Major oil and gas firms abandoned most of their leases in the Arctic this week, just as President Obama and others are coming under increased pressure to avert dangerous warming in the region.

Royal Dutch Shell, ConocoPhillips, Eni and Iona Energy have relinquished all but one lease in the Chukchi Sea, company officials confirmed Tuesday, as well as some in the Beaufort Sea. The move to give back roughly $2.5 billion worth of oil and gas leases spanning 2.2 million acres of the Arctic Ocean, in the same week that the leaders of five Arctic nations are coming to Washington for a White House summit, has reignited the debate over how best to protect an area that is showing new signs of vulnerability to climate change.

“Today we are an important step closer to a sustainable future for the Arctic Ocean,” said Michael Levine, Pacific senior counsel for the advocacy group Oceana. “Hopefully, today marks the end of the ecologically and economically risky push to drill in the Arctic Ocean.”

In a statement Tuesday, Shell spokesman Curtis Smith said, “After extensive consideration and evaluation, Shell will relinquish all but one of its federal offshore leases in Alaska’s Chukchi Sea.”

“Separate evaluations are underway for our federal offshore leases in the Beaufort Sea,” Smith said, adding that the company plans to remove its remaining drilling equipment from the Arctic in the summer. “This action is consistent with our earlier decision not to explore offshore Alaska for the foreseeable future.”

Many Democratic lawmakers and environmental activists, however, are pushing for the administration to ban Arctic drilling altogether as part of the next five-year leasing plan, which runs from 2017 to 2022. Rep. Jared Huffman (D-Calif.), joined by Robert Dold (R-Ill.) and 66 House Democrats, sent a letter last week to Interior Secretary Sally Jewell calling for the administration to revise the leasing plan before it becomes final.

“As this administration laid out in the U.S.-Canada Joint Agreement, our nation should be focusing on achieving strong conservation goals for the Arctic and making decisions to develop oil and gas resources only when the highest safety and environmental standards are met, including national and global climate and environmental goals,” they wrote. “To meet these goals, the Arctic Ocean should be permanently protected from oil drilling, not used to drill for more fossil fuels that we will not need — and must not burn — if we are serious about powering our future with clean energy.”

Cindy Shogan, executive director of the Alaska Wilderness League, said Tuesday that there was no longer a way to reconcile oil and gas extraction in the Arctic with the administration’s climate goals. “The president has made a commitment to address climate change and protecting the Arctic must be part of that equation,” she said.

Some advocacy groups, such as the Natural Resources Defense Council, are lobbying Obama to ban leasing in the Arctic altogether, under a provision in the Outer Continental Shelf Lands Act. The president has invoked that authority twice, once to protect Alaska’s Bristol Bay in 2014, and again in 2015 to safeguard part of Alaska’s Arctic coast.

The new push comes as the leaders of Denmark, Finland, Iceland, Sweden and Norway will meet with Obama at the White House Friday, to discuss issues including global security, trade and climate change. The precarious state of the Arctic will come under discussion, according to both U.S. and foreign officials, and the group is still negotiating the final communique they will issue on the topic.

Rafe Pomerance, who heads a coalition of nongovernmental organizations researching Arctic climate science and policy known as Arctic 21, said that when it comes to the summit, “the real elephant in the room is climate change.”

In March, the maximum winter sea ice extent hit an all-time recorded low, as it shrunk below the 2014-15 record low. That same month, parts of the Arctic were more than 4 degrees Celsius, or more than 7.2 degrees Fahrenheit, higher than the historic average. April marked the lowest Northern Hemisphere snow cover on record.

And further south, in Alberta, raging wildfires have decimated a major oil-producing area for Canada, Fort McMurray. The fires have prompted the evacuation of more than 80,000 people from the northwestern Canadian city and destroyed at least 1,600 buildings there.

“The Arctic is losing its brightness,” Pomerance said, adding that trend will in turn accelerate sea ice loss in an area that warms two to three times as fast as lower parts of the globe.

Walt Meier, a research scientist at the NASA Goddard Space Flight Center’s Cryospheric Sciences Laboratory, said that “weather conditions in a given year, and even in a given location” help determine the maximum extent of the winter ice each year. But the fact that the maximum winter ice cover is now 7 percent below the average for the past three decades, he added, is significant.

“The main thing is there’s a downward trend since 1979,” Meier said in an interview. “That’s an indication that warming’s going on.”

Officials from the Nordic nations are debating whether to call for a study of how a global temperature rise of 1.5 degrees Celsius from pre-industrial levels–which is below the 2 degree C increase the world’s nations pledged to meet as part of the recent Paris accord–would impact the Arctic. Scientists such as Meier noted that even the lower temperature increase would have an enormous affect on the Arctic. because the region warms so much faster than other parts of the world.

“A 1 or 1.5 degree temperature rise in a place like Washington is something you may not notice that much, but up in the Arctic it can be the difference between skating on the ice, and swimming,” Meier said.

In an interview Monday, Sweden’s ambassador to the United States, Bjorn Lyrvall, said that the energy and climate components of this week’s agreement “will be substantial,” but the world’s nations must focus on implementing the global climate accord reached in December in Paris before committing to more ambitious climate targets.

“We’re obviously concerned about the science and the recent developments being reported,” he said. “First of all, we have to make sure what has been agreed will be implemented.”

Norway’s ambassador to the United States, Kare Aas, said in an interview that his nation was keenly aware of climate impacts, which is why it had pledged to spend $366 million a year for the next two decades to preserve forests in poorer countries.

“As an Arctic country, we are really witnessing the climate change as we are living. We are happy to see more countries are interested in paying a visit to the Arctic to see what’s happening there for themselves,” he said. “What Norway is doing on forests, including deforestation in developing countries, is part of our global agenda in fighting climate change.”