Melting Glaciers Could Unleash Frozen Viruses That Fuel Future Pandemics: Study

Over two years into the Covid-19 pandemic and amid a worsening climate emergency, researchers released a study Wednesday warning that glacier melt in the Arctic could unleash frozen viruses that lead to new global health crises.

"Obviously we've seen in the past two years what the effects of spillover can be."

While human activities such as burning fossil fuels heat the whole world, studies have shown that the Arctic is warming roughly four times faster than the rest of the planet. The new research exposes how sea-level rise isn't the only danger posed by the region's rapidly melting glaciers.

For the paper, published in the journal Proceedings of the Royal Society B: Biological Sciences, a team from Canada's University of Ottawa focused on Lake Hazen, the largest lake by volume in the High Arctic region.

The researchers took samples of both soil that serves as a riverbed for melted glacier water and lake sediments to study the risk of viral spillover, or the transmission of a virus from one host species to another.

The team found that "spillover risk increases with runoff from glacier melt, a proxy for climate change. Should climate change also shift species range of potential viral vectors and reservoirs northwards, the High Arctic could become fertile ground for emerging pandemics."

As ScienceAlertdetailed:

In line with previous studies, which show how degraded landscapes can thrust pathogens, parasites, and hosts together in new ways, the researchers suggest that increased glacier runoff leads to greater chances of viruses jumping over into eukaryote hosts.

The increased spillover risk differed, though, in the soil and lake sediment samples. In soil, with high glacial melt flows, the spillover risk increased to a point before declining, whereas the risk continued rising in lake sediment samples.

One explanation put forward by the researchers is that increased runoff means more organic material--and the organisms in it--gets washed into the lake rather than remaining on land.

The paper points out that "Lake Hazen was recently found to have undergone a dramatic change in sedimentation rates since 2007 compared to the previous 300 years." Lead author Audree Lemieux explained that water from melted glaciers depositing more sediment into the lake is "going to bring together hosts and viruses that would not normally encounter each other."

While recognizing that the researchers provide "a novel approach to assessing spillover risk," the study also states that "this is not the same as predicting spillovers or even pandemics, first because we rely on known virus/host associations, and also because as long as viruses and their 'bridge vectors' are not simultaneously present in the environment, the likelihood of dramatic events probably remains low."

For now, "the only take-home that we can confidently put forward is that as temperatures are rising, the risk of spillover in this particular environment is increasing," co-author Stephane Aris-Brosou toldThe Guardian. "Will this lead to pandemics? We absolutely don't know."

However, the study notes, "as climate change leads to shifts in species ranges and distributions, new associations can emerge, bringing in vectors that can mediate viral spillovers, as simulations recently highlight."

"This twofold effect of climate change, both increasing spillover risk and leading to a northward shift in species ranges, could have dramatic effect in the High Arctic," the paper warns. "Disentangling this risk from actual spillovers and pandemics will be a critical endeavor to pursue in parallel with surveillance activities, in order to mitigate the impact of spillovers on economy- and health-related aspects of human life, or on other species."

Echoing the study, Lemieux stressed that "the likelihood of dramatic events remains very low" but also that new hosts can emerge as the region warms up. These hosts, she said, "could be anything from ticks to mosquitoes to certain animals, to bacteria and viruses themselves."

"It's really unpredictable... and the effect of spillover itself is very unpredictable, it can range from benign to an actual pandemic," she added. "Obviously we've seen in the past two years what the effects of spillover can be."

Though researchers have not yet determined when and how the virus that causes Covid-19 transferred to humans, it has killed over 6.5 million people and generated warnings from experts worldwide about the need for humanity to repair its exploitative relationship with nature to prevent future pandemics.