On a sparkling day on May 18, the nearly 300-meter-long tanker Christophe de Margerie set sail from the northern Russian port of Sabetta. Crossing the so-called Northern Sea Route in the Arctic waters, in just under three weeks it moored at the Chinese port of Yangkou, unloading its shipment of liquefied natural gas.

That relatively routine journey has now entered the record books: the earliest date a cargo ship took what’s usually an ice-blocked route. It’s yet another sign of how climate change is shrinking the Arctic.

Around the same time the gas reached port, a ship called the Polarstern was also sailing in Arctic waters. But it was loaded with about 100 climate scientists from some 20 countries engaged in an exhaustive, year-long examination of the warming environment. To put it another way, the crew of the scientific ship is trying to understand why the tanker was able to leave so early in the season and what it means for the future of the planet.

The two vessels tell the tale of a tug of war now playing out in Earth’s last frontier. One is looking for clues to climate change, and the other is racing to exploit that change for financial profit. It’s another kind of feedback loop, with ships passing in melting waters.

Unlike other areas of the planet, the Arctic is so inaccessible that there’s very little data to predict with precision how the ice cap will change under rapid warming. Researchers on the Polarstern’s MOSAiC mission—the largest polar expedition in history and the first modern vessel to spend a full winter close to the North Pole—are aiming to fill in the gaps of knowledge.

Scientists are certain that the Arctic ice is disappearing. The shrinking ice cap accelerates warming globally. As Greenland and other Arctic glaciers lose ice, they help raise sea levels, potentially exposing millions of people to flooding. Nearly every dramatic, the headline-grabbing effect of climate change, from alarming coastal erosion to intense and frequent fires, is already happening in the Arctic, at a fast pace and at a giant magnitude.

“These individual things are part of a very complex system that’s changing dramatically,” says Guido Grosse, head of the permafrost research unit at the Alfred Wegener Institute, Helmholtz Institute for Polar and Sea Research, or AWI. “Because it is very remote people have a hard time understanding how it might affect our life in more temperate regions. But it will.”

About a third of the size of the Christophe de Margerie gas tanker, the Polarstern is almost like a second home for polar scientists. The ship has been sailing Arctic and Antarctic waters for almost four decades. Spending months on the blue and white research vessel means sharing a tiny cabin with another scientist, sleeping in tight bunk beds and sipping infinite amounts of tea and coffee in the ship’s Red Saloon.

A satellite internet connection allows the researchers to communicate with loved ones on the mainland via Whatsapp. On the long winter days, Agatha Christie-style murder mystery games are organized to kill the hours. Friendships are forged–and broken—and the vessel’s sauna, gym and the small swimming pool become welcomed distractions. With no goals and multiple balls, scientists have invented a special discipline of water polo that only exists on the Polarstern.