| July 30, 2009 |  |
Contrarians Promote Study That Masks Warming Trend
Climate contrarians are promoting a study published on July 23 in the Journal of Geophysical Research that they mistakenly claim overturns decades of scientific evidence that human activity is driving global warming. In fact, the study's mathematical methodology would obscure any long-term trend in global temperatures.
The study, "Influence of the Southern Oscillation on tropospheric temperature," by two authors from Australia and one from New Zealand, focuses on the difference between monthly average temperature at a point during the year with the monthly average temperature at the same point during the prior year. By focusing on year-to-year changes in monthly temperature, the study misses the long-term upward trend in global temperatures over many years.
If the subject were baseball rather than climate science, it would be akin to treating a game in which the Yankees defeat the Red Sox 2-1 the same as one in which they win 4-3 or 10-9. Although the difference between the scores in each game is the same, the absolute run totals increase over time.
It's therefore no surprise that the Journal of Geophysical Research study confirms what scientists have long established—that the El Niño cycle in the Pacific is a major driver of natural climate variability for temperature. But it misses the role that human-induced warming has played in raising the baseline on which up-and-down natural cycles operate over the past several decades.
RealClimate.org, a scientific community blog on climate topics highlighted a blog entry that recently examined the mathematical methods used in the paper, demonstrating that they can obscure nearly any long-term trend, even one much larger than observed global warming.
The Journal of Geophysical Research likely will publish comment letters pointing out the study's flaws in a future issue, elucidating the disadvantages of using this mathematical method to examine climate trends. Regardless, we expect contrarian organizations and politicians to continue to cite this study long after the scientific community has moved on.
The Union of Concerned Scientists puts rigorous, independent science to work to solve our planet's most pressing problems. Joining with citizens across the country, we combine technical analysis and effective advocacy to create innovative, practical solutions for a healthy, safe, and sustainable future.
