There are layers of frozen ground that haven’t thawed since the last ice age somewhere beneath Siberia’s flat, grey-brown terrain, which for the majority of the year appears to be the end of something. There are deeper layers that completely predate modern humans. Above them walked woolly mammoths. Above them, cave lions were born and died. And things have been waiting inside, trapped in an oxygen-free blackness that has never seen light. Some of those things are still capable of awakening, according to researchers who have drilled into that permafrost and extracted soil cores.
A virus that had been frozen in Siberian permafrost for about 48,500 years was revived in 2023 by a team of researchers under the direction of Jean-Michel Claverie, an emeritus professor of medicine and genomics at the Aix-Marseille University School of Medicine in Marseille, France. It was still contagious. The fact that the virus survived after being frozen in the ground for almost 50,000 years is not insignificant, but the fact that it targets amoebas rather than humans kept the immediate alarm level manageable. It raises a question that scientists have been carefully considering: if that one survived, what else is there? It also provides insight into how well permafrost preserves biological material.
| Category | Details |
|---|---|
| Permafrost Coverage | Covers approximately 23 million sq km in the Northern Hemisphere |
| Permafrost Age (deepest layers) | Up to one million years old |
| Regions Affected | Alaska, Canada, Russia (Siberia), Arctic tundra and boreal forests |
| Arctic Warming Rate | Up to four times faster than the global average |
| Oldest Revived Virus | 48,500 years old — amoeba-targeting virus, revived from Siberian permafrost |
| First Permafrost Virus Revival | 2014 — 30,000-year-old virus extracted from Siberia; infected amoebas only |
| Lead Researcher (zombie viruses) | Prof. Jean-Michel Claverie, Aix-Marseille University School of Medicine, France |
| Key NASA Scientist | Kimberley Miner, NASA Jet Propulsion Laboratory, Pasadena, California |
| Antibiotic-Resistant Microbes | Over 100 diverse microorganisms found in deep Siberian permafrost |
| Permafrost Loss Projection | Up to two-thirds of near-surface permafrost could be lost by 2100 |
| Additional Hazards Released | Cold War nuclear waste, DDT insecticide, arsenic, mercury, nickel deposits |
| Human Settlements on Permafrost | More than 1,000 settlements built on permafrost over the last 70 years |
| Research Program | ESA–NASA Arctic Methane and Permafrost Challenge |
| Permafrost Function | Oxygen-free, light-free environment — acts as a natural long-term preservative |
Permafrost, or permanently frozen ground, extends beneath the tundra and boreal forests of Russia, Canada, and Alaska over an area of about 23 million square kilometers in the Northern Hemisphere. Up to a million years have passed since the deeper layers were formed. It essentially acts as a huge natural freezer, devoid of light and oxygen, and cold enough to preserve biological and chemical materials in a state of suspended preservation for unfathomably long periods of time. This was a stable state of affairs for the majority of recorded history. It isn’t anymore. The Arctic is currently warming at a rate that is up to four times faster than the rest of the planet, and this warming is penetrating ground that has been frozen since pre-agricultural times.
Since melting permafrost releases greenhouse gases into the atmosphere in a feedback loop with direct and quantifiable climate consequences, it makes sense that the biological risks receive less attention than the methane issue. However, studies carried out under the ESA-NASA Arctic Methane and Permafrost Challenge and published in Nature Climate Change have been painting a more nuanced picture of what is emerging alongside that methane.
At depths of more than three meters, deep permafrost is one of the few environments on Earth that has never been exposed to contemporary antibiotics. More than 100 different microorganisms found in Siberia’s deep permafrost have already been identified as antibiotic resistant. It is possible that those bacteria will grow into new antibiotic-resistant strains that are incapable of being treated by current therapies as that ground thaws and combines with meltwater. That’s a different kind of public health issue, one that doesn’t need an old virus to pose a direct threat to people.
Climate scientist Kimberley Miner of NASA’s Jet Propulsion Laboratory in Pasadena, California, has been candid about how little is known about this aspect of permafrost thawing. Tens of thousands of years ago, giant sloths, woolly mammoths, and other extinct species coevolved with the microbes preserved in these frozen layers. It is truly unknown what happens when organisms shaped by that ancient ecosystem reappear in a world that has moved on without them. “We have no idea what they could do when released into our ecosystems,” Miner said. Most might not pose a serious threat. It’s also possible that some do, and the truth is that there is currently no reliable way for science to distinguish between the two.
Additionally, the risks posed by microbes and viruses are not isolated. Nuclear waste from the Cold War era, radioactive material from decommissioned reactors and submarines, DDT and other currently prohibited pesticides that were transported to the Arctic through the atmosphere decades ago, and natural deposits of arsenic, mercury, and nickel from decades of mining operations are all stored in the same permafrost. All of this becomes mobile as the ground thaws and water movement increases; it spreads through meltwater systems, enters food chains, and reaches communities that are frequently isolated and ill-prepared to recognize or address contamination. Over the past 70 years, over 1,000 settlements—from military and scientific facilities to resource extraction outposts—have been constructed on permafrost. The residents and employees of those locations are more than just abstract data points.
Upon closely examining this research, it seems that the public’s understanding of the implications of permafrost thawing has not yet fully taken hold. The atmosphere—temperatures, sea levels, and storm frequency—is frequently the subject of climate discussions. Secondary attention is given to the ground beneath the Arctic and its contents. It might not be. More comprehensive research, improved modeling of when and where particular hazards will appear, and mitigation strategies—which do not yet exist in any comprehensive form—are all demanded by scientists. For a very long time, the permafrost kept its secrets. Regardless of whether anyone is prepared or not, it is giving them up now.
