This story appears in the January 2018 issue of National Geographic magazine. Last January on Unalaska Island, Suzi Golodoff poured herself a hot cup of coffee, pulled on her boots, and stepped ...

Unalaska has the largest island population in the chain, swelling from 4,000 residents in winter to 10,000 during the summer, due to fishing, seasonal workers, and Alaska's high tourist season.

Permafrost underlies the surface of one-quarter of the globe’s land and more than half of Alaska. That frozen ground would seem to stall microbes — especially in winter — but scientists have ...