In his first speech after taking office, Secretary of State James A. Baker III called for immediate steps to combat the threat of global warming, noting that even though scientific questions remain, "Time will not make the problem go away."

His call to action in January 1989 cast Baker against the grain of Bush administration policy -- a skeptical, go-slow approach to the problem. Still, he stuck to his guns in internal debates, siding with environmental officials and pushing for stronger U.S. leadership on an increasingly important diplomatic issue.

Now as support builds in Europe for a treaty to cut warming gases, the top U.S. foreign policy officer has taken himself out of the debate, further isolating environmentalists in the administration.

According to administration officials, Baker has formally recused himself because of oil and gas holdings that create the potential for conflict of interest. When burned by cars or factories, oil produces the primary warming gas. Every plan to curb global warming includes measures to discourage or cut oil use.

In a statement filed Feb. 5, Baker listed his oil interests and said that he would abstain from "any particular matter that has a direct and predictable effect upon the price of domestic oil and gas."

The statement does not specifically rule out participation in global warming decisions, and a State Department spokesman refused to clarify how the recusal works in practice. But administration officials say that Baker has not been involved in the issue for months and indicated last summer he would remain uninvolved.

His recusal leaves Environmental Protection Agency Administrator William K. Reilly among Bush's top advisers as the lone advocate of aggressive policy measures to head off what many scientists predict will be significant warming of the Earth's surface by the middle of the next century. Eighteen European nations are committed to freezes or cuts in emissions of carbon dioxide -- the principal warming gas -- by 2005.

Reilly has enjoyed Baker's support at key junctures of administration debates, forming an alliance against White House Chief of Staff John H. Sununu and Office of Management and Budget Director Richard G. Darman. They belittle global warming as scientifically unproven and too costly to combat in an economy that runs on coal, oil and gas.

Last February, Sununu ordered major revisions in a presidential speech endorsed by Reilly and Baker that was designed to underline the seriousness of the problem and burnish Bush's reputation as the world leader most dedicated to its solution.

Baker, officials said, also played a key role in persuading Bush to host the first negotiating session for a framework convention on global warming to be held here this February.

Since Baker dropped out of the debate, the administration has moved even further from U.S. allies and leading trading partners. At an international conference this week, the United States refused to join the Western European nations, Japan and Australia in setting targets limiting the emission of carbon dioxide.

The February meeting is expected to measure the impact of Baker's recusal. With European nations likely to press for protocols committing participants to stabilization policies, administration conservatives would prefer to scuttle negotiations rather than accept global warming targets, officials said.

"When it comes to facing down Sununu and Darman, there's no substitute for Baker," one official said. The official did not rule out intervention by Baker if he considered it politically beneficial to Bush.

Environmentalists who had been counting on Baker as an ally question why his involvement in global warming would pose any more of a conflict than the Persian Gulf policy.

Bush addressed such potential conflicts of interest on Aug. 8 when he directed the White House counsel to review the financial interests of several Cabinet officers, including Baker, involved in the Iraq crisis.