Permafrost usually hits the news as a hazard; a planetary risk. When this ice-rich ground thaws, it damages roads and building foundations. It drains lakes and tips trees into drunken forests. It releases greenhouse gases that have been locked in carbon-rich soils for thousands of years, amplifying warming, driving further thaw.

These are serious concerns, and we spend a good deal of time studying their causes. But another consequence of permafrost thaw receives far less attention: As the climate warms, we are losing our frozen heritage.

Permafrost contains the most exceptional archive of the distant past on the planet, a record of ancient life preserved in a way that exists almost nowhere else on Earth.

A recent study we led, published in Nature Communications, recovered DNA from Arctic ground squirrel droppings preserved in permafrost in Klondike, Yukon. In these pellets, we found plants the squirrels had eaten, parasites they carried and even traces of the larger animals — mammoths, horses and bison — that shared their grassland.

A single dropping held a detailed portrait of a vanished ecosystem, spanning an extraordinary depth of time — from around 14,000 to 700,000 years ago.

Fossils in the ‘muck’

In the Klondike region of central Yukon, within the traditional territories of the Tr'ondëk Hwëch'in and the First Nation of Na-Cho Nyäk Dun, placer gold........

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