC AR4 WG3 2007.
^ IPCC, Summary for Policymakers, Introduction, paragraph 6, in IPCC TAR WG3 2001.
^ Prentence et al., Chapter 3: The Carbon Cycle and Atmospheric Carbon Dioxide Executive Summary, in IPCC TAR WG1 2001.
^ Newell, P.J., 2000: Climate for change: non-state actors and the global politics of greenhouse. Cambridge University Press, ISBN 0-521-63250-1.
^ Talk of the Nation. "Americans Fail the Climate Quiz". Npr.org. Retrieved 27 December 2011.
^ Shindell, Drew; Faluvegi, Greg; Lacis, Andrew; Hansen, James; Ruedy, Reto; Aguilar, Elliot (2006). "Role of tropospheric ozone increases in 20th-century climate change". Journal of Geophysical Research 111 (D8): D08302. Bibcode:2006JGRD..11108302S. doi:10.1029/2005JD006348.
^ Solomon, S; D. Qin; M. Manning; Z. Chen; M. Marquis; K.B. Averyt; M. Tignor; H.L. Miller, eds. (2007). "220.127.116.11 Surface Radiation". Climate Change 2007: Working Group I: The Physical Science Basis. ISBN 978-0-521-88009-1.
^ Hansen, J; Sato, M; Ruedy, R; Lacis, A; Oinas, V (2000). "Global warming in the twenty-first century: an alternative scenario". Proc. Natl. Acad. Sci. U.S.A. 97 (18): 9875–80. Bibcode:2000PNAS...97.9875H. doi:10.1073/pnas.170278997. PMC 27611. PMID 10944197.
^ Ramanathan, V.; Carmichael, G. (2008). "Global and regional climate changes due to black carbon". Nature Geoscience 1 (4): 221–227. Bibcode:2008NatGe...1..221R. doi:10.1038/ngeo156.
^ V. Ramanathan and G. Carmichael, supra note 1, at 221 (". . . emissions of black carbon are the second strongest contribution to current global warming, after carbon dioxide emissions.") Numerous scientists also calculate that black carbon may be second only to CO2 in its contribution to climate change, including Tami C. Bond & Haolin Sun, Can Reducing Black Carbon Emissions Counteract Global Warming, ENVIRON. SCI. TECHN. (2005), at 5921 ("BC is the second or third largest individual warming agent, following carbon dioxide and methane."); and J. Hansen, A Brighter Future, 53 CLIMATE CHANGE 435 (2002), available at http://pubs.giss.nasa.gov/docs/2002/2002_Hansen_1.pdf (calculating the climate forcing of BC at 1.0±0.5 W/m).
^ Twomey, S. (1977). "Influence of pollution on shortwave albedo of clouds". J. Atmos. Sci. 34 (7): 1149–1152. Bibcode:1977JAtS...34.1149T. doi:10.1175/1520-0469(1977)034<1149:TIOPOT>2.0.CO;2. ISSN 1520-0469.
^ Albrecht, B. (1989). "Aerosols, cloud microphysics, and fractional cloudiness". Science 245 (4923): 1227–1239. Bibcode:1989Sci...245.1227A. doi:10.1126/science.245.4923.1227. PMID 17747885.
^ IPCC, "Aerosols, their Direct and Indirect Effects", pp. 291–292 in IPCC TAR WG1 2001.
^ Ramanathan, V.; Chung, C.; Kim, D.; Bettge, T.; Buja, L.; Kiehl, J. T.; Washington, W. M.; Fu, Q.; Sikka, D. R.; Wild, M. (2005). "Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle" (Full free text). Proceedings of the National Academy of Sciences 102 (15): 5326–5333. Bibcode:2005PNAS..102.5326R. doi:10.1073/pnas.0500656102. PMC 552786. PMID 15749818. edit
^ Ramanathan, V., et al. (2008). "Report Summary" (PDF). Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia. United Nations Environment Programme.
^ 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.
^ IPCC, Summary for Policymakers, Human and Natural Drivers of Climate Change, Figure SPM.2, in IPCC AR4 WG1 2007.
