Climate change may increase the Arctic virus spread.

New research published on Wednesday suggests that a warmer Arctic may increase the risk of "viral spillover" by exposing viruses to new environments and hosts.

To multiply and spread, viruses require hosts such as humans, animals, plants, or fungi; yet, as was observed during the COVID-19 pandemic, viruses can occasionally jump to a new host that lacks immunity.

Canadian researchers hoped to learn more about the potential effects of climate change on spillover risk by studying Arctic landscape samples from Lake Hazen.

The Arctic Ocean's largest lake is "really unlike any other location I've been," according to researcher and current University of Toronto medical student Graham Colby.

Even in May, when the research was conducted, the crew had to clear snow and dig through two metres of ice to collect samples from the lakebed and the soil that becomes a riverbed for melting glacier water in the summer.

They hauled the lake silt up over 300 metres (980 feet) of water using ropes and a snowmobile and then sequenced DNA and RNA from the samples.

"This allowed us to identify what viruses are in a given environment, and what possible hosts are also present," said Stephane Aris-Brosou, the study's lead author and an associate professor in the biology department at the University of Ottawa.

However, the scientists needed to look at the evolutionary history of each virus and host to determine the likelihood of host switching.

Audree Lemieux, the study's first author, explained, "Basically what we sought to do is measure how similar these trees are."

Genetic similarity between a virus and its host indicates coevolution, while genetic divergence indicates spillover.

A virus already infected multiple hosts is more likely to do so again.

Distinct variations in viruses and hosts were discovered in the lake bottom, "which is directly associated with the probability of spillover," as explained by Aris-Bros.

The researchers hypothesise that this difference is attenuated in riverbeds because water erodes the topsoil, eliminating organisms and reducing interactions between viruses and potential new hosts.

Instead, they've been washing into the lake, which has seen "dramatic alteration" in recent years due to the increased sediment deposition caused by the high water flow brought about by the melting of glaciers, as reported in the study.

Lemieux predicted that this would result in meeting previously undiscovered hosts and viruses.

The study's authors, who warned that they are not predicting either a spillover or a pandemic, had their findings published in the journal Proceedings of the Royal Society B: Biological Sciences.

However, "the possibility of dramatic events remains very low," Lemieux emphasised.

They also caution that further research is needed to determine how much variation between viruses and hosts is necessary to pose a significant spillover danger.

They point out that additional potential hosts moving into formerly hostile places due to warming weather could significantly increase hazards.

Lemieux speculated that "everything from ticks and mosquitoes to particular animals to bacteria and viruses themselves" could be to blame.

There's a lot of uncertainty there... The spillover impact is highly speculative; it can have no effect or cause a global epidemic.

The group is seeking more excellent investigation and monitoring in the area to comprehend the dangers better.

Lemieux said that spillover effects have been "evident in the past two years," Lemieux said.