Juliet Eilperin/Washington Post, 6/23/2004

Wednesday, June 16, 2004; Page A09

Ten of the nation's top climate researchers warned yesterday that policymakers must act soon to address the dangers associated with global warming, which they described as a looming threat that will hit hardest and soonest at the world's poor and at farmers.

"By mid-century, millions more poor children around the world are likely to face displacement, malnourishment, disease and even starvation unless all countries take action now to slow global warming" and sea-level rises that will follow, Michael Oppenheimer, who teaches geosciences and international affairs at Princeton University, said at a conference. "Imagine the difficulties faced by families in Bangladesh. An area where about 8 million people now live would be underwater if global sea level were to rise half a meter. Where are they going to go?"

The day-long conference, organized by Donald Kennedy, editor of Science magazine, and Albert Teich, director of science and policy for the American Association for the Advancement of Science, was aimed at convincing the public and politicians that there is ample evidence that the buildup of carbon dioxide is transforming ecosystems worldwide.

Bush administration officials have consistently sparred with environmentalists on how hard it should crack down on carbon dioxide emissions and other heat-trapping industrial and tailpipe gases. In 2001, Bush opted out of the Kyoto agreement on global warming, which would have forced the United States to impose stricter limits on greenhouse gases, on grounds that it would cost American jobs and exempt developing countries from the new standards.

Kennedy called climate change "the most serious issue" we face and said the scientific community must "make a clear expression" on the subject.

The academics emphasized that if international leaders do not act soon, they will not have the option of reversing global warming. David S. Battisti, who teaches at the University of Washington, said it is "a huge risk" not to curb greenhouse gases.

"You have to start doing things now," he said. "To undo it or stop it is not possible."

Researchers, including Chris Field of the Carnegie Institution, said scientists have begun to detect evidence that various species are having to adjust to global warming. Hundreds of species have moved to cooler regions, Field said, and agricultural yields are declining.

"We're seeing the least-competitive species in the ecosystem being winnowed out," he said. "If pushed hard enough, this sensitivity is going to blossom into profound problems."

Bob Hopkins, spokesman for the White House Office of Science and Technology Policy, said the administration has taken steps, including devoting $4 billion to climate change science and technology programs. The Commerce Department is also speeding up deployment of technology to measure atmospheric aerosols and carbon.

"The administration takes this issue very seriously and the president has laid out an aggressive plan to address climate change," he said.