Moment of Truth

No sooner did James McCarthy's name turn up in an associated Press story on the outlook for global warming than he started getting outraged e-mails from colleagues. All that McCarthy, a Harvard oceanographer who studies how climate change affects marine life, told the AP last week was that "the worst stuff is not going to happen ... not that I think the projections aren't that [accurate], but because we can't be that stupid." The overwhelming response, he said, was, What do you mean, we can't be that stupid? Just look around!

On that very question could hinge the fate of much of life on Earth. Last week was bracketed by two events that could make 2007 a turning point in the effort to control global warming. On Monday, by a 5-4 vote, the Supreme Court ruled that the federal government had the power under the Clean Air Act to regulate carbon dioxide emissions from vehicles. This victory for environmentalists was quickly snatched away by President Bush, who announced the next day that his administration had no intention of doing anything of the sort. But the ruling set an important precedent for treating carbon dioxide as a threat to human welfare, and opens the way to regulating it by tightening fuel-economy standards. On Friday, the Intergovernmental Panel on Climate Change, marshaling the research of nearly 1,000 scientists from 74 countries, issued a long-awaited report on climate-change "impacts, adaptation and vulnerability." The study found that global warming was already affecting the Earth's ecosystems; it predicted that continued climate change, in combination with other environmental stressors such as population increases and greater urbanization, would lead to more-severe and widespread drought, greater coastal and riverine flooding, and "increased risk of extinction" for 20 to 30 percent of plant and animal species. Depending on how much temperature rises, food production in the temperate regions (including parts of the United States and Canada) could actually increase, but would probably decline in much of the tropics.

Yet at least since last year's congressional elections it's been clear that 2007 would be a critical year for what former vice president Al Gore has called the "planetary emergency." A half-dozen bills to control greenhouse gases have already been introduced or are being prepared for introduction to the Senate, according to the National Environmental Trust. Some version of the "cap and trade" market-based system that has already shown its value in reducing acid-rain pollution is virtually certain to pass this Congress. "The key question now," says NET president Phil Clapp, "is, will President Bush sign a meaningful bill? But I don't think there's any question that if this Congress doesn't produce one, the next one will and the next president will sign it. We're in the endgame now, after 10 years on this issue."

The intellectual journey to reach this point has taken much longer than a decade. It began in the 19th century on two tracks. One was the invention of climate science and the discovery that carbon dioxide traps heat in the atmosphere. It would take until the 1980s to develop the climate models and computers that could quantify this "greenhouse effect," an effort that is still ongoing. The other was the dawning realization that human activity could wreak lasting, perhaps irreversible, change on the natural world. That was a novel idea all by itself, and it was even more shocking to the progress-obsessed 19th-century mind that this change might not be an improvement. Thoreau anticipated it, but as a historical proposition it dates to the 1864 publication of George Perkins Marsh's "Man and Nature," which the environmental activist Paul Hawken calls "arguably the most important book ever published on the environment." As a congressman from Vermont, Marsh "witnessed the forests of the northeastern United States clear-cut and razed in front of his eyes," Hawken recounts in his upcoming history of the environmental movement, "Blessed Unrest." Later, as ambassador to Italy and Turkey, Marsh saw "what deforestation and overgrazing had wrought over longer historical periods ... temperature swings, loss of fertility, less rainfall, and failed civilizations." You can draw a straight line from Marsh through Jared Diamond's influential best seller of 2005, "Collapse: How Societies Choose to Fail or Succeed."

This was the intellectual backdrop for the political struggle that is now playing out. If "Silent Spring," Rachel Carson's 1962 jeremiad against pesticides, helped create the modern environmental movement, it also called into being an organized opposition on the part of businesses (and unions) that saw their interests threatened. The technological obstacles to pollution control were portrayed as insurmountable, the costs unaffordable. The mighty oil industry quailed at the burden of producing lead-free gasoline; automakers warned that Americans would never pay for putting catalytic converters on their cars. But lead is directly harmful to health in a way that carbon dioxide is not, so there was a conceptual leap required before "global warming" could get on the political agenda. Scientists were starting to worry seriously about it at least as far back as 1969, when the phrase appeared in a back-page story in The New York Times about a scientific conference. But the concept didn't begin to penetrate the media until almost a decade later, and then typically in the guise of the "greenhouse effect." Long after the need for action became apparent, says Clapp, energy companies "all took the approach that [regulation] may be inevitable, but just give us another five years."

Yet sometime in the past 24 months that ironclad coalition began to crumble. Science chipped away at the ranks of global-warming deniers, who have mostly been forced to concede that the Earth really is warming, and that industrial pollution is at least partly to blame. They are now reduced to arguing that it may actually be good for you, or that the cost of reducing carbon dioxide pollution will be enormous, and fall most heavily on the developing world—without acknowledging that those are the same countries that will bear the greatest burden of drought, disease and famine as the climate changes. The success of hybrid cars set an example for the rest of the transportation industry. War in the Mideast called attention to America's reliance on imported oil, and environmentalists were happy to make common cause with the security-minded advocates of "energy independence" to promote conservation and the production of renewable fuels such as ethanol. The deadly European summer heat wave of 2003 and the flooding of New Orleans by Hurricane Katrina in 2005 were reminders—even as scientists point out that no specific incident of weather can be directly linked to long-term climate trends—of the primal power of Nature even over the industrialized world.