LONDON • Climate change is melting permafrost soil that has been frozen for thousands of years, releasing ancient, once-dormant viruses and bacteria that are springing back to life, the BBC reported.
Last August, in a remote part of the Siberian tundra called the Yamal Peninsula in the Arctic Circle, a 12-year-old boy died and at least 20 people were hospitalised after contracting anthrax, a serious infectious disease caused by bacteria.
Theory has it that more than 75 years ago, a reindeer infected with anthrax died and its frozen carcass became trapped beneath a layer of frozen soil, or permafrost.
It stayed there until a heatwave in the summer last year caused the permafrost to thaw.
This exposed the reindeer carcass, releasing infectious anthrax into nearby water and soil, and then into the food supply. Over 2,000 reindeer grazing nearby became infected, which then led to the small number of human cases.
Investigations into the anthrax outbreak also sparked concern that smallpox could return, as Siberia's melting permafrost exposes ancient graves. The BBC said there are fears that the anthrax outbreak will not be an isolated case.
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.
PROFESSOR JEAN-MICHEL CLAVERIE, an evolutionary biologist at Aix-Marseille University in France, on deep permafrost layers and the hidden microbes and viruses that could be exposed by industrial exploitation.
In normal situations, superficial permafrost layers about 50cm deep melt every summer. But global warming is now gradually exposing older permafrost layers.
Bacteria can remain alive in frozen permafrost soil for very long periods of time - possibly as long as a million years.
The temperature in the Arctic Circle is rising about three times faster than in the rest of the world. Other infectious agents could be released as the ice and permafrost melt.
"Permafrost is a very good preserver of microbes and viruses, because it is cold, there is no oxygen, and it is dark," said evolutionary biologist Jean-Michel Claverie at Aix-Marseille University in France, the BBC reported. "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."
As humans and animals have been buried in permafrost for centuries, it is possible that other infectious agents could be released.
Scientists have discovered intact 1918 Spanish flu virus in corpses buried in mass graves in Alaska's tundra. Smallpox and the bubonic plague are also likely buried in Siberia, the BBC added.
Global warming does not have to directly melt permafrost to pose a threat. The melting of Arctic sea ice has made the north shore of Siberia more easily accessible by sea. As a result, industrial exploitation, including mining for minerals and drilling for oil and natural gas, is now becoming profitable.
"At the moment, these regions are deserted and the deep permafrost layers are left alone," Professor Claverie was quoted by the BBC as saying. "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."
Stocks of vaccine should be kept as a precaution, said Prof Claverie.
In February this year, Nasa scientists announced they had found microbes up to 50,000 years old inside crystals in a Mexican mine. Even older bacteria have been found in the Lechuguilla Cave in New Mexico. These microbes, which are resistant to natural antibiotics, have not seen the surface for over four million years.
Said Prof Claverie: "There is now a non-zero probability that pathogenic microbes could be revived, and infect us.
"How likely that is is not known, but it's a possibility. It could be bacteria that are curable with antibiotics, or resistant bacteria, or a virus. 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."