As the planet warms due to climate change, fears are growing among scientists that ancient disease-causing pathogens could be unleashed from the melting permafrost in the Arctic Circle.
Those fears are already being borne out. Just last August, in the tundra of the Yamalo-Nenets region of Siberia, nearly 100 people and 2,300 reindeer became infected with anthrax in the first outbreak there since 1941. One 12-year-old boy died.
Scientists believe the anthrax was released into the environment after being trapped in a long-frozen reindeer carcass that thawed during a summer-long heatwave.
Scientists have also discovered two viruses in the Siberian permafrost that were still infectious, even after 30,000 years.
Thankfully, those viruses infect only amoebas and aren’t dangerous to humans. But the French scientific team that discovered the second virus noted "[the] fact that two different viruses retain their infectivity in prehistorical permafrost layers should be of concern in a context of global warming."
Dr. Stuart Harris, chief of the division of wilderness medicine at Massachusetts General Hospital, says it’s not unreasonable to think that more such outbreaks could happen as climate change brings warmth to soils that have been frozen for thousands of years.
He told CTV’s Your Morning on Tuesday that, given the thousands of hectares of ice that is covering 30,000 or 40,000 years of biologic history, “the likelihood, if this melts, that you’re going to have something revealed would strike me as not trivial; it’s pretty high.”
Harris says permafrost is a great preserver and “acts like the best freezer you could have in your basement.” It’s not only very cold, it’s continuously cold -- at least beneath the top few metres that melt and freeze with the season.
What’s more, the ice protects organisms and potential pathogens in ice that is preserved from ultraviolet light, which can break down DNA and RNA.
Harris said he wasn’t surprised to learn that anthrax managed to revive and spread, given that anthrax bacteria reproduce through spores, and spores are “remarkably resistant” and able to survive longer than average bacteria.
“So that is not at all surprising that it would be able to come back after 60, 80 or 100 years if it’s well-preserved,” he said.
Other bacteria are more complex and fragile and may not survive as easily. But viruses, which are not organisms, can go dormant for years while waiting for a host cell to infect.
Harris says permafrost has proven to be a “remarkably good preserver of biological specimens,” which is why so many skeletons are found almost fully intact when the ice melts.
That’s good news if you’re looking to find bones and fossils of ancient animals, he says, “(but) it’s kind of scary if those ancient animals are harbouring pathogens that the human species has kind of forgotten about and can’t mount a good response against.”
