global warming

G L O B A L WA RMIN GAT C-IBARRA

GLOBAL WARMING

Etymology

The term global warming was probably first used in its modern sense on 8 August 1975 in a science paper by Wally Broecker in the journal Science called "Are we on the brink of a pronounced global warming?". Broecker's choice of words was new and represented a significant recognition that the climate was warming; previously the phrasing used by scientists was "inadvertent climate modification," because while it was recognized humans could change the climate, no one was sure which direction it was going. The National Academy of Sciences first used global warming in a 1979 paper called the Charney Report, which said: "if carbon dioxide continues to increase, [we find] no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible." The report made a distinction between referring to surface temperature changes as global warming, while referring to other changes caused by increased CO2 as climate change.

Global warming became more widely popular after 1988 when NASA climate scientist James Hansen used the term in a testimony to Congress. 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." His

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testimony was widely reported and afterwardglobal warming was commonly used by the press and in public discourse:

Effects of global warming on oceans Environmental impact of the coal industry Glossary of climate change History of climate change science Index of climate change articles

Science

Global warming refers to the rising average temperature of Earth's atmosphere and oceans since the late 19th century, as well as its projected continuation. Since the early 20th century, Earth's mean surface temperature has increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980. Warming of the climate system is unequivocal, and scientists are more than 90% certain that it is primarily caused by increasing concentrations of greenhouse gases produced by human activities such asdeforestation and the burning of fossil fuels. These findings are recognized by the national science academies of all major industrialized nations.

Climate model projections are summarized in the 2007 Fourth Assessment Report (AR4) by the Intergovernmental Panel on Climate Change (IPCC). They indicate that during the 21st century the global surface temperature is likely to rise a further 1.1 to 2.9 °C (2 to 5.2 °F) for their lowest emissions scenario and 2.4 to 6.4 °C (4.3 to 11.5 °F) for their highest. The ranges of these estimates arise from the use of models with differing sensitivity to greenhouse gas concentrations.

An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, as well as cause a probable expansion of subtropicaldeserts. Warming is expected to be strongest in the Arctic and would be associated with the continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming

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include a more frequent occurrence of extreme-weather events including heat waves, droughts and heavy rainfall, species extinctions due to shifting temperature regimes, and changes in crop yields. Warming and related changes will vary from region to region around the globe, with projections being more robust in some areas than others. If global mean temperature increases to 4 °C (7.2 °F) above preindustrial levels, the limits for human adaptation are likely to be exceeded in many parts of the world, while the limits of adaptation for natural systems would largely be exceeded throughout the world. Hence, the ecosystem services upon which human livelihoods depend would not be preserved.

Policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geoengineering. Most countries are parties to the United Nations Framework Convention on Climate Change (UNFCCC), whose ultimate objective is to prevent dangerous anthropogenic (i.e., human-induced) climate change. Parties to the UNFCCC have adopted a range of policies designed to reduce greenhouse gas emissions :9 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. A 2011 report of analyses by the United Nations Environment Programme[23] andInternational Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequately stringent to meet the UNFCCC's 2 °C target.

Main article:

T hi s a r ti cl e i s a b o ut th e c ur r e nt c h a n g e in E a r th' s c li m at e .

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Global mean land-ocean temperature change from 1880–2011, 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

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 CO2 emissions compared to five of IPCC's emissions scenarios. The dips are related to global recessions. Data from IPCC SRES scenarios; Data spreadsheet included with International Energy Agency's "CO2 Emissions from Fuel Combustion 2010 – Highlights"; andSupplemental IEA data. Image source:Skeptical. 1

Reconstructed temperature

Two millennia of mean surface temperatures according to different reconstructions from climate proxies, each smoothed on a decadal scale, with theinstrumental temperature record overlaid in black.

Evidence for warming of the climate system includes observed increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level. The Earth's average surface temperature, expressed as a linear trend, rose by0.74±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, versus0.07±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.[28] Temperatures in the

1 http://www.aida-americas.org/en/pubs/human-rights-impacts-climate-change-latin-america?gclid=CIHxot_V9LACFQS0nQodiXtm6A

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lowertroposphere 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.

“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) 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..." 2

NOAA graph of Global Annual Temperature Anomalies 1950–2011, showing the El Niño-Southern Oscillation

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

2. https://www.wikipedia.com

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temperature from 2002 to 2009 is consistent with such an episode. 2010 was also an El Niño year. On the low swing of the oscillation, 2011 as an 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 Hemispherewarms faster than the Southern Hemisphere because it has more land and because it has extensive areas of seasonal snow and sea-ice cover subject to ice-albedo feedback. 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 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.

Initial causes of temperature changes (external forcings)

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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/m2).

