Four years after the "Earth Summit" in Rio, a UN-sponsored scientific advisory body, the Intergovernmental Panel on Climate Change (IPCC), is warning that the effect of greenhouse gases on global warming "must now be taken seriously." This remarkable statement was released at a London press conference, held to usher in the latest IPCC report, "Climate Change 1995." In 1992, the world's statesmen, including George Bush, were induced to sign the Global Climate Treaty. The data have not changed since 1992 and the present scientific evidence is still insufficient to take global warming seriously. The fact is that IPCC predictions of global warming have been based on nothing more than imperfect theoretical climate models never validated by observations.
The IPCC's numbers change constantly, depending on the audience. For example, at the press conference, Sir John Houghton, co-chairman of IPCC, reportedly claimed that "an increase of global temperature of between 1.5 C and 4.0 C, [is] expected by the year 2100." The 1995 report itself claims an increase of 1 C to 3.5 C-- while a July 1995 US government report gave a lowest value of only 0.5 C, one-third of Houghton's value. These substantial discrepancies are nowhere explained. (A temperature rise of half a degree over a century, comparable to natural changes, would barely be detectable and would certainly be inconsequential.)
Even worse, the IPCC has managed to suppress relevant data showing that no warming is taking place. For nearly 20, earth satellites have been providing accurate and truly global temperature data. These data show no increase whatsoever -- contrary to all of the predictions of theoretical climate models. Yet if one examines the 1995 Summary for Policymakers, one finds absolutely no mention of satellite data--or even of the existence of satellites. The "Technical Summary" (of the IPCC Working Group I Report) grudgingly allocates three lines to satellite data and manages to misrepresent an observed cooling as a warming.
In view of such contrary evidence, it is absolutely astounding that Mr. Houghton can claim "serious impacts on human habitats and society", and urge policy makers to set targets to reduce greenhouse gas emissions. Unmentioned is the fact that stabilization of carbon dioxide, the major anthropogenic greenhouse gas, requires a reduction of 60% to 80%, according to the IPCC's own studies. This translates into huge and crippling reductions of energy use that can hardly be achieved simply by "aggressive efficiency measures."
Mr. Houghton's boss, British environment minister John Gummer, goes even further. He labels the IPCC's Summary for Policymakers "authoritative", and says that "action by the international community is now urgent." He wants a reduction, by developed countries, of over 50%, with 5 to 10% by the year 2010 "as a first step in the process." He apparently relies on the IPCC analysis that "10-30 percent of greenhouse gas emissions in most countries could be reduced at negative or zero cost".
But Mr. Gummer's unrealistic targets are not radical enough to satisfy environmental activists. Friends of the Earth terms his attitude to the threat of climate change as "complacent in the extreme." Neglected in all of this fantasizing: IPCC's labeling of global warming as "potentially the greatest global environmental challenge facing mankind" is not taken seriously by most responsible scientists.
There is certainly no scientific consensus supporting the IPCC report. At the 1992 Earth Summit, a group of several hundred independent scientists released the "Heidelberg Appeal", warning the assembled statesmen not to be stampeded by hyped stories of global disasters. (The number of signers is now well over 4,000 worldwide, including some 70 Nobel Prize winners.) Recently, a group of some 100 climate scientists signed the "Leipzig Declaration," which calls for completion of ongoing research and urges against hasty and economically damaging policies: "We consider the Global Climate Treaty...to be unrealistic... In a world in which poverty is the greatest social pollutant, any restriction on energy use that inhibits economic growth should be viewed with caution. For this reason, we consider "carbon taxes" and other drastic control policies--lacking credible support from the underlying science--to be ill-advised..."