The phrase "zombie virus detected in Russian ice" sounds like it belongs in a horror movie, but after the epidemic, it's hard to startle anyone anymore.
But this week, scientists published findings showing that viruses that have been trapped in Siberian permafrost for tens of thousands of years are thawing out.
13 new varieties of viruses that had lain dormant in Siberian soil for between 27,000 and 48,500 years have been brought back to life by researchers from France, Germany, and Russia.
In contrast to other researchers searching frozen mammoth, woolly rhinoceros, or prehistoric horse remains for ancient viruses, they claimed their approach posed minimal risk to humanity.
The so-called zombie viruses don't harm people because they only affect microorganisms, but other pathogens that could be released as permafrost melts in the future could be dangerous to people, according to scientists.
The environmental organization Greenpeace has even questioned whether such "back-from-the-dead" pathogens could cause a new pandemic.
The discoveries are reminiscent of the 1993 movie Jurassic Park, when dinosaurs were cloned using DNA from insects preserved in amber, only for the beasts towreak havoc on humanity.
A quarter of the Northern Hemisphere is covered in permafrost, or permanently frozen soil. Permafrost is primarily found in Alaska, Canada, and Siberia, but some areas are thawing as the climate warms.
Many additional research teams are investigating the pathogens, such as bacteria, and larger organisms that are released as a result.
An ice cap in Tibet has been found to contain viruses that are 15,000 years old, according to research that was published last year.
More astoundingly, reports from 2018 claimed that soil samples from Siberia that had been frozen for up to 42,000 years had revived small nematode worms.
The study's authors were certain that sample contamination was not to blame for the creatures, which started to move and eat after being kept at 20°C in Petri dishes containing a nutrient medium.
Prof. Birgitta Evengard, of the Department of Clinical Microbiology at Umea University in Sweden, is one of many with an interest in the disease hazards posed by permafrost microbes.
Understanding and Responding to Global Health Security Risks from Microbial Threats in the Arctic, a 2019 conference, was organized in part by Prof. Evengard.
There was a chance that some of the pathogens discovered in the thawing permafrost would endanger people, but it was impossible to say for sure.
"There’s a Pandora’s box ― they have the potential to be human pathogens," she said, adding that there would be spillover into the environment.
"In Siberia you have three rivers bringing out debris from permafrost into the Bering Sea, ocean currents that are quite busy.
"They will take it around the world in a couple of weeks. People don’t realise that. The world is very, very connected by all ecosystems ― the oceans, terrestrial and the air."
The risks have increased as a result of recent research that showed that the Arctic has warmed since 1979 almost four times faster than the rest of the world, a finding that Prof. Evengard called alarming.
"This means what’s happening in the Arctic is the driver for what’s going to happen in the rest of the world," she said.
She went on to say that it was critical for scientists to have access to places like Siberia so they could examine what was taking place.
Because they eat soil organic matter, these microbes cause the release of carbon dioxide and methane, both of which are greenhousey gases, as the ground thaws.