Areas covered by tundra are warming at a far faster rate than other parts of the world. Some scientists predict that as much as half of all permafrost in the Northern Hemisphere will disappear completely by the mid-century.
Ignoring the havoc this will cause to wildlife, the impact on the climate will likely be disastrous. The thawing of the permafrost will release gigatonnes of carbon dioxide and methane into the atmosphere. How much exactly depends on which estimate you look at, but one predicts it will average 1.5 billion tons a year over the course of the next century. To put this into perspective, that's roughly the amount the United States produces in one year from burning fossil fuels.
Permafrost (as of 2017) covers roughly 24 percent of land surface in the Northern Hemisphere. It's a thick coating of soil that remains frozen all year long.
Right now, it acts like a storage room for carbon. Scientists reckon that, worldwide, permafrost contains something like twice the amount of carbon currently in the atmosphere. But when the permafrost thaws, microbes convert the carbon into carbon dioxide and methane. This process could result in an extra 1°C (1.7°F) of warming.
Max Holmes, a senior scientist at the Woods Hole Research Center, led a group of scientists to the Yukon Delta National Wildlife Refuge in Alaska. Here, they embedded temperature probes into the frozen ground and collected samples of permafrost cores, sediment, and water to analyze the carbon content and nutrients.
They discovered that 1 meter (3 feet) below surface level, temperatures are less than half a degree below freezing. This suggests we'll lose much of the permafrost that currently covers the Earth by mid-century.
“[That] has all kinds of consequences both locally for this region, for the animals and the people who live here, as well as globally,” Holmes told the New York Times. “It’s sobering to think of this magnificent landscape and how fundamentally it can change over a relatively short time period.”
Further north, scientists measured the temperature of ice 20 meters (65 feet) below surface level. Temperatures here have risen by 3°C (5.5°F) in just decades. At one site, near-surface changes rose from -8°C to -3°C.
"Minus 3 is not that far from zero," Vladimir E. Ramonovsky, permafrost researcher at the University of Alaska, told the New York Times.
Scientists can't agree when and how much of Alaska's permafrost will thaw - no doubt it will take thousands of years to thaw completely - but as Dr Romanovsky points out, it "is not as stable as people thought."
As Holmes said, there are vast amounts of carbon locked in the ground built up over millennia. "It's been in a freezer, and that freezer is now turning into a refrigerator."