Some sections of a grim scientific assessment of the impact of global warming on human, animal and plant life issued in Brussels yesterday were softened at the insistence of officials from China and the United States, participants in the negotiations said.

In particular, U.S. negotiators managed to eliminate language in one section that called for cuts in greenhouse gas emissions, said Patricia Romero Lankao, a scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., who was one of the report's lead authors.

In the course of negotiations over the report by the second working group of the U.N. Intergovernmental Panel on Climate Change, U.S. officials challenged the wording of a section suggesting that policymakers need to reduce greenhouse gas emissions because countries will not be able to respond to climate change simply by using adaptive measures such as levees and dikes.

In that instance, the original draft read: "However, adaptation alone is not expected to cope with all the projected effects of climate change, and especially not over the long run as most impacts increase in magnitude. Mitigation measures will therefore also be required." That second sentence does not appear in the final version of the IPCC Summary for Policymakers.

In a conference call with reporters early yesterday morning, Sharon Hayes, associate director of the White House Office of Science and Technology Policy, said there was "a good deal of discussion" in Brussels over how best to summarize the report's scientific conclusions.

"And in this summary document there was a lot of care taken by all of the nations involved in the discussion to make sure that the certainty statements in this document -- whether scientists felt they had medium certainty or high certainty or very high certainty about different projected impacts -- were accurately reflected," Hayes said.

She declined to discuss specific negotiations over language, saying only that the U.S. government is satisfied with the final report.

Washington was not alone in seeking to alter some of the scientists' findings. China objected to wording that said "based on observed evidence, there is very high confidence that many natural systems, on all continents and in most oceans, are being affected by regional climate changes, particularly temperature increases." The term "very high confidence" means researchers are at least 90 percent sure of their findings.

When China asked that the word "very" be stricken, three scientific authors balked, and the deadlock was broken only by a compromise to delete any reference to confidence levels.

"That was a really hard discussion," said Romero Lankao, who participated in the talks. But the scientist, a lead author on the chapter examining the effect of global warming on industry, settlements and society, said the panel's overall message remained clear: "No one on Earth will escape the impacts of a warming planet."

Yesterday's report, titled, "Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability," warned that human-generated warming is already making oceans more acidic and parched regions even drier. Twenty to 30 percent of the world's species may disappear if the world warms another 2.7 to 4.5 degrees Fahrenheit, the authors concluded, and the risk of massive floods will increase significantly along the coasts because of rising seas and more intense storms.

Much of the report focuses on how particular regions will fare in a warming world, concluding that less-developed countries will experience more upheaval than developed ones. River runoff and water availability is likely to increase 10 to 40 percent at high latitudes and in wet, tropical areas; the regions that already suffer from shortages of water are likely to have 10 to 30 percent less available.