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[[Image:Google2.gif|thumb|right|200px|Google againist [[global warming]] at the [[Earth's day]], 22.[[április]], [[2007]].

[[Image:Google2.gif|thumb|right|200px|Google againist [[global warming]] at the [[Earth's day]], 22.[[április]], [[2007]].]]

'''Global warming''' is a natural periodic increase in the average temperature of the Earth's atmosphere, and it has always been followed by period of global cooling. During the recorded history of mankind, these cycles of warming and cooling have occurred every 1,500 years.<ref>''Unstoppable Global Warming'' by [[Fred Singer]] </ref>

'''Global warming''' is a natural periodic increase in the average temperature of the Earth's atmosphere, and it has always been followed by period of global cooling. During the recorded history of mankind, these cycles of warming and cooling have occurred every 1,500 years.<ref>''Unstoppable Global Warming'' by [[Fred Singer]] </ref>