The Info List - Global Warming

--- Advertisement ---

(i) (i) (i) (i) (i)

GLOBAL WARMING, also referred to as CLIMATE CHANGE, is the observed century-scale rise in the average temperature of the Earth
's climate system and its related effects. Multiple lines of scientific evidence show that the climate system is warming. Many of the observed changes since the 1950s are unprecedented in the instrumental temperature record which extends back to the mid-19th century, and in paleoclimate proxy records covering thousands of years.

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

Future climate change and associated impacts will differ from region to region around the globe. Anticipated effects include warming global temperature, rising sea levels , changing precipitation , and expansion of deserts in the subtropics . Warming is expected to be greater over land than over the oceans and greatest in the Arctic , with the continuing retreat of glaciers , permafrost and sea ice . Other likely changes include more frequent extreme weather events such as heat waves , droughts , heavy rainfall with floods and heavy snowfall ; 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 abandonment of populated areas due to rising sea levels . Because the climate system has a large "inertia " and greenhouse gases will remain in the atmosphere for a long time, many of these effects will persist for not only decades or centuries, but for tens of thousands of years to come.

Possible societal 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 agreed that deep cuts in emissions are required and that global warming should be limited to well below 2.0 °C (3.6 °F) compared to pre-industrial levels, with efforts made to limit warming to 1.5 °C (2.7 °F).

Public reactions to global warming and concern about its effects are also increasing. A global 2015 Pew Research Center
Pew Research Center
report showed that a median of 54% of all respondents asked consider it "a very serious problem". Significant regional differences exist, with Americans
and Chinese (whose economies are responsible for the greatest annual CO2 emissions ) among the least concerned.


* 1 Observed temperature changes

* 1.1 Regional trends and short-term fluctuations * 1.2 Warmest years vs overall trend

* 2 Initial causes of temperature changes (external forcings)

* 2.1 Greenhouse gases * 2.2 Aerosols and soot * 2.3 Solar activity * 2.4 Variations in Earth\'s orbit

* 3 Feedback * 4 Climate

* 5 Observed and expected environmental effects

* 5.1 Extreme weather
Extreme weather
* 5.2 Sea level rise
Sea level rise
* 5.3 Ecological systems * 5.4 Long-term effects * 5.5 Large-scale and abrupt impacts

* 6 Observed and expected effects on social systems

* 6.1 Habitat inundation * 6.2 Economy * 6.3 Infrastructure

* 7 Possible responses to global warming

* 7.1 Mitigation * 7.2 Adaptation * 7.3 Climate

* 8 Discourse about global warming

* 8.1 Political discussion * 8.2 Scientific discussion

* 8.3 Discussion by the public and in popular media

* 8.3.1 Surveys of public opinion

* 9 Etymology * 10 See also * 11 Notes * 12 Citations * 13 References * 14 Further reading

* 15 External links

* 15.1 Research * 15.2 Educational


Main article: Instrumental temperature record World map showing surface temperature trends (°C per decade) between 1950 and 2014. 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. NOAA
graph of global annual temperature anomalies 1950–2012, showing the El Niño Southern Oscillation

In the period from 1880 to 2012, the global average (land and ocean) surface temperature has increased by 0.85 °C, multiple independently produced datasets confirm. In the period from 1906 to 2005, Earth\'s average surface temperature rose by 7002273890000000000♠0.74±0.18 °C. The rate of warming almost doubled in the last half of that period (7002273279999999999♠0.13±0.03 °C per decade, against 7002273219999999999♠0.07±0.02 °C per decade). Although the popular press often reports the increase of the average near-surface atmospheric temperature as the measure of global warming, most of the additional energy stored in the climate system since 1970 has gone into the oceans. The rest has melted ice and warmed the continents and the atmosphere .

Since 1979, the average temperature of the lower troposphere has increased between 0.12 and 0.135 °C (0.216 and 0.243 °F) per decade, satellite temperature measurements confirm. 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 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 , widespread melting of snow and land 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.


Play media Temperature anomalies arranged by country 1900 - 2016. Deviation from the 1951-1980 mean temperature. Visualization based on GISTEMP data.

Temperature increases vary a lot across the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (7002273399999999999♠0.25 °C per decade against 7002273279999999999♠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 oceans lose more heat by evaporation. Since the beginning of industrialisation in the eighteenth century, the temperature difference between the hemispheres has increased due to melting of sea ice and snow in the North. In the past one hundred years, average arctic temperatures have been increasing at almost twice the rate of the rest of the world; however, arctic temperatures are also highly variable. Although more greenhouse gases are emitted in the Northern than in the Southern Hemisphere, this fact does not contribute to the difference in warming because the major greenhouse gases persist long enough to diffuse within as well as between the hemispheres.

The thermal inertia of the oceans and the slow responses of other indirect effects occasion the climate to take centuries or longer to adjust to past changes in forcings. One climate commitment study concluded that if greenhouse gases were stabilized at year 2000 levels, surface temperatures would still increase by about one-half degree Celsius, and another found that if they were stabilized at 2005 levels, surface warming could exceed a whole degree Celsius. Some of this surface warming will be driven by past natural forcings which are still seeking equilibrium in the climate system . One study using a highly simplified climate model indicates these past natural forcings may account for as much as 64% of the committed 2050 surface warming and their influence will fade with time compared to the human contribution.

