James Hansen

For the American politician from Idaho, see Jim D. Hansen. For the American politician from Utah, see James V. Hansen.

Dr. James E. Hansen

James E. Hansen (born March 29, 1941 in Denison, Iowa), heads the NASA Goddard Institute for Space Studies in New York City, a part of the Goddard Space Flight Center in Greenbelt, Maryland, Earth Sciences Division. He is also currently an adjunct professor in the Department of Earth and Environmental Sciences at Columbia University. Hansen is best known for his research in the field of climatology and his testimony on climate change to congressional committees in the 1980s that helped raise broad awareness of the global warming issue. He is a vocal critic of the current Bush Administration's stance on climate change.

Education

Hansen was trained in physics and astronomy in the space science program of Dr. James Van Allen at the University of Iowa. He obtained a B.A. in Physics and Mathematics with highest distinction in 1963, an M.S. in Astronomy in 1965 and a Ph.D. in Physics, in 1967, all three degrees from the University of Iowa. He participated in the NASA graduate traineeship from 1962 to 1966 and, at the same time, between 1965 and 1966, he was a visiting student at the Institute of Astrophysics at the University of Kyoto and in the Department of Astronomy at the University of Tokyo.

Honors and awards

Hansen was elected to the National Academy of Sciences in 1996 and he received the Heinz Environment Award for his research on global warming in 2001. He was listed as one of Time Magazine's 100 Most Influential People in the Time 100 (2006) list and, in 2007, he was awarded the Dan David Prize.

Field of research and interests

As a college student in the University of Iowa, Hansen was attracted to science and research by James Van Allen's space science program in the physics and astronomy department. A decade later, he started focusing on planetary research that involved trying to understand the climate change on earth that will result from anthropogenic changes of the atmospheric composition.

One of Hansen’s research interests is radiative transfer in planetary atmospheres, especially interpreting remote sounding of the earth's atmosphere and surface from satellites. Such data, appropriately analyzed, may be one of the most effective ways to monitor and study global change on the earth.

Hansen is also interested in the development and application of global numerical models for the purpose of understanding current climate trends and projecting humans' potential impacts on climate. He also developed early models in the 1970s that predicted global cooling would occur over the coming decades.

Statements

Hansen has made a number of statements concerning global warming. Among these are:

• A global tipping point will be reached in 10 years (starting from 2006) if levels of greenhouse gases such as methane and CO₂ are not reduced. Global warming at this point becomes unstoppable.
• Global warming was 0.5–0.75 °C in the past century, and about 0.3 °C in the last 25 years
• Climate sensitivity to CO₂ doubling is 3±1 °C.
• The dangerous concentration of CO₂ can be no more than approximately 450 ppm. However, he now believes that it is "probable that the dangerous level is even lower."
• A feasible strategy for planetary rescue almost surely requires a means of extracting greenhouse gases from the air.

Publications

In 1981 Hansen and a team of scientists at Goddard had reached the conclusion that carbon dioxide in the atmosphere would lead to global warming sooner than previously predicted. While other climatoligists had already predicted that a trend would be apparent by 2020, Hansen predicted, in a paper published in Science, that the change was already occuring and that there would record high temperatures early as 1990. He also predicted that it would be difficult to convince politicians and the public to react.

In 2000 he authored a paper called Global warming in the twenty-first century: an alternative scenario in which he presents a more optimistic way of dealing with global warming focusing on non-CO₂ gases and black carbon in the short run, giving more time to make reductions in fossil fuel emissions. He notes that warming observed to date is largely due to non-CO₂ gases. This is because CO₂ warming is offset by climate-cooling aerosols emitted with fossil fuel burning and because non-CO₂ gases, taken together, are responsible for roughly 50% of greenhouse gas warming.

Estimated climate forcings between 1850 and 2000

In 2003 Hansen wrote a paper called Can We Defuse the Global Warming Time Bomb . In it, he argues that human-caused forces on the climate are now greater than natural ones, and that this, over a long time period, can cause large climate changes. He further states that a lower limit on “dangerous anthropogenic interference” is set by the stability of the Greenland and Antarctic ice sheets. His view on actions to mitigate climate change is that "halting global warming requires urgent, unprecedented international cooperation, but the needed actions are feasible and have additional benefits for human health, agriculture and the environment."

