The temperature in the Arctic is rising faster than elsewhere, about three times faster than in the rest of the world. As a result, the permafrost that has been frozen for thousands of years is melting, releasing ancient viruses and bacteria are springing back to life.
A recent case in Siberia illustrates what can happen. Last August, a 12-year-old boy died and at least twenty people were hospitalized after being infected by anthrax.
It is thought that, over 75 years ago, a reindeer infected with anthrax died and its frozen carcass became trapped under a layer of frozen soil, known as permafrost. There it stayed until a heatwave in the summer of 2016, when the permafrost thawed. This exposed the reindeer corpse and released infectious anthrax into nearby water and soil, and then into the food supply. More than 2,000 reindeer grazing nearby became infected, which then led to the small number of human cases.