Beneath the icy surface of Alaska, an ancient world is coming back to life. Scientists have revived microorganisms that were frozen for nearly 40,000 years in a tunnel near Fairbanks. Initially dormant, these microbes are now multiplying and releasing greenhouse gases that could accelerate climate change.
For the first six months, these tiny organisms showed little life. Then, something changed. Microbial colonies exploded into visible biofilms and began emitting carbon dioxide and methane, both potent climate change gases. This surprising shift suggests that biological processes may already be at play under Arctic soils.
This research, published in the Journal of Geophysical Research: Biogeosciences, is crucial as permafrost—covering nearly a quarter of the Northern Hemisphere—is rapidly melting due to human-induced climate change. When permafrost thaws, it releases organic carbon that can break down, leading to billions of tons of additional greenhouse gases.
Researchers from the University of Colorado Boulder gathered soil cores from the Permafrost Research Tunnel near Fox, Alaska, operated by the U.S. Army Corps of Engineers. Some of the samples were taken from more than 20 meters deep and date back to the late Pleistocene.
After thawing the samples at temperatures mimicking modern Arctic summers, scientists noted a slow but definite biological response. They tracked the growth using water enriched with deuterium, an isotope that gets absorbed into the cell membranes of active microbes.
At first, the activity was minimal. Some days showed only slight changes in cell count. But by the sixth month, microbial communities transformed rapidly. Beautiful biofilms appeared, showcasing the revival of ancient life.
This discovery shows that permafrost microbes can return to life under current climate conditions—an alarming realization given their potential impact on our atmosphere.
The findings are significant. Once these microbes wake up, they consume organic matter trapped in the frozen soil and release greenhouse gases like CO₂ and methane. NASA’s Earth Observatory estimates that the carbon locked in permafrost is about twice the amount currently in the atmosphere. This shift from frozen storage to active emissions poses a serious threat to climate stability.
Tristan Caro, the study’s lead author, emphasized that it’s not just short heatwaves driving this activity, but the lengthening of the warm season. In Alaska, a few hot days aren’t the issue; it’s the extended warm temperatures leading into fall and spring that matter most.
What’s concerning is the lag between thawing and microbial activity. Initial signs of life might not be apparent right away, but in a few weeks, growth can be explosive. This delay suggests that warming may not cause immediate carbon releases but could lead to cascading emissions in the following months. As climate models are updated to include permafrost thaw, this timing mismatch might result in significant underestimations of how quickly permafrost can contribute to climate change.
Sebastian Kopf, a co-author and professor at CU Boulder, pointed out that the connection between permafrost and climate remains uncertain. Different microbial communities respond uniquely based on their environment and nutrient supply, meaning permafrost biology varies significantly from place to place. Yet, a common thread runs through these communities: they are all caught in a feedback loop driven by warming.
While this study focused on Alaskan permafrost, similar ecosystems likely exist in vast areas of Siberia, Canada, Greenland, and even parts of South America. The reality is that much of what lies beneath those frozen soils remains unmapped and unmonitored. As climate change continues, understanding these hidden ecosystems becomes more critical than ever.
For more about the impacts of permafrost on climate change, check out NASA’s insights here.
