CLIMATE CHANGE FACTS & MYTHS

Chris Mooney
March 21, 2009

A recent controversy over claims about climate science by Post op-ed columnist George F. Will raises a critical question: Can we ever know, on any contentious or politicized topic, how to recognize the real conclusions of science and how to distinguish them from scientific-sounding spin or misinformation?

Congress will soon consider global-warming legislation, and the debate comes as contradictory claims about climate science abound. Partisans of this issue often wield vastly different facts and sometimes seem to even live in different realities.

In this context, finding common ground will be very difficult. Perhaps the only hope involves taking a stand for a breed of journalism and commentary that is not permitted to simply say anything; that is constrained by standards of evidence, rigor and reproducibility that are similar to the canons of modern science itself.

Consider a few of Will's claims from his Feb. 15 column, "Dark Green Doomsayers": In a long paragraph quoting press sources from the 1970s, Will suggested that widespread scientific agreement existed at the time that the world faced potentially catastrophic cooling. Today, most climate scientists and climate journalists consider this a timeworn myth. Just last year, the Bulletin of the American Meteorological Society published a peer-reviewed study examining media coverage at the time and the contemporary scientific literature. While some media accounts did hype a cooling scare, others suggested more reasons to be concerned about warming. As for the published science? Reviewing studies between 1965 and 1979, the authors found that "emphasis on greenhouse warming dominated the scientific literature even then."

Yet there's a bigger issue: It's misleading to draw a parallel between "global cooling" concerns articulated in the 1970s and global warming concerns today. In the 1970s, the field of climate research was in a comparatively fledgling state, and scientific understanding of 20th-century temperature trends and their causes was far less settled. Today, in contrast, hundreds of scientists worldwide participate in assessments of the state of knowledge and have repeatedly ratified the conclusion that human activities are driving global warming -- through the U.N. Intergovernmental Panel on Climate Change, the scientific academies of various nations (including our own), and leading scientific organizations such as the American Association for the Advancement of Science, the American Geophysical Union and the American Meteorological Society.

Will wrote that "according to the University of Illinois' Arctic Climate Research Center, global sea ice levels now equal those of 1979." It turns out to be a relatively meaningless comparison, though the Arctic Climate Research Center has clarified that global sea ice extent was "1.34 million sq. km less in February 2009 than in February 1979." Again, though, there's a bigger issue: Will's focus on "global" sea ice at two arbitrarily selected points of time is a distraction. Scientists pay heed to long-term trends in sea ice, not snapshots in a noisy system. And while they expect global warming to reduce summer Arctic sea ice, the global picture is a more complicated matter; it's not as clear what ought to happen in the Southern Hemisphere. But summer Arctic sea ice is indeed trending downward, in line with climatologists' expectations -- according to the Arctic Climate Research Center.

Will also wrote that "according to the U.N. World Meteorological Organization, there has been no recorded global warming for more than a decade." The World Meteorological Organization (WMO) is one of many respected scientific institutions that support the consensus that humans are driving global warming. Will probably meant that since 1998 was the warmest year on record according to the WMO -- NASA, in contrast, believes that that honor goes to 2005 -- we haven't had any global warming since. Yet such sleight of hand would lead to the conclusion that "global cooling" sets in immediately after every new record temperature year, no matter how frequently those hot years arrive or the hotness of the years surrounding them. Climate scientists, knowing that any single year may trend warmer or cooler for a variety of reasons -- 1998, for instance, featured an extremely strong El Niño -- study globally averaged temperatures over time. To them, it's far more relevant that out of the 10 warmest years on record, at least seven have occurred in the 2000s -- again, according to the WMO.

Readers and commentators must learn to share some practices with scientists -- following up on sources, taking scientific knowledge seriously rather than cherry-picking misleading bits of information, and applying critical thinking to the weighing of evidence. That, in the end, is all that good science really is. It's also what good journalism and commentary alike must strive to be -- now more than ever.

Chris Mooney is the author of "The Republican War on Science" and co-author of the forthcoming "Unscientific America: How Scientific Illiteracy Threatens Our Future."