^ US Environmental Protection Agency (2009). "3.2.2 Solar Irradiance". Volume 3: Attribution of Observed Climate Change. Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act. EPA's Response to Public Comments. US Environmental Protection Agency. Archived from the original on 16 June 2011. Retrieved 2011-06-23.
^ US NRC 2008, p. 6
^ Hegerl, et al., Chapter 9: Understanding and Attributing Climate Change, Frequently Asked Question 9.2: Can the Warming of the 20th century be Explained by Natural Variability?, in IPCC AR4 WG1 2007.
^ Simmon, R. and D. Herring (November 2009). "Notes for slide number 7, titled "Satellite evidence also suggests greenhouse gas warming," in presentation, "Human contributions to global climate change"". Presentation library on the U.S. National Oceanic and Atmospheric Administration's Climate Services website. Archived from the original on 3 July 2011. Retrieved 2011-06-23.
^ Hegerl et al., Chapter 9: Understanding and Attributing Climate Change, Frequently Asked Question 9.2: Can the Warming of the 20th century be Explained by Natural Variability?, in IPCC AR4 WG1 2007.
^ Randel, William J.; Shine, Keith P.; Austin, John et al. (2009). "An update of observed stratospheric temperature trends". Journal of Geophysical Research 114 (D2): D02107. Bibcode:2009JGRD..11402107R. doi:10.1029/2008JD010421.
^ USGCRP 2009, p. 20
^ Jackson, R. and A. Jenkins (17 November 2012). "Vital signs of the planet: global climate change and global warming: uncertainties". Earth Science Communications Team at NASA's Jet Propulsion Laboratory / California Institute of Technology.
^ Riebeek, H. (16 June 2011). "The Carbon Cycle: Feature Articles: Effects of Changing the Carbon Cycle". Earth Observatory, part of the EOS Project Science Office located at NASA Goddard Space Flight Center.
^ US National Research Council (2003). "Ch. 1 Introduction". Understanding Climate Change Feedbacks. Washington, D.C., USA: National Academies Press., p.19
^ Lindsey, R. (14 January 2009). "Earth's Energy Budget (p.4), 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.
^ US National Research Council (2006). "Ch. 1 Introduction to Technical Chapters". Surface Temperature Reconstructions for the Last 2,000 Years. Washington, D.C., USA: National Academies Press., pp.26-27
^ AMS Council (20 August 2012). "2012 American Meteorological Society (AMS) Information Statement on Climate Change". Boston, Massachusetts, USA: AMS.
^ Meehl, G.A., et al. "Ch 10: Global Climate Projections". Sec 10.5.4.6 Synthesis of Projected Global Temperature at Year 2100]., in IPCC AR4 WG1 2007
^ NOAA (January 2007). "Patterns of greenhouse warming". GFDL Climate Modeling Research Highlights (Princeton, New Jersey, USA: The National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL)) 1 (6)., revision 2/2/2007, 8:50.08 AM.
^ NOAA Geophysical Fluid Dynamics Laboratory (GFDL) (9 October 2012). "NOAA GFDL Climate Research Highlights Image Gallery: Patterns of Greenhouse Warming". NOAA GFDL.
^ IPCC, Glossary A-D: "Climate Model", in IPCC AR4 SYR 2007.
^ Karl, TR, et al., ed. (2009). "Global Climate Change". Global Climate Change Impacts in the United States. Cambridge University Press. ISBN 978-0-521-14407-0.
^ KEVIN SCHAEFER, TINGJUN ZHANG, LORI BRUHWILER, ANDREW P. BARRETT (2011). "Amount and timing of permafrost carbon release in response to climate warming". Tellus Series B 63 (2): 165–180. Bibcode:2011TellB..63..165S. doi:10.1111/j.1600-0889.2011.00527.x.
^ Hansen, James (2000). "Climatic Change: Understanding Global Warming". In Robert Lanza. One World: The Health & Survival of the Human Species in the 21st century. Health Press (New Mexico). pp. 173–190. ISBN 0-929173-33-3. Retrieved 18 August 2007.
