By CRAIG CROSBY
Staff Writer Saturday, February 03, 2007

"The discussion is no longer whether climate change is happening, it's how likely climate change is caused by human activity," said John Zavodny, associate professor of philosophy at Unity College. "The report today says they're 90 percent sure what we've been doing since the industrial revolution is resulting in global warming. It forces us as humans to take responsibility."

Scientists for the Intergovernmental Panel on Climate Change said in a report released Friday that there is at least a 90 percent chance that global warming is being caused by human activity. The report depicts ominous effects on sea levels, ice cover on the poles and extreme weather by the end of the century if the warming process continues unchecked.

The report issued by the panel, which the United Nations established in 1988, represents the research of more than 2,000 scientists appointed by 154 participating countries.

"The message is clear," said Tom Tietenberg, economics professor at Colby College and an environmental consultant. "To get a bunch of scientists, who are circumspect by their very nature, to come to this conclusion is very striking. I think this is a very strong message that action is merited and merited soon."

Researchers have suspected for years that the buildup of greenhouse gas emissions, which are generated by the burning of fossil fuels, directly leads to the warming of the planet. It has taken scientists years to process the information required to transform a theory into a near certainty, according to Gordon Hamilton, associate professor of climate science for the University of Maine's Climate Change Institute. He compared the process to the theory of plate tectonics, which was first put forward in the 1950s, but took several years to be accepted.

"You can't ever prove anything in science," Hamilton said. "Everything is a consensus or a preferred opinion."

Friday's report was the fourth released by the intergovernmental panel. The certainty of human responsibility has increased with each report.

"The work of this report confirms what we have been seeing for years," said Will Ambrose, Bates College Oceanographer. "Parts of the Alaskan town I work in are falling into the ocean, so I've experienced the impact of Arctic warming firsthand."

Scientists are calling for the reduction in greenhouse gas emissions, particularly here in the United States.

Beverly Johnson, geology professor at Bates College, said the U.S. produces up to 20 percent of all carbon dioxide emissions.

"Congress has a responsibility to act now," Johnson said.

Action will become natural once people allow the magnitude of the report's message to sink in, according to Zavodny. For the first time in history, human beings have affected the globe itself and not just a species or habitat.

"I personally think a lot of the denial that human beings, as individuals or cultures, engage in really comes from a sense of guilt, a feeling of strong moral guilt," Zavodny said. "Because we want to avoid that, we tend to ignore the impact we have.

"When people can look squarely at the reality, usually the good, the right thing to do, presents itself and it becomes very, very clear what is required of us."

Tietenberg acknowledged there is still evidence that contradicts the findings in the report, but he takes the view of an economist.

"You hold the extent and value of the data on one side against the other," Tietenberg said. "It seems to me the data on one side is overwhelming. The cost of inaction at this point is becoming extraordinarily large."

Craig Crosby -- 861-9253

ccrosby@centralmaine.com