On June 19, 2015, Mats Granskog and his 35 crewmates found themselves drifting slowly southwestward, toward the edge of the Arctic Ocean’s floating lid of sea ice. The R/V Lance, their sturdy former sealing boat and now a Norwegian research vessel, was hitching a ride in an ice floe about a kilometer across. They were about as far from the North Pole as San Francisco is from Portland, Oregon.

Granskog, a sturdy 43-year-old of Finnish origin, is chief scientist in an unusual and ambitious effort to study the full life cycle of Arctic sea ice, from its formation in winter to melt-out in summer. He and his colleagues on the Norwegian Young Sea Ice Cruise, or N-ICE2015, hoped they would gain new insights into what some experts are calling the “new Arctic,” a region that’s feeling the brunt of human-caused climate change more intensely than any other.

Shifting sea ice can crush a boat, so mariners don’t typically freeze themselves into it on purpose. But that’s precisely what the crew of the Lance had done that January, in the dead of the polar night.

With just a small bubble of illumination from the boat, they had managed to unload tons of equipment onto the ice: scooters, sheds, buoys, ice drills, a tent and a 33-foot-tall weather mast. As the expedition progressed, they endured violent storms and temperatures plunging below minus 40 degrees Fahrenheit.

“There was also the threat that a hungry polar bear comes along and wants to chew on your equipment, or your leg,” Granskog recalls, with a hint of a smile. “We had a few close encounters in the dark, nothing serious, but of course it was a reminder that we are not the king in this place.”

By June 19, with the late spring sun doing a lazy 360 around the sky, they could at least see the polar bears coming. And conditions had improved considerably, with temperatures hovering around freezing. After breakfast, several crew members were preparing to head out onto the ice to squeeze in some final scientific work. The Lance would soon head for port in Svalbard, about a day’s cruise to the south.

Sea ice can melt quickly in June – especially these days, with global warming leaving the frozen layer much thinner and less extensive than it used to be. “We’re losing the sea ice,” observes Mark Serreze, director of the National Snow and Ice Data Center.

Studies suggest that the decline in summer Arctic sea ice has been steeper since the late 20th century than at any time in the past 1,450 years. Serreze predicts that within the next couple of decades, human-caused warming will leave the Arctic with no significant summer sea ice cover.

The melting ice has already turned the region into something of a new frontier, with many nations eyeing its sea routes, its strategic position between Eurasia and North America, and its potentially huge reserves of oil and gas. Indeed, the area north of the Arctic Circle may harbor an estimated 90 billion barrels of oil and 47 trillion cubic meters (1,670 trillion cubic feet) of natural gas, as well as 44 billion barrels of technically recoverable natural gas liquids. This amounts to 22 percent of the world’s undiscovered stores of these fuels. All that from an area comprising just 6 percent of Earth’s surface, according to a U.S. Geological Survey assessment.

And herein lies the polar paradox: As global warming from burning fossil fuels and other human activities causes sea ice to shrink, it helps open the Arctic to offshore fossil fuel exploration. Should large amounts be discovered and burned, it will be all the more challenging to meet the Paris Agreement goal to keep the rise in global temperatures this century well below 2C (3.6F) – and to limit the already significant impact on this and other regions. Meeting that goal was a stretch even before President Donald Trump announced he would pull the United States out of the accord. This latest move – and the burning of Arctic fossil fuel resources made accessible by continued warming – would likely put the 2C limit well out of reach.

Russia and Norway are already drilling in their own Arctic waters. So far, the output is relatively modest. Russia’s single Arctic offshore operation produced just 2.1 million tons of oil in 2016, which is not even enough to cover a single day’s consumption of petroleum in the U.S. But Arctic oil output could grow significantly in the coming years. And Moscow is definitely dreaming big. The country is laying claim, via peaceful means through the United Nations, to a vast swath of offshore territory – for exclusive rights to drilling, as well as fishing and other economic activities.

Russia also seems to have placed an iron fist into the velvet glove of its legal claim. In recent years, the nation has staged a major military buildup in the Arctic – more than what’s necessary for simple defense, says Heather A. Conley, a specialist in Arctic affairs at the Center for Strategic and International Studies. She argues that Moscow is trying to bring down an “ice curtain” in the region. While the Iron Curtain of the Cold War excluded citizens of the Soviet Union and its satellites from contact with the West, the ice curtain appears aimed at a different kind of exclusion: denying other nations access to large swaths of the Arctic.

Conley believes there’s a window of opportunity to prevent confrontation. “But windows can close,” she says.

The Arctic “is not only a potential environmental and ecological disaster,” Sweden’s foreign minister, Margot Wallström, told fellow European ministers and others at a conference in Norway earlier this year. Developments in the region “could also well develop into a security threat of global proportions.”

Out on the ice itself, though, the threat facing Granskog was tangible and immediate. He knew the ice could split open instantly, sending his N-ICE2015 researchers and their equipment tumbling into the drink. “Mother Nature is in control,” he says. “You’re walking on a thin piece of ice, and anything can happen.”

This is an excerpt from an article originally published by bioGraphic, an online magazine about nature and sustainability.