Rising sea levels, sweltering temperatures, deeper droughts, and heavier downpours -- global warming's serious effects are already here and getting worse, the Obama administration warned on Tuesday in the grimmest, most urgent language on climate change ever to come out of any White House.
But amid the warnings, scientists and government officials seemed to go out of their way to soften the message.
It is still not too late to prevent some of the worst consequences, they said, by acting aggressively to reduce worldemissions of heat-trapping gases, primarily carbon dioxide from the burning of fossil fuels.
The new report differs from a similar draft issued with little fanfare or context by George W. Bush'sadministration last year. It is paradoxically more dire about what's happening and more optimistic about whatcan be done.
The Obama administration is backing a bill in Congress that would limit heat-trapping pollution from powerplants, refineries and factories. A key player on a climate bill in the Senate, California Democrat Barbara Boxer,said the report adds "urgency to the growing momentum in Congress" for passing a law.
"It's not too late to act," said Jane Lubchenco, one of several agency officials at a White House briefing.
"Decisions made now will determine whether we get big changes or small ones." But what has happened alreadyis not good, she said: "It's happening in our own backyards and it affects the kind of things people care about."Lubchenco, a marine biologist, heads the National Oceanic and Atmospheric Administration.
In one of its key findings, the report warned: "Thresholds will be crossed, leading to large changes in climate andecosystems." The survival of some species could be affected, it said.
The document, a climate status report required periodically by Congress, was a collaboration by about threedozen academic, government and institute scientists. It contains no new research, but it paints a fuller and darkerpicture of global warming in the United States than previous studies.
Bush was ultimately forced by a lawsuit to issue a draft report last year, and that document was the basis forthis one. Obama science adviser John Holdren called the report nonpartisan, started by a Republicanadministration and finished by a Democratic one.
"The observed climate changes that we report are not opinions to be debated. They are facts to be dealt with,"said one of the report's chief authors, Jerry Melillo of Marine Biological Lab in Woods Hole, Mass. "We can actnow to avoid the worst impacts." Among the things Melillo said he would like to avoid are more flooding disastersin New Orleans and an upheaval of the world's food supply.
The scientists softened the report from an earlier draft that said "tipping points have already been reached andhave led to large changes." Melillo said that is because some of the changes seen so far are still reversible. Even so, Tom Karl of the National Climatic Data Center said that at least one tipping point -- irreversible sealevel rise -- has been passed.
A point of emphasis of the report, which is just under 200 pages, is what has already happened in the UnitedStates. That includes rapidly retreating glaciers in the American West and Alaska, altered stream flows, troublewith the water supply, health problems, changes in agriculture, and energy and transportation worries.
"There are in some cases already serious consequences," report co-author Anthony Janetos of the University ofMaryland told The Associated Press. "This is not a theoretical thing that will happen 50 years from now. Thingsare happening now." For example, winters in parts of the Midwest have warmed by 7 degrees in just 30 years andthe frost-free period has grown a week, the report said.
Shorter winters have some benefits, such as longer growing seasons, but those are changes that requireadjustments just the same, the authors note.
The "major disruptions" already taking place will only increase as warming continues, the authors wrote. Theworld's average temperature may rise by as much as 11.5 degrees by the end of the century, the report said. Andthe U.S. average temperature could go even higher than that, Karl said.
Environmental groups praised the report as a call for action, with the Union of Concerned Scientists calling itwhat "America needs to effectively respond to climate change." Scott Segal, a Washington lobbyist for the coalindustry, was more cautious: "Fast action without sufficient planning is a route to potential economic catastrophewith little environmental gain."