Lawmakers on Tuesday night agreed to end a 40-year-old ban on crude oil exports as a condition of the $1.1 trillion omnibus spending and taxation bill, paving the way—environmental organizations warn—for a dramatic increase in drilling, fracking, and carbon emissions.

The development comes just days after the COP21 climate talks in Paris, and according to green groups, threatens to undo the limited progress made at the United Nations-brokered negotiations.

“Lifting the ban on crude oil exports would undercut all the other progress our nation may make in fighting climate change,” said Kassie Siegel of the Center for Biological Diversity’s Climate Law Institute in a statement released Wednesday. “It would increase planet-warming pollution and deliver more fracking and dangerous drilling in America’s vulnerable communities and precious wildlife habitat.”

The lifting of the export ban marks a key victory for Republicans, which they won in exchange for a separate agreement to renew a series of expired tax breaks for renewable energy. House Speaker Rep. Paul Ryan (R-Wis.) “told fellow Republicans in a closed-door meeting Tuesday night” that the deal had been struck, Bloomberg reports.

Campaigners say the deal constitutes a gift to the very oil industry driving the climate crisis. In a study published in the journal Nature earlier this year, scientists concluded that, in order to stave off climate disaster, the vast majority of fossil fuel deposits around the world—including 92 percent of U.S. coal, all Arctic oil and gas, and a majority of Canadian tar sands—must stay “in the ground.”

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