Mi­cro­bial dis­eases

PER­MAFROST ISN’T JUST CHILLED DIRT: IT’S COLD stor­age for ev­ery­thing from mam­moths to the mi­crobes in­side them. Though any soil that stays frozen for at least two years is tech­ni­cally per­mafrost, the frigid lay­ers can be tens of thou­sands of years old and

Popular Science - - CONTENTS - by Amelia Urry / il­lus­tra­tion by Kelsey Dake

1 Ex­humed fumes

The scari­est en­tity to emerge from the melt so far is meth­ane, a green­house gas 30 times more po­tent than CO2. Re­leased when formerly frozen mat­ter de­com­poses in thawed tun­dra, the gas boosts at­mo­spheric tem­per­a­tures, de­frost­ing more acreage—a spine-chill­ing feed­back loop.

2 Tiny but tena­cious

Bac­te­ria that form pro­tected spores, such as tetanus and bot­u­lism, are the most likely to pose a threat once de­frosted. No one knows how long mi­crobes can sur­vive a hard freeze, but in 2007, sci­en­tists re­ported signs of cel­lu­lar life in 8-mil­lion-year-old Antarc­tic ice.

3 Ye olde mal­adies

In 1918, a vir­u­lent flu killed tens of mil­lions. Sci­en­tists have found frag­ments of the virus in thawed graves of its Arc­tic victims. And in 2004, traces of small­pox— of­fi­cially erad­i­cated in 1980—showed up on 18th-cen­tury Siberian corpses.

4 Oh, deer

In the early 1900s, Bacil­lus an­thracis in­fec­tions killed 1.5 mil­lion rein­deer in north­ern Rus­sia. In 2016, ris­ing tem­per­a­tures re­leased the bac­terium’s spores to cause an­thrax poi­son­ing in thou­sands of deer (and a few dozen hu­mans).

5 Un­known dis­eases

In 2017, a teacher con­tracted a bac­te­rial in­fec­tion while ex­ca­vat­ing seal re­mains from an 800-year-old Alaskan dwelling. Old dis­eases, in­clud­ing those that plagued our hu­manoid an­ces­tors, could lurk any­where—and our mod­ern im­mune de­fenses might not work against them.

6 Big-shot mi­crobes

In 2014, vi­rol­o­gists dis­cov­ered a pathogen 10 times big­ger than the flu in 30,000year-old per­mafrost. Once warmed, it started prey­ing upon amoe­bas. It doesn’t seem to in­fect hu­mans, but reports of an­tibi­otic-re­sis­tant bac­te­ria from the same era could be a cause for worry.

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