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As Peatlands Thaw, Two Gases Much Worse Than Carbon Are Being Unchained

Jun 28, 2017 05:55 PM EDT
Melting Permafrost Creates Atmospheric Methane Hazard
New vegetation growing on formerly permafrost areas will release more methane into the atmosphere.
(Photo : GettyImages)

Thawing of permafrost peatlands of the Arctic could release so much methane and nitrous oxide that our planet might never recover. These permanently frozen areas cover 625,000 square miles around the Arctic Circle--and as you read this, they are melting.

Without intervention to prevent it, dozens of billions of tons of carbon will be released by 2100 as the permafrost peatlands thaw and the plant materials become subjected to microbial breakdown.

Carbon will be release in the forms of carbon dioxide gas and the more dangerous greenhouse gas methane, two gases that our atmosphere doesn't need any more of. Additionally, nitrous dioxide (N2O) will be released in amounts matching those from tropical rainforests. N2O is another greenhouse gas and more of it in the atmosphere can't be a good thing.

Although carbon dioxide is the better-known greenhouse gas, methane is up to 30 times as potent in terms of the heat trapping that powers global warming. And nitrous oxide leaves both in the dust: A single molecule of nitrous oxide has the warming potential of 300 molecules of carbon dioxide.

Permafrost peatlands are formed as eons of dead vegetation accumulate. The dead plant material, peat, mixes with water to form a kind of slurry--and when the slurry freezes it becomes a permafrost peatland. When frozen, the organic material ceases to decompose.

About 20% of all permafrost areas on earth are peat-based, but when a peat area thaws, bacterial go to work, and it releases five times as much carbon into the air as mineral-based soils.

But where does the carbon come from? Current thinking suggests that as the permanently frozen peat thaws, microbial action will work on the dead organic matter. Is it this area that most of the methane will come from? Perhaps most of the methane comes when new plants on the surface die and decompose.

Knowing where the methane comes from is key to getting a hold on managing climate change.

Researchers conducted studies near Teslin in the Yukon Territory and near Yellowknife in the Northwest Territories. They took peat cores from formerly permafrost areas and conducted radiocarbon studies. The percent of 14C in released methane or carbon dioxide is different in the old peat than in new vegetation, so it is possible to determine what percent of the methane comes from the thawed portion and what comes from the new growth.

Surprisingly, researchers from the Universities of Exeter, Sussex, and Sheffield found that most of the methane that is released comes from decay of the new vegetation from the recently thawed top layers.

With this knowledge, it becomes important to use aerial surveys to check when and where wetland form, where new vegetation is springing up. New wetlands mean new plants--which means more methane. Photographic analysis will give scientists quantitative data on the levels of methane that are being into the air.

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