While conducting research in Greenland, ice scientist Twila Moon was struck this summer by what climate change has doomed Earth to lose and what could still be saved.

The Arctic is warming three times faster than the rest of the planet and is on such a knife’s edge of survival that the UN climate negotiations underway in Scotland this week could make the difference between ice and water at the top of the world in the same way that a couple of tenths of a degree matter around the freezing mark, scientists say.

Arctic ice sheets and glaciers are shrinking, with some glaciers already gone. Permafrost, the icy soil that traps the potent greenhouse gas methane, is thawing. Wildfires have broken out in the Arctic. Siberia even hit 100 degrees Fahrenheit (38 degrees Celsius). Even a region called the Last Ice Area showed unexpected melting this year.

In the next couple of decades, the Arctic is likely to see summers with no sea ice.

As she returns regularly to Greenland, Moon, a researcher with the U.S. National Snow and Ice Data Centre, said she finds herself “mourning and grieving for the things we have lost already” because of past carbon dioxide emissions that trap heat.

But the decisions we make now about how much more carbon pollution Earth emits will mean “an incredibly large difference between how much ice we keep and how much we lose and how quickly,” she said.

The fate of the Arctic looms large during the climate talks in Glasgow — the farthest north the negotiations have taken place — because what happens in the Arctic doesn’t stay in the Arctic. Scientists believe the warming there is already contributing to weather calamities elsewhere around the world.

“If we end up in a seasonal sea ice-free Arctic in the summertime, that’s something human civilization has never known,” said former NASA chief scientist Waleed Abdalati, who runs the University of Colorado’s environment program. “That’s like taking a sledgehammer to the climate system.”

What’s happening in the Arctic is a runaway effect.

“Once you start melting, that kind of enhances more melt,” said University of Manitoba ice scientist Julienne Stroeve.

When covered with snow and ice, the Arctic reflects sunlight and heat. But that blanket is dwindling. And as more sea ice melts in the summer, “you’re revealing really dark ocean surfaces, just like a black T-shirt,” Moon said. Like dark clothing, the open patches of sea soak up heat from the sun more readily.

Between 1971 and 2019, the surface of the Arctic warmed three times faster than the rest of the world, according to the Arctic Monitoring and Assessment Program.