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[[Image:Rogerrevelle.jpg|thumb|right|200px|[[Roger Revelle]]]]

[[Image:Rogerrevelle.jpg|thumb|right|200px|[[Roger Revelle]]]]

'''Global warming''' is the increase of average temperature since 1880. This increase in temperature is mainly caused by the increases in [[carbon dioxide]] and other [[greenhouse gas]]es.<ref>[http://www.pnas.org/cgi/reprint/104/10/3713 Solar influence on climate during the past millennium: Results from transient simulations with the NCAR Climate System Model (pdf)]</ref> During the last century near surface tempertures rose about 0.8 K.<ref>[http://data.giss.nasa.gov/gistemp/2005/ GISS Surface Temperature Analysis 2005]</ref> The possibility of adverse consequences (especially: sea level rise, retreating of glaciers and water scarity) has become a major concern for environmentalists and some scientists.

'''Global warming''' is the idea that the Earth has warmed somewhat over the past few decades, and that the warming appears to be related to increases in carbon dioxide and other greenhouse gases. The possibility of adverse consequences has become a major concern for some environmentalists.

According to geologists, the Earth has experience numerous [[ice age]]s during which the temperature dropped so far that [[glacier]]s could cover [[North America]] and [[Europe]].  

According to some research, warming comes and goes in natural cycles of approximately 1,500 years. During these natural periodic increases in the average temperature of the Earth's atmosphere, crops grow better in northern latitudes and deaths from extreme weather decrease. The large arctic island of [[Greenland]] was colonized during the [[Medieval Warm Period]], but the colonies there had to be abandoned during the [[Little Ice Age]] which followed.  

There is a close correlation between the average temperature of the Earth's atmosphere and the amount of [[carbon dioxide]] in the atmosphere. During warm periods, the carbon dioxide level increases, and during cool periods it decreases.<ref>[http://www.nature.com/nature/journal/v399/n6735/abs/399429a0.html Climate and Atmospheric History of the Past 420,000 years from the Vostok Ice Core]</ref> Today the carbon dioxid concentration is 380 ppm. The pre-industrial level was 280 ppm. The current carbon dioxide concentration ist the highest since at least 650,000 years.

 

 

There is a close correlation between the average temperature of the Earth's atmosphere and the amount of [[carbon dioxide]] in the atmosphere. During warm periods, the carbon dioxide level increases, and during cool periods it decreases.

==Politics of global warming==

==Politics of global warming==

Assessments of climate science by the [[United Nations]] (see [[Intergovernmental Panel on Climate Change]])

Assessments of climate science by the United Nations (see [[IPCC]] - ''Intergovernmental Panel on Climate Change'')

have claimed that there is a scientific consensus on the subject. According to their latest report, scientists are 90% sure that over 50% of the observed global warming in recent decades is human-caused, and that continued global warming could be expected to raise sea levels by one foot over the next century.

have claimed that there is a scientific consensus on the subject. According to their latest report, scientists are 90% sure that over 50% of the observed global warming in recent decades is human-caused, and that continued global warming could be expected to raise sea levels by one foot over the next century.

Some prominent scientists have pointed out the [[politicized science]] of the UN's assessment methods. The scientific reports are submitted to a panel of representatives appointed by each country in the IPCC. The panel picks and chooses what they want to put in the [[Summary for Policymakers]], over the objections of scientists whose actual evaluations are disregarded when the do not fit the preordained conclusions of the panel.

Several prominent scientists have pointed out the [[politicized science]] of the UN's assessment methods. The scientific reports are submitted to a panel of representatives appointed by each country in the IPCC. The panel picks and chooses what they want to put in the [[Summary for Policymakers]], over the objections of scientists whose actual evaluations are disregarded when the do not fit the preordained conclusions of the panel.

==Notes==

==Notes==

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* [[Roger Revelle]]

* [[Roger Revelle]]

* [[Fred Singer]]

* [[Fred Singer]]

* [[Richard Lindzen]]

* [[Richard Lindzen]]

==External links==

==External links==

*[http://www.ipcc.ch Intergovernmental Panel on Climate Change (IPCC)]

*[http://www.magma.ca/~hurleyp/FightingTheHoax.htm Fighting the Hoax]

*[http://www.aip.org/history/climate/ The Discovery of Global Warming]

* [http://www.climatecrisis.net/ ''An Inconvenient Truth''] - Propaganda film by [[Al Gore]]

 

*[http://www.cato.org/pubs/regulation/regv15n2/reg15n2g.html Global Warming: The Origin and Nature of the Alleged Scientific Consensus] - [[Richard S. Lindzen]], Alfred P. Sloan Professor of Meteorology at the [[Massachusetts Institute of Technology]]

[[category:earth science]]

[[category:earth science]]