The next pandemic may not be caused from bats or birds. A recent scientific study has implied that it may result from melting glaciers. An analysis of an arctic lake showed that frozen viruses and bacteria may soon thaw out and infect wildlife. The results derive from genetic analysis of soil and lake sediments from Lake Hazen, the biggest and highest arctic freshwater body in the world.
According to the findings, the risk of a virus infecting a new host for the first time may be higher close to melting glaciers. Thus, as global temperatures rise due to climate change, it becomes more likely that viruses and bacteria locked up in glaciers and permafrost reawaken and infect local wildlife, particularly as their range also shifts closer to the poles.
Viruses frozen in the ice
Back in 2016, a heatwave which melted a similar permafrost in northern Siberia, exposed a contagious corpse that. The anthrax outbreak killed a child and infected at least seven other people. Prior to the outbreak, the last epidemic in the region was in 1941.
To better understand the risk of viruses frozen in ice, Dr Stéphane Aris-Brosou and his colleagues at the University of Ottawa in Canada collected soil and sediment samples from Lake Hazen, close to where small, medium and large quantities of meltwater from local glaciers poured in.
Next, the scientists used an algorithm to determine the likelihood that these viruses might infect unrelated groups of organisms. Finally, they analysed the RNA and DNA in the samples collected to identify signatures closely matching those of known viruses as well as potential animal, plant, or fungal hosts.
The study, which was published in Proceedings of the Royal Society B, suggested that the risk of viruses spreading to new hosts was higher in areas close to where significant amounts of glacial meltwater poured in. Such a situation will become more probable as the climate warms.
The scientists did not quantify how many of the viruses they had identified were previously unknown. They plan however to address this in the coming months. They also did not assess whether these viruses were capable of triggering an infection.
Ancient viruses linger according to other studies
Other studies have nonetheless suggested that unknown viruses can, and do, linger in glacier ice. Researchers at Ohio State University in the US, for instance, reported last year that they had found genetic material from 33 viruses, 28 of them unique, in ice samples collected from the Tibetan plateau in China. The viruses were estimated to be approximately 15,000 years old based on their location.
What is more, the team identified 27,000 potential virulence factors that help bacteria invade and colonise potential hosts. Even if these potentially pathogenic bacteria do not survive for long after escaping their glaciers, they can still cause problems, they said.
Then, in 2014, scientists at France’s National Centre for Scientific Research in Aix-Marseille managed to bring back to life a giant virus they had isolated from Siberian permafrost, making it infectious for the first time in 30,000 years. The study’s author, Jean-Michel Claverie, said at the time that exposing such ice layers could be “a recipe for disaster”.
Possible pandemic caused by melting glaciers still under investigation
Despite this fact, Aris-Brosou’s team warned that predicting a high risk of spillover was not the same as predicting actual spillovers or pandemics.
“As long as viruses and their ‘bridge vectors’ are not simultaneously present in the environment, the likelihood of dramatic events probably remains low,” the team wrote.
That being said, it is highly likely that climate change could alter the range of existing species, potentially bringing new hosts into contact with ancient viruses or bacteria.
“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,” said Aris-Brosou. “Will this lead to pandemics? We absolutely don’t know,” the team added.
Also unclear is whether the potential for host switching identified in Lake Hazen is unique within lake sediments.
“For all we know, it could be the same as the likelihood of host switching posed by viruses from the mud in your local pond,” said Arwyn Edwards, the director of the Interdisciplinary Centre for Environmental Microbiology at Aberystwyth University.
“We do urgently need to explore the microbial worlds all over our planet to understand these risks in context,” he said.
“Two things are very clear now. Firstly, that the Arctic is warming rapidly and the major risks to humanity are from its influence on our climate. Secondly, that diseases from elsewhere are finding their way into the vulnerable communities and ecosystems of the Arctic.”
Climate change to blame
Glaciers melting is an alarming problem. If the findings further confirm that a new pandemic could be caused from melting glaciers, then this could turn into a global emergency. Just as worrying is the fact that they are melting faster, losing 31% more snow and ice per year than they did 15 years earlier. This, according to three-dimensional satellite measurements of all the world’s mountain glaciers.
Scientists blame human-caused climate change. Using 20 years of declassified satellite data, in 2021 they calculated that the world’s 220,000 mountain glaciers have lost more than 328 billion tons of ice and snow per year since 2015. That is enough melt flowing into the world’s rising oceans to put Switzerland under almost 24 feet (7.2 meters) of water each year.
Half the world’s glacial loss, it seems, is coming from the United States and Canada. Yet almost all of them are melting, even ones in Tibet that used to be stable, a study published in Journal Nature found. Except for a few in Iceland and Scandinavia that are fed by increased precipitation, melt rates are accelerating around the world.