^ Stocker et al., Chapter 7: Physical Climate Processes and Feedbacks, Section 7.2.2: Cloud Processes and Feedbacks, in IPCC TAR WG1 2001.
^ Torn, Margaret; Harte, John (2006). "Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming". Geophysical Research Letters 33 (10): L10703. Bibcode:2006GeoRL..3310703T. doi:10.1029/2005GL025540. Retrieved 4 March 2007.
^ Harte, John; et al. (2006). "Shifts in plant dominance control carbon-cycle responses to experimental warming and widespread drought". Environmental Research Letters 1 (1): 014001. Bibcode:2006ERL.....1a4001H. doi:10.1088/1748-9326/1/1/014001. Retrieved 2 May 2007.
^ Scheffer, Marten; et al. (2006). "Positive feedback between global warming and atmospheric CO2 concentration inferred from past climate change". Geophysical Research Letters 33 (10): L10702. Bibcode:2006GeoRL..3310702S. doi:10.1029/2005gl025044. Retrieved 4 May 2007.
^ Randall et al., Chapter 8, Climate Models and Their Evaluation, Sec. FAQ 8.1 in IPCC AR4 WG1 2007.
^ IPCC, Technical Summary, p. 54, in IPCC TAR WG1 2001.
^ Stroeve, J., et al. (2007). "Arctic sea ice decline: Faster than forecast". Geophysical Research Letters 34 (9): L09501. Bibcode:2007GeoRL..3409501S. doi:10.1029/2007GL029703.
^ Wentz,FJ, et al. (2007). "How Much More Rain Will Global Warming Bring?". Science 317 (5835): 233–5. Bibcode:2007Sci...317..233W. doi:10.1126/science.1140746. PMID 17540863.
^ Liepert, Beate G.; Previdi (2009). "Do Models and Observations Disagree on the Rainfall Response to Global Warming?". Journal of Climate 22 (11): 3156. Bibcode:2009JCli...22.3156L. doi:10.1175/2008JCLI2472.1. "Recently analyzed satellite-derived global precipitation datasets from 1987 to 2006 indicate an increase in global-mean precipitation of 1.1%–1.4% decade−1. This trend corresponds to a hydrological sensitivity (HS) of 7% K−1 of global warming, which is close to the Clausius–Clapeyron (CC) rate expected from the increase in saturation water vapor pressure with temperature. Analysis of two available global ocean evaporation datasets confirms this observed intensification of the atmospheric water cycle. The observed hydrological sensitivity over the past 20-yr period is higher by a factor of 5 than the average HS of 1.4% K−1 simulated in state-of-the-art coupled atmosphere–ocean climate models for the twentieth and twenty-first centuries."
^ Rahmstorf, S.; Cazenave, A.; Church, J. A.; Hansen, J. E.; Keeling, R. F.; Parker, D. E.; Somerville, R. C. J. (4 May 2007). "Recent Climate Observations Compared to Projections". Science 316 (5825): 709–709. doi:10.1126/science.1136843.
^ 4. Global Mean Sea Level Rise Scenarios, in: Main Report, in Parris & others 2012, p. 12
^ Executive Summary, in Parris & others 2012, p. 1
^ IPCC, Glossary A-D: "Detection and attribution", in IPCC AR4 WG1 2007. See also Hegerl et al., Section 9.1.2: What are Climate Change Detection and Attribution?, in IPCC AR4 WG1 2007.
^ Rosenzweig et al., Chapter 1: Assessment of Observed Changes and Responses in Natural and Managed Systems Section 1.2 Methods of detection and attribution of observed changes, in IPCC AR4 WG2 2007 .
^ IPCC, Synthesis Report Summary for Policymakers, Section 1: Observed changes in climate and their effects, in IPCC AR4 SYR 2007.
