Showing posts with label Permafrost. Show all posts
Showing posts with label Permafrost. Show all posts

Sunday, August 30, 2020

New research finds - global heating is melting vast northern fields of permafrost so fast that - within decades - they'll likely stop cooling the planet as they have for millennia - and start doing just the opposite.

by Larry Powell
Permafrost Slide at Big Fox Lake, Ontario, Canada - 2015.
A Creative Commons photo by MIKOFOX. 

For thousands of years, so-called "permafrost peatlands" in Earth's Northern Hemisphere have been cooling the global climate. They’ve done it by trapping large amounts of carbon and nitrogen which would otherwise escape into the air as harmful greenhouse gases. 

More recently however, scientists have observed, they've been melting due to manmade global heating. As they melt, they're releasing large amounts of substances like methane - a potent greenhouse gas - into the air. 

But, without proper maps, it's been hard for scientists to get a handle on the degree to which this might be happening - until now. New ones drawn up using thousands of field observations, show; Permafrost peatlands cover a vast area of almost four million square kilometres.

And, to quote from the study, "Under future global warming scenarios, half to nearly all of peatland permafrost could be lost this century.” 

This means their age-old role, mostly as net “sinks,” keeping harmful greenhouse gases in the ground, would transform to a net source of atmospheric carbon, primarily methane.

A permafrost "slump" in Alaska. A USGS photo.

The research concludes that, “Although northern peatlands are currently a source of global cooling, permafrost thaw attributable to anthropogenic climate warming may convert peatlands into a net source of warming."

The findings were published recently in PNAS, the proceedings of the National Academy of Sciences (US). 

But the impact of the nitrogen trapped in these fields cannot be underestimated, either. A separate study, also published in PNAS about three years ago, reveals, "Some 67 billion tons of it, accumulated thousands of years ago, could now become available for decomposition, leading to the release of nitrous oxide (N2O) to the atmosphere. N2O is a strong greenhouse gas, almost 300 times more powerful than CO2 for warming the climate. Although carbon dynamics in the Arctic are well studied, the fact that Arctic soils store enormous amounts of nitrogen has received little attention so far. We report that the Arctic may become a substantial source of N2O when the permafrost thaws, and that N2O emissions could occur from surfaces covering almost one-fourth of the entire Arctic."


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