Global warming science uncertain

Major uncertainties exist as to whether human activity has caused any warming of the planet, concluded a much-anticipated study conducted by the National Academy of Sciences (NAS). Nevertheless, the ambiguous report touched off a media and political frenzy trumpeting the "uncontestable truth" about human-induced warming.

President George W. Bush had requested the study for clarification of the science regarding global warming issues.

The NAS panel concluded that greenhouse gases have been accumulating in the Earth's atmosphere and that global temperatures have increased slightly since the start of the industrial age. The report's summary links the warming to human activity, but the study itself does not. While the summary speaks of potential catastrophic harms associated with future warming, the study itself notes such results are impossible to predict right now.

Alarmists claim study supports them

Leading Democrats trumpeted the study's summary and blasted the Bush administration for holding out for more scientific data before taking decisive action. "It confirms in stark terms the reality that many of us had accepted a considerable amount of time ago and refutes an effort by the White House to seek some sort of escape hatch from that reality," said Senator John Kerry (D-Massachusetts). "The report underscores . . . the full measure of the vacuum in the administration's leadership on this issue."

"Frankly, the time for study has to yield to leadership," Senator Joe Lieberman (D-Connecticut) concluded after receiving the report.

Other warming alarmists similarly sold the report as an indictment of the need for further study. "Our highest scientific body has reiterated thesituation is serious and getting worse, and now the President has no excusenot to act," concluded Philip Clapp of the National Environmental Trust.
"A National Academy of Sciences report reaffirming the threat of globalwarming, and declaring fearlessly that human activity is largely responsiblefor it, virtually requires President Bush to engage an issue he has consistentlyunderestimated," admonished the New York Times.
"The academy has previously reached similar conclusions about climatechange and it was unclear why the administration went back to it on the sameissue," added the Washington Post.

NAS panelist offers more measured view
After the initial media and political frenzy, however, the true nature of theNAS findings began to be circulated. Richard Lindzen, a professor ofmeteorology at MIT and one of the authors of the study, took specialexception to a CNN portrayal of the study as "a unanimous decision thatglobal warming is real, is getting worse, and is due to man. There is nowiggle room."

Responded Lindzen, "As one of 11 scientists who prepared the report, I canstate that this is simply untrue. For starters, the NAS never asked that allparticipants agree to all elements of a report, but rather that the reportrepresent the span of views. This the full report did, making clear that there isno consensus, unanimous or otherwise, about long-term climate trends andwhat causes them."

Lindzen chastised the press for paying too much attention to "the hastilyprepared summary rather than to the body of the report" that placednecessary qualifications on the issued-in-advance summary. "Our primaryconclusion," asserted Lindzen, "was that despite some knowledge andagreement, the science is by no means settled."

Lindzen noted that global surface temperatures are slightly warmer todaythan they were a century ago. "But--and I cannot stress this enough--we arenot in a position to confidently attribute past climate change to carbondioxide or to forecast what the climate will be in the future."

Continued Lindzen, "Science, in the public arena, is commonly used as asource of authority with which to bludgeon political opponents andpropagandize uninformed citizens. This is what has been done with both thereports of the IPCC and the NAS. It is a reprehensible practice that corrodesour ability to make rational decisions. A fairer view of the science will showthat there is still a vast amount of uncertainty . . . and that the NAS report hashardly ended the debate. Nor was it meant to."

"The report," added Kenneth Green, director of the environmental program atthe Reason Public Policy Institute, "confirms important points that manyanalysts critical of mainstream portrayals of climate change science andpolicy have argued for years." For example, "When it comes to the all-important questions of causality, the NAS report contains cautionarystatements far stronger than those seen from other august scientific panels."

Steve Milloy, an adjunct scholar at the Cato Institute and publisher ofJunkScience.com, further noted that even the slight surface warmingmeasured this century is suspect. The measured warming occurred just afterthe end of the "Little Ice Age," he explained, a period of cooling unequaledsince the last major Ice Age. Moreover, surface temperature readings areoften taken at weather stations near ever-growing cities, which serve asartificial heat islands.

"The recent temperature record compiled from balloon and satellitemeasurements inexplicably don't show any warming," observed Milloy.

"It's unfortunate the report was written in such a way that it could bemisinterpreted and misused by global warming alarmists. A careful reading ofthe report will lead to a far clearer picture of the true state of global warmingscience," agreed Myron Ebell, director of global warming policy at theCompetitive Enterprise Institute (CEI).

CEI policy analyst Paul Georgia noted further that a recent study in theBulletin of the American Meteorological Society found that clouds act as aself-regulating mechanism relative to greenhouse gases. Increasingtemperatures lead to more cumulus clouds as the result of increasing surfacewater evaporation. The cumulus clouds then deflect incoming sunlight backinto space, with a resulting cooling. As a result of the mitigating effects ofcumulus clouds, NAS panelist Richard Lindzen doesn't expect "much morethan a degree warming and probably a lot less by 2100."

Georgia also observed that even if warming were to occur, mean surfacetemperatures were much higher during the Medieval Warm Period (roughly800 to 1200 AD) than they are today. The warmer temperatures during thatperiod allowed the Vikings to settle presently inhospitable Greenland.

Moreover, "The period of highest temperatures since the last Ice Age, fromabout 5000-3000 BC, is known as the 'climatic optimum,' a time whenmankind began to build its first civilizations," observed James Plummer andFrances B. Smith in a study for Consumer Alert. "There is good reason tobelieve that a warmer climate would have a similar effect on the health andwelfare of our own far more advanced and adaptable civilization today."

"The small amount of warming that occurred during the past centuryconsisted primarily of increased minimum temperatures at night and duringwinters," observed Joseph Bast, president of The Heartland Institute."Warmer winters would mean longer growing seasons and less stress onmost plants and wildlife, producing a substantial benefit for the global ecosystem."

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