^ Hegerl, G.C., et al. "Ch 9: Understanding and Attributing Climate Change". Executive Summary., in IPCC AR4 WG1 2007
^ Global mean sea level rise in 2090–2099 relative to 1980–1999
^ IPCC, "Summary for Policymakers", 3. Projected climate change and its impacts, in IPCC AR4 SYR 2007
^ PROJECTIONS OF FUTURE SEA LEVEL RISE, pp.243-244, in: Ch. 7. Sea Level Rise and the Coastal Environment, in National Research Council 2010
^ BOX SYN-1: SUSTAINED WARMING COULD LEAD TO SEVERE IMPACTS, p.5, in: Synopsis, in National Research Council 2011
^ IPCC, Synthesis Report Summary for Policymakers, Section 3: Projected climate change and its impacts, in IPCC AR4 SYR 2007.
^ Meehl, G.A., et al. "Ch 10: Global Climate Projections". Box 10.1: Future Abrupt Climate Change, ‘Climate Surprises’, and Irreversible Changes: Glaciers and ice caps., in IPCC AR4 WG1 2007, p. 776
^ Meehl, G.A., et al. "Ch 10: Global Climate Projections". Sec 10.3.3.2 Changes in Snow Cover and Frozen Ground., in IPCC AR4 WG1 2007, pp. 770, 772
^ Meehl, G.A., et al. "Ch 10: Global Climate Projections". Sec 10.3.3.1 Changes in Sea Ice Cover., in IPCC AR4 WG1 2007, p. 770
^ Wang, M; J.E. Overland (2009). "A sea ice free summer Arctic within 30 years?". Geophys. Res. Lett 36 (7). Bibcode:2009GeoRL..3607502W. doi:10.1029/2009GL037820. Retrieved 2 May 2011.
^ Met Office. "Arctic sea ice 2012". Exeter, UK: Met Office.
^ NOAA (February 2007). "Will the wet get wetter and the dry drier?". GFDL Climate Modeling Research Highlights (Princeton, New Jersey, USA: National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL)) 1 (5)., p.1. Revision 10/15/2008, 4:47:16 PM.
^ "D. Future Climate Extremes, Impacts, and Disaster Losses, in: Summary for policymakers". MANAGING THE RISKS OF EXTREME EVENTS AND DISASTERS TO ADVANCE CLIMATE CHANGE ADAPTATION., in IPCC SREX 2012, pp. 9–13
^ Fischlin, et al., Chapter 4: Ecosystems, their Properties, Goods and Services, Executive Summary, p. 213, in IPCC AR4 WG2 2007. Executive summary not present in on-line text; see pdf.
^ Schneider et al., Chapter 19: Assessing Key Vulnerabilities and the Risk from Climate Change, Section 19.3.4: Ecosystems and biodiversity, in IPCC AR4 WG2 2007.
^ Ocean Acidification, in: Ch. 2. Our Changing Climate, in NCADAC 2013, pp. 69–70
^ Introduction, in Zeebe 2012, p. 142
^ Ocean acidification, in: Executive summary, in Good & others 2010, p. 14
5. Ocean acidification, in Good & others 2010, pp. 73–81
Summary, pp.14-19, in National Research Council 2011
FAQ 12.3, in: Chapter 12: Long-term Climate Change: Projections, Commitments and Irreversibility, in IPCC AR5 WG1 2013, pp.88-89 (pp.90-91 of PDF chapter)
^ BOX 2.1: STABILIZATION AND NON-CO2 GREENHOUSE GASES (p.65), in: Chapter 2: Emissions, Concentrations, and Related Factors, in National Research Council 2011
^ Smith, J.B., et al. "Ch. 19. Vulnerability to Climate Change and Reasons for Concern: A Synthesis". Sec 19.6. Extreme and Irreversible Effects., in IPCC TAR WG2 2001
^ Smith, J. B.; Schneider, S. H.; Oppenheimer, M.; Yohe, G. W.; Hare, W.; Mastrandrea, M. D.; Patwardhan, A.; Burton, I.; Corfee-Morlot, J.; Magadza, C. H. D.; Füssel, H.-M.; Pittock, A. B.; Rahman, A.; Suarez, A.; van Ypersele, J.-P. (17 March 2009). "Assessing dangerous climate change through an update of the Intergovernmental Panel on Climate Change (IPCC) 'reasons for concern'". Proceedings of the National Academy of Sciences 106 (11): 4133–7. doi:10.1073/pnas.0812355106. PMC 2648893. PMID 19251662. edit
^ Clark, P.U., et al. (December 2008). "Executive Summary". Abrupt Climate Change. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. Reston, Virginia, USA: U.S. Geological Survey., pp. 1–7. Report website
^ "Siberian permafrost thaw warning sparked by cave data". BBC. 22 February 2013. Retrieved 24 February 2013.
