Frozen viruses, modern risks: Could melting permafrost spark future pandemics?

It starts with a crack in the ice. Then another.
Beneath the frozen soil of the Arctic, something ancient is waking up — and it’s not a mammoth.

In recent years, scientists have revived viruses frozen in permafrost for tens of thousands of years. These microbes, long thought dormant and harmless, are showing signs of activity in lab experiments. As climate change accelerates the thawing of Earth's oldest ice, some researchers are asking a startling question: What happens when the microbial past collides with the modern world?

Permafrost is ground that’s remained frozen for at least two consecutive years — and in some regions of the Arctic, it’s been frozen for tens of thousands. It stretches across vast expanses of Siberia, Alaska, northern Canada, and Greenland, acting as a natural deep freezer for ancient organic material. As global temperatures rise, this permafrost is thawing faster and deeper than expected, revealing not just bones or moss but biological matter. And some of it is still alive.

So, what exactly is emerging from the ice, and how far back does it take us?

In 2022, researchers in France led by virologist Jean-Michel Claverie revived 13 previously unknown viruses from Siberian permafrost. The oldest, Pandoravirus yedoma, was estimated to be 48,500 years old and still capable of infecting amoebas. These findings confirmed what many scientists had long suspected: ancient viruses can survive in frozen conditions and remain infectious.

While these viruses aren’t known to infect humans, their survival raises serious questions. If one virus can endure nearly 50,000 years in the frozen permafrost, what else might be preserved beneath the surface? What could happen if those microbes are reintroduced into today’s ecosystems? 

"The permafrost isn’t just melting—it’s unlocking a biological archive."

-- Douglas Johnson

The idea of a deadly contagion emerging from ancient ice sounds like science fiction — and in some ways, it is. One of the most compelling recent examples is HBO’s hit series The Last of Us, which imagines a global fungal pandemic triggered by rising temperatures. In the show’s opening scene, a scientist warns that climate change could push certain pathogens — like Cordyceps — to evolve the ability to survive in the human body, setting off a chain reaction of infection and collapse. The series, adapted from the critically acclaimed video game of the same name, became a cultural phenomenon.

What resonated with many viewers wasn’t just the drama but the premise: warming temperatures could turn once-benign organisms into global threats. While The Last of Us focuses on fungi, the broader message mirrors real scientific concerns about climate change reintroducing or reshaping pathogens that have long been thought to be buried by time.

In 2016, an anthrax outbreak occurred in Russia’s Yamal Peninsula, linked to the thawing of permafrost that exposed a decades-old reindeer carcass. An unusually warm summer accelerated permafrost melt, releasing dormant Bacillus anthracis spores into the environment. The spores were released from the frozen remains, leading to the infection of over 2,000 reindeer and spreading to nearby communities. While the outbreak was contained, it resulted in numerous hospitalizations and an unfortunate pediatric death. The incident underscored how climate-induced permafrost thaw can reactivate long-dormant pathogens, posing renewed threats to both animal and human health.

Could an ancient virus be similarly reactivated and infect humans today? Possibly—but not easily. Most of the viruses revived so far only infect amoebas, not animals or humans. However, viral evolution is unpredictable. With the right conditions and intermediate hosts, there is a theoretical risk that an ancient virus could adapt to infect new species, including humans. Spillover events like these are not uncommon in recent history—SARS-CoV-2, HIV, and Ebola all emerged through animal-to-human transmission.

The bigger concern is our immune system’s lack of recognition. Our adaptive immune systems rely on memory—previous exposure to similar pathogens. If a virus from the Ice Age reappears, our bodies might not recognize it. Even our innate immune defenses, which identify general patterns associated with microbes, might struggle to respond to something ancient and unfamiliar.

Of course, there are also reasons to believe these viruses may pose little danger. Many scientists point out that revived viruses are often too fragile to survive modern environmental conditions—ultraviolet light, oxygen, and microbial competition may destroy them before they can spread. However, the fact that some can still infect host cells under the right lab conditions suggests they can’t be entirely dismissed.

And this all points to a broader issue: permafrost isn’t just melting—it’s unlocking a biological archive.

Alongside viruses, melting permafrost releases methane and carbon dioxide trapped in ice for centuries. These greenhouse gases accelerate global warming, which in turn causes more melting—a dangerous feedback loop. If viruses are the microscopic echo of past pandemics, then the melting permafrost is the amplifier that could carry their voices into the future.

This growing concern has prompted calls for better microbial surveillance in the Arctic. Scientists argue we need early warning systems, improved climate infrastructure, and clearer ethical standards when handling ancient biological material. Revising these viruses isn’t inherently dangerous but requires caution, transparency, and strict containment protocols.

If the COVID-19 pandemic taught us anything, it’s that new pathogens can reshape the world in unexpected ways. While the next outbreak may not come from melting ice, climate change is expanding the range of microbial risks — and blurring the lines between ancient and modern ecosystems.

Reviving viruses from permafrost isn’t cause for alarm, but it does highlight the need for preparedness. Continued investment in virology, climate science, and disease surveillance will be essential, especially in vulnerable regions like the Arctic.

Through responsible research, consistent monitoring, and international collaboration, we can better understand these ancient microbes and the conditions that may bring them back into circulation. As the climate continues to shift, so too must our scientific focus. The more we study what’s beneath our feet, the better prepared we’ll be for what lies ahead.