Silencing science.

Byline: The Register-Guard

It's become a depressingly familiar scenario: Federal scientists urge prompt action to address global warming, and the Bush administration reacts by downplaying, suppressing or even censoring the warnings.

The latest example involves James E. Hansen, the top climate scientist at the National Aeronautics and Space Administration. The New York Times reports that the administration has tried to silence Hansen after he delivered a talk calling for prompt reductions in emissions of greenhouse gases that are a primary cause of global warming.

Hansen, longtime director of NASA's Goddard Institute for Space Studies, says agency administrators ordered public affairs staff to review his upcoming lectures, papers, postings on the institute's Web site and even the interview requests he received from journalists. He was warned of "dire consequences" if he persisted in sounding the alarm on climate change.

So what exactly was Dr. Hansen's mortal sin? In a Dec. 6 lecture at the annual meeting of the American Geophysical Union in San Francisco, Hansen said significant emissions cuts could be achieved with existing technologies, and he cited motor vehicles as a prime example. Without leadership by the United States, climate change would eventually leave the Earth "a different planet," Hansen warned. Shortly after that speech, Hansen released data showing that 2005 was the warmest year in at least a century.

When faced with calls for mandatory limits on emissions, the president declares that "our nation will continue to lead the world in basic climate and science research." Yet when the top climate scientist at NASA says the research shows limits are urgently needed, well, it's time to get out muzzle and chains.

Such tactics are hardly new. White House officials have routinely edited government climate reports to weaken or eliminate references to connections between emissions and climate change.

While administration officials are scurrying around trying to silence government scientists, researchers elsewhere are warning that the pace of climate change is accelerating at such a rate that it may be nearing a "tipping point" from which it can't recover in the foreseeable future.

Yet there's reason to believe - and hope - that there's still time to slow, perhaps even reverse, this trend. Many scientists believe that cutting carbon dioxide emissions in half over the next 50 years is possible and could make a decisive difference and avert catastrophic consequences, such as the melting of the Greenland ice cap.

That would require strong U.S. leadership on global warming and a nationwide program of mandatory controls on emissions. It would require the Bush administration to start listening to its own scientists instead of trying to silence them.

So far, they haven't had much success in silencing Hansen. He told The Times he has no choice but to keep speaking out on global warming because NASA's mission statement includes the phrase "to understand and protect our home planet"

Too bad the president doesn't feel a similar obligation.