July 22, 2003
by Dennis T. Avery
For those of us huddled in fear of global warming—or the fear of losing our furnaces and air conditioners to the harsh energy rationing of the Kyoto treaty—new research has been swatting aside some of the frightening claims.
The latest encouraging study comes from the University of Maryland, where Dr. Eugenia Kalnay, Distinguished Professor of Meteorology, says changes in U.S. land use—bigger urban “heat islands” and more intensive cropping—may account for half of the warming in the official U.S. temperature record. That’s twice as big a “heat island” factor as had previously been estimated. It means much of the observed surface warming has nothing to do with greenhouse gases, and a great deal to do with the increasing amounts of masonry and steel that surround our official thermometers at post offices and airports. (Even a town of 1,000 can raise its own temperature by 4 or 5 degrees Fahrenheit, and as cities grow their heat islands get hotter.)
Dr. Kalnay compared the records from 2,000 official thermometers with the temperature trends from the highly-accurate weather satellites and high-altitude balloons. When she ‘trued up” the official thermometers’ readings, up to half of the warming trend disappeared. Her study was published in the May 29 issue of the journal Nature.
By the way, those satellites and high-altitude balloons have found virtually no warming trend since 1979 at 30,000 feet where theory says any greenhouse warming is supposed to start. That almost certainly means you won’t have to deal with the extreme warming projections (10 degrees F) with which the UN’s Intergovernmental Panel on Climate Change grabbed headlines two years ago.
Our planet will probably get moderately warmer, however. One of the landmark scientific studies of recent times, by Dr. Gerard Bond of the Lamont-Doherty Earth Observatory in New York, was published in Science on November 16, 2001. Dr. Bond’s team analyzed iceberg debris on the floor of the North Atlantic alongside records of solar activity in carbon-dated tree rings and beryllium-10 in Greenland ice cores. They found that Earth has had nine moderate global warmings and nine global coolings in the last 12,000 years—in a 1300-year cycle that coincides almost exactly with a known cycle in the magnetic activity of the sun.
We’d known about the Medieval Warming, from 950 to 1300 AD, and the Little Ice Age which followed, from 1300 AD to 1850. We’d also had historic records of a Roman Warming (200 BC to 400 AD) and an icy age which followed that. The Bond study, however, took our knowledge of climate history back another 10,000 years and connected it directly with the sun’s variability.
Dr. Sally Baliunas of the Harvard-Smithsonian Center for Astrophysics says, “Twentieth century temperature changes show a strong correlation with the sun’s changing energy output. . .The low magnetism of the seventeenth century [during the Little Ice Age] coincides with the coldest century of the last millennium, and there is sustained high magnetism in the latter twentieth century [when temperatures rose].”
Are you still worried about the sea level rising and flooding all the coastal cities? The alarmists say that huge chunks of ice are falling off the Antarctic ice sheet, due to warming that could erase the ice sheet and suddenly raise sea levels by fifteen to twenty feet.
A study led by Howard Conway of the University of Washington (Science, October 10, 1999) found that the West Antarctic ice sheet has been melting at its current pace for 7,600 years—since the end of the Ice Age 15,000 years ago. The Antarctic ice may be entirely gone in just 7,000 more years—if another Ice Age doesn’t intervene. In the meantime, Dr. Conway says we can expect the sea level to continue rising as it has, about six inches per century, whether you drive an SUV or not.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.
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