^ US National Research Council (2010). "Advancing the Science of Climate Change: Report in Brief". Washington, D.C., USA: National Academies Press., p.3. PDF of Report
^ IPCC. "Summary for Policymakers". Sec. 2.6. The Potential for Large-Scale and Possibly Irreversible Impacts Poses Risks that have yet to be Reliably Quantified., in IPCC TAR WG2 2001
^ Cramer, W., et al., Executive summary, in: Chapter 18: Detection and attribution of observed impacts (archived July 8 2014), pp.3-4, in IPCC AR5 WG2 A 2014
^ FAQ 7 and 8, in: Volume-wide Frequently Asked Questions (FAQs) (archived July 8 2014), pp.2-3, in IPCC AR5 WG2 A 2014
^ Oppenheimer, M., et al., Section 19.6.3: Updating Reasons for Concern, in: Chapter 19: Emergent risks and key vulnerabilities (archived July 8 2014), pp.39-46, in IPCC AR5 WG2 A 2014
^ Field, C., et al., B-3: Regional Risks and Potential for Adaptation, in: Technical Summary (archived July 8 2014), pp.27-30, in IPCC AR5 WG2 A 2014
^ Oppenheimer, M., et al., Section 19.6.3: Updating Reasons for Concern, in: Chapter 19: Emergent risks and key vulnerabilities (archived July 8 2014), pp.42-43, in IPCC AR5 WG2 A 2014
^ Porter, J.R., et al., Executive summary, in: Chapter 7: Food security and food production systems (archived July 8 2014), p.3, in IPCC AR5 WG2 A 2014
^ Reference temperature period converted from late-20th century to pre-industrial times (approximated in the source as 1850-1900).
Assessment Box SPM-1 (p.14) and B-2. Sectoral Risks and Potential for Adaptation: Food security and food production systems (p.18), in: Summary for Policymakers (archived July 8 2014), in IPCC AR5 WG2 A 2014
^ Smith, K.R., et al., FAQ 11.2, in: Chapter 11: Human health: impacts, adaptation, and co-benefits (archived July 8 2014), p.37, in IPCC AR5 WG2 A 2014
^ Smith, K.R., et al., Section 11.4: Direct Impacts of Climate and Weather on Health, in: Chapter 11: Human health: impacts, adaptation, and co-benefits (archived July 8 2014), pp.10-13, in IPCC AR5 WG2 A 2014
^ Smith, K.R., et al., Section 11.6.1. Nutrition, in: Chapter 11: Human health: impacts, adaptation, and co-benefits (archived July 8 2014), pp.10-13, in IPCC AR5 WG2 A 2014
^ IPCC AR4 SYR 2007. 3.3.3 Especially affected systems, sectors and regions. Synthesis report.
^ Mimura, N., et al. (2007). "Executive summary". In Parry, M.L., et al. (eds.). Chapter 16: Small Islands. Climate change 2007: impacts, adaptation and vulnerability: contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press (CUP): Cambridge, UK: Print version: CUP. This version: IPCC website. ISBN 0521880106. Retrieved 15 September 2011.
^ "Climate change and the risk of statelessness" (PDF). May 2011. Retrieved 13 April 2012.
^ PBL Netherlands Environment Agency (15 June 2012). "Figure 6.14, in: Chapter 6: The energy and climate challenge". In van Vuuren, D. and M. Kok. Roads from Rio+20. ISBN 978-90-78645-98-6., p.177, Report no: 500062001. Report website.
^ Fisher, B.S., et al. "Ch. 3: Issues related to mitigation in the long-term context". 3.5 Interaction between mitigation and adaptation, in the light of climate change impacts and decision-making under long-term uncertainty., in IPCC AR4 WG3 2007
^ IPCC, Glossary J-P: "Mitigation", in IPCC AR4 WG3 2007.
