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[[Image:Composite antarctic NASA.jpg|thumb|right|250px|A composite map of [[Antarctica]] showing areas of greatest warming in red, other colors indicate cooling. The Wilkins Ice Shelf lies off the peninsula in the top left corner, and shows extensive warming. Overall, Antarctica shows more cooling than warming, especially in the east, the area to the right.]]

[[Image:Composite antarctic NASA.jpg|thumb|right|250px|A composite map of [[Antarctica]] showing areas of greatest warming in red, other colors indicate cooling. The Wilkins Ice Shelf lies off the peninsula in the top left corner, and shows extensive warming. Overall, Antarctica shows more cooling than warming, especially in the east, the area to the right.]]

'''Global warming''', scientifically speaking, is a worldwide increase in atmospheric temperature. Such increases have alternated with periods of global cooling throughout geological history in regular, natural cycles.  

'''Global warming''', scientifically speaking, is a worldwide increase in atmospheric temperature. Such increases have alternated with periods of global cooling throughout geological history in regular, natural cycles.<ref>"After any given warming phase begins, thousands of years later the cyclical [[Milankovitch]] decrease in the sun's heat kicks in. The warming stops, reverses and an [[ice age]] ensues." [http://www.counterpunch.org/cockburn06092007.html Counterpunch], June 2007</ref>

Many political activists use the term '''"global warming"''' to refer the anthropogenic global warming theory (AGW), which asserts that human activity such as spewing "[[greenhouse gases]]" is causing more temperature increase than all natural causes combined.

Many political activists use the term '''"global warming"''' to refer the anthropogenic global warming theory (AGW), which asserts that human activity such as spewing "[[greenhouse gases]]" is causing more temperature increase than all natural causes combined.