Tuesday, June 19, 2007

The Truth Catches Up With Al Gore

One of the responsibilities of presenting yourself conspicuously as a defender of "truth" and "reason" is that you had better work very hard to make sure that you are actually employing reason and that you really care about the truth. If you make an extravagant show of possessing these virtues, while actually engaging in the crudest kind of propaganda, you must always fear exposure as a fraud.

That's what Al Gore is discovering. The truth is turning out to be very inconvenient for the chief promoter of the global warming hysteria. In his film, he presented several dramatic visuals that were supposed to be symbols of the threat of global warming. One was the claim that global warming would produce more hurricanes—a claim widely rejected by scientists who actually specialize in studying hurricanes.

Now reality is catching up with Gore on another of his visual symbols: the snows of Kilimanjaro, the ice-capped African mountain that Gore used as a dramatic example of global warming causing the shrinking of glaciers. In the long article linked to below (I have excerpted a few of the most relevant sections), two leading experts on Kilimanjaro conclude that the mountain's glacier has been shrinking since the 1880s, that most of the reduction occurred by 1953, and that the whole process has nothing to do with global temperatures.

"The Shrinking Glaciers of Kilimanjaro: Can Global Warming Be Blamed?" Philip W. Mote and Georg Kaser, American Scientist , July-August 2007 The shrinking glacier is an iconic image of global climate change. Rising temperatures may reshape vegetation, but such changes are visually subtle on the landscape; by contrast, a vast glacier retreated to a fraction of its former grandeur presents stunning evidence of how climate shapes the face of the planet. Viewers of the film An Inconvenient Truth are startled by paired before-and-after photos of vanishing glaciers around the world. If those were not enough, the scars left behind by the retreat of these mountain-grinding giants testify to their impotence in the face of something as insubstantial as warmer air.

But the commonly heard—and generally correct—statement that glaciers are disappearing because of warming glosses over the physical processes responsible for their disappearance. Indeed, warming fails spectacularly to explain the behavior of the glaciers and plateau ice on Africa's Kilimanjaro massif, just 3 degrees south of the equator, and to a lesser extent other tropical glaciers. The disappearing ice cap of the "shining mountain," which gets a starring role in the movie, is not an appropriate poster child for global climate change. Rather, extensive field work on tropical glaciers over the past 20 years by one of us (Kaser) reveals a more nuanced and interesting story. Kilimanjaro, a trio of volcanic cones that penetrate high into the cold upper troposphere, has gained and lost ice through processes that bear only indirect connections, if any, to recent trends in global climate….

Observations of Kilimanjaro's ice from about 1880 to 2003 allow us to quantify changes in area but not in mass or volume. The early European explorers Hans Meyer and Ludwig Purtscheller were the first to reach the summit in 1889. Based on their surveys and sketches, but mainly from moraines identified with aerial photographs, Henry Osmaston reconstructed (in 1989) an 1880 ice area of 20 square kilometers. In 1912, a precise 1:50,000 map based on terrestrial photogrammetry done by Edward Oehler and Fritz Klute placed the area at 12.1 square kilometers. By 2003 that area had declined to 2.5 square kilometers, a shrinkage of almost 90 percent. Much of that decline, though, had already taken place by 1953, when the area was 6.7 square kilometers (down 66 percent from 1880)….

Focusing on measurements of air temperatures at the 500-millibar air-pressure level (roughly 5,500 meters altitude) from balloons, one paper suggests a warming trend in the tropical middle troposphere from about 1960 to 1979, followed by cooling from 1979 to 1997, although this study has not been updated….

Another important observation is that the air temperatures measured at the altitude of the glaciers and ice cap on Kilimanjaro are almost always substantially below freezing (rarely above -3 degrees). Thus the air by itself cannot warm ice to melting….

The observations described above point to a combination of factors other than warming air—chiefly a drying of the surrounding air that reduced accumulation and increased ablation—as responsible for the decline of the ice on Kilimanjaro since the first observations in the 1880s….

An additional clue about the pacing of ice loss comes from the water levels in nearby Lake Victoria. Long-term records and proxy evidence of lake levels indicate a substantial decline in regional precipitation at the end of the 19th century after some considerably wetter decades. Overall, the historical records available suggest that the large ice cap described by Victorian-era explorers was more likely the product of an unusually wet period than of cooler global temperatures.

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