http://www.nytimes.com/1988/08/23/science/his-bold-statement-transforms-the-debate-on-greenhouse-effect.html

August 23, 1988

His Bold Statement Transforms the Debate On Greenhouse Effect

By JOHN NOBLE WILFORD

SITTING in his office near the Columbia University campus, seven floors above the internal combustion of fossil fuel along Broadway, James E. Hansen held a large pair of what he called loaded dice. He was making a point last week about the probabilities of drastic climate change as a result of the greenhouse effect.

In testimony before a Senate subcommittee in June, Dr. Hansen, an atmospheric physicist and director of the Goddard Institute for Space Studies, sounded the alarm with such authority and force that the issue of an overheating world has suddenly moved to the forefront of public concern.

What had been theory about future consequences of human activity affecting the atmosphere now seemed to be coming true, he said, and not only elaborate data of temperature trends but also this summer's withering drought and heat wave challenged most lingering doubts.

Reputation at Risk

With his decision to come right out and say the greenhouse effect was here, Dr. Hansen knew he was risking his reputation as a cautious and careful scientist. But in an interview he said he had no reason to soften his assessment. He had made the cardboard dice to illustrate the trend in climate change as projected in mathematical models developed from the observations of increasing carbon dioxide, methane, chlorofluorocarbons and other ''greenhouse'' gases in the atmosphere.

Like glass in a greenhouse, these gases are transparent to incoming sunlight, but they absorb heat radiated from the ground and prevent it from escaping into space.

He held up one die representing the climate for the period 1950-1980. Two sides were white for an average summer, and two other sides were blue for colder-than-average summers. The other two sides were red for hotter-than-average summers. Thus, on a roll of the die for that period, there were two chances in six of having a hot summer at any given location in the country.

Then Dr. Hansen picked up the die for the 1990's and explained:

''If our climate model calculations are approximately correct, the greenhouse warming in the 1990's will be sufficient to shift the probabilities such that the chance of a hot summer in most of the country will be in the range of 55 to 80 percent. Four sides of the die are red. I believe it is obvious that the man in the street will notice that by then the dice are loaded. There will be more hot summers than normal, and the hottest ones will be hotter than they used to be.''

Support in Congress

Dr. Hansen's message, a mix of data-based analysis and plain-spoken conviction, has had a stunning impact on political thinking, say experts on the environment and public policy. Bipartisan support is growing in Congress to increase financing for climate research and to consider legislation aimed at controlling the introduction of greenhouse gases into the atmosphere.

At a 46-nation Conference on the Changing Atmosphere in Toronto shortly after Dr. Hansen's testimony, scientists and policy makers urged development of energy consumption policies that would drastically reduce carbon dioxide emissions. Carbon dioxide in the atmosphere is increasing at an annual rate of one-half a percent because of the burning of fossil fuels - oil, gas and especially coal - and the destruction of tropical forests.

Michael Oppenheimer, an atmospheric scientist with the Environmental Defense Fund, a public advocacy group, said Dr. Hansen's Senate testimony ''shook up a lot of people'' in Washington and offered an air of scientific respectability and immediacy to the environmental movement's longstanding warnings about the build-up of carbon dioxide in the atmosphere.

Maturing 'Almost Overnight'

''I've never seen an environmental issue mature so quickly, shifting from science to the policy realm almost overnight,'' Mr. Oppenheimer said. ''It took a Government forum during a drought and a heat wave and one scientist with guts to say, 'Yes, it looks like it has begun and we've detected it.' He felt comfortable saying clearly and loudly what others were saying privately. That's mighty important in the public policy business.''

Some scientists believe Dr. Hansen jumped the gun in asserting so strongly that the projected consequences of the greenhouse effect had already arrived. The problem is separating a trend in climate change from normal fluctuations in the weather; a trend cannot be proved until decades after the fact.

But Dr. Hansen, speaking this month to a National Governor's Association meeting on energy and environment, countered with data showing that average global temperatures had risen by one degree Fahrenheit over the last 100 years and had been higher in the 1980's than at any time in that period. The four warmest years on record, moreover, have all been in this decade, and so far 1988 is the warmest year of all.

''It became quite clear this summer,'' Dr. Hansen said, ''that what we had been predicting is just what's happening.''

By Way of Venus

A scientific report on the data supporting his statements will be published soon in the Journal of Geophysical Research.

Dr. Hansen came to the study of the earth's atmosphere by way of Venus. After earning a Ph.D. in physics at the University of Iowa, where he worked under Dr. James A. Van Allen, who discovered the radiation belts encircling earth, Dr. Hansen joined the Goddard Institute, which is operated as a research center by the National Aeronautics and Space Administration. One of his major projects was the spacecraft study of Venusian atmosphere, where a rampant greenhouse effect has produced surface temperatures hot enough to melt lead.

Asked what NASA's reaction has been to his recent bold statements, Dr. Hansen gave a nervous smile. ''They're still trying to make up their minds,'' he said.

He recalled that on previous occasions the Office of Management and Budget, which reviews official statements that have implications for the budget, had forced him to delete from the text of proposed Congressional testimony any recommendations for increased research spending. Last November, rather than remove such statements, he testified as a private citizen from Ridgewood, N.J., not as a Government employee.

Somehow, the budget office overlooked his proposed statements for this June. ''I understand they were really upset,'' Dr. Hansen said. ''Next time, I may be back testifying as a private citizen again.''

More Data Collection

One of his recommendations is an expansion of global meteorological observations, including more data collection from the oceans. Most weather stations are on land. But proposed satellites for the 1990's could fill in observational gaps and answer questions about how much heat is being stored in the oceans and the potential impact on climate.

A NASA task force, headed by Dr. Sally K. Ride, the former astronaut, proposed last year a ''mission to planet earth'' as one of the agency's long-term goals. The mission would involve a coordinated scientific study of earth resources and environment from American and international satellites. No official action has been taken on any of the task force's proposals.

''NASA is an agency without a mission,'' Mr. Oppenheimer said. ''If it was smart, NASA would treat Hansen as a star. Here is a problem and a mission that the public might really get behind.''