An minor controversy over his support for "objective" and "realistic" climate scenarios centers on what detractors call a justification for "extreme" scenarios in this quote:

"Emphasis on extreme scenarios may have been appropriate at one time, when the public and decision-makers were relatively unaware of the global warming issue, and energy sources such as “synfuels”, shale oil and tar sands were receiving strong consideration. Now, however, the need is for demonstrably objective climate forcing scenarios consistent with what is realistic under current conditions. Scenarios that accurately fit recent and near-future observations have the best chance of bringing all of the important players into the discussion, and they also are what is needed for the purpose of providing policy-makers the most effective and efficient options to stop global warming."

Rewriting the science

In 2005 and 2006, Hansen claimed in interviews with the Washington Post and the New York Times that NASA administrators have tried to influence his public statements about the causes of climate change. Hansen claims that NASA public relations staff were ordered to review his public statements and interviews after a December 2005 lecture at the American Geophysical Union in San Francisco.

James Hansen has also appeared on 60 Minutes claiming that the White House edited climate-related press releases reported by federal agencies to make global warming seem less threatening. He is unable to speak "freely", without the backlash of other government officials. "In my more than three decades in the government I've never witnessed such restrictions on the ability of scientists to communicate with the public," he said in one of his many public appearances.

Hansen has said that a global tipping point (also known as the runaway effect) will be reached by 2016 if the human population is unable to reduce greenhouse gases . Hansen has said that IPCC scenarios for future sea level rise do not take into account ice sheet disintegration, which could cause several meters of sea level rise during the next century with unchanged climate forcings .

There is a short clip in the 2006 documentary An Inconvenient Truth that shows Hansen being questioned by Al Gore on May 8, 1989, at what appears to be a Congress meeting. Gore criticizes Hansen for apparently contradicting himself in a written testimony on global warming. At that point, Hansen reveals that the last paragraph in the testimony was not written by him, but added by someone else.

Responsibility for climate change

Hansen notes that in determining responsibility for climate change, the effect of greenhouse gas emissions on climate is not determined by current emissions, but by accumulated emissions over the lifetime of greenhouse gases in the atmosphere. By this measure the U.S. will be the largest single cause of climate change even after its current emissions are surpassed by China and other developing countries.

On public policy, Hansen is critical of what he sees as efforts to mislead the public on the issue of climate change. He points specifically to the Competitive Enterprise Institute's commercials with the tagline "you call CO2 pollution, we call it life", and politicians who accept money from fossil fuel interests and then describe global warming as "a great hoax." He also says that changes needed to reduce global warming do not require hardship or reduction in the quality of life, but will also produce benefits such as cleaner air and water, and growth of high-tech industries.

Most recent statements

In a paper published May 18, 2007, Hansen presented new evidence. The journalist George Monbiot summarises his findings as follows:

"The IPCC predicts that sea levels could rise by as much as 59cm this century. Hansen’s paper argues that the slow melting of ice sheets the panel expects doesn’t fit the data. The geological record suggests that ice at the poles does not melt in a gradual and linear fashion, but flips suddenly from one state to another. When temperatures increased to 2-3 degrees above today’s level 3.5 million years ago, sea levels rose not by 59 centimetres but by 25 metres. The ice responded immediately to changes in temperature."

It should be noted that Hansen stresses the uncertainties around these predictions:

"It is difficult to predict time of collapse in such a nonlinear problem ... An ice sheet response time of centuries seems probable, and we cannot rule out large changes on decadal time-scales once wide-scale surface melt is underway."

Hansen concludes:

"Present knowledge does not permit accurate specification of the dangerous level of human-made GHGs. However, it is much lower than has commonly been assumed. If we have not already passed the dangerous level, the energy infrastructure in place ensures that we will pass it within several decades."

External links

• Dr. James E Hansen's Homepage
• NASA GISS Biography
• James E Hansen timeline at the History Commons
• The Global Warming Debate by James Hansen
• "Scientist Inspires Anger, Awe for Challenges on Global Warming" Washington Post
• "Climate Expert Says NASA Tried to Silence Him" New York Times
• "NASA and Global Warming" Audio Interview with WBUR OnPoint
• Soviet style "minder(s)" are being used on American scientists
• 29 Jan 2006 Hansen in the New York Times
• 13 Feb 2006 Time Magazine Cover Story: The Political Science Test
• Sequence of stories in The New York Times, from January to July 2006, exposing political interference with climate scientists at NASA"