"I don't like having to talk to people about something they don't particularly want to hear," he said in an interview, "but I see what the climate models are telling us.

"I think by ignoring projections on global warming, we are making a negative gift to our successors -- human, animal and plant -- of enormous dimension."

..."These people [who oppose climate science] remind me of the folks who kept trying to cast doubt on the science linking cancer to tobacco use. In both situations, the underlying scientific knowledge was quite well established, while the uncertainties were never enough to render the problem inconsequential. Yet, this offered misguided incentives to dismiss a danger."

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Copyright The New York Times
December 16, 2003
By CLAUDIA DREIFUS, Science Desk

In the stormy world of climate science, Dr. Jerry D. Mahlman, 63, is considered a giant.

Until three years ago, Dr. Mahlman, now a senior researcher at the National Center for Atmospheric Research here in Colorado, headed the federal Geophysical Fluid Dynamics Laboratory in Princeton, N.J. There he studied how the earth's troposphere and stratosphere work.

To that end, he developed mathematical models showing how natural forces and chemicals interact in the atmosphere. The models consistently show that carbon dioxide emissions are likely to heat up the air, water and land.

It was this prediction of an overly warm future that transformed Dr. Mahlman into a reluctant activist. He travels the country on his own time, warning religious, civic and educational groups about the dangers of global warming.

"I don't like having to talk to people about something they don't particularly want to hear," he said in an interview, "but I see what the climate models are telling us. I think by ignoring projections on global warming, we are making a negative gift to our successors -- human, animal and plant -- of enormous dimension."

Q. Let's begin with basics. Is there actually a global warming phenomenon?
A. Yes, there really is. We know that the earth's climate has been heating up over the past century. This is happening in the atmosphere, ocean and on land.

Q. People often make off-the-cuff jokes about global warming, but why would a warmer earth be such a terrible thing?
A. The serious heat wave in Europe last summer is one example of how warming can affect people. Also, if the climate model projections on the level of warming are right, sea level will be rising for the next thousand years, the glaciers will be melting faster and dramatic increases in the intensity in rainfall rates and hurricanes are expected. It means a summer drying out of the interiors of continents, with a threat to agriculture systems, planet-wide.

In the winter, it will rain more in our latitudes. There will be a major melting of Arctic Sea ice, and therefore a megathreat to life there. That is already happening. If sea levels rise as fast as we think they will, the Florida Everglades are doomed. Low-lying countries like Bangladesh and Holland will be in serious trouble. And you can say goodbye to any islands that were formed by corals.

In 1979, a National Academy of Sciences report said the climate was likely to warm if you keep putting CO2 into the atmosphere. Though in the intervening years, we've gotten much more information proving this, little has been done since on the policy side of reducing CO2 emissions. All of this raises deep ethical questions.

For me, the biggest one is, Do we accept a responsibility for the welfare of our descendants and for life in general 100, 200, 1,000 years from now?

Q. With many forecasters unable to predict if it is going to rain on Thursday, how can you predict the weather in a hundred years?
A. In some ways, weather prediction is harder because we are forecasting detailed short-term events that depend in detail upon our current weather. Climate projections are mathematically easier because we can only identify changes in averaged weather in the far future.

I've spent most of my professional life using mathematical models to calculate weather and climate all over the earth using the basic laws of physics. We solve those equations on supercomputers to evaluate future climate over many, many places on the world. And we check what the climate models give us against data from the real world. These models give us the future climate projections I'm speaking of here.

Q. How did the weather become such an important part of your life?
A. I grew up in the high plains of Nebraska, and we had severe hailstorms and blizzards. They were a source of fascination to me as a kid. On the prairie, you are marked by the weather. I never took weather for granted. I wanted to understand it.

Q. Could you be wrong with your predictions on global warming?
A. It would be wonderful to be wrong.

Unfortunately, these projections are based on strong science that refuses to go away. Oh sure, there are people insisting that warming is just a part of natural weather cycles, but their claims are not close to being scientifically credible. And while there certainly are long climate cycles, the fact is that the strong warming we are seeing is happening in an era of ever increasing CO2 emissions.

These people remind me of the folks who kept trying to cast doubt on the science linking cancer to tobacco use. In both situations, the underlying scientific knowledge was quite well established, while the uncertainties were never enough to render the problem inconsequential. Yet, this offered misguided incentives to dismiss a danger.

Global warming is unpleasant news. The costs of doing something substantial to arrest it are daunting, but the consequences of not doing anything are staggering.

One attempt by the international community to get a handle on global warming was the so-called Kyoto accords, which the Clinton administration supported tepidly, the United States Senate refused to ratify and the Bush administration openly opposed. The core of the treaty involved a national quota system for fossil fuel use.

Q. You've said elsewhere that Kyoto wouldn't have solved the global warming problem. Why?
A. Because it was a valid first step, and only that. The best Kyoto could have done was lower the increase rate of carbon dioxide in the atmosphere, somewhat. Thirty Kyotos might do the job. The real value of Kyoto was to start the process of putting a brake on fossil fuel use.

Q. Did you ever see Henrik Ibsen's "An Enemy of the People," about a health worker whose life is destroyed after he tells his community about typhoid in its water supply?
A. I am familiar with the story. I too have been under tremendous pressure at times to tone down my message, to make the science appear less alarming. When I was head of my laboratory at Princeton, I was often asked to give Congressional testimony. In three events, two senators and a congressman -- I won't give you their names because I consider that cheap -- attacked me in the most personal way. They were trying to intimidate me into denying my testimony.

Also, during my tenure in government, there were three instances where people in the government attempted to alter my prepared testimony. In each instance, I successfully challenged the requested changes as being scientifically insupportable.

Q. Nonscientists often say that science will come up with something to counter global warming. Is this wishful thinking?
A. So far, most of the alternatives that people are talking about have their own problems. We should start by curbing some fossil fuel use, of course. One idea you hear a lot about is called capturing carbon, where you burn coal and then sequester the CO2 deep under the earth. But if you start burying the stuff, you might be inviting other environmental problems. Does the CO2 ooze out? Does it leak into water systems? People have said, "how about putting the CO2 at the bottom of the ocean?" Well, what about the ecosystems there?

Yet another strategy is nuclear energy, but the reactors can be used for making weapons of mass destruction.

Frankly, I don't have a quick-fix answer. I do know we have a very serious problem, but one that won't impact our entire planet dangerously until you and I are safely dead -- which is perhaps why so few people care about it.

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