The Trump administration said Monday it will open up the Arctic National Wildlife Refuge to drilling, a move that will allow oil and gas rights to be auctioned off in the heart of one of the nation’s most iconic wild places. Achieving a goal Republicans have sought for 40 years, the action marks a capstone for an administration that has ignored calls to reduce fossil fuel consumption in the face of climate change.

The move will allow leasing on the 1.6 million-acre coastal plain, part of a nearly pristine wilderness that is home to migrating caribou and waterfowl as well as polar bears and foxes that live there year-round. It marks a major step toward reviving fossil fuel development in an area that has been untouched for three decades.

In a conference call with reporters Monday, Interior Secretary David Bernhardt said that his department was following through on the 2017 budget bill that instructed the federal government to conduct oil and gas leasing on the refuge.

“President Trump’s leadership brought more than three decades of inaction to an end,” he said, adding that the plan was “carefully tailored” to minimize its impact on the surrounding environment. “This is no ordinary oil and gas program on public lands.”

The push to grant rights to drill on the refuge represents one of the most significant energy policy decisions President Trump will make before his first term ends in January. He has doggedly worked to expand fossil fuel production in the United States, even as the climate impacts of burning those fuels — scorching temperatures, increased flooding and more-intense storms — have battered the country. In recent months, the administration has expanded oil and gas drilling, weakened gas mileage standards and rolled back energy efficiency standards for appliances.

According to an analysis by the Center for American Progress, a liberal think tank, the lease sales would result in the release of more than 4.3 billion metric tons of carbon dioxide over the projected life of the field. That total, which includes the impact of oil and gas once it is burned, is equal to roughly three-quarters of U.S. annual emissions.

Environmentalists and some Alaska Natives — including the Gwich’in, who live outside the refuge but rely on the Porcupine Caribou Herd, which migrates through it — have pledged to fight the drilling plan in court. Under the 2017 law, the federal government must conduct two lease sales of 400,000 acres each by December 2024.

The first auction would be held by Dec. 22, 2021, according to the plan, though Bernhardt said it was possible that it could take place by the end of this year. “I am confident that we can move forward quite promptly after this decision is rendered,” he said.

Bernhardt estimated that drilling could begin in roughly eight years and that the operations could last for about half a century.

Stretching into the Arctic Ocean’s frigid waters and 200 miles south on land, the refuge encompasses rolling tundra, jagged mountains and boreal forest. It provides habitat for more than 270 species, including the world’s remaining Southern Beaufort Sea polar bears, 250 musk oxen and 300,000 snow geese. While Congress authorized exploration activities on the coastal plain in 1980, opponents have blocked energy development there for decades.

The move opens up all of the coastal plain’s polar-bear denning habitat to energy exploration. The overall number of bears, some of which den on land, has declined 50 percent since 1980 to a total of roughly 900.

In issuing a “record of decision,” officials at the Interior Department’s Bureau of Land Management concluded that establishing a network of well pads and pipelines would not pose an undue threat to the wildlife that depends on the refuge for survival. The plan calls for the construction of as many as four airstrips and major well pads, 175 miles of roads, vertical supports for pipelines, a seawater treatment plant and a barge landing and storage site.

Adam Kolton, executive director of the Alaska Wilderness League, said in a statement that the administration ignored science and the law in making this decision.

“Our climate is in crisis, oil prices have cratered, and major banks are pulling out of Arctic financing right and left. And yet the Trump administration continues its race to liquidate our nation’s last great wilderness, putting at risk the indigenous peoples and iconic wildlife that depend on it,” Kolton said, adding, “We will continue to fight this at every turn, in the courts, in Congress and in the corporate boardrooms.”

Bernhardt said that while Democrats might want to scuttle the lease sale after taking office, they must contend with the fact that Congress has legally mandated auctions there. “They can’t just simply unduly delay,” he said. “So that is a reality that Congress created.”

If Democrats win control of the White House and both the House and Senate, experts said, they could pass new legislation overriding the 2017 law. The party’s presumptive presidential nominee, Joe Biden, has vowed to permanently protect the refuge from development, and his campaign reiterated that commitment Monday. Senate Minority Leader Charles E. Schumer (D-N.Y.) tweeted after the announcement, “I will not stop fighting to protect the Arctic National Wildlife Refuge and stop the Trump admin’s plan for drilling.”

David J. Hayes, who served as deputy interior secretary under Presidents Bill Clinton and Barack Obama, said he believes the administration’s decision is legally vulnerable because it restricted its environmental analysis to the leasing stage and said it would affect only 2,000 acres on the surface. The 2017 law, he noted, instructs Interior to conduct an oil and gas program that covers “the leasing, development, production and transportation of oil and gas in and from the Coastal Plain area within the Arctic refuge.”

“You can’t just take the first step of the program,” Hayes said. “I think that statutory language is a real tripwire for these guys.”

Bernhardt, who noted that he had significant experience litigating cases related to the Interior Department’s oil and gas leasing programs, said the department had crafted the decision within the confines of the law. “I would not be going forward if I was not very comfortable with the lines that we drew in this case,” he said.

Alaska Republicans hailed the decision as an economic boost for their state. Gov. Mike Dunleavy said in a statement that the vision of Trump and Bernhardt “will lead to the responsible development of Alaska’s abundant resources, create new jobs, support economic growth and prosperity.”

Sen. Lisa Murkowski (R-Alaska) agreed, saying, “This is a capstone moment in our decades-long push to allow for the responsible development of a small part of Alaska’s 1002 area.”

Frank Macchiarola, senior vice president of policy, economics and regulatory affairs at the American Petroleum Institute, said in a statement that the oil and gas industry has proved it can drill on Alaska’s North Slope safely.

“The industry has a well-established record of safe and environmentally responsible development of Alaska’s energy resources and has been recognized for its success in being respectful of Alaska’s wildlife and surrounding communities,” he said.

It is unclear which companies will bid on leases in the refuge and risk a potential backlash from conservation groups and the public. In an April poll, Yale and George Mason universities found that 33 percent of registered voters supported drilling for oil there, while 67 percent opposed it. And the low price of oil has made projects on Alaska’s North Slope, where operations are more costly, less attractive recently.

Some major banks, including JPMorgan Chase and Goldman Sachs, have already announced they will not finance projects in the refuge, and other financial institutions are under pressure to follow suit.

The government estimates there could be 7.7 billion barrels of recoverable oil on the coastal plain, though seismic surveys have not been conducted since the 1980s. Initially the administration projected that leasing would generate $1.8 billion in revenue over a decade, but it has subsequently cut that estimate in half.

One of the unanswered questions is how much oil lies beneath the refuge’s surface. There has not been seismic testing to identify potential deposits since the 1980s, and the results of any new testing will not be released before companies are asked to make bids on leases there.

But Bernhardt said he did not think that would deter bidders. “I think a lot of people will bid for leases without seismic data,” he said.

correction

An earlier version of this report had an incorrect figure for government estimates for recoverable oil on the coastal plain. The correct figure is 7.7 billion barrels, not 11 billion gallons.