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 since been dubbed the global warming hiatus by the media and some scientists, is an example of such an episode. 2015 updates to account for differing methods of measuring ocean surface temperature measurements show a positive trend over the recent decade.


Sixteen of the seventeen warmest years on record have occurred since 2000. While record-breaking years attract considerable public interest, individual years are less significant than the overall trend. Some climatologists have criticized the attention that the popular press gives to "warmest year" statistics. In particular, ocean oscillations such as the El Niño Southern Oscillation (ENSO) can cause temperatures of a given year to be abnormally warm or cold for reasons unrelated to the overall trend of climate change. Gavin Schmidt stated "the long-term trends or the expected sequence of records are far more important than whether any single year is a record or not."


CO2 concentrations over the last 400,000 years. Greenhouse effect schematic showing energy flows between space, the atmosphere, and Earth's surface. Energy exchanges are expressed in watts per square metre (W/m2). Main article: Attribution of recent climate change

The climate system can spontaneously generate changes in global temperature for years to decades at a time but long-term changes in global temperature require external forcings. These forcings are "external" to the climate system but not necessarily external to Earth. 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.


Main articles: Greenhouse gas
Greenhouse gas
, Greenhouse effect
Greenhouse effect
, Radiative forcing , Carbon dioxide
Carbon dioxide
in Earth\'s atmosphere , and Earth\'s energy budget See also: List of countries by carbon dioxide emissions and History of climate change science

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 its scientific description was developed in the 1930s through 1960s by Guy Stewart Callendar . Annual world greenhouse gas emissions, in 2010, by sector. Percentage share of global cumulative energy-related CO2 emissions between 1751 and 2012 across different regions.

On Earth, an atmosphere containing naturally occurring amounts of greenhouse gases causes air temperature near the surface to be about 33 °C (59 °F) warmer than it would be in their absence. Without the Earth's atmosphere, the Earth's average temperature would be well below the freezing temperature of water. The major greenhouse gases are water vapour , which causes about 36–70% of the greenhouse effect; carbon dioxide (CO2), which causes 9–26%; methane (CH4), which causes 4–9%; and ozone (O3), which causes 3–7%. Clouds also affect the radiation balance through cloud forcings similar to greenhouse gases.

Human activity since the Industrial Revolution
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 had 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
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 . Another significant non-fuel source of anthropogenic CO2 emissions is the calcination of limestone for clinker production, a chemical process which releases CO2. 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. Monthly global CO2 concentrations exceeded 400 ppm in March 2015, probably for the first time in several million years. On 12 November 2015, NASA scientists reported that human-made carbon dioxide continues to increase above levels not seen in hundreds of thousands of years: currently, about half of the carbon dioxide released from the burning of fossil fuels is not absorbed by vegetation and the oceans and remains in the atmosphere. Global carbon dioxide emissions by country.

Over the last three decades of the twentieth century, gross domestic product per capita and population growth were the main drivers of increases in greenhouse gas emissions. CO2 emissions are continuing to rise due to the burning of fossil fuels and land-use change. :71 Emissions can be attributed to different regions . Attributions of emissions due to land-use change are subject to considerable uncertainty. :289

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
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 (e.g., the ozone layer) 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.


Ship tracks can be seen as lines in these clouds over the Atlantic Ocean on the east coast of the United States. Atmospheric particles from these and other sources could have a large effect on climate through the aerosol 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. Solid and liquid particles known as aerosols, produced by volcanoes and human-made pollutants , are thought to be the main cause of this dimming. They exert 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 aerosols is temporally limited due to the processes that remove aerosols from the atmosphere. Removal by clouds and precipitation gives tropospheric aerosols an atmospheric lifetime of only about a week, while stratospheric aerosols can remain for a few years. Carbon dioxide
Carbon dioxide
has a lifetime of a century or more, and as such, changes in aerosols will only delay climate changes due to carbon dioxide. Black carbon is second only to carbon dioxide for its contribution to global warming (contribution being estimated at 17 to 20%, whereas carbon dioxide contributes 40 to 45% to global warming ).

In addition to their direct effect by scattering and absorbing solar radiation, aerosols have indirect effects on the Earth\'s radiation budget . Sulfate aerosols act as cloud condensation nuclei and thus lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets, a phenomenon known as the Twomey effect . 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 aerosols represent the largest uncertainty in radiative forcing.

Soot may either cool or warm Earth's climate system , 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 atmospheric particles, 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. Changes in total solar irradiance (TSI) and monthly sunspot numbers since the mid-1970s. Contribution of natural factors and human activities to radiative forcing of climate change. Radiative forcing
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 article: Solar activity and climate

Since 1978, solar irradiance has been measured by satellites . These measurements indicate that the Sun's radiative output has not increased since then, so the warming that occurred in the past 40 years cannot be attributed to an increase in solar energy reaching the Earth.

