Global-warming skeptics: Is it only the news media who need to chill?

Some who discount humans' role in altering Earth's climate point to the 'global-cooling' scare of the 1970s.

By Tony Azios | Contributor to The Christian Science Monitor

from the October 11, 2007 edition

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In the 1970s, mainstream media outlets published stories about a coming age of "global cooling" and the climate disaster it would trigger. Headlines of the time proclaimed "The Cooling World" (Newsweek, 1975), "Scientists Ask Why World Climate Is Changing: Major Cooling May Be Ahead" (The New York Times, 1975), and "Earth Seems to be Cooling Off Again" (The Christian Science Monitor, 1974).

Today, skeptics of global warming sometimes point to what they call the "global-cooling scare" of the 1970s as a reason to discount what they hear now. If the news media 30 years ago hyped "global cooling" and were wrong, skeptics say, doesn't it follow that "global warming" coverage might prove equally wrong?

But those who have looked closely at the two eras or have been part of the scientific community then and now say the comparison is unfair. William Connolley, a sort of self-appointed historian of the global-cooling theory, says that although global cooling was briefly but prominently covered in some speculative news articles,

the idea never got much traction within the scientific community. New data and research over the decades has convinced the vast majority of scientists that global warming is real and under way.

Dr. Connolley's full-time job is climate modeler for the British Antarctic Survey. But on his personal website, and as a contributor to RealClimate.org (a website written and edited by working climate scientists), he's authored a number of articles that try to clarify the place of global cooling in the history of science.

In the mid-1970s, scientists were researching the possibility that the nearly three decades of cooling experienced in the Northern Hemisphere since World War II might be the beginning of a new ice age. Data suggested that perhaps the huge increase in dust and aerosols (tiny airborne particles that reflect sunlight back into space) from pollution and human development might be stepping up the cooling process.

The investigation didn't last long. Temperatures began to rise. Improving climate methodologies revealed that, although aerosols did indeed have a cooling effect, CO2 and other greenhouse gases were more potent in bringing about atmospheric change on a global scale. Once this became known, scientists moved on to other things.

Scientists change their minds as data change

Today's global-warming contrarians have resurrected the short-lived theory as a reason to doubt what the recent Intergovernmental Panel on Climate Change (IPCC) assessment report calls "unequivocal" evidence that global warming is happening.

"Scientists are criticized by global-warming skeptics for making new claims and revising theories, as if we are required to stay politically consistent," says Stephen Schneider. As a young scientist, Dr. Schneider served as second author of a 1971 paper in the journal Science that discussed the cooling effects of aerosols.

"But that goes against science," Schneider says now. "We must allow for new evidence to influence us." His 1971 paper, called "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate," was one of the first studies on the issue and was soon overtaken by further research.

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