Global warming skeptics just got the political rug pulled out from under their feet. In a newly released report, the U.S. Environmental Protection Agency admitted that climate change is real and that humans are causing it. For George W. Bush's oil-friendly administration, it was a first.

Though Mr. Bush himself downplays the document as the work of a government "bureaucracy," the report is significant nonetheless. For years, right-wing think-tanks have been trying to convince the world that the Kyoto Protocol on global warming is a conspiracy hatched by enemies of capitalism. By graphing temperature data in creative ways, and hyping the work of a dwindling group of dissident climatologists, they have succeeded in creating reasonable doubt among ordinary people on the question of whether humans are really making the world hotter.

The skeptics' theories have increasingly been rejected by mainstream scientists: Last year, the UN's Intergovernmental Panel on Climate Change and the United States' own National Academy of Sciences both released studies concluding that human activity is likely responsible for the bulk of global warming. But conservatives were undeterred: To this day, it seems anyone with a science degree and a theory about sunspots can get an op-ed published in The Wall Street Journal. It's to be hoped the EPA's new report will sound the death knell for this vocal minority.

But conservatives have not been the only ones standing in the way of intelligent debate. The pro-Kyoto camp has also been peddling a fantasy: They argue not only that global warming is real, but that it can be effectively fought without incurring economic hardship.

The numbers tell a different story. The Kyoto protocol, even if fully implemented, would have only a small effect on world carbon dioxide output: Without Kyoto, emissions would rise by 34% over the 1990-2010 period; with Kyoto, they would rise by 26%. Yet according to government agencies, achieving this 8% reduction could cost the developed world more than a trillion dollars in lost GDP by 2010. In Canada alone, the figure could be as high as $40-billion. In the United States, it could be as high as $500-billion. None of Kyoto's supporters have made a serious effort to justify this price tag in domestic cost-benefit terms.

Nor could they. Kyoto's signatories are mostly cold countries. While global warming will likely cause a variety of serious problems for Europe and North America --such as coastal erosion and regional droughts -- it will also lower heating costs and provide benefits to farmers. That is why the EPA's report properly focuses on "adapting" to climate change, not preventing it. Thanks to pressure from Alberta, Canada will probably be moving that way too.

Does all of this mean there is no good argument for reducing carbon dioxide emissions? Of course not. While rich, cool countries probably have little to fear from warming, the already overheated Third World will be devastated. In Africa, crops will likely fail and infectious diseases will spike upwards. And in South Asia, rising seas and cyclones could devastate coastal villages, displacing tens of millions. It is these people, not anyone in the West, who has a real life-and-death stake in Kyoto.

In other words, an honest debate about global warming should be akin to a debate about foreign aid: By agreeing to limit ourselves to Kyoto's limitations, we sacrifice economic growth for the benefit of the Third World. And so the basic question we confront is the same one we confront in any foreign-aid debate: Is the sacrifice worth it?

To answer this question, let's start with the status quo. Canada budgets about $2-billion in foreign aid every year. The government presumably did not choose this number randomly: This is roughly what Canadians think is an appropriate amount to spend on helping poor countries with AIDS, poverty, illiteracy and all of the other myriad problems they confront. Given this benchmark, it seems ridiculous to argue that we should now earmark up to $40-billion -- 20 times the existing foreign aid budget -- to global warming, which probably poses less of a humanitarian threat to the developing world than AIDS alone. If we really are willing to spend anywhere near $42-billion on foreign aid, we would save a lot more lives by ignoring Kyoto and carpeting the Third World with hospitals, anti-viral drugs and water filtration plants.

Until now, the global-warming debate has been dominated by two rival camps -- scientifically illiterate conservative skeptics, and economically illiterate environmentalists -- each of which denies reality in its own way. This week's EPA report puts another nail in the skeptics' coffin. But before we can have an intelligent debate about Kyoto, the left has to give up its myths as well: Global warming may be real, but so are the costs of dealing with it.