Preparing for renewed international negotiations on cutting levels of heat-trapping gases that may be warming the climate, the United States is proposing that countries get just as much credit for using forests and farmer's fields to sop up carbon dioxide, the chief warming gas, as they would for cutting emissions from smoke stacks and tail pipes.
Scientists have known for decades that trees and other plants absorb carbon dioxide as they grow and that some soils do as well. In theory, pulling carbon dioxide out of the atmosphere would allow countries to emit some heat-trapping, or greenhouse, gases without adding to the overall problem.
Clinton administration officials and some scientists said Tuesday night that incentives to plant trees and to farm in ways that lock away carbon is an essential part of any strategy to stabilize the climate. In addition, they said, bringing farmers and foresters into the battle is likely to be essential if the Senate, which has so far firmly opposed ratifying any international climate treaty, is to change its view.
But the position is being criticized by some private environmental groups that have focused on cutting the burning of coal and oil, which caused most of the buildup of carbon dioxide. They point to uncertainties about how long plants and soils could continue to absorb carbon and contend that reducing emissions is by far the safer course.
And the proposal is at odds with the stance of the European Union which, given its relative lack of open land for tree-planting, would be at a disadvantage should the approach be endorsed.
The State Department laid out the United States' approach in documents filed Tuesday night with a U.N. office that is overseeing talks aimed at carrying out the 1997 Kyoto Protocol, an international agreement aimed at averting any dangerous climate warming. Thirty-eight other industrialized countries were scheduled to file their proposals Tuesday night as well.
The Kyoto agreement has been signed by the United States and more than 100 other countries, but has not yet been ratified. Many details remain to be ironed out, with two rounds of negotiations coming in September and again in November.
If the agreement is ratified, the United States will commit to cutting its emissions of carbon dioxide by 2010 to 7 percent below where they were in 1990. Given the growth in the economy and fuel use since 1990, administration officials say, the only way to come anywhere near that target is by adopting every possible strategy, including the agricultural approach.
Vice President Al Gore was deeply involved in crafting the Kyoto treaty, and any deadlock in talks would be a blow to him. On the other hand, although Gov. George W. Bush of Texas has said he believes global warming is a significant problem, he opposes ratification of the Kyoto Protocol, saying it would unfairly burden the United States.
White House officials said Gore was being appraised of the proposed strategy.
Michael Oppenheimer, chief scientist of Environmental Defense, a private group, said that whatever program finally emerges in the next rounds of talks, it must not allow any country to get too much credit for things it is already doing, such as, for example, planting trees on land that was clearcut several years ago.
"Done well, credit for forests and farming could help jumpstart a solution to the global warming problem," Oppenheimer said. "Done poorly, it could undermine the credibility of the whole Kyoto agreement."
David B. Sandalow, the assistant secretary of state for oceans and environmental affairs, said the United States would not want any final climate plan to permit loopholes allowing clearcutting or other bad land practices to get credit in the climate fight.
But, taking a position at odds with some environmental groups, he added that the country's position would be to try to get credit for most of the carbon dioxide being absorbed by the country's trees and crops — about 300 million metric tons a year is the projection for that tally by 2010.
That compares with the projected total emissions of more than 2.1 billion metric tons of carbon dioxide a year from industry, cars and other sources if current energy trends continue, he said.
He added that keeping some focus on farming and trees will keep the cost of fighting global warming down. Estimates are that it will be much cheaper for a country to absorb pollution than to reduce the output of these gases.
"We need strong incentives for parties to adopt practices that protect the atmosphere at low cost," Sandalow said Tuesday night.
According to several Japanese news services, the Japanese government on Tuesday night also submitted plans similar to those of the United States, anticipating a large role for tree planting.
Some private environmental groups are vigorously opposing this approach.
Jennifer Morgan, the director of the climate change campaign at the World Wildlife Fund, an international group, said that forests and soils are, at best, a temporary storehouse for carbon, and one that can broken open by later changes in practices or by unforseen forces like wildfire, droughts, or insect infestations — all of which could abruptly unlock millions of tons of banked carbon.
"Soil can be a great absorber of carbon, but if you plow too deeply two years in a row, you can release it all back into the air," she said. "We need to find the most secure way of reaching these goals, and that is to focus on cutting emissions from things like power plants."
Tuesday night a White House official said that some environmental groups — historically focused on cleaning pollution — were being too inflexible on the issue. "Carbon is carbon, right?" the official said. "Some of these groups have been locked in a philosophical approach as opposed to a practical or scientific one."