James Hansen

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Dr. James E. Hansen
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Dr. James E. Hansen

Dr. James Hansen heads the NASA Institute for Space Studies[1] in New York City, which is a division of Goddard Space Flight Center's in Greenbelt, MD, Earth Sciences Directorate[2] . Dr. Hansen is currently an adjunct professor in the Earth and Environmental Sciences at Columbia University[3]. He is best known for 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 Republican administrations and a longtime ally of Al Gore.

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[edit] Education

He was born in Iowa in 1941. He 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 to 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[4] and in the Department of Astronomy at the University of Tokyo[5].

Dr. Hansen was elected to the National Academy of Sciences in 1995 and he received the prestigious Heinz Environment Award for his research on global warming in 2001 along with many others [6].

[edit] 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 provide one of the most effective ways to monitor and study global change on the earth.

Dr. 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.


[edit] Convictions

  • A global tipping point will be reached in 10 years if levels of greenhouse gases like methane and CO2 are not reduced. Global warming at this point becomes unstoppable. [7].
  • Global warming is 0.5–0.75 °C in the past century, and about 0.3 °C or more in the last 25 years
  • climate sensitivity to CO2 doubling is 3±1 °C

[edit] Publications

In 2000 he authored a paper called Global warming in the twenty-first century: an alternative scenario[8] 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.

Thus, assuming only that our estimates are approximately correct, we assert that the processes producing the non-CO2 GHGs have been the primary drive for climate change in the past century.

In 2004 he wrote a paper called Defusing the global warming time bomb [9], containing:

At present, our most accurate knowledge about climate sensitivity is based on data from the earth’s history, and this evidence reveals that small forces, maintained long enough, can cause large climate change.

Human-made forces, especially greenhouse gases, soot and other small particles, now exceed natural forces, and the world has begun to warm at a rate predicted by climate models.

The stability of the great ice sheets on Greenland and Antarctica and the need to preserve global coastlines set a low limit on the global warming that will constitute “dangerous anthropogenic interference” with climate.

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.

He also commented on the past usefulness of extreme warming scenarios to obtain political and policy actions on page 30 here:[10]

[edit] Opposing Greenhouse Skeptics

He has taken an active part in the debate around global warming, and has argued that:

Some "greenhouse skeptics" subvert the scientific process, ceasing to act as objective scientists, rather presenting only one side, as if they were lawyers hired to defend a particular viewpoint. But some of the topics focused on by the skeptics are recognized as legitimate research questions, and also it is fair to say that the injection of environmental, political and religious perspectives in midstream of the science research has occurred from both sides in the global warming debate.

—[11]

Climate model calculations reported in Hansen et al. (1988)
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Climate model calculations reported in Hansen et al. (1988)


Hansen argued in a book review[12] that some “greenhouse skeptics subvert the scientific process, ceasing to act as objective scientists, rather presenting only one side, as if they were lawyers hired to defend a particular viewpoint. James Hansen and Patrick Michaels conflict started as far back as 1988. On June 23, 1988, as director of the NASA Institute for Space Studies, Hansen testified before the House of Representatives that there was a strong "cause and effect relationship" between observed temperatures and human emissions into the atmosphere. The hearing brought the issue to national attention and attracted much criticism. Questions were raised by the global warming skeptics, especially by Michaels. Ten years after Hansen, Micheals tried to convince the House of Representatives that the “forecasts of dramatic and deleterious global warming were likely to be in error because of the very modest climate changes that had been observed to that date”. Following Michaels speech at the House of Representatives, Hansen claimed that misrepresented his work to Congress[13]. Both Scientist were invited to attend a live debate hosted by the AARST Science Policy Forum“ A Public Debate on the Science of Global Warming”[14]

In 1998 Hansen argued that uncertainties in climate forcings have supplanted global climate sensitivity as the predominant issue [15]; the paper is discussed here.

