'''Global warming''' is an increase in average air temperature in the [[Earth]]'s atmosphere.
'''Global warming''' is an increase in average air temperature in the [[Earth]]'s atmosphere.
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]].