Most of the findings, like the spread of warmth-loving pests and the inevitable loss of low-lying lands to rising seas, are not new. But the report included new projections of how the poor, elderly and communities with lagging public-health and public-works systems will face outsize health risks from warming.
Among the reportâ€™s new conclusions on health: â€œAn increased frequency and severity of heat waves is expected, leading to more illness and death, particularly among the young, elderly, frail and poor.â€ It added that deaths from cold would decline, but said uncertainties on both projections made it impossible to characterize the overall risk.
It gave high odds (essentially a two out of three chance) that Lyme disease and West Nile virus would have expanded ranges because of warming. The report gave the same odds that some food- and water-borne diseases would also increase among susceptible populations, but said “major human epidemics” were unlikely as long as public-health systems remained effective.
Under a 1990 law, presidents must submit a report to Congress every four years summarizing what is known about impacts of climate change and other global environmental problems on the United States.
The last such assessment, undertaken in the Clinton administration and published in 2000, was attacked by groups and industries opposing restrictions on greenhouse gases. References to it were deleted from some government reports by political appointees in the White House.
Environmental groups sued to force the completion of a new study. In court, the White House contended that a series of more than 20 studies requested by President Bush in 2003 satisfied the 1990 law, but Judge Saundra Brown Armstrong of Federal District Court for the Northern District of California rejected that assertion last August and ordered a comprehensive assessment to be published by the end of May.
“This assessment is an example of what federal scientists can and should be doing when they are freed from political interference and allowed to actually do their jobs,” said Kassie Siegel, climate program director for the Center for Biological Diversity, the lead plaintiff in the lawsuit.
Senator John Kerry, the Massachusetts Democrat who was the lead author of the 1990 law, strongly criticized the White House.
“The three-year delay of this report is sadly fitting for an administration that has wasted seven years denying the real threat of global climate change,” Mr. Kerry said in a statement. “In these lost years, we could have slowed global warming and advanced clean energy solutions, but instead Americaâ€™s climate change strategy has been at best rhetorical, not real.”