James Hansen

2001 Roger Revelle Medal Winner

Goddard Institute for Space Studies, NASA, New York

James E. Hansen received the Roger Revelle Medal at the 2001 Fall Meeting Honors Ceremony on 12 December in San Francisco, California. The medal is given for outstanding contributions toward an understanding of the Earth’s atmospheric processes, including its dynamics, chemistry, and radiation; the roles of atmosphere, atmosphere-ocean coupling, or atmosphere-land coupling in determining the climate, biogeochemical cycles, or other key elements of the integrated climate system.


“James Hansen has been a lightning rod for climate-change science over the past two decades. As an original, inventive, and outspoken scientist, he has been thrust into the limelight of our national debate over climate change, as was Roger Revelle, who was willing to speak out for the science he believed and who, for many of us, brought global change to the forefront of our scientific research. We celebrate the award of the 2001 Roger Revelle Medal to James E. Hansen, Director of NASA’s Goddard Institute for Space Studies and Adjunct Professor at Columbia University.

“As a student of James Van Allen at Iowa, Hansen may have drawn his global perspective in part from those first scientific satellite observations of the Earth that began with Explorer 1. His breadth of research includes radiative transfer, the atmosphere of Venus, and the Earth’s climate. His publications have proven original and long-lasting. In the late 1960s, he developed new methods (doubling/adding) and computer codes to calculate the scattering of sunlight in planetary atmospheres that remain in use today. In the 1970s as a principal investigator on the Pioneer Venus mission, Jim’s analysis of the scattering and polarization of Venusian clouds led him to deduce cloud-particle shapes, sizes, and refractive index and allowed others to identify the particles as concentrated sulfuric acid. One of his first contributions to climate research, the 1974 paper with Andy Lacis on atmospheric absorption of sunlight, was used in climate models for more than two decades and still receives more than twenty citations a year.

“Jim is known for his hard-nosed investigation of climate sensitivity. He has examined both natural and human influences, from volcanoes to greenhouse gases to aerosols and dust, leaving no stone unturned. He has welcomed collaborations with the paleoclimate community as a key to understanding climate sensitivity today. Continuing his Iowa tradition, Jim has pushed hard for small satellites to monitor climate change. He has led and developed Goddard Institute for Space Studies (GISS) into one of the top climate research laboratories. In the late 1980s, Jim and others were instrumental in bringing Roger Revelle to an innovative series of seminars on global change at Columbia University that for many of us attendees placed our own research in the perspective of what would become the U.S. Global Change Research Program.

“Jim has always pressed the importance of science education. I remember his attempt to educate some ‘Washington staffers’ on the concept of statistics in global warming by bringing along a set of loaded dice with more ‘hot’ sides than ‘cold.’ (I never did find out the bets that were placed on the role of those dice.) In the 1980s, GISS built up a summer science institute in Earth and planetary sciences that brought some of the brightest new students into graduate programs in Earth studies. It was so successful that Goddard took it to Maryland. Jim saw the next challenge in the public schools: bring New York City public school teachers and their top students to GISS, have them model and analyze climate change of the past two decades, and then participate as co-authors of a significant JGR research paper.

“Most recently, Jim has again identified a scientific issue that affects us all. By defining an alternative scenario for human greenhouse forcing over the 21st century that combines fossil fuel conservation with a vigorous effort to reduce non-CO2 greenhouse gases, he argues for positive approaches that could control climate change. Earlier this year, when the White House sought experts to explain the science behind global warming and possible mitigation, they invited a few scientists, Jim among them, to brief the Vice President and Cabinet. Jim’s counsel is sought from Pennsylvania Avenue to the Bronx. It is truly a pleasure to recognize James E. Hansen’s scientific accomplishments with the award of the Roger Revelle Medal. Congratulations, Jim!”

—MICHAEL J. PRATHER, University of California, Irvine


“Thanks Michael. I’m old enough to know not to take it too seriously, but I appreciate very much your effort in putting the citation together. I’m also old enough to have known Roger Revelle. He was a visiting scholar at GISS and Columbia University for several months in the 1980s. So I realize what a special honor it is to receive an award named for Roger Revelle.

“Roger had broad interests, including not just science, but its relevance to people. He would have recognized the potential educational value of the minor brouhaha that occurred after he died, which concerned an article that he had co-authored with Fred Singer titled ‘What to do about Greenhouse Warming: Look Before You Leap.’ That incident epitomizes the complex interactions among all interested parties in the global warming story, which somehow, with help from the media, result in emphasis on two improbable extremes: imminent catastrophe and denial of any problem. Roger appreciated the beauty and integrity of unbiased scientific investigation, and I am confident that he would have insisted that people and the environment are served best by rigorous scientific objectivity.

“I would like to use my few minutes here to mention a workshop, ‘Air Pollution as a Climate Forcing,’ which is being organized for April 29 through May 3. This may be an unusual ‘response,’ but I know that Roger would approve.

“The workshop aims to illuminate the role of air pollution as a global climate forcing, and it will consider human health and environmental impacts. The workshop’s scope will be limited by focusing on the two significant air pollution climate forcings: (1) aerosols, and (2) two greenhouse gases controlled by air pollution, tropospheric ozone (O3) and methane (CH4).

“A theme of the workshop will be composition specificity, of aerosols and pollutant emissions that affect O3 and CH4. Determination of the best strategies to reduce air pollution’s impact on climate, health, and the environment requires knowledge of the effects of specific emissions. We will ask what is required to halt and reverse the growth of CH4, O3 and black carbon aerosols, the impact this would have on climate forcing and climate change, the contributions technologies can make to reducing these air pollutants, and the benefits for human health and the environment.

“We are driven by the realization that actions to address air pollution and climate forcings are being made now at all levels of government, in industry, and by consumers. Communication of current knowledge and uncertainties, including the linkages between these two global environmental problems, may be helpful to all parties.

“Business-as-usual scenarios presume that air pollution will get worse and worse over the next 50 years and CO2 emissions will grow larger and larger each year. Perhaps, with informed actions, an alternative is feasible in which global air pollution stops growing during the next 10 years and declines in absolute amount by 2050, and CO2 emissions flatten out this decade and begin to decline before 2050.

“Day 1 of the workshop will consider aerosols, day 2 O3 and CH4, day 3 technologies, day 4 health, agricultural, and ecological impacts, and day 5 summaries and implications. We welcome suggestions and participation in the workshop.”

—JAMES E. HANSEN, Goddard Institute for Space Studies, NASA, New York