Not long after George W. Bush proudly declared last year that he had no intention of watching Al Gore's An Inconvenient Truth, he told reporters that there was a "fundamental debate" about whether global warming was "manmade or natural." It was an ignorant statement utterly at odds with the scientific consensus. Recently, however, he tried to walk it back. "Beginning in June 2001," read a White House letter released last month, "President Bush has consistently acknowledged climate change is occurring and humans are contributing to the problem." (A second letter claiming that the White House consistently acknowledged that Saddam Hussein had no WMD is said to be forthcoming.)

Revisionism aside, it's nice to see the administration swear off pointless skepticism about the science of global warming. Indeed, as the Intergovernmental Panel on Climate Change prepares to release its latest report, declaring with 90 percent certainty that manmade greenhouse gases are heating the planet, the debate over global warming has shifted. Erstwhile skeptics are scattering for cover. Businesses are lining up in support of a mandatory cap on carbon emissions. Democrats have declared the issue a top priority.

It's not a moment too soon. To stave off melting ice sheets, rising sea levels, and other potentially calamitous effects of large-scale climate change, we should have started working to stabilize carbon-dioxide levels in the atmosphere years ago. But, while there are unimpeachable policy grounds for rushing to action, the political logic of hastily moving forward is less convincing. Public alarm over global warming is just beginning to build. And the president, despite his shift in rhetoric, still opposes mandatory reductions in emissions. If Democrats in Congress act tomorrow and produce a bill that can pass muster with the White House, they will end up with an inadequate half-measure that could deflate the growing pressure to act meaningfully.

Consider the current raft of climate-change legislation. The only piece that has a chance of surviving a GOP filibuster and Bush veto is one sponsored by New Mexico Senator Jeff Bingaman. His bill would implement a cap-and-trade regime, setting a national limit on carbon emissions and allowing companies to buy and sell pollution credits--a system that worked with acid-rain legislation in the 1990s. But Bingaman's proposal includes "safety valves" that give companies an out, and it doesn't reduce emissions quickly enough. Unfortunately, stronger bills--such as one sponsored by John McCain, Joe Lieberman, and Barack Obama--stand almost no chance, even with the current Democratic majority. (Last time around, that bill netted only 38 votes.)

Democrats, eager to show that they are capable of governing, could rally around Bingaman's toothless bill. Or they could pursue a course that offers the promise of truly meaningful action: They should embrace the strongest bill possible, suffer a Senate filibuster or Bush veto, raise public awareness, and simply bide their time until 2008. Most political observers like the Democrats' chances of picking up seats in the Senate then, and nearly all of the leading presidential contenders--from McCain to Hillary Clinton--take climate change more seriously than Bush. Public pressure will also continue to intensify (already, the Climate Action Partnership, a coalition of companies led by GE and Duke Energy, is pushing for legislation along the lines of McCain-Lieberman-Obama). Then, and only then, will effective action be possible.

Waiting, of course, entails potentially grave risks--especially since the process of reducing emissions is likely to move slowly no matter what. For one thing, wending any meaningful piece of legislation past retrograde committee chairmen and meddling industry lobbyists will take years. For another, averting drastic climate change will involve a mix of emissions caps and mandates for renewable energy--all of which will take time to perfect. The cap-and-trade regime in Europe has faltered in its early stages, suggesting that any new system will invariably arrive with kinks that need to be worked out.

But what other choice is there? Thus far, on issues ranging from the minimum wage to Medicare, congressional Democrats have, appropriately, crafted moderate legislation that has some chance of passing, rather than trying to jam through ambitious policies that would only get smacked down by the White House. After all, a modest minimum-wage hike beats none at all. But climate change is different. There won't be many chances to get this right, and Democrats will need to wait until they can go for broke.

By The Editors