Permafrost is one the weirder concoctions of the Earth’s Ice Ages. In the abstract, it sounds like a simple substance—any earth material that stays frozen for two or more years. In reality, it is a shape-shifting material that underlies about 24 percent of land in the Northern Hemisphere—from the Tibetan Plateau to Siberia and parts of Arctic and sub-Arctic North America. Now many such areas are becoming both volatile and fragile. Permafrost can be hard as bedrock, but when it thaws, if it’s rich in ice and silt, it can morph into something like glue or chocolate milk or wet cement. In its frozen state, it can hoard materials for thousands of years without allowing them to decay. It can suspend bacteria in a kind of cryo-sleep—still alive for millennia.

And microbes may have an even more disturbing role in shaping the fate of the atmosphere: It is the microbes that will determine how much of the permafrost’s carbon escapes into the air and how much can be stored again in the dirt. In 2013, Wickland and a group of her collaborators came to the tunnel to gather bits of 35,000-year-old permafrost that had been carved out of the walls during the recent excavation. They collected these scrapings in several coolers packed with dry ice then flew with them to their laboratory in Colorado. They suspended the samples in water, then strained them, like tea, and measured how much carbon dioxide leached from the water.

The thawed, awakened bacteria in the tea began breaking down the organic carbon in the sample; in less than a week, about half of it was emitted into the air as carbon dioxide. It was a disturbing finding. Scientists had long debated how quickly or gradually the thawing of permafrost would affect the global climate. But this study suggested the warming of ancient soils could produce a giant burst of emissions into the atmosphere in a short period of time—one more reason to be wary of the stuff.

In the next 80 years, in just one lifetime, most of Alaska’s near-surface permafrost will fall apart, Douglas explains. “That will fundamentally alter hydrology, vegetation, the snowpack, the timing of spring melt, heat exchange, habitats for animals, and it’ll basically completely change the landscape.” The work ahead at Fox, he adds, is to understand the staggering ramifications of this loss. Alaska and all of the far North, he says, are “just going to be a fundamentally different place.”

https://www.smithsonianmag.com/science-nature/tunnel-beneath-alaska-180974804/