^ IPCC, Synthesis Report Summary for Policymakers, Section 4: Adaptation and mitigation options, in IPCC AR4 SYR 2007.
^ IPCC (2007), IPCC AR4 WG1 2007, ed., Summary for Policymakers, ISBN 978-0-521-88009-1
^ Rom, Joe (12 May 2011). "National Academy calls on nation to 'substantially reduce greenhouse gas emissions' starting ASAP". ThinkProgress. Retrieved 7 February 2012.
^ IEA (30 May 2011). "Prospect of limiting the global increase in temperature to 2°C is getting bleaker". International Energy Agency. Retrieved 7 February 2012.
^ Smit et al., Chapter 18: Adaptation to Climate Change in the Context of Sustainable Development and Equity, Section 18.2.3: Adaptation Types and Forms, in IPCC TAR WG2 2001.
^ "Appendix I. Glossary". "Adaptive capacity"., in IPCC AR4 WG2 2007
^ "Synthesis report". Sec 6.3 Responses to climate change: Robust findings]., in IPCC AR4 SYR 2007
^ "New Report Provides Authoritative Assessment of National, Regional Impacts of Global Climate Change" (PDF) (Press release). U.S. Global Change Research Program. 6 June 2009. Retrieved 27 June 2009.
^ "Workshop on managing solar radiation". NASA. April 2007. Retrieved 23 May 2009.
^ "Stop emitting CO2 or geoengineering could be our only hope" (Press release). The Royal Society. 28 August 2009. Retrieved 14 June 2011.
^ P. Keller, David; Ellias Y. Feng & Andreas Oschlies (January 2014). "Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario". Nature 5: 3304. doi:10.1038/ncomms4304. Retrieved March 31, 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."
^ Quoted in IPCC SAR SYR 1996, "Synthesis of Scientific-Technical Information Relevant to Interpreting Article 2 of the UN Framework Convention on Climate Change", paragraph 4.1, p. 8 (pdf p. 18.)
^ Granger Morgan, M. (Lead Author), H. Dowlatabadi, M. Henrion, D. Keith, R. Lempert, S. McBride, M. Small and T. Wilbanks (Contributing Authors) (2009). "Non-Technical Summary: BOX NT.1 Summary of Climate Change Basics". Synthesis and Assessment Product 5.2: Best practice approaches for characterizing, communicating, and incorporating scientific uncertainty in decisionmaking. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. Washington, D.C., USA.: National Oceanic and Atmospheric Administration. p. 11. Retrieved 1 June 2011.
^ UNFCCC (n.d.). "Essential Background". UNFCCC website. Retrieved 18 May 2010.
^ UNFCCC (n.d.). "Full text of the Convention, Article 2". UNFCCC website. Retrieved 18 May 2010.
^ Rogner et al., Chapter 1: Introduction, Executive summary, in IPCC AR4 WG3 2007.
^ Raupach, R.; Marland, G.; Ciais, P.; Le Quere, C.; Canadell, G.; Klepper, G.; Field, B. (Jun 2007). "Global and regional drivers of accelerating CO2 emissions" (Free full text). Proceedings of the National Academy of Sciences 104 (24): 10288–10293. Bibcode:2007PNAS..10410288R. doi:10.1073/pnas.0700609104. ISSN 0027-8424. PMC 1876160. PMID 17519334. edit
^ Dessai, S. (2001). "The climate regime from The Hague to Marrakech: Saving or sinking the Kyoto Protocol?" (PDF). Tyndall Centre Working Paper 12. Tyndall Centre website. Retrieved 5 May 2010.
^ Grubb, M. (July–September 2003). "The Economics of the Kyoto Protocol" (PDF). World Economics 4 (3): 144–145. Retrieved 25 March 2010.
^ UNFCCC (n.d.). "Kyoto Protocol". UNFCCC website. Retrieved 21 May 2011.
^ Müller, Benito (February 2010). Copenhagen 2009: Failure or final wake-up call for our leaders? EV 49 (PDF). Oxford Institute for Energy Studies. p. i. ISBN 978-1-907555-04-6. Retrieved 18 May 2010.
