Permafrost, the frozen earth that covers a vast expanse of the Arctic is home to growing microbial communities. These microbes lay dormant, barely active or completely suspended for centuries, surviving on the pockets of water that exist between the ice.
Nearly a quarter of the Earth's northern hemisphere is covered in permafrost, and this permafrost stores not only water but microbes and viruses as well. As global warming thaws the ice, the Arctic is warming at two to five times the global average. These water pockets are becoming pools; rivulets, rivers; and puddles, ponds. The microscopic organisms embedded in the land are coming back to life.
In November 2019, 50 scientists from around the world assembled at Herrenhausen Palace in Hannover, Germany, to talk through this emerging threat to public health: "zombie" viruses and microbes emerging from the thawing ground. They conceded that the climate is warming and the permafrost is thawing. But they wanted to know what it all means for humans and the future of infectious disease.
"The impetus from the meeting was determining what's going to thaw out of the permafrost and kill us," said Susan Kutz, a professor of ecosystem public health at the University of Calgary and one of the scientists at the Hannover meeting.
A massive bank of ancient microbes or viruses
This threat is not a new headache, but has been the cause of concern to scientists for a while. There have been instances where long dormant or frozen microbes were successfully resurrected.
In a 2017 paper, a team of Belgian researchers described the threats to human health from microbes that were previously frozen in permafrost.
"Over the past few years, there has been increasing evidence that the permafrost is a gigantic reservoir of ancient microbes or viruses that may come back to life if environmental conditions change and set them free again," the authors wrote.
The paper also described a separate study in which two viruses emerged from a single sample of 700-year-old caribou droppings. They were both able to be resurrected.
In 2014, scientists discovered a giant virus frozen in a 30,000-year-old ice core. The scientists thawed it and watched it take over an amoeba.
Though not part of the Arctic, Tibet also contains permafrost and it also showed evidence of storing microbes. In 2015, researchers from China and the US embarked on a field trip to Tibet, and discovered 28 previously undiscovered virus groups—in a melting glacier.
Permafrost thawing as a result of global warming or industrial exploitation of circumpolar regions might cause more instances like these, and pose a threat to human or animal health - the scientists concluded.
Evolutionary ecologist Ellen Decaestecker, co-author of a 2017 paper, commented that the increasing encroachment of people into natural areas worldwide is presenting new opportunities for health crises.
"We are changing the environment very fast at this moment in terms of habitat fragmentation and climate change," she said, adding that people are also travelling more and more (before COVID-19 hit). "The chance that an outbreak happens as a result of the combination of these factors is quite high."
Not only do the viruses and microbes pose a risk of infectious diseases, but there is another dire possibility. They could contain the blueprints for resistance to antibiotics or other medicines. They could share that information with their modern relatives, given the chance.
An outbreak of anthrax in the warm summer of 2016 was the first warning the world received. The outbreak happened in the Yamal Peninsula in Siberia. Thousands of reindeer succumbed to it, while one human child died and dozens of people were hospitalised with bacterial infections.
Headlines at that time claimed that this was the start of a new wave of diseases that would not only reawaken from their frozen slumber but also infect and kill people.
The reality, as is often the case, is a little more nuanced.
A recently published paper suggests that a Russian anthrax vaccination program for reindeer that was halted in 2007 probably played a bigger role in the outbreak than a warm summer. The reindeer that died may have been one of the first ones without the vaccination who were exposed to the bacterium, which can survive for hundreds of years in the soil.
While the permafrost theory shouldn't be discarded entirely, it "might be a bit oversimplified," said study lead author KarstenHueffer, a veterinary microbiologist at the University of Alaska, Fairbanks.
However, the emergence of old 'zombie' viruses is only the tip of the iceberg. Thawing of the permafrost could pose a much greater threat to the people living in the arctic.
The bigger picture
"I really think that with climate change, we probably have — to put it flippantly — bigger fish to fry here," Hueffer said.
Climate change, as well as human intervention paves new ways for the microbes to spread.
New roads, new mines and new drilling programs are bringing more people to the Arctic than ever before. Not only humans. The warmer weather is also luring in new species north, who can act as hosts for pathogens that can infect humans, for example beavers and mosquitoes.
"I'm concerned about the fact that we don't understand — and we very, very likely underestimate — the effect of infectious disease on wildlife," Susan Kutz stated.
If wildlife is affected, humans can be affected, too. Diseases can jump from animals to humans and deplete animal food sources people rely on.
Meanwhile, the infrastructure used to transport sewage is built on rapidly thawing and heaving ground. Pipes are vulnerable to rupture and spill, causing outbreaks of waterborne diseases.
The final report of the meeting in Hannover hasn't been released yet. But the general consensus, according to Kutz, was that we don't need to worry about a disease as contagious and deadly as COVID-19 coming out of the permafrost based on what's been seen so far — but there are other reasons to be concerned.
While it is true that the thawing permafrost may be home to bacteria and viruses, we haven't yet encountered or troublingly, ones that we have encountered with disastrous results, such as the Spanish flu or smallpox. However, much of their DNA is in fragments, is adapted to infect other creatures or likely won't come into contact with humans.
According to Kutz, the key is to keep an eye on the wildlife and their health, which is exactly what she and her lab works on.
The writer, KN Deya, is a Journalist.