For years, Ronald Prinn, ScD '71, had watched policymakers' eyes glaze over when he presented them with alarming evidence of human-caused climate change. So naturally, the professor of atmospheric science was pleasantly surprised when he learned in October that the Intergovernmental Panel on Climate Change would share the 2007 Nobel Peace Prize with Al Gore for documenting and raising awareness of global warming.

The recognition of climate change as a vital problem has been a long time coming. But action is finally being taken, thanks to the many scientists who have spent years gathering and interpreting data--and publicizing its significance. That action includes a new push by members of the U.S. Congress to pass legislation aimed at curbing greenhouse-gas emissions.

As director of MIT's Center for Global Change Science, Prinn has played a key role in bringing climate change to the public's attention. His Advanced Global Atmospheric Gases Experiment (AGAGE) is cele­brating its 30th year of monitoring ozone-­depleting compounds (including the chlorofluorocarbons once widely used in aerosols) and greenhouse gases like methane. And a program that he founded in 1991 with Sloan School professor Henry Jacoby, an economist, has brought physical and social scientists into unusually close, ongoing collaboration with environmentalists to create climate models that account for the human causes and costs of global warming. They're also trying to figure out what must be done to mitigate or stop it. An early advocate of incorporating science into public ­policy, Prinn has testified before Congress and served as a lead author on the Nobel Prize-winning climate panel's 2007 report.

When he and Jacoby started the modeling project, Prinn says, they faced basic questions: "Could we ever credibly forecast climate?" And what was the best way to factor in human activity? Some colleagues "thought it was crazy" to tackle so complex a task, Prinn recalls. Even he considered the undertaking quixotic. But to him, it was a moral duty. "If you're getting funding to study planet Earth, and you can help decision-making, you ought to do it," he insists.

"The thing that's unusual about Ron in relation to many other scientists," says Jacoby, "[is that] from the earliest, he understood that the science, to be truly useful, needed to be integrated with the public policy, and he was willing to devote time and energy to that aspect of the work. There are many good scientists in the world. But not many of them are good at that kind of collaborative work."

Prinn has watched his colleagues come around to the idea of modeling that includes inputs from many areas of research, including the social sciences. And he's seen the public become concerned about the global warming predicted by those models. "It's been interesting to see the evolution," he says.

When Prinn was a graduate student at MIT in the late 1960s, only a few scientists in the world were studying the chemistry of Earth's atmosphere. The space program was in its infancy, and Prinn earned his chemistry doctorate investigating the atmospheres of other planets: the composition of Jupiter's clouds, the photo­chemistry of Venus. He was appointed an assistant professor in meteorology at MIT around the time he defended his thesis in 1971.