ANCHORAGE, Alaska— A federal court in Alaska Wednesday vacated the approval of a large oil and gas project known as the Willow Master Development Plan in Alaska’s Western Arctic. The project was approved by the Trump administration but was being defended in court by the Biden administration, despite its climate action pledges and temporary suspension of fossil fuel leasing on public lands.

“This is a huge victory for our climate and polar bears,” said Kristen Monsell, a senior attorney at the Center for Biological Diversity. “It’s a message to the Biden administration that Arctic drilling threatens our climate and vulnerable species. This project never should have been approved, and it can’t be defended. If President Biden is serious about addressing the climate crisis, he has to reject any further attempts to move this project forward and prohibit all new oil and gas activity in the Arctic.”

In a 110-page decision, the court held that the Bureau of Land Management had failed to properly consider the impacts of greenhouse gas emissions generated by the project, in violation of the National Environmental Policy Act, and to properly consider the impacts of the project on polar bears, in violation of the Endangered Species Act.

The Trump administration approved the project in October 2020. The Biden administration pledged to review that approval upon taking office. It then reversed course and defended the approval of the project in court. The Biden administration seemingly defended the project in court to garner favor with Sen. Lisa Murkowski, a key project supporter.

“We don’t have time to be playing politics with our climate,” Monsell said. “Any reasonable, comprehensive review would show that this project would be a disaster for our climate, local communities and wildlife. Arctic oil needs to stay in the ground, and the Western Arctic needs to be protected, not turned into an oilfield.”

ConocoPhillips’ plan involved using giant chillers to refreeze thawing permafrost to ensure a solid drilling surface. The project would have also involved drilling up to 250 wells and building and operating a processing facility, hundreds of miles of ice roads, hundreds of miles of pipelines, an airstrip, and a gravel mine in the northeastern corner of the National Petroleum Reserve-Alaska.

Burning the estimated 590 million barrels of oil to be extracted during the life of the project would result in nearly 280 million tons of greenhouse gas emissions — the equivalent of nearly 65 coal plants operating for a year.

The Center challenged the project along with Friends of the Earth, Greenpeace and other groups. Earthjustice represented the groups in the case.