Mark Trahant: Science still clear on global warming

Monday, July 2, 2007  

"If you listen to critics of global warming (or more precisely, those who do not believe that humans have contributed to climate change), they say that science is always changing its story. That's flat out wrong, [science historian Naomi ] Oreskes says. The big picture view hasn't changed since a National Academy of Science report in 1979. The main difference is that the evidence is clearer now than it was back then. We're seeing observed facts, not theoretical atmospheric models.

But what makes science different from, say, storytelling, is that there are standards for developing and testing evidence. These standards range from induction from observed facts, deduction based on a hypothesis, a falsification test -- or disproving an idea -- and other evaluations of evidence.

Perhaps the most important scientific test is the consilience of evidence. Oreskes defines that as multiple, independent lines of evidence converging on a single coherent account. The Mauna Loa Observatory has been measuring the steady increases in carbon dioxide in the atmosphere since 1958, corresponding to temperature changes.

And both studies are corroborated by climate measures in tree ring data.

In other words, studies from a variety of sources, different disciplines -- some atmospheric, others geological, or those who measure carbon dioxide -- tell the same story. Oreskes says if you look at the big picture, the science is compelling, clear and consistent.

It is the sheer amount of data, the variety of studies, the multiple layers of peer review unique to the history of science. The standard of evidence about human contributions to global warming -- at least in our political discourse -- has to be the best ever, way beyond reasonable doubt. "

Get the Story:
Mark Trahant: The time to solve global warming is now (The Seattle Post-Intelligencer 7/1)

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