How scientists can see Earth’s permafrost thawing from space

To start, the US has significant military infrastructure in Alaska: It’s home to six military bases and 49 National Guard posts, as well as 21 missile-detecting radar sites. Most are vulnerable to thaw now or in the near future, given that 85% of the state is on permafrost. 

Beyond American borders, the broader north is in a state of tension. Russia’s relations with Northern Europe are icy. Its invasion of Ukraine has left those countries fearing that they too could be invaded, prompting Sweden and Finland, for instance, to join NATO. The US has threatened takeovers of Greenland and Canada. And China—which has shipping and resource ambitions for the region—is jockeying to surpass the US as the premier superpower. 

Permafrost plays a role in the situation. “As knowledge has expanded, so has the understanding that thawing permafrost can affect things NGA cares about, including the stability of infrastructure in Russia and China,” read the NGA article. Permafrost covers 60% of Russia, and thaws have affected more than 40% of buildings in northern Russia already, according to statements from the country’s minister of natural resources in 2021. Experts say critical infrastructure like roads and pipelines is at risk, along with military installations. That could weaken both Russia’s strategic position and the security of its residents. In China, meanwhile, according to a report from the Council on Strategic Risks, important moving parts like the Qinghai-Tibet Railway, “which allows Beijing to more quickly move military personnel near contested areas of the Indian border,” is susceptible to ground thaw—as are oil and gas pipelines linking Russia and China. 

In the field

Any permafrost analysis that relies on data from space requires verification on Earth. The hope is that remote methods will become reliable enough to use on their own, but while they’re being developed, researchers must still get their hands muddy with more straightforward and longer tested physical methods. Some use a network called Circumpolar Active Layer Monitoring, which has existed since 1991, incorporating active-layer data from hundreds of measurement sites across the Northern Hemisphere. 

Sometimes, that data comes from people physically probing an area; other sites use tubes permanently inserted into the ground, filled with a liquid that indicates freezing; still others use underground cables that measure soil temperature. Some researchers, like Schaefer, lug ground-penetrating radar systems around the tundra. He’s taken his system to around 50 sites and made more than 200,000 measurements of the active layer.

The field-ready ground-penetrating radar comes in a big box—the size of a steamer trunk—that emits radio pulses. These pulses bounce off the bottom of the active layer, or the top of the permafrost. In this case, the timing of that reflection reveals how thick the active layer is. With handles designed for humans, Schaefer’s team drags this box around the Arctic’s boggier areas. 

The box floats. “I do not,” he says. He has vivid memories of tromping through wetlands, his legs pushing straight down through the muck, his body sinking up to his hips.

Zwieback also needs to verify what he infers from his space data. And so in 2022, he went to the Toolik Field station, a National Science Foundation–funded ecology research facility along the Dalton Highway and adjacent to Schaefer’s Toolik Lake. This road, which goes from Fairbanks up to the Arctic Ocean, is colloquially called the Haul Road; it was made famous in the TV show Ice Road Truckers. From this access point, Zwieback’s team needed to get deep samples of soil whose ice content could be analyzed in the lab.