With melting glaciers as a backdrop, Vice President Al Gore visited Glacier National Park on Tuesday to reiterate the recently coined Clintonian dictum, "Global warming is for real." However, both science and millions of years of history recommend different conclusions.
Yes, the Earth may be warmer than it was several hundred years ago, or even 10,000 years ago. And yes, the glaciers in Northern Montana are melting. But are these things occurring because of modern human activities? Are increases in the levels of atmospheric carbon dioxide to blame? These questions have yet to be answered conclusively.
Lack of proof notwithstanding, the Clinton administration is committed to legally binding limits on man-made C02 emissions - limits that could cost the U.S. economy more than a third of a trillion dollars a year. As a result, the Clinton administration now needs to invent catastrophic scenarios in order to justify such action.
But melting glaciers are not proof of global warming. Any good ninth grade earth sciences textbook will tell you the process of glaciation and deglaciation is completely natural and has occurred many times in Earth's history, and will occur again many times in its future.
Evidence of repeated cycles of glaciation and deglaciation has been found going back at least 2.3 million years. Such glacial eras are called "ice ages" and until just a few years ago, global warming activists like Dr. Stephen Schneider (recently showcased at the White House's July 24 "Climate Change Event") were claiming we were headed straight for one. During glacial periods, great ice sheets migrated back and forth across the Earth's surface over periods of thousands of years. According to the National Park Service, "As the climate changed over the last 2 million years, glaciers formed and melted away several times." Evidence concerning glacial and deglacial periods is conclusive: They happen, they are cyclical, and no amount of taxpayer dollars or hot rhetorical gases will stop them.
Obviously, man-made or "anthropogenic" C02 emissions are not the cause of these cycles; the last glacial period subsided thousands of years before industrialization. Many scientists now believe some trigger mechanism, most likely from outside the Earth or its atmosphere, is necessary to bring about climatic change on a global scale. One class of theories deals with solar irradiance. The energy output of the sun is not uniform, it will emit more or less light and heat in any given moment. Climatologists have noted a particularly strong relationship between levels of solar irradiance and global temperature patterns.
Other plausible theories address the effects of cyclical changes in the Earth's orbit. Long term orbital variations produce effects large enough to cause cyclical expansion and contraction of the ice sheets as part of another global-warming/ cooling cycle. One form of orbital variation is a 22,000-year cycle in which the Earth's axis changes its alignment among the stars, thereby altering the periods of Earths closest approach to the sun. The closer Earth gets to the sun in a given cycle, the warmer it gets, and vice versa.
Simply put, there are a host of plausible, well-established climatological explanations that preclude the need to stampede toward the more improbable global warming scenarios currently in vogue. Although environmentalists would like us to believe that anthropogenic greenhouse gas emissions are the cause of any number of climatic events including deglaciation, the evidence does not support such claims.
Man-made C02 emissions total about 10 billion metric tons a year. Mother Nature releases almost 200 billion metric tons into the atmosphere in the same period. Nor can climatologists claim that global temperatures are rising. National Oceanic and Atmospheric Administration (NOAA) satellites, the most accurate measuring instruments currently available, have shown no net warming over the last 18 years. Moreover, the satellite findings are verified by temperature readings from weather balloons that are launched twice daily throughout the world. Even if temperatures were rising, the hypothesis that warming is due to human factors still would be problematic. Most of the highly disputed, one-half degree Celsius of warming claimed by environmental groups occurred before 1940, while the intensity of man-made greenhouse gases emissions was greater after 1940. No anthropogenic smoking gun here.
The debate over global warming in the coming months is enormously important to the future of all Americans. A $350 billion annual loss from the U.S. economy from mandated greenhouse gas reductions is a hard pill to swallow considering the nature of the claims on which it rests. Expect more improbable claims about the socalled dangers of global warming in the coming months.
Patrick Burns is an environmental policy analyst for Citizens for a Sound Economy Foundation.
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