As the opinions of the global warming debate do not seem to converge, Hansen found it useful to delinatate the fundamental differences[16]. He lists a number of areas where he disagrees with the global warming skeptic, Richard Lindzen [17].

1. Observed global warming: real or measurement problem?

  • Hansen: global warming is 0.5-0.75°C in past century, at least ~0.3°C in past 25 years.
  • Lindzen: since about 1850 "...more likely ... 0.1±0.3°C" (MIT Tech Talk, 34, #7, 1989).

2. Climate sensitivity (equilibrium response to 2×CO2)

  • Lindzen: ~< 1°c Hansen: 3±1°C
  • Comments: paleoclimate data, improved climate models, and process studies may narrow uncertainties; observed climate change on decadal time scales will provide constraint if climate forcings are measured; implicit information on climate sensitivity can be extracted from observed changes in ocean heat storage.

3. Water vapor feedback

  • Lindzen: negative, upper tropospheric water vapor decreases with global warming.
  • Hansen: positive, upper and lower tropospheric water vapor increase with global warming.
  • References: (these include references by Lindzen stating that, in response to global warming, water vapor will decrease at altitudes above 2-3 km).
  • Comment: accurate observations of interannual changes (several years) and long-term changes (1-2 decades) of upper tropospheric water vapor could provide defining data.

4. CO2 contribution to the ~33°C natural greenhouse effect

  • Lindzen: "Even if all other greenhouse gases (such as carbon dioxide and methane) were to disappear, we would still be left with over 98 percent of the current greenhouse effect." Cato Review, Spring issue, 87-98, 1992; "If all CO2 were removed from the atmosphere, water vapor and clouds would still provide almost all of the present greenhouse effect." Res. Explor. 9, 191-200, 1993.
  • Lacis and Hansen: removing CO2, with water vapor kept fixed, would cool the Earth 5-10°C; removing CO2 and trace gases with water vapor allowed to respond would remove most of the natural greenhouse effect.

5. When will global warming and climate change be obvious?

  • Lindzen: I personally feel that the likelihood over the next century of greenhouse warming reaching magnitudes comparable to natural variability remains small.
  • Hansen: "With the climatological probability of a hot summer represented by two faces (say painted red) of a six-faced die, judging from our model by the 1990s three or four of the six die faces will be red. It seems to us that this is a sufficient 'loading' of the dice that it will be noticeable to the man in the street." J. Geophys. Res. 93, 9341-9364, 1988.

6. Planetary disequilibrium

  • Hansen: Earth is out of radiative equilibrium with space by at least approximately 0.5 W/m2 (absorbing more energy than it emits).
  • Comments: This is the most fundamental measure of the state of the greenhouse effect. Because the disequilibrium is a product of the long response time of the climate system, which in turn is a strong function of climate sensitivity, confirmation of the disequilibrium provides information on climate sensitivity and an indication of how much additional global warming is "in the pipeline" due to gases already added to the atmosphere.
  • This disequilibrium could be measured as the sum of the rate of heat storage in the ocean plus the net energy going into the melting of ice. Existing technology, including very precise measurements of ocean and ice sheet topography, could provide this information.

In September 2005, in response to Michael Crichton's novel State of Fear[18], which attempted to disprove global warming, Hansen offerred a rebuttal[19]. Hansen argues that Michael Crichton “designed [his novel] to discredit concerns about global warming, purports to use the scientific method”. The rebuttal centered on a claim made by Crichton that Hansen in 1988 made predictions about global warming that ended up being "300% too high" and that Crichton and others cherry-picked data from his research.


In 2005 and 2006, Hansen claimed in interviews with the Washington Post[20] and the New York Times[21] 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.


[edit] Rewriting The Science

James Hansen has also appeared on 60 Minutes[22] claiming that the White House has been editing 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.

He makes claims that the tipping point (also known as the runaway effect) is upon us, and that if in 10 years the human population is unable to reduce greenhouse gases, that the oceans might rise as much as 10 feet by 2100.

[edit] References

[edit] External links

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