A Greenpeace poll shows that a worryingly high proportion of climate scientists believe it possible that continuing emissions of greenhouse gases can awaken synergistic feedbacks capable of generating a runaway greenhouse effect.
Bad though the best- estimate of the future, as portrayed by the IPCC would be, there is a worst-case view, which is that the IPCC estimates will prove to be underestimates, and that natural amplifications of warming (positive feedbacks) will be awakened, potentially even generating a point of no return beyond which might lie unstoppable heating of the planet, no matter how deeply anthropogenic emissions might ultimately be cut.
The results of an opinion survey on this subject, published by Greenpeace at the 1992 American Association for the Advancement of Science annual meeting in Chicago, show that almost half of surveyed world climate scientists believe that a runaway greenhouse effect is possible if action is not taken to cut greenhouse gas emissions. More than one-in-ten of those polled believe this worst-case analysis - a point of no return beyond which lies unstoppable heating of the atmosphere - to be probable.
Greenpeace International polled 400 climate scientists during December 1991 and January '92. The sample included all scientists involved in the 1990 study of the Intergovernmental Panel on Climate Change, and others who have published on issues relevant to climate change in `Science' or `Nature' during 1991. Scientists were asked whether they thought there would be a point of no return at some time in the future, if emissions continued at their present rate. By the end of January 1992, 113 had replied, in the following way: probably - 15 (13%), possibly - 36 (32%), probably not - 53 (47%). In other words, 45% believe the runaway greenhouse effect to be possible.
("Fear expressed of runaway greenhouse effect," Boston Globe, 10 February 1992; and for further details see: J.K.Leggett, "Global warming: the worst- case," Bulletin of the Atomic Scientists, v. 85, p. 28-32, June 1992; and "Running down to Rio," New Scientist, p. 38-41, 2 May 1992).
NOTES: This survey was misreported on a number of occasions in the US media as showing that only 13% of scientists thought global warming itself was probable. The Greenpeace press release was specific about what a runaway greenhouse effect was: it talked about "a point of no return beyond which lies unstoppable heating of the atmosphere," and the risk of "unleashing global warming at a rate which threatens the future of the human species, and indeed most life forms."
The misreporting began in the Washington Times on May 2nd, when an editorial opined that "Greenpeace, which polled around 400 climate scientists around the turn of the year, was disconcerted to find that only 13 percent subscribe to their alarmist version of the greenhouse warming. Thirty-two percent said that the theory was possible and 47 percent that it was probably not' true." From here there was a ripple effect. On CNN's "Crier & Co," Nancy Mitchell of Vice- President Dan Quayle's Council for Competitiveness volunteered in a debate that according to a Greenpeace study, only 13% of scientists polled were concerned about global warming. In the Wall Street Journal, an op-ed by Fred Smith, President of the Competitive Enterprise Institute, echoed the same line, and he put it in words on the MacNeil/Lehrer News Hour, where he concluded that the poll "suggests there is no consensus that carbon dioxide is a serious threat to the future." This, of course, is exactly the reverse of what it suggests.
On CNBC's "McLaughlin Report, Greenpeace USA's Peter Bahouth was faced with Jeremy Taylor of the Cado Institute, who continued the confusion of worst-case runaway warming with the best-estimate view that the IPCC had spent three years thrashing out. Perhaps the worst use of the distortion came in the New Republic on July 6, where Gregg Easterbrook, a Newsweek writer, spun the survey against Al Gore. "Gore, for example, asserts that reporters should attach little weight to scientists who question greenhouse emergency claims, because perhaps 2 percent of credentialed researchers feel that way. This simply isn't true. Greenpeace recently surveyed climatologists, doubtless hoping for evidence of global warming panic; instead it found that the largest group of respondents, 47 percent, believe runaway greenhouse effect is nearly impossible."
Finally, on July 27th, the survey made the New York Times. Keith Schneider's story again confused runaway warming with IPCC best- estimate warming. "The survey did not reflect the considerable causes for concern outlined by a succession of international and national scientific panels over the last few years," Schneider concluded.
GREENPEACE Climate Impacts Database