But they are only clutching at semantic straws in a sea of overwhelming evidence that shows the planet is unusually, and dangerously, hot - and likely to get hotter very soon.

The report concludes that the past 25 to 30 years have been warmer than any comparable period in 400 years and potentially in the past several millennia, and that humans are the likely cause.

Scientists are very nearly unanimous in predicting fearsome consequences if global warming is not reversed, yet there remains mind-boggling denial among those in the Bush administration, including the president himself, who long ago should have taken the lead on this critical issue.

They stubbornly insist that, unless all scientists agree, with no qualifications whatever, there is no reason to take any substantive action to reduce the carbon dioxide and methane created by the burning of fossil fuels.

That is willful blindness. Because the National Academy of Sciences report clearly substantiates earlier studies that show a sharp spike in greenhouse gases, and a corresponding 1 degree rise in average surface temperatures in the Northern Hemisphere, during the 20th century.

The data compiled by a panel of 12 climate experts into a 141-page report should, finally, push President Bush and other politicians to take action to control pollution from cars and power plants. The study was requested by the House Science Committee from the group chartered by Congress to advise the government on scientific matters.

But, although the technology exists today to trade coal-burning for nuclear or renewable-energy power plants and to replace gas-powered cars, trucks and SUVs with electric vehicles, we fear little is likely to change until oceans lap at the foundations of our largest cities, food sources dry up, more species go extinct and savage hurricanes wipe out more coastal communities.

Fighting global warming will require leadership. We wonder who will provide it and whether it will come in time.