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[[Image:RobinsonWhatWarmsTheEarth.gif|right|frame]]

[[Image:RobinsonWhatWarmsTheEarth.gif|right|frame]]

'''Global warming''' is a term generally used to describe an increase in the global average surface (air at surface) temperature.  

'''Global warming''' is a term generally used to describe an increase in the global average surface (air at surface) temperature.  

As far back as temperature records can be reconstructed, periods of global warming and [[global cooling]] have alternated; see [[ice age]]s and [[interglacial warming]].

As far back as temperature records can be reconstructed, periods of global warming and global cooling have alternated; see [[ice age]]s and [[interglacial warming]].

The term is most often used to refer to the  modern period of global warming, an increase of {{temperature|0.8|1.4}} has been measured at weather stations throughout the world, since around 1850, when instrumental measurements began to be taken and organized records began to be kept. Although only a small increase in absolute terms, the temperature increase is unprecedented within at least the last 14,000 years according to the reconstructions by Viau et al. (2006) <ref>http://www.citeulike.org/user/kmcolo/article/618203 Viau et al. (2006) 'Millennial-scale temperature variations in North America during the Holocene' in Journal of Geophysical Research, 111</ref> and can have a significant impact upon the earth. Since this happens to correlate with increases in [[carbon dioxide]], many have speculated about their possible relationship.  Despite this, there is no completely proven model explaining the rise in global temperatures.

The term is most often used to refer to the  modern period of global warming, an increase of {{temperature|0.8|1.4}} has been measured at weather stations throughout the world, since around 1850, when instrumental measurements began to be taken and organized records began to be kept. Although only a small increase in absolute terms, the temperature increase is unprecedented within at least the last 14,000 years according to the reconstructions by Viau et al. (2006) <ref>http://www.citeulike.org/user/kmcolo/article/618203 Viau et al. (2006) 'Millennial-scale temperature variations in North America during the Holocene' in Journal of Geophysical Research, 111</ref> and can have a significant impact upon the earth. Since this happens to correlate with increases in [[carbon dioxide]], many have speculated about their possible relationship.  Despite this, there is no completely proven model explaining the rise in global temperatures.