As global temperatures head north, Arctic permafrost is thawing to unprecedented depths, reanimating a small army of deadly microbes – dormant, in some cases, for millennia – that could rise from the slush to infect humanity.

“Frozen permafrost soil is the perfect place for bacteria to remain alive for very long periods of time, perhaps as long as a million years,” noted the BBC’s Jasmin Fox-Skelly in May. “That means melting ice could potentially open a Pandora’s box of diseases.”

Last year, ice melt in the Siberian tundra uncovered an anthrax-ridden reindeer carcass that then infected thousands of live reindeer, a score of locals and left a 12-year-old boy dead. Excavation of Inuit mass graves has thrown up RNA from the 1918 Spanish Flu virus. Three-hundred-year-old frozen mummies unearthed in Southern Siberia have shown signs of smallpox.

In February, NASA scientists took fears about intergenerational contagion to another level, isolating microbes between 10,000 and 50,000 years old from crystals in a Mexican cave. Those time frames, according to some experts, mean that catching something nasty from a Neanderthal is very much a live possibility.

Read the full article with picture gallery in Cosmos magazine here