Now that most scientists agree human activity is causing Earth to warm, the central debate has shifted to whether climate change is progressing so rapidly that, within decades, humans may be helpless to slow or reverse the trend.
This “tipping point” scenario has begun to consume many prominent researchers in the United States and abroad, because the answer could determine how drastically countries need to reduce their greenhouse gas emissions in the coming years. While scientists remain uncertain when such a point might occur, many say it is urgent that policymakers cut global carbon dioxide emissions in half over the next 50 years or risk the triggering of changes that would be irreversible.
There are three specific events that these scientists describe as especially worrisome and potentially imminent, although the time frames are a matter of dispute: widespread coral bleaching that could damage the world’s fisheries within three decades; dramatic sea level rise by the end of the century that would take tens of thousands of years to reverse; and, within 200 years, a shutdown of the ocean current that moderates temperatures in northern Europe.
The debate has been intensifying because Earth is warming much faster than some researchers had predicted. James E. Hansen, who directs NASA’s Goddard Institute of Space Studies, last week confirmed that 2005 was the warmest year on record, surpassing 1998. Earth’s average temperature has risen nearly 1 degree Fahrenheit over the past 30 years, he noted, and another increase of about 4 degrees over the next century would “imply changes that constitute practically a different planet.”
“It’s not something you can adapt to,” Hansen said in an interview. “We can’t let it go on another 10 years like this. We’ve got to do something.”
The WaPo story mentions NASA’s silencing of Hansen, but that issue is covered in more detail by the NY Times in another chilling example of Bush’s War on Science.
The top climate scientist at NASA says the Bush administration has tried to stop him from speaking out since he gave a lecture last month calling for prompt reductions in emissions of greenhouse gases linked to global warming.
The scientist, James E. Hansen, longtime director of the agency’s Goddard Institute for Space Studies, said in an interview that officials at NASA headquarters had ordered the public affairs staff to review his coming lectures, papers, postings on the Goddard Web site and requests for interviews from journalists.
Dr. Hansen said he would ignore the restrictions. “They feel their job is to be this censor of information going out to the public,” he said.
By the way, have you read Chris Mooney’s book, yet?