Today's
Seattle Times has a major spread on
global warming. They discuss scientists who were skeptical until they checked out lots of alternative explanations, none of which could explain the phenomenon. Some excerpts:
Like many of his peers, [John M.] Wallace wasn't convinced greenhouse gases were altering the world's climate, and he thought Gore [in 1994] was straining scientific credibility to score political points.
More than a decade later, Wallace still won't blame global warming for any specific heat wave, drought or flood -- including the recent devastating hurricanes. But he no longer doubts the problem is real and the risks profound.
"With each passing year the evidence has gotten stronger -- and is getting stronger still."
As one study after another has pointed to carbon dioxide and other man-made emissions as the most plausible explanation, the cautious community of science has embraced an idea initially dismissed as far-fetched. The result is a convergence of opinion rarely seen in a profession where attacking each other's work is part of the process. Every major scientific body to examine the evidence has come to the same conclusion: The planet is getting hotter; man is to blame; and it's going to get worse.
"There's an overwhelming consensus among scientists," said UW climate researcher David Battisti, who also was dubious about early claims of greenhouse warming.
The article remarks on how significant the consensus is on the cause of global warming. A random sampling of 10% of the 10,000 research papers on the found 0 that explicitly rejected the idea that people are causing the warming.
The consensus is most clearly embodied in the reports of the 100-nation Intergovernmental Panel on Climate Change (IPCC), established by the United Nations in 1988. Every five to six years, the panel evaluates the science and issues voluminous reports reviewed by more than 2,000 scientists and every member government, including the United States.
The early reports reflected the squishy state of the science, but by 2001, the conclusion was unequivocal: "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."
The next IPCC report is due in 2007. Among the new evidence it will include are the deepest ice cores ever drilled, which show carbon-dioxide levels are higher now than any time in the past 650,000 years.
In the history of science, no subject has been as meticulously reviewed and debated as global warming, said science historian Spencer Weart, author of "The Discovery of Global Warming" and director of the Center for History of Physics.
"The most important thing to realize is that most scientists didn't originally believe in global warming," he said. "They were dragged -- reluctant step by step -- by the facts."
They also discuss how the energy industry has skewed the reporting on global warming.
From 2001 to 2003, Exxon Mobile donated more than $6.5 million to organizations that attack mainstream climate science and oppose greenhouse-gas controls. These think tanks and advocacy groups issue reports, sponsor briefings and maintain Web sites that reach a far wider audience than scholarly climate journals.
There are side articles for "Setting the Record Straight" on explanations that skeptics have tried to float, like "Blame the Sun."
But in 1991, Danish scientists reported a statistical correlation between the length of sunspot cycles and Northern Hemisphere temperatures over the past 130 years. Coupled with the fact that sunspot activity had climbed steeply between 1900 and 1960, the results led the Exxon-backed George C. Marshall Institute to argue that the sun might be to blame for global warming...
All the efforts to blame the sun for global warming founder on one simple observation that most scientists accept as true: For the past three decades -- when warming has intensified and accelerated -- solar activity hasn't increased.
Scientists still don't agree
how much the Earth will warm. But it will be significant.
Models have improved greatly in the past 30 years but still can't anticipate all the ways the atmosphere will respond as greenhouse gases climb. The dozen models in use today predict average temperature increases of 3 to 11 degrees by the end of the century.
Though the numbers sound modest, it took only a 10-degree drop to encase much of North America in mile-deep glaciers during the ice age that ended about 12,000 years ago.
Here's a link to the story
Some great graphics with the story here.