Melting Permafrost May Unlock Ancient, Deadly Diseases

Eric Chaney
Published: November 7,2016
As global temperatures creep upward, humanity may soon find itself face to face with a new adversary: our own ancestors.
Melting permafrost in the planet’s northern hemisphere is threatening to unlock old, and possibly some entirely new, risks to human existence.
An anthrax outbreak in Siberia earlier this year killed a 12-year-old nomad boy, and sparked renewed discussion about the dangers that may lay beneath the Arctic’s frozen surface.

Methane gas bubbles became trapped in lake ice when microbes consume the carbon in permafrost that has thawed and subsided, Alaska.
(Smith Collection/Gado/Getty Images)

“There are hints that Neanderthals and Denisovans could have settled in northern Siberia and were plagued by various viral diseases, some of which we know, like smallpox, and some others that might have disappeared,” Jean-Michel Claverie, head of the Mediterranean Institute of Microbiology and a professor at Aix-Marseille University in France, told Scientific American. “The fact that there might be an infection continuity between us and ancient hominins is fascinating—and might be worrying.”
In a study published in 2011, Russian scientists Boris A. Revich and Marina A. Podolnaya catalogued outbreaks of anthrax in Siberia between 1949 and 1993, which killed nearly two dozen people, the study says. Cases of anthrax have been recorded in 28,986 settlements of the Russian Federation, many connected to 13,885 cattle burial grounds, of which 4,961 do not meet veterinary and sanitary standards.
“As a consequence of permafrost melting, the vectors of deadly infections of the 18th and 19th centuries may come back, especially near the cemeteries where the victims of these infections were buried,” reads the study, published in the journal Global Health Action.
(MORE: Anthrax Outbreak Unleashed by Siberian Heat Wave Turns Deadly)
Most bacteria can’t survive extreme low temperatures for long periods (anthrax bacteria is particularly hardy), but viruses can, and do. In 2014, researchers discovered a giant virus that had lain buried for 30,000 years in Siberian permafrost, LiveScience reports.
The virus only infects single-celled organisms and doesn't closely resemble any known pathogens that harm humans, but the discovery has experts wondering what other diseases might be hiding in the frozen soil of the arctic.

Scientists worry that melting permafrost will expose ancient animals, such as this 39,000-year-old female baby woolly mammoth extracted from permafrost in Siberia in 2013, which may carry unknown diseases.
(KAZUHIRO NOGI/AFP/Getty Images)

"Those pathogens could be banal bacteria (curable with antibiotics) or resistant bacteria or nasty viruses. If they have been extinct for a long time, then our immune system is no longer prepared to respond to them,” Claverie told LiveScience. "There is now a non-zero probability that the pathogenic microbes that bothered [ancient human populations] could be revived, and most likely infect us as well,"Microbiologist Janet Jansson, of the Department of Energy's Pacific Northwest National Laboratory, is less worried about ancient microbes’ effect on humans than on the climate itself.
(MORE: Arctic's Melting Permafrost Problem Is Slowly Destroying Russian Cities)
"Estimates are that permafrost stores between 780 and 1,400 gigatons of terrestrial carbon. That's a huge reservoir. What happens when permafrost thaws and trapped carbon is available for microbes?" she said in a press release last year. "The microbes in permafrost are part of Earth's dark matter. We know so little about them because the majority have never been cultivated and their properties are unknown."
It’s that unknown that makes melting permafrost such a worry. We simply don't know what might be trapped there, and what effect it may have if released.
MORE: Historic Luxury Cruise Through Melting Arctic