Permafrost on the mountains of the Ladakh Mountains in India (Image from 2019)
Photo: Prashanth Vishwanathan/Bloomberg via Getty Images
A quarter of the northern hemisphere is covered with permafrost – i.e. with soil that is permanently frozen.
Due to global warming, this soil is slowly thawing.
For example, animal carcasses and plant remains are uncovered and with them viruses that have been inactive since prehistoric times.
This is what researchers write in an as yet unpublished study on the preprint server Biorixv.
The team characterized and reactivated 13 new viruses that came from seven different samples of Siberian permafrost.
A virus, for example, was revived from a sample that dates back to 27,000 BC, and traces of mammoth wool were found on the sample.
Potential health problem
Organic material frozen for up to a million years is released as the ice sheets melt.
Most of it is broken down into carbon dioxide and methane, which in turn increases the greenhouse effect.
An immediate public health concern, the researchers say, could be the release of live bacteria trapped in deep permafrost and isolated from the Earth's surface for up to two million years.
According to the researchers, it is likely that permafrost that is more than 50,000 years old may harbor viruses that can be released by the thawing ice.
However, it is not certain how long the viruses remain infectious once they come into contact with light, oxygen and heat outdoors.
"However, the risk will increase in the context of global warming as permafrost thaw accelerates further and more people colonize the Arctic for industrial ventures," the study says.
More recently, the repeated return of anthrax epidemics in reindeer has been linked to the thawing of the active surface permafrost layer during exceptionally hot summers.
Centuries-old spores from old animal graves or carcasses could have reappeared in this way.
Federal Health Minister Karl Lauterbach responded to a report by "Spektrum" on the study on Twitter on Sunday and warned of the consequences that the released viruses could have.
"The permafrost is thawing as a result of climate change," writes Lauterbach.
“There are viruses in the thawed carcasses, more than 10,000 years old.
This is also an example of how we use the chain of first climate change, then zoonosis, then outbreak, then pandemic.«