Omitted: The Bright Side of Global Warming

It seems the U.N. IPCC only tabulates the benefits of climate change when they are outweighed by the costs.
By ANNE JOLIS
Could global warming actually be good for humanity? Certainly not, at least if we're to believe the endless warnings of floods, droughts, and pestilences to which we are told climate change will inevitably give rise. But a closer look at the science tells a more complex story than unmitigated disaster. It also tell us something about the extent to which science has been manipulated to fit the preconceptions of warming alarmists.
According to a 2004 paper by British geographer and climatologist Nigel Arnell, global warming would likely reduce the world's total number of people living in "water-stressed watersheds"—that is, areas with less than 1,000 cubic meters of water resources per capita, per year—even though many regions would see increased water shortages. Using multiple models, Mr. Arnell predicted that if temperatures rise, between 867 million and 4.5 billion people around the world could see increased "water stress" by 2085. But Mr. Arnell also found that "water stress" could decrease for between 1.7 billion and 6 billion people. Taking the average of the two ranges, that means that with global warming, nearly 2.7 billion people could see greater water shortages—but 3.85 billion could see fewer of them.
Mr. Arnell's paper, funded by the U.K. government, was duly cited in the U.N. Intergovernmental Panel on Climate Change's supposedly authoritative 2007 assessment report. But the IPCC uses Mr. Arnell's research to give the opposite impression, by a form of single-entry book-keeping. While it dutifully tallies the numbers of people he predicts will be left with less water access, it largely ignores the greater number likely to see more water courtesy of climate change.

The IPCC's much-shorter "Summary for Policy Makers" is even more one-sided. It is riddled with warnings of warming-induced drought and—while acknowledging that a hotter Earth would bring "increased water availability" in some areas—warns that rising temperatures would leave "hundreds of millions of people exposed to increased water stress." Nowhere does it specify that even more people would probably have more water supplies.
The IPCC also neglects to mention Mr. Arnell's baseline forecasts—that is, the number of people expected to experience greater "water stress" simply due to factors like population growth and resource use, regardless of what happens with temperatures. This leaves readers with the misleading impression that all, or nearly all, of the IPCC's predicted "water stress" increases are attributable to climate change.
These omissions were no accident. In 2006, prior to the release of the IPCC's report and the all-important policy makers' summary, Indur Goklany—at the time with the U.S. Department of the Interior—alerted the summary's authors that it was "disingenuous" to report on a warmer world's newly "water-stressed" without mentioning that "as many, if not more, may no longer be water stressed (if Arnell's analyses are to be trusted)." Mr. Goklany's advice was dismissed.
Mr. Arnell, who helped author the summary and some sections in the full report, told your correspondent he is "happy" with the way his work was represented. He said one reason for the omissions was "space"—apparently there was a "big constraint on the number of words" in texts that total 2,823 pages. The other reason Mr. Arnell cited—which he emphasized in his 2004 paper—is that increased and decreased water stress are asymmetrical indicators, and comparing them is "misleading."
"Having a bit more [water] is not as good as having a bit less is bad," Mr. Arnell explained, though he admitted the degree of asymmetry remains undefined. That defense of IPCC accounting dissolves even faster if you examine a separate section of the IPCC's full report, which cites one of Mr. Arnell's regional breakdowns to show that Latin America will likely see more people with greater water troubles than with less. So apparently it's only misleading to tabulate the benefits of global warming when they outweigh the costs.
On the subject of selective climateering, it's worth noting that Mr. Arnell's 22-page paper is rife with caveats and uncertainties, and the results are highly dependent on the assumptions one adopts—as witnessed by the wide ranges of his estimates. In the 2004 paper he notes, for example, that "the numerical estimates of the implications of climate change on future water resources stresses are not to be taken too literally. . . . The estimated impact of climate change on global water resources depends least on the rate of future [greenhouse gas] emissions, and most on the climate model used to estimate changes in climate and the assumed future population." (Emphasis added).
These nuances—along with the billions of people who might see more water in their lives thanks to climate change—get lost in the translation from the original research to the scientific "consensus." The point here is not to suggest that pollution and any resulting warming will deliver the Third World from its troubles, or that emitting ever-more carbon dioxide should be pursued as humanitarian policy. Clearly any benefits of global warming are extremely speculative—but then so are the costs. Such seemingly deliberate efforts to overstate the risks of climate change while obscuring the possible benefits not only hobbles serious debate, but also raises the question of why such tactics are necessary for supposedly "overwhelming scientific evidence," to quote U.S. President Obama.
With last month's news of non-disappearing glaciers, the IPCC's misuse of data on storm damage, and now its highly selective use of water-availability forecasts, the IPCC's reputation is increasingly looking as tarnished as that of the rest of the U.N.
Miss Jolis is an editorial page writer for The Wall Street Journal Europe.