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 only taking 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, consisting of both human influences and natural forcings.

Another line of evidence for the Sun's non-attributability is the differing temperature changes at different levels in the Earth's atmosphere. According to basic physical principles, the greenhouse effect produces warming of the lower atmosphere (the troposphere), but cooling of the upper atmosphere (the stratosphere). If solar variations were responsible for the observed warming, warming of both the troposphere and the stratosphere would be expected.


Main article: Milankovitch cycles

The tilt of the Earth’s axis and the shape of its orbit around the Sun vary slowly over tens of thousands of years. This changes climate by changing the seasonal and latitudinal distribution of incoming solar energy at Earth's surface. During the last few thousand years, this phenomenon contributed to a slow cooling trend at high latitudes of the Northern Hemisphere during summer, a trend that was reversed by greenhouse-gas-induced warming during the 20th century. Orbital cycles favorable for glaciation are not expected within the next 50,000 years.


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 it.

There are a range of feedbacks in the climate system, including water vapour , 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 the Earth's surface radiates into space as infrared radiation . According to the Stefan-Boltzmann law
Stefan-Boltzmann law
, if the absolute temperature (as measured in kelvins ) 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 previously mentioned 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.


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. 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 . Main article: Global climate model

A climate model is a representation of the physical, chemical and biological processes that affect the climate system. Such models are based on scientific disciplines such as fluid dynamics and thermodynamics as well as physical processes such as radiative transfer . The models may be used to predict a range of variables 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; and chemical and biological processes, among 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 humanity's 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. Warming or cooling is thus a result, not an assumption, of the models.

Clouds and their effects are especially difficult to predict. Improving the models' representation of clouds is therefore an important topic in current research. Another prominent research topic is expanding and improving representations of 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 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 anthropogenic 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 proportionally 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.


Main article: Effects of global warming 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.

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, glacier retreat , and greening of the Sahara .

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.

"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 articles: Extreme weather
Extreme weather
and Physical impacts of climate change § Extreme events

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
Southern Ocean
and parts of the North Atlantic Ocean.

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 .

A 2015 study published in Nature Climate
Change , states:

About 18% of the moderate daily precipitation extremes over land are attributable to the observed temperature increase since pre-industrial times, which in turn primarily results from human influence. For 2 °C of warming the fraction of precipitation extremes attributable to human influence rises to about 40%. Likewise, today about 75% of the moderate daily hot extremes over land are attributable to warming. It is the most rare and extreme events for which the largest fraction is anthropogenic, and that contribution increases nonlinearly with further warming.

Data analysis of extreme events from 1960 until 2010 suggests that droughts and heat waves appear simultaneously with increased frequency. Extremely wet or dry events within the monsoon period have increased since 1980.


Map of the Earth
with a six-metre sea level rise represented in red. Main articles: Sea level rise
Sea level rise
and Retreat of glaciers since 1850 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).

The sea level rise since 1993 has been estimated to have been on average 2.6 mm and 2.9 mm per year ± 0.4 mm. Additionally, sea level rise has accelerated from 1995 to 2015. Over the 21st century, the IPCC projects for a high emissions scenario, that global mean sea level could rise by 52–98 cm. The IPCC's projections are conservative, and may underestimate future sea level rise. Other estimates suggest that for the same period, 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
Greenland ice sheet
could contribute an additional 4 to 7.5 m over many thousands of years. It has been estimated that we are already committed to a sea-level rise of approximately 2.3 metres for each degree of temperature rise within the next 2,000 years.

Warming beyond the 2 °C target would potentially lead to rates of sea-level rise dominated by ice loss from Antarctica
. Continued CO2 emissions from fossil sources could cause additional tens of metres of sea level rise, over the next millennia and eventually ultimately eliminate the entire Antarctic ice sheet, causing about 58 metres of sea level rise.


Main article: Climate change and ecosystems

In terrestrial ecosystems , the earlier timing of spring events, as well as poleward and upward shifts in plant and animal ranges, have been linked with high confidence to recent warming. Future climate change is expected to affect particular ecosystems, including tundra , mangroves , coral reefs , and caves . 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, measured by lower pH values. Between 1750 and 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.

Ocean deoxygenation is projected to increase hypoxia by 10%, and triple suboxic waters (oxygen concentrations 98% less than the mean surface concentrations), for each 1 °C of upper ocean warming.


Main article: Long-term effects of global warming
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 the global average temperature would require large reductions in CO2 emissions, as well as reductions in emissions of other greenhouse gases such as methane and nitrous oxide. Emissions of CO2 would need to be reduced by more than 80% relative to their peak level. Even if this were achieved, global average temperatures would remain close to their highest level for many centuries. As of 2016, emissions of CO2 from burning fossil fuels had stopped increasing, but The Guardian
The Guardian
reports they need to be "reduced to have a real impact on climate change". Meanwhile, this greenhouse gas continues to accumulate in the atmosphere. In that context, the New York Times reported that scientific installations analyzing oceanic air detected the excess carbon dioxide in the atmosphere "rose at the highest rate on record in 2015 and 2016." It hs been suggested that this rise in CO2 levels is the result of changing absorption patterns of the ocean and land surface in that they may have reached the limit of their ability to absorb carbon dioxide.

