Melting permafrost may turn out to be Pandora’s box.

Due to global warming, the permafrost is thawing: the previously permanently frozen soil that we mainly know from the Arctic region. And that’s a problem. Because that frozen soil harbors dead plant material that has never broken down due to the low temperatures. Once the permafrost melts, the decomposition of the plant materials—sometimes preserved in that frozen soil for hundreds or even thousands of years—is set in motion. And this also releases the carbon that they have absorbed during life. And that in turn contributes to global warming.

Worrying

It’s a pretty well-known story and definitely cause for concern. But there are many more reasons to watch the thawing of permafrost with care, researchers write in the journal. Nature Climate Change. Because in addition to greenhouse gases, the melting permafrost can also give us unknown and potentially dangerous microbes and viruses. And even the release of nuclear waste is possible.

nuclear waste

“There is a lot of talk about the fact that thawing permafrost leads to the release of carbon,” said Kimberley Miner, a climate scientist at NASA’s Jet Propulsion Laboratory and first author of the review in Nature Climate Change. “But little attention is paid to everything that people have put in permafrost and what can now – because the permafrost thaw – be released again.” Nuclear waste is a good example of this. “During the Cold War, permafrost was used to store nuclear waste. And some of that waste is still there.” It is feared that the melting of permafrost could lead to the nuclear waste coming back to the surface. “That is very worrying, because nuclear waste can last for a long time and can have major effects on the local environment.”

Heavy metals

But nuclear waste is not the only thing that ended up in permafrost through our actions. The researchers also point out that mining has been going on in the Arctic for decades. The resulting mining waste is rich in toxic heavy metals such as nickel, cadmium and arsenic and has become part of the frozen soil in several places. The release of these heavy metals could put further pressure on Arctic species and the ecosystems they are part of.

Viruses and bacteria

In addition to the materials that we ourselves have put in the permafrost, it also harbors natural phenomena that worry researchers. Such as, for example, viruses unknown to us. Samples show that these are abundantly available in permafrost. For example, scientists recently collected 197 samples from Swedish permafrost in 1907, finding previously undescribed virus populations. And more than 58 percent of those unknown viruses were still active. Studies on bacteria in permafrost paint a similar picture. And all those unknown viruses and bacteria still trapped in the permafrost could be released if the permafrost thaws and further disrupts Arctic ecosystems, which are already under pressure from the rapid warming of the area.

Danger to people?

In theory, the viruses and bacteria that manage to escape from the permafrost could of course also pose a danger to humans. But at the moment, researchers consider the chance that a person will be infected by such a virus or bacterium is small. “That simply has to do with the fact that there aren’t that many people living in the areas where permafrost can be found,” explains Miner.

There have been concrete concerns in the past about pathogens that live in permafrost and can be released when it melts. For example, victims of the smallpox virus are also buried in permafrost. And the thawing of permafrost near such a cemetery a few years ago fueled fears that the deadly virus from the permafrost would make a comeback. To date, that fear seems unfounded; the smallpox virus particles recovered in the permafrost are fragmented and thus unable to infect humans.

The greatest concerns are therefore about the potential impact that the viruses and microbes have on ecosystems. “In ecosystems, everything is interconnected,” emphasizes Miner. “And so the introduction of a small microbe could even have consequences for large polar bears.”

Much is uncertain or even unknown

What consequences we then have to think about is coffee grounds. This is of course mainly because we do not know most of the microbes and viruses in the ice. What also doesn’t help is that we haven’t witnessed permafrost thawing so quickly and on such a large scale before. “With the help of models, we can try to get a grip on the short-term consequences of the release of certain microbes. But when we talk about the long term, it is mainly a question of ‘wait and see(wait and see what happens).” The same applies to the consequences of ‘leaking’ nuclear waste or heavy metals from the thawing permafrost. “There’s so much we don’t know.”

Target

And that has also been the reason for Miner and colleagues to Nature Climate Change to draw attention to all the other possible consequences that the thawing of permafrost can have. “We delved into the published literature for this, with the aim of bringing together in one place everything that has not actually received any attention until now.” It results in a less rosy review in which thawing permafrost seems to emerge as a real Pandora’s box. “We hope the article will encourage other scientists to do more research on this,” Miner said. Because there are still many unanswered questions.

What is certain amid all the uncertainty is that Pandora’s Arctic box is already ajar. And in many places in the Arctic we are already catching a glimpse of what it has in store for us. “It is well established that the thawing of permafrost has negative consequences for nature and people,” emphasizes Miner. Some of them – such as the release of greenhouse gases that further exacerbate the climate problem – are known to us. Others are – along with their secrets – literally still locked in the permafrost. And if it is normally up to the profession to always be very curious scientists, they will stay there. “Our very best option is to limit warming and preserve permafrost.”