Ancient viruses could re-emerge as permafrost melts, posing 'unpredictable threats' to our communities, new study says

• Scientists are studying a new threat emerging from melting permafrost: ancient viruses.
• A new study says these pathogens could pose significant risks to modern-day humans.

As permafrost thaws across the world due to a warming climate, scientists are researching a potential new threat: The emergence of ancient viruses trapped in the frost for tens of thousands of years.

The authors of the study — published in PLOS Computational Biology, a peer-reviewed scientific journal — used computer simulations to model how ancient viruses could survive, evolve, and persist in our modern-day communities. This research marks the first "extensive exploration of the ecological risk" these viruses pose, according to the authors.

Melting permafrost is already revealing organisms that have been trapped beneath the ice for millennia. In a study published last month, scientists said they discovered a 46,000-year-old microscopic worm trapped in Siberian permafrost that was still capable of producing offspring. And earlier this year, a French scientist identified a 48,000-year-old virus in Siberian permafrost that could still infect single-celled organisms.

In many of the simulations conducted in the study of the ancient viruses, researchers found that they could thrive in modern communities without making a catastrophic impact, but still caused "non-negligible ecological change."

The simulations found that just 1% of cases resulted in major ecological damage. But within this small percentage, the simulations found that the pathogens would either increase species diversity by 12% or decrease species diversity by 32%, according to the authors.

That 1% is important, the authors warn, and these low-probability yet catastrophic re-emergence scenarios require further attention.

"Risk does not emerge solely from the chance of the event occurring, but from the combination of probability and the magnitude of the event's potential effects," the authors wrote. "From that perspective, our results are worrisome, as they point to an actual risk deriving from the rare events where time-traveling invasions produce severe ecological impacts."

Plus, the pathogens that were most successful in the past are the most likely to successfully re-establish themselves today, according to the researchers. This means the viruses most likely to re-emerge successfully could also be the most likely to pose an ecological risk.

Experts have been sounding the alarm on melting permafrost for years, identifying it as just one of countless reasons to slow carbon emissions. Not only is the thawing permafrost a sign that global climate change is worsening, vast swaths of melting ice also pose a significant threat to human infrastructure.