Also, CO2 is not the only factor driving climate change. Concentrations of atmospheric methane, another greenhouse gas, rose dramatically between 2006–2016 for unknown reasons. This undermines efforts to combat global warming and there is a risk of an uncontrollable runaway greenhouse effect .

Long-term effects also include a response from the Earth's crust, due to ice melting and deglaciation, in a process called post-glacial rebound , when land masses are no longer depressed by the weight of ice. This could lead to landslides and increased seismic and volcanic activities. Tsunamis could be generated by submarine landslides caused by warmer ocean water thawing ocean-floor permafrost or releasing gas hydrates . Some world regions, such as the French Alps, already show signs of an increase in landslide frequency.


Main article: Abrupt climate change See also: Cold blob (North Atlantic)

Climate change could result in global, large-scale changes in natural and social systems . Examples include the possibility for the Atlantic Meridional Overturning Circulation to slow- or shutdown, which in the instance of a shutdown would change weather in Europe and North America considerably, 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 . Examples of abrupt climate change are the rapid release of methane and carbon dioxide from permafrost , which would lead to amplified global warming, or the shutdown of thermohaline circulation . 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.


Further information: Effects of global warming § Social systems , and Regional effects of global warming § Regional impacts See also: Climate change and national security

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. A study from 2015 concluded that economic growth (gross domestic product) of poorer countries is much more impaired with projected future climate warming, than previously thought.

A meta-analysis of 56 studies concluded in 2014 that each degree of temperature rise will increase violence by up to 20%, which includes fist fights, violent crimes, civil unrest or wars.

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
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 .


Further information: Effects of climate change on humans § Displacement/migration See also: Climate

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


See also: Economics of global warming
Economics of global warming

Estimates based on the IPCC A1B emission scenario from additional CO2 and CH4 greenhouse gases released from permafrost, estimate associated impact damages by US$43 trillion.


Continued permafrost degradation will likely result in unstable infrastructure in Arctic regions, or Alaska before 2100. Thus, impacting roads, pipelines and buildings, as well as water distribution, and cause slope failures .



Main article: Climate change mitigation The graph on the right shows three "pathways" to meet the UNFCCC's 2 °C target, labelled "global technology", "decentralized solutions", and "consumption change". Each pathway shows how various measures (e.g., improved energy efficiency, increased use of renewable energy) could contribute to emissions reductions. Image credit: PBL Netherlands Environmental Assessment Agency .

Mitigation of climate change are actions to reduce greenhouse gas emissions, or enhance the capacity of carbon sinks to absorb GHGs from the atmosphere. There is a large potential for future reductions in emissions by a combination of activities, including energy conservation and increased energy efficiency ; the use of low-carbon energy technologies, such as renewable energy , nuclear energy , and carbon capture and storage ; and enhancing carbon sinks through, for example, reforestation and preventing deforestation . A 2015 report by Citibank
concluded that transitioning to a low carbon economy would yield positive return on investments.

Near- and long-term trends in the global energy system are inconsistent with limiting global warming at below 1.5 or 2 °C, relative to pre-industrial levels. Pledges made as part of the Cancún
agreements are broadly consistent with having a likely chance (66 to 100% probability) of limiting global warming (in the 21st century) at below 3 °C, relative to pre-industrial levels.

In limiting warming at below 2 °C, more stringent emission reductions in the near-term would allow for less rapid reductions after 2030. Many integrated models are unable to meet the 2 °C target if pessimistic assumptions are made about the availability of mitigation technologies.


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 (sometimes called geoengineering or climate intervention) 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.



Main article: Politics of global warming
Politics of global warming
Further information: 2011 , 2012 , 2013 , and 2015 sessions of United Nations Climate
Change Conference Article 2 of the UN Framework Convention refers explicitly to "stabilization of greenhouse gas concentrations." To stabilize the atmospheric concentration of CO 2, emissions worldwide would need to be dramatically reduced from their present level.

Most countries in the world 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 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) :4 pushed for a mandate requiring developed countries to " the lead" in reducing their emissions. This was justified on the basis that: the developed world's emissions had contributed most to the cumulation 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. :290

This mandate was sustained in the Kyoto Protocol to the Framework Convention, :290 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. United States President George W. Bush
George W. Bush
rejected the treaty on the basis that "it exempts 80% of the world, including major population centres such as China and India, from compliance, and would cause serious harm to the US economy." :5

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) :9 aim to limit the future increase in global mean temperature to below 7002275149999999999♠2 °C. 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 7002275149999999999♠2 °C above pre-industrial temperatures. It also recognized the need to consider strengthening the goal to a global average rise of 7002274649999999999♠1.5 °C.


