The Arctic — that remote, largely undisturbed, 5.5 million square miles of frozen terrain — is warming rapidly. In fact, it is warming almost four times faster than the rest of the world, with disastrous consequences for the region and its inhabitants. You probably know many of these effects from nature documentaries: melting ice caps, rising sea levels and polar bears losing their homes. But good news! There’s another knock-on effect to worry about: the warming landscape is rewiring viral dynamics, with the potential to unleash new pathogens.
An underappreciated consequence of climate change is how it will exacerbate the spread of infectious diseases. As the world warms, many species are expected to lift sticks and wander miles from their typical habitat, carrying various pathogens with them for the ride. This means that previously unknown viruses and hosts will meet for the first time, potentially leading to viral spillover — where a virus jumps from one reservoir host to a new one, like our old friend SARS-CoV-2.
And one part of the world where this has a good chance is the Arctic. In a new paper published in the journal Proceedings of the Royal Society B, a group of researchers from the University of Ottawa sought to quantify the overflow risk in the region. They went to Lake Hazen, a freshwater lake in Canada located within the Arctic Circle, and sampled the bottom and lake sediment before sequencing the genetic material in these samples to identify which viruses were present. They also sequenced the genomes of potential hosts in the area, including animals and plants.
Then they tried to gauge how likely it was that a virus would jump into a new species. To do this, they looked at the genetic history of a virus and its typical host. If a host and a virus show similar patterns in how they have evolved, it suggests that they have lived together for a long time and that the virus has no tendency to move to other species. If their evolutionary patterns are very different, it suggests that the virus has lived in other hosts for some time, jumped before, and is more likely to do so again.
Knowing the propensity of viruses in the region to move species, they then used a computer algorithm to estimate how climate change would change the likelihood of them doing so. They used the increasing flow of meltwater from nearby glaciers as a proxy for rising temperatures, and found that as temperatures rise and glacier runoff increases, the risk of viruses in the area jumping on hosts also increases. Why? As meltwater flows into the lake, the sediment carries and deposits, upsetting the lake’s population and, by disrupting this environment, accelerates the evolution of pathogens against their hosts’ immune defenses.
An important caveat is that it is not possible to give a definitive answer as to what will actually happen. “We can’t say, ‘We’re getting serious pandemic problems in the high Arctic,'” said Stéphane Aris-Brosou, an author of the paper and an associate professor of biology at the University of Ottawa. The work is really just trying to quantify the risk of a spillover. “It is absolutely impossible to predict events like this.”
