The Paul Revere of global warming.

• Author: Johansen, Bruce E.
• Position: James E. Hansen of National Aeronautics and Space Administration - Biography

James E. Hansen is the Paul Revere of global warming. The director of NASA's Goddard Institute for Space Studies in New York City since 1981, Hansen was in the news last year when the White House saddled him with a twenty-four-year-old media handler, who ordered Hansen to clear all his statements first. Sixty-four at the time, Hansen had been waging weather wars since before his minder was born. Resisting the gag order, Hansen ultimately prevailed.

Six feet tall, with receding, light-brown hair, Hansen favors plaid shirts that would put him at home on an Iowa farm, which is where he was born. Growing up in Denison, about sixty miles northeast of Omaha, Nebraska, Hansen was the fifth of seven children (he has four older sisters). Hansen's father, a tenant farmer, moved to Denison when Jim was four years old, and took up work as a bartender; his mother worked as a waitress.

With a scholarship and money saved from his Omaha World-Herald paper route, Hansen attended the University of Iowa, graduating summa cure laude in 1963, while majoring in mathematics and physics. Hansen then earned a master's degree in astronomy there.

The University of Iowa was an exciting place to study astronomy. The department had its own satellite, and its chairman was James Van Allen, who discovered the Earth-girdling radiation belts that later were named after him. "I was so shy and unconfident that when I had an opportunity to take a course under Professor Van Allen, I avoided it because I didn't want him to realize how ignorant I was," Hansen told an audience at his alma mater in 2004.

Hansen decided to specialize in the atmosphere of Venus at a time when scientists were discovering that the planet's super-hothouse atmosphere (with temperatures above 850 Fahrenheit) was 95 percent carbon dioxide. He earned a doctorate in 1967 with a dissertation on Venus and then went to work at the Goddard Institute.

Hansen's interest in global warming began accidentally. In 1976, he was serving as a principal investigator on the Pioneer Venus Orbiter when a Harvard postdoctoral researcher asked him to help calculate the greenhouse effect of human-generated emissions on the Earth's atmosphere. Even since, Hansen has immersed himself in the problem, and he has not minced words about global warming's dangers.

In 1981, Hansen, with several Goddard colleagues, was the first to use the term "global warming" in a scientific context. Following an important article in Science, Reagan...