Saturday, April 28, 2007

News Alert: Trees Don't Cause Global Warming

One of the memes in conservative circles (e.g., Rush Limbaugh) is that global warming is not caused by humans, but rather by trees. The basis of this strange assertion? A study by scientists at the Max Planck Institute and published in Nature last year that asserted that they had found evidence that plants release huge amounts of the gas--perhaps accounting for ten to thirty percent of all the methane found in the atmosphere. Apparently, that assertions was, well, in error, according to Carl Zimmer:


You may perhaps recall a lot of attention paid to methane from plants back in January 2006. A team of scientists from the Max Planck Institute reported in Nature that they had found evidence that plants release huge amounts of the gas--perhaps accounting for ten to thirty percent of all the methane found in the atmosphere.


The result was big news for several reasons. It was a surprise just in terms of basic biology--scientists have been studying the gases released by plants for a long time, and so it was surprising that they could have missed such a giant belch. Making the matter of pressing interest was methane's ability to trap heat in the atmosphere. Suddenly plants became a much bigger player in the global warming game.


Many news outlets covered the paper, and many made a muddle of it. Their wording implied that the scientists were claiming that plants, not humans, might be responsible for the recent rise in the global average temperature. The Max Planck Institute released a press release clarifying that plants are not to blame, and the Guardian and National Geographic published corrections.


Some pundits didn't heed the scientists, though. At Foxnews.com, columnist Steven Milloy declared that deforestation ought to reduce global warming. "Our understanding of global climate system is woefully insufficient to support the rush-to-judgment advocated by celebrity-backed global warming alarmists," he claimed. The folks from the Wall Street Journal editorial page declared that "this is causing big problems for the tree-huggers." Rush Limbaugh sarcastically said, "Well, hot damn. God is to blame for global warming."


Fast-forward eighteen months. A group of Dutch researchers put the Max Planck team's conclusions to the test by tracing radioactive carbon isotopes through plants. Their conclusion: "There is no evidence for substantial aerobic methane emission by terrestrial plants."


The paper went online today, published in the journal New Phytologist. (It's free here.) The publisher sent out a press release, but my search has turned up almost no news coverage. There were three stories that were nothing more than cut-and-paste copies of the press release. I found just one piece of original reporting, at a site called Chemistry World, which I now intend to read regularly. The article casts the new paper as the first in a series of new publications that support both sides of this methane vs no-methane debate.


Read it all. I guess we need to work on reducing our green house gas emissions after all.

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