See also: Scientific opinion on climate change and Surveys of scientists\' views on climate change

The discussion continues in scientific articles that are peer-reviewed and assessed by scientists who work in the relevant fields and participate in the Intergovernmental Panel on Climate Change . The scientific consensus as of 2013 stated in the IPCC Fifth Assessment Report is that it "is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century". A 2008 report by the U.S. National Academy of Sciences stated that most scientists by then agreed that observed warming in recent decades was primarily caused by human activities increasing the amount of greenhouse gases in the atmosphere. In 2005 the Royal Society
stated that while the overwhelming majority of scientists were in agreement on the main points, some individuals and organizations opposed to the consensus on urgent action needed to reduce greenhouse gas emissions had tried to undermine the science and work of the IPCC. 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 .


Main articles: Climate change denial , Global warming controversy , and Media coverage of climate change Global warming
Global warming
was the cover story in this 2007 issue of Ms. magazine

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 completely or partially an artefact of poor measurements. Additional disputes concern estimates of climate sensitivity, predictions of additional warming, and what the consequences of global warming will be.

By 1990, American conservative think tanks had begun challenging the legitimacy of global warming as a social problem. They challenged the scientific evidence , argued that global warming would have benefits , 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
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. On the other hand, some fossil fuel companies have scaled back their efforts in recent years, or even called for policies to reduce global warming. Global oil companies have begun to acknowledge climate change exists and is caused by human activities and the burning of fossil fuels.

Surveys Of Public Opinion

Main article: Public opinion on climate change

The global warming problem came to international public attention in the late 1980s. Polling groups began to track opinions on the subject, at first mainly in the United States. The longest consistent polling, by Gallup in the US, found relatively small deviations of 10% or so from 1998 to 2015 in opinion on the seriousness of global warming, but with increasing polarization between those concerned and those unconcerned.

The first major worldwide poll, conducted by Gallup in 2008–2009 in 127 countries, found that some 62% of people worldwide said they knew about global warming. In the advanced countries of North America, Europe and Japan, 90% or more knew about it (97% in the U.S., 99% in Japan); in less developed countries, especially in Africa, fewer than a quarter knew about it, although many had noticed local weather changes. Among those who knew about global warming, there was a wide variation between nations in belief that the warming was a result of human activities.

By 2010, with 111 countries surveyed, Gallup determined that there had been a substantial decrease since 2007–2008 in the number of Americans
and Europeans who viewed global warming as a serious threat. In the US, just a little over half the population (53%) viewed it as a serious concern for either themselves or their families; this was 10 points below the 2008 poll (63%). Latin America had the biggest rise in concern: 73% said global warming was a serious threat to their families. This global poll also found that people were more likely to attribute global warming to human activities than to natural causes, except in the US where nearly half (47%) of the population attributed global warming to natural causes.

A March–May 2013 survey by Pew Research Center
Pew Research Center
for the People border:solid #aaa 1px">

* Global warming
Global warming
portal * Science portal

* Book: Global warming
Global warming

* Anthropocene * Climate change and agriculture * Effects of global warming on oceans * Environmental impact of the coal industry * Geologic temperature record * Global cooling * Glossary of climate change * Greenhouse gas
Greenhouse gas
emissions accounting * History of climate change science
History of climate change science
* Holocene extinction * Index of climate change articles * Scientific opinion on climate change


* ^ 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
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 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 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
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. * ^ Scientific journals use "global warming" to describe an increasing global average temperature just at earth's surface, and most of these authorities further limit "global warming" to such increases caused by human activities or increasing greenhouse gases. * ^ 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 %.


* ^ Gillis, Justin (2015-11-28). "Short Answers to Hard Questions About Climate
Change". The New York Times. ISSN 0362-4331 . Retrieved 2017-08-07. * ^ "global warming - definition of global warming in English Oxford Dictionaries". Oxford Dictionaries English. Retrieved 2017-08-07. * ^ Hartmann, D. L.; Klein Tank, A. M. G.; Rusticucci, M. (2013). "2: Observations: Atmosphere and Surface" (PDF). IPCC WGI AR5 (Report). p. 198. Evidence for a warming world comes from multiple independent climate indicators, from high up in the atmosphere to the depths of the oceans. They include changes in surface, atmospheric and oceanic temperatures; glaciers; snow cover; sea ice; sea level and atmospheric water vapour. Scientists from all over the world have independently verified this evidence many times. CS1 maint: Multiple names: authors list (link ) * ^ EPA,OA, US. "Myths vs. Facts: Denial of Petitions for Reconsideration of the Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act US EPA". US EPA. Retrieved 2017-08-07. The U.S. Global Change Research Program, the National Academy of Sciences, and the Intergovernmental Panel on Climate
Change (IPCC) have each independently concluded that warming of the climate system in recent decades is "unequivocal." This conclusion is not drawn from any one source of data but is based on multiple lines of evidence, including three worldwide temperature datasets showing nearly identical warming trends as well as numerous other independent indicators of global warming (e.g., rising sea levels, shrinking Arctic sea ice). * ^ " Climate change evidence: How do we know?". Climate
Change: Vital Signs of the Planet. Retrieved 2017-08-07. * ^ "IPCC, Climate
Change 2013: The Physical Science Basis - Summary for Policymakers (AR5 WG1)" (PDF). p. 4. Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. * ^ "IPCC, Climate
Change 2013: The Physical Science Basis - Summary for Policymakers (AR5 WG1)" (PDF). p. 17. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. * ^ "IPCC, Climate
Change 2013: The Physical Science Basis -Technical Summary" (PDF). pp. 89, 90. * ^ "Joint Science Academies\' Statement" (PDF). Retrieved 6 January 2014. * ^ Kirby, Alex (17 May 2001). "Science academies back Kyoto". BBC News. Retrieved 27 July 2011. * ^ "Scientific consensus: Earth\'s climate is warming". Climate Change: Vital Signs of the Planet. Retrieved 2017-08-07. * ^ California, State of. "List of Organizations". www.opr.ca.gov. Retrieved 2017-08-07. * ^ "IPCC, Climate
Change 2014: Impacts, Adaptation, and Vulnerability - Technical Summary" (PDF). pp. 44–46. * ^ Solomon et al., Technical Summary, Section TS.5.3: Regional-Scale Projections, in IPCC AR4 WG1 2007 . * ^ Zeng, Ning; Yoon, Jinho (2009-09-01). "Expansion of the world\'s deserts due to vegetation-albedo feedback under global warming". Geophysical Research Letters. 36 (17): L17401. ISSN 1944-8007 . doi :10.1029/2009GL039699 .

