Washington ? Just six weeks before President-elect Barack Obama takes office, the Bush administration issued revised endangered species regulations Thursday to reduce input of federal scientists and to block the law from being used to fight global warming.

The changes, which will go into effect in about 30 days, were completed in just four months. But they could take Obama much longer to reverse.

They will eliminate some of the mandatory, independent reviews that government scientists have performed for 35 years on dams, power plants, timber sales and other projects, a step that developers and other federal agencies have blamed for delays and cost increases.

The rules also prohibit federal agencies from evaluating the effect on endangered species and the places they live from a project’s contribution to increased global warming.

Interior Department officials described the changes as “narrow,” but admitted that the regulations were controversial inside the agency. Environmentalists viewed them as eroding the protections for endangered species.