^ United Nations Environment Programme (November 2010). "Technical summary" (PDF). The Emissions Gap Report: Are the Copenhagen Accord pledges sufficient to limit global warming to 2 °C or 1.5 °C? A preliminary assessment (advance copy). UNEP website. Retrieved 11 May 2011. This publication is also available in e-book format
^ UNFCCC (30 March 2010). "Decision 2/CP. 15 Copenhagen Accord. In: Report of the Conference of the Parties on its fifteenth session, held in Copenhagen from 7 to 19 December 2009. Addendum. Part Two: Action taken by the Conference of the Parties at its fifteenth session" (PDF). United Nations Office at Geneva, Switzerland. p. 5. Retrieved 17 May 2010.
^ "Outcome of the work of the Ad Hoc Working Group on long-term Cooperative Action under the Convention". PRESIDENCIA DE LA REPÚBLICA, MÉXICO. 11 December 2010. p. 2. Retrieved 12 January 2011.
^ Royal Society (13 April 2005). "Letter from The Royal Society: A GUIDE TO FACTS AND FICTIONS ABOUT CLIMATE CHANGE: Misleading arguments: Many scientists do not think that climate change is a problem. Some scientists have signed petitions stating that climate change is not a problem.". Economic Affairs – Written Evidence. The Economics of Climate Change, the Second Report of the 2005–2006 session, produced by the UK Parliament House of Lords Economics Affairs Select Committee. UK Parliament website. Retrieved 9 July 2011. This document is also available in PDF format
^ John Cook, Dana Nuccitelli, Sarah A Green, Mark Richardson, Bärbel Winkler, Rob Painting, Robert Way, Peter Jacobs. Andrew Skuce (15 May 2013). "Quantifying the consensus on anthropogenic global warming in the scientific literature". Environmental Research Letters 8 (2): 024024. Bibcode:2013ERL.....8b4024C. doi:10.1088/1748-9326/8/2/024024.
^ Wihby, John (4 November 2011). "Structure of Scientific Opinion on Climate Change". Journalist's Resource (Harvard Kennedy School).
^ Stephen J. Farnsworth, S. Robert Lichter (October 27, 2011). "The Structure of Scientific Opinion on Climate Change". International Journal of Public Opinion Research. Retrieved December 2, 2011.
^ 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". US National Academies website. Retrieved 5 May 2010.
^ Julie Brigham-Grette et al. (September 2006). "Petroleum Geologists' Award to Novelist Crichton Is Inappropriate" (PDF). Eos 87 (36). Retrieved 23 January 2007. "The AAPG stands alone among scientific societies in its denial of human-induced effects on global warming."
^ DiMento, Joseph F. C.; Doughman, Pamela M. (2007). Climate Change: What It Means for Us, Our Children, and Our Grandchildren. The MIT Press. p. 68. ISBN 978-0-262-54193-0.
^ Boykoff, M.; Boykoff, J. (July 2004). "Balance as bias: global warming and the US prestige press1" (Full free text). Global Environmental Change Part A 14 (2): 125–136. doi:10.1016/j.gloenvcha.2003.10.001. edit
^ Oreskes, Naomi; Conway, Erik. Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming (first ed.). Bloomsbury Press. ISBN 978-1-59691-610-4.
^ Aaron M. McCright and Riley E. Dunlap, "Challenging Global Warming as a Social Problem: An Analysis of the Conservative Movement's Counter-Claims", Social Problems, November 2000, Vol. 47 Issue 4, pp 499–522 in JSTOR
^ Weart, S. (July 2009). "The Public and Climate Change (cont. – since 1980). Section: After 1988". American Institute of Physics website. Retrieved 5 May 2010.
SEPP (n.d.). "Frequently Asked Questions About Climate Change". Science & Environmental Policy Project (SEPP) website. Archived from the original on 11 May 2008. Retrieved 5 May 2010.
^ Begley, Sharon (13 August 2007). "The Truth About Denial". Newsweek. Retrieved 13 August 2007.