* ^ On snowfall:

* Christopher Joyce (15 February 2010). "Get This: Warming Planet Can Mean More Snow". NPR. * " Global warming
Global warming
means more snowstorms: scientists". 1 March 2011. * "Does record snowfall disprove global warming?". 9 July 2010. Retrieved 14 December 2014.

* ^ Battisti, David S.; Naylor, Rosamond L. (2009-01-09). "Historical Warnings of Future Food Insecurity with Unprecedented Seasonal Heat". Science. 323 (5911): 240–244. ISSN 0036-8075 . PMID 19131626 . doi :10.1126/science.1164363 . * ^ US NRC 2012 , p. 26 * ^ Peter, U.; et al. "Clark et al. 2016 Consequences of twenty-first-century policy for multi-millennial climate and sea-level change". Nature Climate
Change . 6: 360–369. doi :10.1038/NCLIMATE2923 . CS1 maint: Explicit use of et al. (link ) * ^ 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 7002275149999999999♠2 °C limit. As of 25 November 2011, there are 195 parties (194 states and 1 regional economic integration organization (the European Union
European Union
)) to the UNFCCC. * ^ "Introduction to the Convention". unfccc.int. Retrieved 2017-08-07. Preventing “dangerous” human interference with the climate system is the ultimate aim of the UNFCCC. * ^ 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: 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 7002275149999999999♠2 °C above preindustrial levels" * ^ 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.

* ^

* Sutter, John D.; Berlinger, Joshua (12 December 2015). "Final draft of climate deal formally accepted in Paris". CNN. Cable News Network, Turner Broadcasting System, Inc. Retrieved 12 December 2015. * Vaughan, A. (12 December 2015). "Paris climate deal: key points at a glance". The Guardian. London and Manchester, UK. Archived from the original on 13 December 2015. Retrieved 12 December 2015. CS1 maint: BOT: original-url status unknown (link ). Archived .

