FOR THE PAST four years members of the Bush administration have cast doubt on the scientific community's consensus on climate change. But even if they don't like the science, British Prime Minister Tony Blair, one of their closest allies in Iraq and elsewhere, has given the administration another, more realpolitik, reason to rejoin the climate change debate: "If America wants the rest of the world to be part of the agenda it has set, it must be part of their agenda, too," the prime minister said this week.

Mr. Blair's speech came at an interesting moment, both for the administration's energy and climate change policies and for the administration's diplomatic agenda. In the next few weeks, the House will almost certainly vote once again on last year's energy bill, a mishmash of subsidies and tax breaks that finally proved too expensive even for a Republican Senate to stomach. After a House vote, there may be an attempt to trim the cost of the bill and add measures to make it acceptable to more senators -- including the growing number of Republicans who have, sometimes behind the scenes, indicated an interest in climate change legislation. Indeed, any new discussion of energy policy could allow Sens. John McCain (R-Ariz.) and Joseph I. Lieberman (D-Conn.) to seek another vote on their climate change bill, which would establish a domestic "cap and trade" system for controlling the greenhouse gas emissions that contribute to global warming.

If domestic politics could prompt the president to look again at the subject, international politics certainly should. Administration officials assert that mending fences with Europe is a primary goal for this year; if so, the relaunching of a climate change policy -- almost any climate change policy -- would be widely interpreted as a sign of goodwill, as Mr. Blair made clear. Beyond the problematic Kyoto Protocol, there are ways for the United States to join the global discussion, not least by setting limits for domestic carbon emissions.

Although environmentalists and the business lobby sometimes make it sound as if no climate change compromise is feasible, several informal coalitions in Washington suggest the opposite. The Pew Center on Global Climate Change got a number of large energy companies and consumers -- including Shell, Alcoa, DuPont and American Electric Power -- to help design the McCain-Lieberman legislation. A number of security hawks have recently joined forces with environmentalists to promote fuel efficiency as a means of reducing U.S. dependence on Middle Eastern oil. Most substantively, the National Commission on Energy Policy, a group that deliberately brought industry, environmental and government experts together to hash out a compromise, recently published its conclusions after two years of debate. Among other things, it proposed more flexible means of promoting automobile fuel efficiency and suggested determining in advance exactly how high the "price" for carbon emissions should be allowed to go, thereby giving industry some way to predict the ultimate cost of a cap-and-trade system.

They also point out that legislation limiting carbon emissions would immediately create incentives for industry to invent new fuel-efficient technologies, to build new nuclear power plants (nuclear power produces no carbon) and to find cleaner ways to burn coal. Technologies to reduce carbon emissions as well as fossil fuel consumption around the world are within reach, in other words -- if only the United States government wants them.