President Joe Biden is limiting oil leasing in Arctic waters and sensitive areas of Alaska, taking steps to expand conservation as his administration prepares to approve a mammoth ConocoPhillips oil development in the region.

Biden is expanding an Obama-era ban on new oil and gas leasing in US Arctic waters and will write new rules barring the sale of new drilling rights across much of the National Petroleum Reserve-Alaska, where ConocoPhillips’s 600-million-barrel Willow venture is planned, the Interior Department said in a news release.

Environmentalists have been imploring the administration to go further and reject the ConocoPhillips project, citing International Energy Agency warnings that the world must forsake developing new oil and gas fields to avoid the worst consequences of global warming and shift to net zero emissions by 2050.

Senior Biden advisers have signed off on the Willow approval — one of the most significant environmental decisions yet for Biden, who campaigned on promises to shift away from fossil fuels. He also enacted the Inflation Reduction Act, a sweeping climate law that dedicates more than $360-billion to clean energy and advanced manufacturing.

New restrictions intended for the National Petroleum Reserve-Alaska could thwart future oil and gas leasing across more than 13-million acres (52,600 square kilometers) in the 23 million-acre site, which is roughly the size of Indiana.

The Interior Department said it intends to issue a proposed rule “in the coming months” to limit oil and gas leasing and industrial development around Teshekpuk Lake, which provides safe haven to birds and caribou, as well as in the Utukok Uplands, Colville River, Kasegaluk Lagoon and Peard Bay Special Areas.

The NPR-A was set aside for oil supply needs roughly a century ago and ConocoPhillips has held leases tied to its $8-billion Willow development since 1999. The Biden administration viewed that as limiting its options to stop or significantly curtail the Willow project, an administration official said.

Yet new conservation moves are seen by the administration as a firewall against future leasing and expanded oil development across much of the Arctic, the official added.

The offshore development limits, imposed under a once-obscure 1953 law, build on former President Barack Obama’s 2016 decision to block new oil and gas leasing across most US Arctic waters. Biden will expand the ban by effectively preventing future oil and gas leasing across the remaining 2.8 million acres of the Beaufort Sea north of Alaska.

The offshore leasing withdrawal “provides additional protections for Teshekpuk Lake, guarding against the potential that future Beaufort Sea oil and gas developments would seek to build onshore pipeline infrastructure into the NPR-A,” the Interior Department said in a news release.

Former President Donald Trump invoked the same 1953 law Biden is wielding now to rule out oil leasing in waters near Florida, Georgia and the Carolinas through mid-2032.

The Interior Department cast the actions as part of Biden’s work delivering “on the most aggressive climate agenda in American history,” after securing “record investments in climate resilience and environmental justice” and “reducing America’s reliance on oil.”

Environmentalists hailed the new conservation measures, but said they do nothing to make up for a potential approval of the Willow oil project.

“The Willow project is designed to open the door to the development of billions of barrels of oil over decades across this biologically rich landscape,” said Kristen Miller, executive director of the Alaska Wilderness League. “We need more than a firewall. We need to put out the fire.”

Athan Manuel, lands protection program director at the Sierra Club, warned “the benefits of these protections can be undone just as quickly by approval of oil and gas projects on public lands.” And right now, he said, “no proposal poses a bigger threat to lands, wildlife, communities and our climate, than ConocoPhillips’s Willow project.”

While it would take years for crude to flow, ConocoPhillips eventually expects Willow to produce 180 000 barrels per day of oil, or roughly 1.6% of current US production. Over a 30-year lifespan, the resulting oil and gas could generate some 280-million tons of carbon dioxide emissions.

Supporters have said that oil would be produced under stronger environmental protections than other crude supplies it could replace, helping boost US energy security while providing an economic lifeline to Alaska’s North Slope.