When the Supreme Court restricted the ability of the Environmental Protection Agency to fight climate change this year, the reason it gave was that Congress had never granted the agency the broad authority to shift America away from burning fossil fuels.

Now it has.

Throughout the landmark climate law, passed this month, is language written specifically to address the Supreme Court’s justification for reining in the E.P.A., a ruling that was one of the court’s most consequential of the term. The new law amends the Clean Air Act, the country’s bedrock air-quality legislation, to define the carbon dioxide produced by the burning of fossil fuels as an “air pollutant.”

That language, according to legal experts as well as the Democrats who worked it into the legislation, explicitly gives the E.P.A. the authority to regulate greenhouse gases and to use its power to push the adoption of wind, solar and other renewable energy sources.

“The language, we think, makes pretty clear that greenhouse gases are pollutants under the Clean Air Act,” said Senator Tom Carper, the Delaware Democrat who led the movement to revise the law. With the new law, he added, there are “no ifs, ands or buts” that Congress has told federal agencies to tackle carbon dioxide, methane and other heat-trapping emissions from power plants, automobiles and oil wells.

This month, in the hours before the bill passed the Senate, Republicans waged a last-minute, mostly unsuccessful predawn battle to remove the language from the legislation. Later that day, the Senate approved the climate-and-tax bill by a vote of 51 to 50, along party lines, with Vice President Kamala Harris casting the tiebreaking vote.

Republicans objected to the language, and to the fact that it appeared in a budget bill, a category of legislation focused on government spending and revenue.

“It’s buried in there,” Senator Ted Cruz, Republican of Texas, said on Fox News Business ahead of the Senate vote. “The Democrats are trying to overturn the Supreme Court’s West Virginia vs. E.P.A. victory,” he added, referring to the ruling that curbed the E.P.A.’s ability to tackle global warming. Mr. Cruz did not respond to requests to discuss his opposition.

Conservative organizations that have challenged the Environmental Protection Agency’s authority in the past said the new law would not stop future lawsuits. Robert Henneke, executive director of the Texas Public Policy Foundation, a conservative nonprofit group, said “sneaking in this verbiage” into the new law “is probably just going to set up future regulatory fights.”

Legal experts, on the other hand, said those fights would almost certainly be harder to win.

Jody Freeman, a professor at Harvard Law School and an expert on the Clean Air Act, said the language cemented E.P.A.’s authority and would be “a powerful disincentive” to new lawsuits.