Outlook: Reporting on Global Warming

On the way to the airport, the taxi driver asked why I was going to D.C. "For a discussion meeting on global warming," I answered.

"Oh, that's never going to happen," he said. I told him I was an expert, but he had read enough. He quoted Reader's Digest to me. "We don't have to worry about global warming," he said. "You're wasting your time."

Why did he think that? We know for certain that CO2 in the atmosphere is transparent to the energy coming from the sun. But when that energy is re-radiated back by the earth, at much cooler temperatures, it has much longer wavelengths. CO2 is a selective absorber at these wavelengths. It absorbs the energy that's trying to leave the earth. This promotes warming.

The question is, how much warming, how fast? Twenty models around the globe are being used to predict what global warming will be like if the amount of CO2 in the atmosphere doubles, as it will if our present output continues until approximately 2035. The predictions of all these models fall between 1.5 and 5.3 degrees C globally averaged surface-temperature warming. An intergovernmental panel has concluded that the best estimate is a 2- to 4.5-degree warming. For comparison, the last Ice Age was a 3- to 5-degree cooling.

The National Academy of Sciences has published one report after another about the urgency of global warming. The American Meteorological Society has made a public statement that global warming is a serious issue of urgent concern. There have been EPA assessments. Yet the American public believes the question is all very unsettled, and why worry about it?

I see three reasons for this confusion. One is how reporters are trained. As director of the Earth System Science Center, I've talked to a fair number of journalism students. We'll discuss the issues, and at the end of the conversation they'll ask, invariably, "Who can I call to get the opposite opinion?" It's not additional opinions, it's the opposite. This is their safety valve, if they're covering a complex issue: They make sure every opinion is balanced. They get one opinion then, at the end of the article, they cite someone else. The result is that every article on global warming ends up saying, "Maybe. Maybe not."

That wouldn't be so bad except that the agreement among scientists is much broader than you would think from the reports. In order to get an opposite opinion, reporters are quoting the same few people nearly every time. And even these naysayers, if you ask the question differently, will agree that global warming is serious. A few years ago, the National Academy of Sciences put a group of global warming researchers in one room to see if they could iron out their differences. Each was asked, What is the probability that the model estimates of global warming are true, that we're going to have a 2.5-degree globally averaged surface-temperature rise with a doubling of CO2? Some said 85 percent, some 65. One said 25. He is one of the scientists frequently cited as saying we don't have anything to worry about, but he thinks there's a 25-percent chance that the models are correct. A 25-percent risk is huge compared to being struck by lightning. To the Defense Department, a 25-percent chance of nuclear attack would seem very serious.

That leads to the second reason for the confusion about global warming: the degree to which we're science literate in this country. How do we interpret a scientific experiment that doesn't find global warming? The last 10 years of satellite observations show little evidence of warming. Should the headline say, Global Warming Not Detected? No. Over the last 10 years there has not been a substantial change. But there has been substantial change over the last century—a total observed warming of four tenths of a degree. So the questions to ask are, how accurate is the satellite? Should you expect to pick up a signal from only 10 years of data?

The final factor is entirely the fault of scientists: We're press shy. Worse, scientists who talk to the press consistently seem to lose the full respect of their peers. Scientists feel that they can't possibly explain the problem in two paragraphs and that to simplify it, to give an imperfect reconstruction of the facts, is somehow dishonest. I think that's a mistake. Scientists have an obligation to communicate better.

One way or another we will have to get the point across about global warming. Because we really are leaving the impression that science doesn't know anything.

Eric Barron, Ph.D., is director of the Earth System Science Center in the College of Earth and Mineral Sciences, 248 Deike Building, University Park, PA 16802; 814-865-1619. This essay was adapted from the Penn State/National Association of Science Writers forum on January 27, 1993.

Last Updated September 01, 1993