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Ancient Microbes

In August 2016, an outbreak of anthrax in Siberia sickened 72 people and took the life of a 12-year-old boy. Health officials pinpointed the outbreak to an unusual source.

Abnormally high temperatures had thawed the corpses of long-dead reindeer and other animals. Some of these bodies may have been infected with anthrax, the soil in Siberia is normally much too cold to dig deep graves. The worse part of this is that the disease from thawing human and animal remains can get into groundwater that people drink. Scientists are worried that as more permafrost thaws, especially in Siberia, there may be more outbreaks of long-dormant anthrax as burial grounds thaw.

That’s because the deep freeze of the permafrost doesn’t just keep carbon from escaping — it keeps microbes intact as well. Permafrost is the place to preserve bacteria and viruses for hundreds of thousands — if not a million — years. It is dark, it is cold, and it is also without oxygen and there is no ultraviolet [sun] light. All the bacteria need is a thaw to wake back up. For example, if you take a yogurt and put it in permafrost, it still will be good to eat even after 10,000 years from now. A scientific team has already determined it’s possible to revive 30,000-year-old viruses trapped in the permafrost. Their work is centered on viruses that infect amoebas, not humans. But there’s no reason why a flu virus, smallpox, or some long-lost human infection couldn’t be revived the same way. These microbes are like time travelers — and they could thrive waking up in an age when humans have lost an immune defense against them.

The limit is the limit given by the permafrost. Permafrost is 1,000 meters deep in places, which make it about a million, 1.5 million year old. The danger here is not from the slow thawing of the permafrost itself. That is, if the permafrost melts, and we leave the land alone, we’re unlikely to come into contact with ancient deadly diseases. The fear is that the thawing will encourage greater excavation in the Arctic. Mining and other excavation projects will become more appealing as the region grows warmer. And these projects can put workers into contact with some very, very old bugs. The threat is tiny. But it exists. The big lesson is that even viruses thought to be eradicated from Earth — like smallpox — may still lurk frozen, somewhere.

This is the third part of a 5 episode series on climate change and new diseases. You can check them all out using this link.


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