Bacteria and viruses that have lain dormant for thousands of years are at risk of being exposed as a result of global warming, scientists have warned.

Climate change is melting permafrost that has been frozen for centuries, while mining and digging operations risk cutting through the soil beneath — and both could have a serious impact on ancient viruses preserved within.

Frozen permafrost soil is a good place for bacteria to remain alive for long periods of time, and as the Arctic Circle melts — rising about three times faster than in the rest of the world — the ice and permafrost melt and other infectious agents may be released, according to scientists.

Jean-Michel Claverie, evolutionary biologist at Aix-Marseille University in France, has been analysing the DNA content of permafrost layers since 2014, searching for the genetic signature of viruses and bacteria that could infect humans, and has found evidence of many bacteria that are probably dangerous to humans.

Mr Claverie said pathogenic viruses — some of which may have caused global epidemics in the past — could be exposed by human digging, in a dangerous move that could “spell disaster”.

“Permafrost is a very good preserver of microbes and viruses, because it is cold, there is no oxygen, and it is dark,” he said.

”Pathogenic viruses that can infect humans or animals might be preserved in old permafrost layers, including some that have caused global epidemics in the past.

“At the moment, these regions are deserted and the deep permafrost layers are left alone. However, these ancient layers could be exposed by the digging involved in mining and drilling operations. If viable virions are still there, this could spell disaster.”

The biologist said the idea that viruses could be completely “eradicated” was giving the world’s population a false sense of security, because although many of the viruses would cease to be infectious when exposed to light, certain “giant” viruses could signal danger.

“Most viruses are rapidly inactivated outside host cells, due to light, desiccation, or spontaneous biochemical degradation,” he continued.

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“For instance, if their DNA is damaged beyond possible repair, the virions will no longer be infectious. However, among known viruses, the giant viruses tend to be very tough and almost impossible to break open.

“The possibility that we could catch a virus from a long-extinct Neanderthal suggests that the idea that a virus could be 'eradicated' from the planet is wrong, and gives us a false sense of security.