This graph, known as the Keeling Curve, shows the increase of atmosphericcarbon dioxide (CO2) concentrations from 1958–2008. Monthly CO2measurements display seasonal oscillations in an upward trend; each year's maximum occurs during theNorthern Hemisphere's late spring, and declines during its growing season as plants remove some atmospheric CO2.

External forcing refers to processes external to the climate system (though not necessarily external to Earth) that influence climate. Climate responds to several types of external forcing, such as radiative forcing due to:

changes in atmospheric composition

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changes in solar luminosity volcanic eruptionsvariations in earth´sorbitaround the sun

Climate models

Global climate model

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.

The geographic distribution of surface warming during the 21st century calculated by the HadCM3 climate model if a business as usual scenario is assumed for economic growth and greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 °C (5.4 °F).

A climate model is a computerized representation of the five components of the climate system: Atmosphere, hydrosphere, cryosphere, land surface, and biosphere.[98] Such models are based on physical principles including fluid dynamics, thermodynamics and radiative transfer. There can be components which represent 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; and others.

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Cli m a t e m o d el

C o m p o n e n t s Prin cipl e s R e pr e s e n t

Atmosphre Fluid dynamics Air movementCirculation

Hydrosphere Thermo dynamics Temperature

Criosphere Radistive transfer Salt content

Climate change and agriculture

Maize Production

Under present trends, by 2030, maize production in Southern Africa could decrease by up to 30% while rice, millet and maize in South Asia could decrease by up to 10%. By 2080, yields in developing countries could decrease by 10% to 25% on average while India could see a drop of 30% to 40%.[129] By 2100, while the population of three billion is expected to double, rice and maize yields in thetropics are expected to decrease by 20–40% because of higher temperatures without accounting for the decrease in yields as a result of soil moisture and water supplies stressed by rising temperatures.

Future warming of around 3 °C (by 2100, relative to 1990–2000) could result in increased crop yields in mid- and high-latitude areas, but in low-latitude areas, yields could decline, increasing the risk of malnutrition. A similar regional pattern of net benefits and costs could occur for economic (market-sector) effects. Warming above 3 °C could result in crop yields falling in temperate regions, leading to a reduction in global food production.

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Habitat inundation

Climate refugee

In small islands and megadeltas, inundation as a result of sea level rise is expected to threaten vital infrastructure and human settlements. This could lead to issues of statelessness for population from countries including the Maldives and Tuvalu andhomelessness in countries with low lying areas such as Bangladesh.

Climate change mitigation

Fee and dividend

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. Many countries, both developing and developed, are aiming to use cleaner, less polluting, technologies.[59]:192 Use of these technologies aids mitigation and could result in substantial reductions in CO2 emissions. Policies include targets for emissions reductions, increased use of renewable energy, and increased energy efficiency. Studies indicate substantial potential for future reductions in emissions.

In order to limit warming to within the lower range described in the IPCC's "Summary Report for Policymakers"[137] 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.

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Since even in the most optimistic scenario, fossil fuels are going to be used for years to come, mitigation may also involve carbon capture and storage, a process that traps CO2 produced by factories and gas or coal power stations and then stores it, usually underground.

Adaptation

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. The ability to adapt is closely linked to socialand economic development. Even societies with high capacities to adapt are still vulnerable to climate change. Planned adaptation is already occurring on a limited basis. The barriers, limits, and costs of future adaptation are not fully understood.

Geoengineering

Geoengineering, the deliberate modification of the climate, has been investigated as a possible response to global warming, e.g. ByNASA, and the Royal Society,. Techniques under research fall generally into the categories solar radiation management andcarbon dioxide removal, although various other schemes have been suggested. Research is at a generally early stage, with no large-scale schemes currently deployed.3

3 Htttp://www.aida.com/globalwarming/d35145

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TABLE OF CONTEXTGLOBAL WARMING..........................................................................................................................1Etymology............................................................................................................................................1Science..................................................................................................................................................2Main article: .........................................................................................................................................3Reconstructed temperature...................................................................................................................4Climate models ....................................................................................................................................8Global climate model ..........................................................................................................................8 Climate change and agriculture...........................................................................................................9Maize Production..................................................................................................................................9Habitat inundation..............................................................................................................................10 Climate refugee.................................................................................................................................10 Climate change mitigation.................................................................................................................10 Fee and dividend................................................................................................................................10Adaptation...........................................................................................................................................11 Adaptation to global warming...........................................................................................................11Geoengineering...................................................................................................................................11

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global warming

Education

effects of global warming

future global warming

global temperature

afterwardglobal warming

observed warming

climate change unfccc

climate change ipcc

global surface temperature