NEW YORK, New York, April 3, 2013 (ENS) – Outspoken climate scientist James Hansen, director of NASA’s Goddard Institute for Space Studies, is retiring as director of the cutting-edge Earth climate research lab to devote more time to climate activism and scientific inquiry.

In an email to the “New York Times” Monday, Hansen wrote that he is stepping down “so that I can spend full time on science, drawing attention to the implications for young people, and making clear what science says needs to be done.”

James Hansen

Dr. James Hansen with other climate scientists at a United States Studies Centre event, March 2010 (Photo by U.S. Studies Centre)

Peter Hildebrand, director of the Earth Sciences Division at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will serve as interim director until a new director is selected through a competitive process.

Hansen, 72, is the longest serving director in the institute’s history. He came to GISS in a post-doctoral appointment in 1967, became a federal employee at GISS in 1972, and became director in 1981.

“It has been a great honor to work for NASA – I still remember my excitement while driving from Iowa to the Goddard Institute in 1967 – and now I look forward to working full-time on climate science and its implications for policy,” said Hansen.

“Throughout his career, Jim Hansen has demonstrated the spirit of an American pioneer. He has pushed forward the frontier of our knowledge of Earth’s climate system and of the impacts that humanity is having on Earth’s climate.” said Nicholas White, director of the Sciences and Exploration Directorate at Goddard.

Hansen’s climate analyses have been based not only on the basic physics that goes into climate model design, but on detailed studies of the geological ice core and isotope records that are used to constrain and confirm climate model sensitivity.

In recent years Hansen has drawn attention to the danger of passing climate tipping points, producing irreversible climate impacts that would yield a different planet from the one on which civilization developed.

He has engaged in climate activism, offering himself for arrest at demonstrations against mountaintop removal coal mining and TransCanada’s Keystone XL tar sands pipeline, among other actions.

James Hansen

NASA climate scientist James Hansen, in trademark hat, at the Forward on Climate rally in Washington, DC, February 17, 2013 (Photo by Christine Irvine)

During the George W. Bush administration, Hansen was often at odds with federal government officials and was forbidden to speak directly to the members of the media.

Environmental activist Bill McKibben, co-founder of the climate action group 350.org, said, “If 350.org has a patron saint, it’s Jim. It was his 2008 paper that gave us our name, identifying 350 parts per million CO2 as the safe upper limit for carbon in the atmosphere.”

“But as much as for his science, we respect him for his courage,” said McKibben. “He’s always been willing to speak the truth bluntly, from the day in 1988 when he told Congress that the time had come “to stop waffling so much and say the planet was warming,” to all he’s done to bring attention to damaging projects like Keystone XL – even to the point of risking arrest to do so. I have no doubt he’ll go on doing science, and speaking plainly.”

“One reason we’re fighting the pipeline,” said McKibben, “is because Jim Hansen did the math to show that if we combusted the tar sands on top of all else we burn, it would be ‘game over for the climate.’”

McKibben is asking that as a “tribute” to Hansen, people send public comments to the U.S. state Department opposing the Keystone XL pipeline, which needs a Presidential Permit to cross the Canada-U.S. border.

“Together with our friends across the movement, we’re aiming for an ambitious target of one million comments to the State Department to stop the pipeline,” McKibben said.

Sierra Club Executive Director Michael Brune said, “As the nation’s foremost climate scientist, he has matched his groundbreaking research with passionate advocacy. Dr. Hansen understands the climate crisis is a moral crisis, and he’s stood up, spoken out, and even engaged in civil disobedience to ensure critical issues about the planet our children will inherit do not vanish from the public debate.”

James Hansen

James Hansen speaks at a 350.org climate action rally, Washington, DC, October 10, 2010 (Photo by 350.org)

Hansen was trained in physics and astronomy in James Van Allen’s space science program at the University of Iowa, receiving his bachelor’s degree with highest distinction in physics and mathematics, master’s degree in astronomy, and Ph.D. in physics in 1967. Except for 1969, when he was a National Science Foundation post-doctoral student at the Leiden Observatory in Holland, Hansen spent his professional career at GISS. Hansen was a visiting student at the Institute of Astrophysics, University of Kyoto and Department of Astronomy, Tokyo University, Japan from 1965-1966.

Since the mid-1970s, he has focused on studies and computer simulations of Earth’s climate, working to understand the climate system and human impacts on global climate. Hansen’s testimony before Congress in 1988 helped to raise the broad public awareness of the global climate change as an important issue for us all.

His research has been aligned with the development of increasingly sophisticated satellite platform measurements, such as the terrestrial radiation budget, ozone and weather-related data, and the need for increasingly sophisticated atmospheric models to assess and evaluate the information content and utility of these measurements.

Current climate models are now able to reproduce the historical temperature record over the past century and to make climate change predictions for the future, keeping pace with NASA’s measurements of solar energy variations, sea level change and polar ice loss with unprecedented precision and accuracy.

Hansen has received many honors worldwide. He was elected to the National Academy of Sciences in 1995; received the Heinz Award for the Environment, and the American Geophysical Union’s Roger Revelle Medal in 2001; the World Wildlife Federation’s Conservation Medal from the Duke of Edinburgh; and was designated by Time Magazine as one of the “World’s Most Influential People” in 2006.

In 2007, Hansen received the Dan David Prize in the field of Quest for Energy and the Leo Szilard Award of the American Physical Society for Outstanding Promotion and Use of Physics for the Benefit of Society. In 2009, he was awarded the American Meteorological Society’s Carl-Gustaf Rossby Research Medal, and the Sophie and Blue Planet Prizes in 2010.

In 2012, he was awarded the Stephen Schneider Award for Climate Science Communications by Climate One, an initiative of the Commonwealth Club of San Francisco.

Hansen is known for the book he wrote in 2009, “Storms of My Grandchildren.” He also serves as adjunct professor for Earth and Environmental Studies at Columbia University’s Earth Institute.