Secretary of State Hillary Rodham Clinton also is expected to appoint a new envoy for climate change to bolster the administration's credentials in environmental policy.
The slowness with which ocean water circulates is central to the new findings. Carbon dioxide is primarily removed from the atmosphere through absorption into seawater, an incredibly slow process because of the time it takes for surface water saturated with the gas to be replaced by deeper water that can further absorb carbon dioxide.
That gas accounts for about half of the global warming caused by greenhouse gases, but the other gases are removed from the atmosphere more quickly. Thus, the long-term influence of carbon dioxide will have the greatest effect on climate change, the report said.
Moreover, heat absorbed by the ocean is released slowly, and will continue to contribute to global warming even if the concentration of greenhouse gases should decline, the authors said.
Solomon said in a statement that absorption of carbon dioxide and release of heat -- one acting to cool the Earth and the other to warm it -- would "work against each other to keep temperatures almost constant for more than 1,000 years."
Geoscientist Jorge L. Sarmiento of Princeton University said, "This is really a wake-up call about the seriousness of this issue."
The study looked particularly at ocean levels and rainfall. The team found that by thermal expansion of ocean water alone, sea levels will rise from 1.3 to 3.2 feet if carbon dioxide climbs from the current level of 385 parts per million to 600 parts per million, and twice that if it peaks at 1,000 parts per million.
Melting of the icecaps could increase sea levels even more, inundating low-lying islands and continental shorelines, but the effects are too uncertain to quantify, Solomon said.
Reductions in rainfall would also last centuries, the report said, decreasing drinking water supplies, increasing fire frequency and devastating dry-season farming of wheat and maize.
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thomas.maugh@latimes.com