^ Adams, David (20 September 2006). "Royal Society tells Exxon: stop funding climate change denial". The Guardian. London. Retrieved 9 August 2007.
^ "Exxon cuts ties to global warming skeptics". MSNBC. 12 January 2007. Retrieved 2 May 2007.
^ Sandell, Clayton (3 January 2007). "Report: Big Money Confusing Public on Global Warming". ABC. Retrieved 27 April 2007.
^ "Greenpeace: Exxon still funding climate skeptics". USA Today. Reuters. 18 May 2007. Retrieved 21 January 2010.
^ "Global Warming Resolutions at U.S. Oil Companies Bring Policy Commitments from Leaders, and Record High Votes at Laggards" (Press release). Ceres. 13 May 2004. Retrieved 4 March 2010.
^ "It's All in a Name: 'Global Warming' Vs. 'Climate Change'".
^ Pelham, Brett (22 April 2009). "Awareness, Opinions About Global Warming Vary Worldwide". Gallup. Retrieved 14 July 2009.
^ "Summary of Findings". Little Consensus on Global Warming. Partisanship Drives Opinion. Pew Research Center. 12 July 2006. Retrieved 14 April 2007.
^ Crampton, Thomas (4 January 2007). "More in Europe worry about climate than in U.S., poll shows". The New York Times. Retrieved 9 June 2010.
^ "Public attitudes towards climate change and the impact on transport (January 2011 report)". Department for Transport. 2011. p. 8. Retrieved 3 February 2011.
^ Damian Carrington (31 January 2011). "Public belief in climate change weathers storm, poll shows | Environment | guardian.co.uk". The Guardian. UK. Retrieved 4 February 2011.
^ Pugliese, Anita (20 April 2011). "Fewer Americans, Europeans View Global Warming as a Threat". Gallup. Retrieved 22 April 2011.
^ Ray, Julie; Anita Pugliese (22 April 2011). "Worldwide, Blame for Climate Change Falls on Humans". Gallup.Com. Retrieved 3 May 2011. "People nearly everywhere, including majorities in developed Asia and Latin America, are more likely to attribute global warming to human activities rather than natural causes. The U.S. is the exception, with nearly half (47%) – and the largest percentage in the world – attributing global warming to natural causes."
^ "Climate Change and Financial Instability Seen as Top Global Threats". Pew Research Center for the People & the Press.
^ Climate Change: Key Data Points from Pew Research | Pew Research Center
^ Erik Conway. "What's in a Name? Global Warming vs. Climate Change", NASA, 5 December 2008
^ U.S. Senate, Committee on Energy and Natural Resources, "Greenhouse Effect and Global Climate Change, part 2" 100th Cong., 1st sess., 23 June 1988, p. 44.
Good, P., et al. (2010), An updated review of developments in climate science research since IPCC AR4. A report by the AVOID consortium, London, UK: Committee on Climate Change, p. 14. Report website.
IAP (June 2009), Interacademy Panel (IAP) Member Academies Statement on Ocean Acidification, Secretariat: TWAS (the Academy of Sciences for the Developing World), Trieste, Italy.
IEA (2009). World Energy Outlook 2009. Paris, France: International Energy Agency (IEA). ISBN 978-92-64-06130-9.
IPCC AR5 WG2 A (2014), Field, C.B., et al., ed., Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects (GSA). Contribution of Working Group II (WG2) to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), Cambridge University Press. Archived 25 June 2014.
IPCC AR5 WG1 (2013), Stocker, T.F., et al., ed., Climate Change 2013: The Physical Science Basis. Working Group 1 (WG1) Contribution to the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report (AR5), Cambridge University Press. Climate Change 2013 Working Group 1 website.
IPCC SREX (2012). Field, C.B., et al., ed. "Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX)". Cambridge University Press.. Summary for Policymakers available in Arabic, Chinese, French, Russian, and Spanish.
IPCC AR4 SYR (2007). Core Writing Team;
NASA Goddard Institute for Space Studies – Global change research
NOAA State of the Climate Report – U.S. and global monthly state of the climate reports
Climate Change at the National Academies – repository for reports
Nature Reports Climate Cha
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