NAS Report Confuses Public

by William Yeatman on June 12, 2001

in Science

NAS Report Confuses Public

The National Academy of Sciences released a rush report reviewing global warming science on June 7. Done at the request of the Bush Administration by a panel of 11 prominent scientists (of whom six are members of the NAS), it was immediately and uniformly hailed by the major print and broadcast outlets as confirming global warming alarmism and therefore a slap in the face to the Bush Administration.

What the report actually says, however, is difficult to determine. The opening summary begins with a fairly strong statement that, “Greenhouse gases are accumulating in Earths atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise. Temperatures are, in fact rising. The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes are also a reflection of natural variability.”

The report also states, “Despite the uncertainties, there is general agreement that the observed warming is real and particularly strong within the past 20 years. Whether it is consistent with the change that would be expected in response to human activities is dependent upon what assumptions one makes about the time history of atmospheric concentrations of the various forcing agents, particularly aerosols” (emphasis added).

It goes on: “The predicted warming of 3 degrees C (5.4 degrees F) by the end of the 21st century is consistent with the assumptions about how clouds and atmospheric relative humidity will react to global warming” (emphasis added).

On the other hand, once you get beyond the summary, the report itself is full of qualifications and expressions of uncertainty. For example, “Because there is considerable uncertainty in current understanding of how the climate system varies naturally and reacts to emissions of greenhouse gases and aerosols, current estimates of the magnitude of future warming should be regarded as tentative and subject to future adjustments upward or downward.”

It also notes, “Because of the large and still uncertain level of natural variability inherent in the climate record and the uncertainties in the time history of the various forcing agents (and particularly aerosols), a causal linkage between the buildup of greenhouse gases in the atmosphere and the observed climate changes during the 20th century cannot be unequivocally established.” A comprehensive listing of the caveats has been produced by Dr. Ken Green of the Reason Public Policy Institute and can be found at

The press downplayed the reports caveats. CNNs Michelle Mitchell stated that the report constituted “a unanimous decision that global warming is real, is getting worse, and is due to man. There is no wiggle room.”

In a June 11 Wall Street Journal op-ed, one of the scientists who helped prepare the report objected to the way it was treated in the press. Dr. Richard S. Lindzen, the Alfred P. Sloan professor of meteorology at MIT, said that the report says nothing of the sort. There are three things that scientists can agree upon, said Lindzen: 1) global mean temperatures have risen 0.5 degrees C over the last century; 2) atmospheric concentrations of carbon dioxide have increased over the last two centuries; and 3) carbon dioxide is a greenhouse gas.

“But,” he said, “we are not in a position to confidently attribute past climate change to carbon dioxide or to forecast what the climate will be in the future. That is to say, contrary to media impressions, agreement with the three basic statements tells us almost nothing relevant to policy discussions.”


Scientists in Australia have developed a vaccine for sheep and cattle that would reduce the amount of methane a greenhouse gas they emit by about twenty percent. The drug, which inhibits methane-producing organisms in the animals digestive tract, is now ready to undergo testing (BBC News, June 7, 2001).

Global warming and even the next ice age are minor problems compared to higher solar radiation that may make the Earth too hot to support life in about a billions years. Luckily, NASA is working on how to prevent the catastrophe.

Londons Observer reported on June 10 that Dr. Greg Laughlin of NASAs Ames Research Center and two colleagues have proposed using the same methods being discussed to prevent asteroids or comets from hitting the Earth to instead bring an asteroid or comet very close to Earth. If done just right, the procedure would transfer some gravitational energy to Earth and move it to an orbit farther away from the Sun.

Dr. Laughlin is quoted as saying, “It is basic rocket science,” but admits that the slightest miscalculation could result in a life-sterilizing collision. NASA, however, has several hundred million years to work on getting it right.

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