Beneath the planet’s permafrost lies a host of malevolent microbes, active long before human civilization arose. Viruses, bacteria, and other ancient microorganisms have rested in a dormant state for tens of thousands of years. Now, as rising temperatures thaw the planet’s ice, they are beginning to stir. The most obvious doomsday scenario is a pandemic, but here’s a threat you likely didn’t anticipate: your potatoes.
In 2022, scientists from Aix-Marseille University in France revived 13 viruses from permafrost samples collected in the icy Russian Far East, including one that dates back 48,500 years—the oldest virus ever awakened.
They also isolated three novel viruses from a 27,000-year-old frozen mammoth dung sample and a chunk of permafrost packed with mammoth hair, naming them Pithovirus mammoth, Pandoravirus mammoth, and Megavirus mammoth, respectively. Two more new viruses were extracted from the frozen stomach contents of a Siberian wolf and christened Pacmanvirus lupus and Pandoravirus lupus.
Most remarkably, the pathogens had not lost their virulence after tens of thousands of years of inactivity. Given some exposure, the viruses remained viable and capable of infecting single-celled amoebas.
Although all this occurred under laboratory conditions, the researchers explained that this risky investigation highlighted serious real-world risks.
“It is therefore plausible that ancient permafrost […] will release these unknown viruses upon thawing,” the researchers wrote in their paper published in the journal Viruses.
“How long these viruses can remain infectious after environmental contact, and how likely they are to encounter and infect a suitable host during this period, cannot yet be assessed, but the risk will inevitably increase in a global warming context where permafrost thaw continues to accelerate, and Arctic populations increase due to industrial activities,” they concluded.
If similar pathogenic microbes were to infect humans on a massive scale, the consequences could be catastrophic. The world brushed up against this scenario once before in 2016 when dozens fell ill on the Yamal Peninsula in Siberia. Heat had apparently thawed the permafrost in the area, exposing the carcass of a reindeer infected with anthrax decades earlier. Somehow, the bacteria spread, killing one child and leading to the culling of over 200,000 reindeer.
This reignited discussions about whether long-extinct microbes could make a comeback and infect humans once more.
But the threats are not limited to human diseases. Far less discussed is the scenario in which thawing permafrost could reveal pathogens that afflict crops, leading to severe disruptions in agriculture and the global food system.
In a recent study, scientists from the Polar Research Institute of Korea brought permafrost samples from Alaska’s Seward Peninsula to the lab and allowed them to thaw. Over 90 days, one microbe staged a silent coup. The bacterium Pseudomonas, a pathogen responsible for potato soft rot—a disease that turns many crops into a mushy mess—proliferated rapidly, reaching new, dramatic levels as the icy grip loosened. Bacteria from the thawed permafrost were then applied to potato tubers, where they infected them and turned them into an inedible pulp.
Numerous other crop-devastating pathogens may also be preserved in the icy deposits. Researchers also found the tomato mosaic virus in ice cores from Greenland dating back 140,000 years. This virus is known for its resilience and can infect not only tomatoes but also cucumbers, peppers, lettuce, and beets.
In the early 21st century, humanity does not typically farm in the northernmost regions of Earth, where most permafrost is concentrated. However, as temperatures rise, more people are venturing north to plant vegetables, grains, and other crops in newly thawed soil.
If this trend continues, it could prove to be a major boon for the frozen microorganisms dwelling there.
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