High up in the Arctic Ocean close to the North Pole, a solitary ship floats in darkness, moored to an expansive piece of ice.
If all goes according to plan, the ship will remain with that ice for an entire year, so that scientists on board can study the Arctic system and how it's responding to climate change.
It's a project called the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC). But finding a piece of ice thick and stable enough to host the mission's science and logistics is not easy, and there may be challenges for the ice and the scientists in the months ahead.
In the Arctic ice north of Siberia, the Russian research vessel Akademik Fedorov is testing the thickness of an ice floe by driving through it. This isn't the ship that will freeze into the ice for the year, but it's out here to help find a suitable floe for the ship that will, the German icebreaker Polarstern.
It's moving through ice that's so consolidated and vast that it looks almost like snow-covered land stretching to the horizon. Where the hull makes contact with the ice, chunks the size of couches and cars break off and turn over, water hissing as it runs down the sides.
Dozens of people have come out on deck to watch.
"It's so amazing," says Ian Raphael, a master's student from Dartmouth College who is part of the MOSAiC group studying sea ice. He's leaning over the bulwark of the ship watching the ice crack and capsize. "It's the deepest blue and there's so much variation in it."
The MOSAiC expedition — about a decade in the planning — is an international collaboration involving hundreds of scientists and almost 20 countries. Their goal is to better understand the changing Arctic and improve how it's represented in climate models.
"We need this information because the Arctic is changing so rapidly, and it's a place that we have not observed very well in the past," says Matthew Shupe, an atmospheric scientist with the University of Colorado and the National Oceanic and Atmospheric Administration and a co-coordinator for MOSAiC.
The last time scientists looked at the Arctic Ocean system so comprehensively was more than 20 years ago. But the Arctic has been warming at twice the rate of the rest of the world, and the picture there has changed dramatically.
That's why these researchers want a year out in the ice: to get an updated look at how the physics, the chemistry and the biology of this area work during all four seasons.
"We can't just go out there for a few weeks at a time to understand how that plays out," says Shupe.
But that design — a yearlong drift with one piece of ice — can have some pitfalls.
For example, they could get too close Russia's exclusive economic zone, where they'd have to stop collecting measurements. They could also get taken to a current north of Canada and Greenland called the "Beaufort Gyre," which could take them in circles.
By drifting on an Arctic current called the Transpolar Drift, they're hoping that in a year they'll wind up near the Fram Strait, the passage between Greenland and the Norwegian archipelago of Svalbard.
They've used ice drift data from the past 15 years to choose a starting area where they think they're likely to reach that ending spot, and avoid those places they don't want to go.
Now their task is finding an ice floe thick and stable enough to support the equipment and machinery they need and to last the whole year without melting or breaking apart.
Back on the ship, the ice hunt moves farther north. The scientists thought the floe they drove through was too close to where the ice meets the water, and they worried that could lead to early breakup from waves.
In the following days, teams go out by helicopter and snowmobiles to gauge ice thickness at different spots. They use airborne sensors and take direct measurements with drills.
But after four days, the picture doesn't look great.
"They're all not looking very promising," says Thomas Krumpen, a sea ice physicist with the Alfred Wegener Institute, which is spearheading the expedition. Krumpen is overseeing the ice search on Akademik Fedorov. "They're all very thin."
MOSAiC will be putting out a ton of equipment on the ice itself: scientific instruments, but also heavier huts and power infrastructure, and big machinery to move things around.
Ideally, to support all that, they're looking for something about 4 feet thick.
But that's not what they've been finding. Krumpen says that even on the thicker floes, only the top foot or so has been solid, stable ice. Underneath, much of the ice is what they call "rotten," meaning it's degraded and slushy.
Different scientists have different ideas about why they're encountering such thin ice conditions in this area. Some think that warm temperatures in the Arctic this summer played a role. Krumpen thinks it has to do with natural variability in the origin of the ice; that it may have developed relatively close to this spot, and as a result may be younger ice that has had less time to thicken.
But there's agreement that a few decades ago, finding ice this thin in this part of the Arctic would have been much less likely.
"There is a change that can be related to Arctic warming," Krumpen says. "Ice is getting thinner; ice is retreating farther north."
Then, there's a breakthrough.
The scientists on the other ship find something they think will work. It's a floe about a mile and a half by 2 miles, and even though parts of it are thin, it has a centerpiece of thicker ice — in some places 13-16 feet.
"Really, it's like a hidden treasure," says Krumpen as he announces the find to the team on the Akademik Fedorov. "And I must say that we can be quite lucky that something like this was discovered."
But the challenges are not over. Fall is a time of year when the ice moves around a lot. Big pieces of it can collide with each other, creating cracks and huge ridges. And areas where the ice is thin are less likely to withstand that pressure.
That dynamism soon becomes evident in different parts of the ice camp, like out at "Met City," an area where they're collecting meteorological data.
"Stay on this side of the tower," says Matthew Shupe, gesturing to a rack of atmospheric instruments that has yet to be erected, "because you can see there's a crack right over there."
He points to a snaking gap in the ice several inches wide that skirts right along the edge of the tower.
"We heard a sound and the surface kind of rumbled," he says. "And then slowly this crack formed literally right under our feet."
Shupe had to wait a bit to stand the tower up because of that crack. "I don't want to be tethered to a piece of ice that might drift away and pull the tower down," he says.
He's not the only one having to accommodate the shifting ground: One ridge that formed from pressure in the ice buried a power cable, and in another area of the camp equipment had to be recovered and relocated after the ice it was on detached.
Dealing with ground that moves, cracks and buckles has always been part of working in this landscape. But scientists know they may face more of that as they try to study the thinner ice of the "new" Arctic.
As things get colder this winter, Shupe thinks the ice should settle a bit. But there's no knowing where exactly this ice will drift and how it will hold up over the next 11 months.
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