* ^ Stokes, Bruce; Wike, Richard; Carle, Jill (2015-11-05). "Global Concern about Climate
Change, Broad Support for Limiting Emissions". Pew Research Center's Global Attitudes Project. Retrieved 2017-08-07. * ^ 16 January 2015: NASA
Find 2014 Warmest Year in Modern Record, in: Research News. NASA
Goddard Institute for Space Studies, New York, US. Retrieved 20 February 2015 * ^ " Climate
Change 2013: The Physical Science Basis, IPCC Fifth Assessment Report (WGI AR5)" (PDF). WGI AR5. IPCC AR5. 2013. p. 5. * ^ " Climate
Change 2007: Working Group I: The Physical Science Basis". IPCC AR4. 2007. * ^ Rhein, M.; Rintoul, S.R. (2013). "3: Observations: Ocean" (PDF). IPCC WGI AR5 (Report). p. 257. Ocean warming dominates the global energy change inventory. Warming of the ocean accounts for about 93% of the increase in the Earth's energy inventory between 1971 and 2010 (high confidence), with warming of the upper (0 to 700 m) ocean accounting for about 64% of the total. Melting ice (including Arctic sea ice, ice sheets and glaciers) and warming of the continents and atmosphere account for the remainder of the change in energy. * ^ "UAH v6.0 TLT data" (trend data at bottom of file). nsstc.uah.edu. The National Space Science & Technology Center. Retrieved 3 February 2017. * ^ "Upper Air Temperature: Decadal Trends". remss.com. Remote Sensing Systems. Retrieved 3 February 2017. * ^ Jansen et al., Ch. 6, Palaeoclimate, Section What Do Reconstructions Based on Palaeoclimatic Proxies Show?, pp. 466–478, in IPCC AR4 WG1 2007 . * ^ A B C D 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
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 Changes in phenology. , in IPCC AR4 WG2 2007 , p. 99 * ^ 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. * ^ Feulner, Georg; Rahmstorf, Stefan; Levermann, Anders; Volkwardt, Silvia (March 2013). "On the Origin of the Surface Air Temperature Difference Between the Hemispheres in Earth\'s Present-Day Climate". Journal of Climate. 26: 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 Carbon monoxide (CO) and hydrogen (H2), p. 256, in IPCC TAR WG1 2001 . * ^ Meehl, Gerald A. ; Washington, Warren M.; Collins, William D.; Arblaster, Julie M.; Hu, Aixue; Buja, Lawrence E.; Strand, Warren G.; Teng, Haiyan (18 March 2005). "How Much More Global Warming and Sea Level Rise" (PDF). Science. 307 (5716): 1769–1772. Bibcode :2005Sci...307.1769M. PMID 15774757 . doi :10.1126/science.1106663 . Retrieved 11 February 2007. * ^ T. M. L. Wigley (2005). "The Climate
Change Commitment" (PDF). doi :10.1126/science.1103934 . Even if atmospheric composition were fixed today, global-mean temperature and sea level rise would continue due to oceanic thermal inertia. These constant-composition (CC) commitments and their uncertainties are quantified. Constant-emissions (CE) commitments are also considered. The CC warming commitment could exceed 1C. The CE warming commitment is 2 to 6C by the year 2400." (...) "A breakdown of the natural and anthropogenic components of the CC commitment, together with uncertainties arising from ocean mixing (Kz) uncertainties, is given in table S1. Past natural forcing (inclusion of which is the default case here) has a marked effect. The natural forcing component is surprisingly large, 64% of the total commitment in 2050, reducing to 52% by 2400. * ^ England, Matthew (February 2014). "Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus". Nature Climate
Change . 4: 222–227. Bibcode :2014NatCC...4..222E. 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? " (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. Archived from the original on 9 December 2010. Retrieved 20 March 2011. * ^ Gavin Schmidt (4 June 2015). " NOAA
temperature record updates and the ‘hiatus’". * ^ NOAA
(4 June 2015). "Science publishes new NOAA
analysis: Data show no recent slowdown in global warming". * ^ "U.S. scientists officially declare 2016 the hottest year on record. That makes three in a row." * ^ Schmidt, Gavin (22 January 2015). "Thoughts on 2014 and ongoing temperature trends". RealClimate. Retrieved 4 September 2015. * ^ 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" (PDF). Arlington, Virginia, USA: Center for Climate
and Energy Solutions. , p.2 * ^ Brown, Patrick T.; Li, Wenhong; Jiang, Jonathan H.; Su, Hui (2015-12-07). "Unforced Surface Air Temperature Variability and Its Contrasting Relationship with the Anomalous TOA Energy Flux at Local and Global Spatial Scales". Journal of Climate. 29 (3): 925–940. ISSN 0894-8755 . doi :10.1175/JCLI-D-15-0384.1 . * ^ US NRC 2012 , p. 9 * ^ A B Hegerl et al., Chapter 9: Understanding and Attributing Climate
Change, Section 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 * ^ Tyndall, John (1861). "On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connection of Radiation, Absorption, and Conduction" (PDF). 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. * ^ Callendar, G. S. (1938) "The artificial production of carbon dioxide and its influence on temperature", Quarterly Journal of the Royal Meteorological Society, doi: 10.1002/qj.49706427503 * ^ 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 . Retrieved 1 Jan 2015. * ^ 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. ISSN 1520-0477 . doi :10.1175/1520-0477(1997)0782.0.CO;2 . Archived from the original (PDF) on 24 June 2008. Retrieved 21 April 2009. * ^ Schmidt, Gavin (6 April 2005). "Water vapour: feedback or forcing?". Real Climate
. 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. Archived from the original on 10 May 2009. Retrieved 21 April 2009. * ^ Spahni, Renato; Jérôme Chappellaz; Thomas F. Stocker; Laetitia Loulergue; Gregor Hausammann; Kenji Kawamura; Jacqueline Flückiger; Jakob Schwander; Dominique Raynaud; Valérie Masson-Delmotte; Jean Jouzel (November 2005). "Atmospheric Methane
