A controversial fighter in the climate-change debate

Among those who've started to worry and maybe do something in their lives about global climate change, James Hansen is not exactly a household name. Not like, say, Al Gore.

But as one of the leading scientific experts and public Jeremiahs on the subject, the head of the National Aeronautics and Space Administration's Goddard Institute for Space Studies in New York has been in the thick of it for many years.

He heads a federal government research team that's butted heads with climate skeptics and sometimes with the Bush administration. Dr. Hansen, who writes prolifically, is often called to testify before Congress. And last week he was tossing rhetorical darts at the Houghton Mifflin publishing company for what he calls "many gross errors" in a textbook used in colleges and Advanced Placement high school classes.

One chapter, written by conservative authors, states that "science doesn't know how bad the greenhouse effect is" and that global warming is "enmeshed in scientific uncertainty." While that may be literally true, it doesn't reflect the expert consensus. As a Boston Globe story observed:

"While there are still some scientists who downplay global warming and the role of burning fossil fuels, the overwhelming majority of climate scientists ... say human activity is causing climate change. Last year an international collection of hundreds of scientists and government officials unanimously approved wording that said the scientific community had 'very high confidence,' meaning more than 90 percent likelihood, that global warming is caused by humans."

In his letter to Houghton Mifflin (a PDF version of which was published online by Friends of the Earth), Hansen wrote:

"I strongly urge that you update the textbook to reflect the broad consensus of the scientific community. Failure to correct the book's errors will leave students gravely misinformed about the facts and science of global warming, one of the most serious problems that we as a society and as a species face."

As an outspoken scientist who warns that the earth already has a dangerous level of carbon dioxide in the atmosphere, Hansen naturally has his critics.

At a recent conference of climate-change skeptics in New York sponsored by the conservative Heartland Institute, William Gray, a retired professor of atmospheric science at Colorado State University in Fort Collins, predicted that the earth would experience a cooling period in 10 years.

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