BOSTON — IF William Cline's calculations are right, then the nations of the world are prudent in moving toward a treaty to confront the threat of global warming.
Mr. Cline, an economist with the Institute for International Economics, has written a book-length analysis of the potential economic impact of climate change caused by the buildup of carbon dioxide and other gases in the atmosphere.
He concludes that the environmental damage would also damage the economy, cutting 6 to 20 percent of gross domestic product of the United States, for example. Losses range from drought-affected farms to cities hurt by rising sea-levels and greater likelihood of hurricanes.
The projections are far higher than previous estimates, in part because Cline looks at a longer 300-year (versus 60-year) period that more accurately states the problem, according to the scientific evidence he uses. Cline's numbers are based on an expected temperature increase of 10 degrees C should nations fail to act.
Scientist have long warned that the earth's climate will be affected by the buildup of "greenhouse" gases that trap more radiation in the earth's atmosphere. But to date no worldwide response to the problem has emerged.
On May 9, negotiators meeting at the United Nations agreed to steps to curb global climate change. Under the accord, developed nations will try to bring their emissions of greenhouse gases down to 1990 levels by the year 2000. The agreement will be presented to more than 100 heads of state at June's Earth Summit in Rio de Janeiro. There would be no assurance that nations would attain the goal.
Cline recommends "carbon taxes" rising by perhaps $5 a year to a total of $40 per ton of emissions by 2000, reduced deforestation, and sending some carbon-tax revenue to help developing nations cut pollution. He says such steps could greatly reduce global warming and related economic problems.