Global warming is politically, if not scientifically, controversial. A few serious scientists caution that we don't know enough to understand whether the current rise in the world's temperature is natural or man-made. There are those less scientifically astute, though, who have been adamant that there could be no way that man could possibly affect the climate.
Now, as if rising to mock such sentiments, there is a scientific
hypothesis that man may have begun to affect climate as long as 8,000 years ago by
clearing forestlands for agriculture and, later, by forming artificial wetlands for
raising rice. Such activities would be expected to release greenhouse
gases—carbon dioxide as forests are cleared and methane from rice paddies. The
evidence? Antarctic ice has captured atmospheric gases for hundreds of thousands of
years. The pattern of changes in the concentrations of the greenhouse gases shows up
very nicely—until broken abruptly by an unexpected rise in carbon dioxide 8,000
years ago and in methane some 3,000 years later—times correlating with the
significant onset of agricultural activities
Listen to the Audio (mp3 format) as
recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.