Climate: How warming in the Arctic could cause new viruses to arrive

Viruses exist deep in the frozen Arctic sea. So far they have been preserved on ice, completely frozen in short. But climate change could change that. Indeed, an English study, published in the biological research journal of the Royal Society of London for the enhancement of natural knowledge (the equivalent of the Academy of Sciences in France), suggests that global warming could cause a “viral overflow”. Which means that hitherto defenseless viruses could come into contact with new hosts in other environments as the ice melts. Recall that viruses need a host (human, plant, moss) to replicate and spread, using a host without immunity if necessary, as demonstrated by the recent Covid-19 pandemic with humans.

Virus 300 meters below the ice

Canadian scientists then investigated whether climate change could favor such a scenario in the Arctic environment of Lake Hazen. Located in the far north of Canada, it is the largest lake located beyond the Arctic Circle. “Indeed, global warming and rapid environmental transitions can increase the risk of spillover by varying the general distribution and dynamics of viruses,” the scientists explain in the introduction. “As the climate changes, so does the metabolic activity of the Arctic microbiosphere, which in turn affects many ecosystem processes such as the emergence of new pathogens.”

For their research, the scientists took samples from a river bed that feeds it when ice melts over the summer, as well as others from the lake bed. They also claim that it was necessary to drill two meters of ice before reaching the bottom of the frozen waters of the lake, nearly 300 meters away. Using ropes, a snowmobile then lifted the sediments, which were subsequently sequenced for their DNA and RNA, the genetic code and tool for life replication. “This allowed us to determine which viruses were in a particular environment and which potential hosts were there too,” Stéphane Aris-Brosou, associate professor in the Department of Biology at the University of Ottawa, told Agence France Presse. supervised the studies. The team of researchers then set out to explore how susceptible the viruses were to changing hosts by looking at the equivalent of their respective family trees.

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Arrivals of new guests in perspective

“We tried to measure how similar these trees (family) were,” Audrée Lemieux, of the University of Montreal, first author of the study, told AFP. Similar genealogies suggest that the virus evolved with its host, while the differences indicate that it may have changed hosts. And if he has done it at least once, he is likely to do it again. Result: The analyzes showed large differences in the family trees of the viruses and their hosts in the sediments extracted from the lake bottom.

The researchers also note that the differences were less pronounced in the river bed that fed the lake. “One possible explanation is that as glacial runoff increases, the strength of glacier erosion also increases, carrying the contents of the river bed and shores into the lake,” the study says. “This erosion would then eliminate the soil organisms from this environment, and therefore would limit the risks of interactions between viruses and hosts, that is, it would limit the risk of spillover.”

On the other hand, the acceleration of the melting of the glaciers that feed the lake has also increased the amount of sediment that is carried there. “This will connect hosts and viruses that normally would not have been,” explained Audrée Lemieux. However, the study authors were careful to specify that they do not predict a viral overflow or pandemic. “The likelihood of dramatic events remains very low,” according to Audrée Lemieux. But according to the researchers, the risk could increase with continued global warming, as new hosts could venture into previously inhospitable regions. The possibility of an overflow is “completely unpredictable, and so are its consequences, which range from a mild to a true pandemic,” she added. This is the first time such a study has been conducted in an environment such as the Arctic.