Scientists Issue Dire Prediction On Warming
Faster Climate Shift Portends Global Calamity This Century
By Philip P. Pan
Washington Post Foreign Service
Tuesday, January 23, 2001; Page A01
BEIJING, Jan. 22 -- In the most forceful warning yet on the threat of global warming, an international panel of hundreds of scientists issued a report today predicting brutal droughts, floods and violent storms across the planet over the next century because air pollution is causing surface temperatures to rise faster than anticipated.
The report, approved unanimously at a U.N. conference in Shanghai and described as the most comprehensive study on the subject to date, says that Earth's average temperature could rise by as much as 10.4 degrees over the next 100 years -- the most rapid change in 10 millennia and more than 60 percent higher than the same group predicted less than six years ago.
If new scientific models are accurate, rising temperatures will melt polar ice caps and raise sea levels by as much as 34 inches, causing floods that could displace tens of millions of people in low-lying areas -- such as China's Pearl River Delta, much of Bangladesh and the most densely populated area of Egypt. Droughts will parch farmlands and aggravate world hunger. Storms triggered by such climatic extremes as El Niño will become more frequent. Diseases such as malaria and dengue fever will spread.
"The scientific consensus presented in this comprehensive report about human-induced climate change should sound alarm bells in every national capital and in every local community," said Klaus Topfler, head of the U.N. Environment Program. "We should start preparing ourselves."
The report was drafted by the Intergovernmental Panel on Climate Change, a group of hundreds of scientists established by the United Nations in 1988 to assess warming. The Shanghai survey relies on complex new computer simulations based on weather records from the last 150 years, as well as data collected from ice corings, coral and tree rings -- all of which can provide information on climate going back millions of years.
The results of the new models persuaded the panel to declare unequivocally for the first time that mankind is responsible for global warming rather than changes brought by the sun or other natural factors. "We see changes in climate, we believe we humans are involved, and we're projecting future climate changes much more significant over the next 100 years than the last 100 years," said Robert T. Watson, an American scientist who is chairman of the panel.
The report cited "new and stronger evidence that most of the observed warming of the last 50 years is attributable to human activities," primarily the burning of oil, gasoline and coal, which produces carbon dioxide and other gases that trap heat in Earth's atmosphere.
Carbon dioxide levels have increased by 31 percent over the past 250 years, reaching a concentration unseen on the planet in 420,000 years and perhaps as far back as 20 million years, the report said. In 1995, by contrast, the panel reported only a "discernible human influence" on global warming.
At that time, the group predicted a temperature rise of no more than 6.3 degrees by 2100.
The panel raised that prediction by more than 4 degrees in part because successful efforts to reduce the air pollutant sulfur dioxide, a common element of smog, have had the unintended effect of reducing particles in the air that help deflect the sun's rays, the report said.
The global warming issue has proved highly contentious among environmental scientists, with many respected figures arguing that Earth undergoes periodic climatic changes with or without contributions from mankind.
Fred Singer, professor emeritus of environmental sciences at the University of Virginia and former director of the U.S. Weather Satellite Service, called the new report "a political statement" based on theoretical models that does not conform to existing scientific data from thermometers at weather stations, Earth-circling satellites and high-altitude balloons. Almost all instrumental data, he said, show no warming trend in the past 60 years, and he called data that do "suspect."
But David Easterling, principal scientist at the Commerce Department's National Climate Data Center, noted that reductions in airborne sulfates, which act to cool temperatures, are expected this century because of such factors as the burning of cleaner coal. He called the "physics pretty well established."
The new calculations add urgency to international treaty talks on curbing greenhouse gas emissions that collapsed in November as participants disagreed over how to cut such emissions under a commitment made by industrialized countries in 1997. Negotiations have been complicated by a U.S.-led effort to soften the impact of required cuts by adjusting for the amount of carbon dioxide that is absorbed by each nation's forests and farmlands. New climate talks are scheduled in Germany in May.
"Only a few countries, such as Britain and Germany, are on track to meet their targets," said Watson, who is the chief science adviser to the World Bank. "The United States is way off meeting its targets."
The United States is the largest producer of greenhouse gases, accounting for a quarter of the world total. China ranks second, but its per cap
ita amount is relatively low.
© 2001 The Washington Post Company