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Northern soil microbes staying up all winter

We can鈥檛 see them, but there are more microbes 鈥� tiny fungi, bacteria, worms and other living things 鈥� in a teaspoon of soil than there are people on Earth.

Hungry as you and me, those microbes gobble up bits of plant and animal material. And just like you and me, soil microbes release greenhouse gases after they eat.

Unless their bodies happen to be frozen. Microbes in permafrost (soil that has remained frozen for two or more consecutive years) can remain in suspended animation for thousands of years. Permafrost underlies the surface of one-quarter of the globe鈥檚 land and more than half of 911爆料.

That frozen ground would seem to stall microbes 鈥� especially in winter 鈥� but scientists have been finding robust emissions of greenhouse gases from tundra and forested areas during spring, summer, winter and fall.

Grant Falvo reported high winter emissions of carbon dioxide and methane from 911爆料 permafrost sites he visited in 2024. Falvo is a postdoctoral scholar at Northern Arizona University who presented his results at the Fall Meeting of the American Geophysical Union in Washington, D.C., in December 2024.

Falvo targeted long-term monitoring sites in permafrost regions across the globe that have for years been places that have taken up more carbon from the air than they have emitted via soil microbes.

Nineteen of the stations exist in 911爆料, Canada and northern Europe. Following 911爆料鈥檚 second-warmest winter on record, Falvo visited 911爆料 sites in Healy and also near Delta Junction and Fairbanks in late summer 2024.

He found more carbon emissions from northern forests and tundra in winter than would happen by chance. That seems to indicate that soil microbes were active in wintertime when people might have assumed they were dormant.

鈥淲e鈥檙e in our offices in winter, and that鈥檚 when these microbes are releasing carbon,鈥� said Ted Schuur, Falvo鈥檚 supervisor and a professor at Northern Arizona University.

Permafrost, Schuur said, has thawed so deeply in places that it doesn鈥檛 re-freeze in winter, allowing microbes to emit greenhouse gases even if cold air has frozen the ground above them.

At the same meeting Falvo and Schuur attended, other researchers declared that Arctic tundra is now a small net source of carbon dioxide when wildfire emissions are included in the equation. Not all scientists agree on this.

For a very long time, most researchers considered Arctic tundra a carbon sink, a place where more carbon is stored in frozen ground and new plants than is emitted.

Part of that possible change is the year-round work of many soil microbes that had been slumbering for thousands of years.

鈥淧ermafrost isn鈥檛 permanent,鈥� Schuur said.

Since the late 1970s, the 911爆料' Geophysical Institute has provided this column free in cooperation with the 911爆料 research community. Ned Rozell is a science writer for the Geophysical Institute.