MARSEILLE, FRANCE — Scientists warn that climate change is melting permafrost soils which may lead to the release of ancient viruses and bacterium.

Permafrost is permanently frozen soil. It is a good preserver for microbes and viruses because of low temperatures and lack of oxygen.

As the temperature in the Arctic Circle rises, the permafrost melts, which may lead to the release of viruses. Layers of permafrost could also be exposed by mining and drilling operations.

“If the pathogen hasn't been in contact with humans for a long time, then our immune system would not be prepared. So yes, that could be dangerous,” Jean-Michel Claverie, evolutionary biologist at Aix-Marseille University in France told the Independent.

According to the BBC, bacterium that can form spores can survive longer than other bacterium in permafrost. This includes anthrax, tetanus and Clostridium botulinum, the pathogen responsible for botulism.