The most commonly discussed measure of global warming is the trend in globally averaged temperature near the Earth's surface.
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Global warming - Wikipedia, the free encyclopedia - 0 views
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An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.[7] The continuing retreat of glaciers, permafrost and sea ice is expected, with warming being strongest in the Arctic. Other likely effects include increases in the intensity of extreme weather events, species extinctions, and changes in agricultural yields.
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Political and public debate continues regarding climate change, and what actions (if any) to take in response. The available options are mitigation to reduce further emissions; adaptation to reduce the damage caused by warming; and, more speculatively, geoengineering to reverse global warming. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions.
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Politics is making the Climate Chnge issue, unimportant, I beleive that Govermnets are just "selling their image", so they would look good. There are many, many policies pacts that have been made in order to "control Clmiate Change/ Global Warming". When will there be a policy that actually help the meniviroment?
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Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. The concentrations of CO2 and methane have increased by 36% and 148% respectively since the mid-1700s.[23] These levels are much higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores.[24] Less direct geological evidence indicates that CO2 values this high were last seen about 20 million years ago.[25] Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, particularly deforestation.[26]
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If the atmosphere is warmed, the saturation vapor pressure increases, and the amount of water vapor in the atmosphere will tend to increase. Since water vapor is a greenhouse gas, the increase in water vapor content makes the atmosphere warm further; this warming causes the atmosphere to hold still more water vapor (a positive feedback), and so on until other processes stop the feedback loop
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When ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continues.
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The Ice is melting. If you look at the The cold continent of Antartica, the ice caps are melting there. The North and the South Poles are melting. The sea levels are rising and inhabitants such as polar bears and Penguins are getting affected. The sea levels are afftecting Island Nations as well as sea bordering nations.
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Global warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-20th century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) between the start and the end of the 20th century.
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However, warming is expected to continue beyond 2100 even if emissions stop, because of the large heat capacity of the oceans and the long lifetime of carbon dioxide in the atmosphere.
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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).
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The Intergovernmental Panel on Climate Change (IPCC) concludes that most of the observed temperature increase since the middle of the 20th century was caused by increasing concentrations of greenhouse gases resulting from human activity such as fossil fuel burning and deforestation.
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The IPCC also concludes that variations in natural phenomena such as solar radiation and volcanoes produced most of the warming from pre-industrial times to 1950 and had a small cooling effect afterward.
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The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions.
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The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in the atmosphere warm a planet's lower atmosphere and surface.
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Clouds also affect the radiation balance, but they are composed of liquid water or ice and so are considered separately from water vapor and other gases.
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Global dimming, a gradual reduction in the amount of global direct irradiance at the Earth's surface, has partially counteracted global warming from 1960 to the present.
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Observations show that temperatures in the stratosphere have been steady or cooling since 1979, when satellite measurements became available.
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Warming is expected to change the distribution and type of clouds. Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect.
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Measures including water conservation,[99] water rationing, adaptive agricultural practices,[100] construction of flood defences,[101] Martian colonization,[102] changes to medical care,[103] and interventions to protect threatened species[104] have all been suggested. A wide-ranging study of the possible opportunities for adaptation of infrastructure has been published by the Institute of Mechanical Engineers.[
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Geoengineering is the deliberate modification of Earth's natural environment on a large scale to suit human needs.[106] An example is greenhouse gas remediation, which removes greenhouse gases from the atmosphere, usually through carbon sequestration techniques such as carbon dioxide air capture.
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In 2007–2008 Gallup Polls surveyed 127 countries. Over a third of the world's population were unaware of global warming, with developing countries less aware than developed, and Africa the least aware. Of those aware, Latin America leads in belief that temperature changes are a result of human activities while Africa, parts of Asia and the Middle East, and a few countries from the Former Soviet Union lead in the opposite belief.
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Geoengineering is the deliberate modification of Earth's natural environment on a large scale to suit human needs.
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one study suggests that projected rates of extinction are uncertain.[80]
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United States President Barack Obama has announced plans to introduce an economy-wide cap and trade scheme
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Measures including water conservation,[100] water rationing, adaptive agricultural practices,[101] construction of flood defences,[102] Martian colonization,[103] changes to medical care,[104] and interventions to protect threatened species[105] have all been suggested. A wide-ranging study of the possible opportunities for adaptation of infrastructure has been published by the Institute of Mechanical Engineers.