The Dry Valleys are home to some of the unfriendliest terrain that humans could contemplate setting foot on. It’s frigidly cold, incredibly dry, and its rust-colored soil is practically lifeless. Yet, despite all appearances to the contrary, these valleys are not 33 million miles away on Mars. They’re right here on Earth–and they’re facing down a very Earth-bound problem.

“A cold day in the Dry Valleys is like an average day on Mars,” explains University of Texas geophysicist Joe Levy, who has been visiting and studying Antarctica’s Dry Valleys since 2004. Those cold temperatures, which regularly dip below -55 degrees Celsius, combine with some of the driest dirt on Earth to form an Earth-based Mars lab.

There (along with a couple other Martian analogues in the Arctic–more on those in a moment) researchers test their ideas about how life, whether something native or a human colonist, could survive on Mars, all within the relative comforts of their home planet. But now, these windows into life on the red planet could be closing. “We’re just beginning to appreciate that the Dry Valleys are on the threshold of this major change,” says Levy. That shift is happening in the context of a much larger rise in global temperature. Just this month, the World Meteorological Organization confirmed, to no one’s surprise, that 2016 was on track to snatch 2015’s title as the hottest year ever recorded.

So far, the permafrost in the high-elevation interiors of the Antarctic Dry Valleys–where the terrain is exceptionally dry and cold, like Mars might see today–has remained largely untouched by the upward swing of global temperatures. But the Dry Valleys are also home to something else just as incredible: a lower, coastal region that mirrors the wetter, warmer Mars that existed millions of years ago.

“There’s a time machine element to the Dry Valleys,” explains Levy. “When you head out into the coastal Dry Valleys, it’s like you’re headed back in time on Mars.”

It’s in that ancient-Martian twin–where researchers hope to find answers about how water once flowed on the planet–that Levy has been tracking signs of accelerating collapse. Since he first arrived over a dozen years ago, he’s observed melting ground ice and an increase in the rate of both melt and breakage in the ice along the coastal deltas. “There’s a risk of seeing a loss of the usefulness of the low parts of the Dry Valleys,” says Levy. “The big question in those warmer, wetter parts is are we going to see more precipitation, or even a change from snowfall to rainfall, that turns a very clear Mars analogue into something that’s just more Arctic-like.”

The upper-region of the Arctic is home to its own set of Martian-cognates–although, not quite as close to Mars in terms of either temperature or dryness as the Antarctic Dry Valleys. Those upper-Arctic regions, however, are providing scientists with a real-time example of just how fragile these mirror environments can be once collapse begins.

NASA researcher Chris McKay has been visiting Martian parallel environments both in Antarctica and the upper-Arctic since the 1980s. In almost four decades, he’s seen “remarkable” changes in the Arctic’s Martian counterparts, including fast-thawing permafrost and melting sea ice. “In 10 years, it’s not going to be like this,” says McKay, “so study it now.”