(LONG) Warning on global warming
From The Oregonian, Jan. 2, 2003, p A1
Warning on global warming 2 studies show the clearest picture yet of how plants, animals are being driven into accelerated changes By ANDREW C. REVKIN, New York Times News Service Global warming is forcing species around the world, from California starfish to Alpine herbs, to move into new ranges or alter habits in ways that could disrupt ecosystems, two groups of researchers say. The two new studies, by researchers at the University of Texas, Wesleyan, Stanford and elsewhere, are reported in today's issue of the journal Nature. Experts not associated with the studies said they provided the clearest portrait yet of a biological world driven into accelerating flux by warming caused at least in part by human activity. Plants and animals always have had to adjust to shifting climates. But climate is changing faster now than in recent millenniums, and many scientists attribute the pace to rising concentrations of heat-trapping greenhouse gases. In some cases, species' ranges have shifted 60 miles or more in recent decades, mainly toward the poles, according to the new analyses. In others, the timing of egg laying, migrations and the like has shifted weeks earlier in the year, potentially throwing species out of sync with needed sources of food. Richard P. Alley, an expert on past climate shifts who teaches at Pennsylvania State University, said climate has changed more abruptly a few times since the last ice age, and nature has shifted in response. But, he noted, "The pre-industrial migrations were made without having to worry about cornfields, parking lots and interstates." Citing the new work and studies of past climate shifts, he said a significant problem looms: Animals and plants that rely on one another are likely to migrate at different rates. Referring to affected species, Alley said, "You'll have to change what you eat, or rely on fewer things to eat, or travel farther to eat, all of which have costs." The results in coming decades could be substantial ecological disruption, losses of wildlife and extinction of some species, the two studies said. The level of certainty in the new studies is far higher than it was in the past decade, when many of the same researchers contributed to reports on biological impacts of warming published by the Intergovernmental Panel on Climate Change, the top international research group on the issue. The authors of one of the new Nature papers, Camille Parmesan, a biologist at the University of Texas, and Gary Yohe, an economist at Wesleyan University, calculated that many ecological changes measured in recent decades had a 95 percent chance of being the result of climate warming and not another factor. "You're seeing the impact of climate on natural systems now," Yohe said. "It's really important to take that seriously." Some butterflies have shifted northward in Europe by 30 to 60 miles or more, with the changes closely matching changes in average warm-season temperatures, Parmesan said. The researchers were able to rule out other factors - habitat destruction, for example - as causes of the changes. In many instances, a central bit of evidence pointing to climate change as the cause were measurements of advances by species in parts of their range where a cool climate previously restricted them and simultaneous retreats in places where an increasingly hot climate now restricted them. When these advances and retreats are concurrent, they provide proof that climate is driving the species' change. Around California's Monterey Bay, warmer waters have caused many invertebrates to shift northward, driving some species out of the bay and allowing others to move in from the south. Authors of both new papers said they were concerned that such significant ecological changes had been detected even though global temperatures had risen only about one degree in the past century. They noted that projections of global warming by 2100 range from 2.5 to 10 degrees, should concentrations of carbon dioxide and other heat-trapping gases continue to rise. The gases flow mainly from smokestacks and tailpipes. By comparison, the world took 18,000 years to climb out of the depths of the last ice age and warm about 5 degrees to 9 degrees to current conditions. Posted as a courtesy by Daniel B. Wheeler www.oregonwhitetruffles.com |
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