Microbes Active In Polar Snow Once Thought to Be Sterile

Life truly does find a way.

Polar ice cap, Glacial landform, Glacier, Ice, Iceberg, Arctic, Arctic ocean, Ice cap, Glacial lake, Mountain,
Marketa JirouskovaGetty Images

For the first time, scientists have directly observed bacteria living in polar ice and snow. Long considered sterile, the finding in both the Arctic and Antarctic speaks to the hardiness of life and calls for a reconsideration of the Earth's climate history.

There's a ubiquitous microbial presence in polar regions, Redeker and his team note in their paper, but finding metabolically active microbes—meaning that they have enzyme-catalyzed reactions occurring in their cells—inside the snowpack is a challenge.

Polar snowpack exists in harsh conditions, with winds blending together top and secondary layers of snow. The quasi-liquid layer on the top a snowpack can seep beneath, ruining a microbial habitat. And on top of all that there's the changing seasons, which expand and contract those habitats.

To deal with the unique environments, Redeker's group developed a trace gas sampling system that "minimizes interfering signals from physical, chemical and alternative biological sources." Using chemical compounds called methyl halides as chemical probes, they were able to detect clear signs of metabolic activity, which shows how life, does indeed find a way.

"The fact that we have observed metabolically active bacteria in the most pristine ice and snow is a sign of life proliferating in environments where you wouldn't expect it to exist," says lead study author Kelly Redeker, from the University of York, in a press release. "This suggests we may be able to broaden our horizons when it comes to thinking about which planets are capable of sustaining life."

The study also looks at microbial climate change. Microorganisms have played a role in the Earth's carbon and nitrogen cycles for as long as they have been around, both consuming and producing greenhouse gases like carbon dioxide. The compounds found in the polar regions, methyl chloride and methyl bromide, are better at capturing sunlight than they are carbon dioxide.

"Respiration by bacteria may have slightly increased levels of CO2 in pockets of air trapped within polar ice caps, meaning that before human activity CO2 levels may have been even lower than previously thought," Redeker says.

While the group's paper warns that "total impacts for any given compound are difficult" to predict in the rough polar conditions, it also suggests that "a diminished snowpack may be, to a small degree, responsible for slightly delaying the recovery of the ozone layer."

While we beat back the hole in the ozone layer in the 1980s through targeted public policy, the Earth has never been one to show its inhabitants many favors. And time is likely running out on making things any easier.

Source: Yorkshire Post

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