SOMETIMES THE AMERICAN people seem convinced that global warming means everything has to change; sometimes they don't. An April poll conducted by The Washington Post, ABC News, and Stanford University showed that 70 percent of U.S. voters think the government should take action to ward off climate change. But even though 84 percent of the poll's respondents said they believed the world's temperature has been rising over the past century, only four in ten said they are "extremely" or "very" sure it is happening.

Meanwhile, in late May, President Bush vowed to alter his hands-off attitude about climate change, announcing that the U.S. would lead talks among the world's largest greenhouse-gas producers in an effort to reach a new accord before he leaves office. But whether he will follow through on that remains to be seen. As for the rest of us, how about all those Live Earth concerts? Did they inspire you to change anything other than your TV channel?

In recent months, Lindzen's circle of allies has appeared to be expanding rather than shrinking. In late May, Michael Griffin, administrator of NASA, which conducts considerable amounts of climate research, told National Public Radio that he was not sure climate change was "a problem we must wrestle with" and that it was "rather arrogant" to suggest that the climate we have now represents the best possible set of conditions. Alexander Cockburn, a maverick journalist who leans left on most topics, lambasted the global-warming consensus last spring on the political Web site CounterPunch.org, arguing that there's no evidence yet that humans are causing the rise in global temperature. Other skeptics include Czech Republic president Václav Klaus; Roy Spencer, a principal research scientist at the University of Alabama in Huntsville; and Patrick J. Michaels, a senior fellow in environmental studies at the libertarian Cato Institute.

Cockburn based much of his article on the work of Martin Hertzberg, a consultant from Copper Mountain, Colorado, who worked as a U.S. Navy meteorologist for three years. According to Hertzberg, the increase in CO2 is happening because the world's oceans are warming up—a natural process that's been occurring since the end of the most recent ice age, 12,000 years ago—and in doing so they're releasing their dissolved carbon into the atmosphere.

Most climate experts react harshly to such backtalk. Sir John Houghton, a British atmospheric physicist who chaired the IPCC's Scientific Assessment Working Group from 1988 to 2002, says skeptics have conducted a "misinformation campaign" in the U.S. that must be brought to an end. Earlier this year, Boston Globe columnist Ellen Goodman hurled one of the worst insults imaginable at the skeptics' camp. "I would like to say we're at a point where global warming is impossible to deny," she wrote in February. "Let's just say that global warming deniers are now on a par with Holocaust deniers, though one denies the past and the other denies the present and future."

This sort of declaration, understandably, makes global-warming skeptics feel persecuted. Lindzen lost almost all of his father's family and most of his mother's to the Holocaust, and he says he considers Goodman's comments "mostly stupid, and a bit disgusting as well."

Other skeptics argue that the normal processes of scientific debate—gathering and analyzing data in order to make a case for a particular set of ideas—are getting pushed aside with this issue, leading to dangerous groupthink about how best to prepare for the future.

Danish writer Bjørn Lomborg underscores this point in his new book, Cool It: The Skeptical Environmentalist's Guide to Global Warming. Though he agrees that global warming is happening and that human-generated CO2 is a contributing factor, Lomborg questions whether "hysteria and headlong spending on extravagant CO2-cutting programs at an unprecedented price is the only possible response."

The skeptics' campaign has drawn fire from some of the nation's top scientists, who say their problem with Lindzen and other doubters is simple: They're wrong. Lindzen's critics say his dissent consists of taking cynical potshots at the consensus model of global warming and that he chooses to pick his fights before general audiences who don't understand the science.

"He is treating this issue like a smart defense attorney," says John Holdren, a prominent environmental scientist and past president of the American Association for the Advancement of Science. "He's trying to get his guilty client off. Dick's guilty client is the proposition that the human impacts on global climate are dangerous."

Senator Barbara Boxer, an influential California Democrat who chairs the Environment and Public Works Committee, is just as critical of Lindzen. "The world's leading scientists are saying we know enough to act now," she says. "If, in the past, we had listened to a small number of skeptics, we wouldn't have addressed dirty air or endangered species or toxic-waste sites, and our quality of life would have suffered greatly.

"It would be irresponsible," she adds, "to let a few skeptics stand in the way of doing what we need to do to stabilize the world's climate."