and Nitrous Oxide of the Late Pleistocene from Antarctic Ice Cores". Science. 310 (5752): 1317–1321. Bibcode :2005Sci...310.1317S. PMID 16311333 . doi :10.1126/science.1120132 . * ^ 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. PMID 16311332 . doi :10.1126/science.1120130 . 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. Bibcode :2008Natur.453..379L. PMID 18480821 . doi :10.1038/nature06949 . * ^ Pearson, PN; Palmer, MR (2000). "Atmospheric carbon dioxide concentrations over the past 60 million years". Nature. 406 (6797): 695–699. PMID 10963587 . doi :10.1038/35021000 . * ^ IPCC, Summary for Policymakers Archived 7 March 2016 at the Wayback Machine
Wayback Machine
., Concentrations of atmospheric greenhouse gases ... Archived 18 January 2004 at the Wayback Machine
Wayback Machine
., p. 7, in IPCC TAR WG1 2001 . * ^ IPCC (2007) AR4. Climate
Change 2007: Working Group III: Mitigation of Climate
Change, section https://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch7s7-4-5.html * ^ 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 . CS1 maint: Multiple names: authors list (link ) * ^ " Carbon dioxide
Carbon dioxide
passes symbolic mark". BBC
. 10 May 2013. Retrieved 27 May 2013. * ^ Pilita Clark (10 May 2013). "CO2 at highest level for millions of years". Financial Times
Financial Times
. Retrieved 27 May 2013. (Registration required (help)). * ^ " Climate
scientists discuss future of their field". 7 July 2015. * ^ Buis, Alan; Ramsayer, Kate; Rasmussen, Carol (12 November 2015). "A Breathing Planet, Off Balance". NASA
. Retrieved 13 November 2015. * ^ Rogner, H.-H., et al., Chap. 1, Introduction, Section Intensities, in IPCC AR4 WG3 2007 . * ^ A B NRC (2008). "Understanding and Responding to Climate Change" (PDF). 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. ISBN 978-0-8213-7987-5 . doi :10.1596/978-0-8213-7987-5 . 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 . * ^ A B C 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 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 Archived 7 December 2009 at the Wayback Machine
Wayback Machine
., 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. 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). " 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
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. PMC 27611  . PMID 10944197 . doi :10.1073/pnas.170278997 . * ^ 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 . * ^ Statement made by Mark Jacobson of the Amosphere Energy Program at Stanford University in the documentary "Sea Blind" * ^ Sea Blind * ^ 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 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/m2). * ^ Twomey, S. (1977). "Influence of pollution on shortwave albedo of clouds". J. Atmos. Sci. 34 (7): 1149–1152. Bibcode :1977JAtS...34.1149T. ISSN 1520-0469 . doi :10.1175/1520-0469(1977)0342.0.CO;2 . * ^ Albrecht, B. (1989). "Aerosols, cloud microphysics, and fractional cloudiness". Science. 245 (4923): 1227–1239. Bibcode :1989Sci...245.1227A. PMID 17747885 . doi :10.1126/science.245.4923.1227 . * ^ 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. PMC 552786  . PMID 15749818 . doi :10.1073/pnas.0500656102 . * ^ Ramanathan, V.; et al. (2008). "Report Summary" (PDF). Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia. United Nations Environment Programme. Archived from the original (PDF) on 18 July 2011. * ^ Ramanathan, V.; et al. (2008). "Part III: Global and Future Implications" (PDF). Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia. United Nations Environment Programme. Archived from the original (PDF) on 18 July 2011. * ^ A B 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 June 23, 2011. * ^ 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.; 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 23 June 2011. * ^ 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 * ^ R.S. Bradley; K.R. Briffa; J. Cole; M.K. Hughes; T.J. Osborn (2003). "The climate of the last millennium". In K.D. Alverson; R.S. Bradley; T.F. Pederson. Paleoclimate, global change and the future. Springer. pp. 105–141. ISBN 3-540-42402-4 . * ^ 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. Bibcode :2009Sci...325.1236K. PMID 19729653 . doi :10.1126/science.1173983 . * ^ "Arctic Warming Overtakes 2,000 Years of Natural Cooling". UCAR. 3 September 2009. Archived from the original on 27 April 2011. 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. Bibcode :2008PNAS..10513252M. PMC 2527990  . PMID 18765811 . doi :10.1073/pnas.0805721105 . * ^ Berger, A. (2002). "CLIMATE: An Exceptionally Long Interglacial Ahead?". Science. 297 (5585): 1287–8. PMID 12193773 . doi :10.1126/science.1076120 . * ^ Masson-Delmotte V.M.; et al. (2013). "Information from paleoclimate archives". In Stocker T.F. et al. Climate
Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. pp. 383–464. ISBN 978-1-107-66182-0 . CS1 maint: Uses editors parameter (link ) * ^ A B Jackson, R.; 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. * ^ "CLIMATE CHANGE 2014: Synthesis Report. Summary for Policymakers" (PDF). IPCC. Retrieved 1 November 2015. The following terms have been used to indicate the assessed likelihood of an outcome or a result: virtually certain 99–100% probability, very likely 90–100%, likely 66–100%, about as likely as not 33–66%, unlikely 0–33%, very unlikely 0–10%, exceptionally unlikely 0–1%. Additional terms (extremely likely: 95–100%, more likely than not >50–100%, more unlikely than likely 0–

Links: ------ /wiki/Earth /wiki/Climate /#cite_note-1 /#cite_note-2 /#cite_note-3 /#cite_note-4 /#cite_note-5 /wiki/Instrumental_temperature_record /wiki/Paleoclimatology /wiki/Proxy_(climate) /#cite_note-6