Measurements of air bubbles trapped in the Antarctic ice sheet show human greenhouse gas emissions staved off a renewed ice age and allowed human civilization to thrive, according to a study published in the journal Climatic Change (http://www.kluweronline.com/issn/0165-0009).
Research by University of Virginia emeritus professor Bill Ruddiman unveiled an unprecedented rise in atmospheric carbon dioxide 8,000 years ago, just as humans began clearing forests, cultivating crops, and raising livestock.
Equally important, atmospheric methane levels began rising 5,000 years ago as humans began flooding rice fields and increasing the number of livestock herds. Methane is an even more powerful greenhouse gas than carbon dioxide, though not as prevalent in the atmosphere.
Ice core samples reveal that regular patterns of warming and cooling prevailed for 400,000 years prior to human-induced changes in the composition of the atmosphere. “You have 395,000 years of history, which sets some rules, and 5,000 years that break those rules,” explained Ruddiman.
According to the long-term climate patterns, the Earth would have entered a significant cooling pattern and a renewed buildup of ice sheets if not for stone age man’s influence on the climate. A period of significant planetary cooling should have occurred several thousand years ago, explained Ruddiman, due to regular variations in the Earth’s orbit around the Sun. Tellingly, the deviation from established climate cycles occurred simultaneous with human release of carbon dioxide and methane into the atmosphere. Those are the same gases targeted for reduction under the Kyoto Protocol.
The new revelation dispels the notion that humans had little or no impact on global climate prior to the industrial revolution. The revelation also dispels the notion that global warming is necessarily harmful to humans or to the planet itself.
James M. Taylor is managing editor of Environment & Climate News. His email address is [email protected].
For more information …
See “NY Times: Greenhouse Gases May Avert Next Ice Age,” Environment & Climate News, January 2004. http://www.heartland.org/Article.cfm?artId=14022.