Far northern permafrost may unleash carbon within decades

Permafrost in the coldest northern Arctic - formerly thought to be at least temporarily shielded from global warming by its extreme environment - will thaw enough to become a permanent source of carbon to the atmosphere in this century, with the peak transition occurring in 40 to 60 years, according to a new NASA-led study.

The study calculated that as thawing continues, by the year 2300, total carbon emissions from this region will be 10 times as much as all human-produced fossil fuel emissions in 2016.

The study, led by scientist Nicholas Parazoo of NASA's Jet Propulsion Laboratory in Pasadena, California, found that warmer, more southerly permafrost regions will not become a carbon source until the end of the 22nd century, even though they are thawing now. That is because other changing Arctic processes will counter the effect of thawing soil in these regions.

The finding that the colder region would transition sooner than the warmer one came as a surprise, according to Parazoo. "Permafrost in southern Alaska and southern Siberia is already thawing, so it's obviously more vulnerable," he said. "Some of the very cold, stable permafrost in the highest latitudes in Alaska and Siberia appeared to be sheltered from extreme climate change, and we didn't expect much impact over the next couple hundred years."

Permafrost is soil that has remained frozen for years or centuries under topsoil. It contains carbon-rich organic material, such as leaves, that froze without decaying. As rising Arctic air temperatures cause permafrost to thaw, the organic material decomposes and releases its carbon to the atmosphere in the form of the greenhouse gases carbon dioxide and methane.

Parazoo and his colleagues used data on soil temperatures in Alaska and Siberia from the University of Alaska, Fairbanks, with a numerical model from the National Center for Atmospheric Research in Boulder, Colorado, that calculates changes in carbon emissions as plants grow and permafrost thaws in response to climate change.

They assessed when the Arctic will transition to a carbon source instead of the carbon-neutral area it is today - with some processes removing about as much carbon from the atmosphere as other processes emit. They divided the Arctic into two regions of equal size, a colder northern region and a warmer, more southerly belt encircling the northern region.

There is far more permafrost in the northern region than in the southern one. Over the course of the model simulations, northern permafrost lost about five times more carbon per century than southern permafrost.

The southern region transitioned more slowly in the model simulations, Parazoo said, because plant growth increased much faster than expected in the south.

Plants remove carbon dioxide from the air during photosynthesis, so increased plant growth means less carbon in the atmosphere. According to the model, as the southern Arctic grows warmer, increased photosynthesis will balance increased permafrost emissions until the late 2100s.

Related Links
Climate Science at NASA
Beyond the Ice Age

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

Spring is springing earlier in polar regions than across the rest of earth
Davis CA (SPX) Mar 05, 2018
Spring is arriving earlier, but how much earlier? The answer depends where on Earth you find yourself, according to a study led by the University of California, Davis. The study, published in Nature's online journal Scientific Reports, found that for every 10 degrees north from the equator you move, spring arrives about four days earlier than it did a decade ago. This northward increase in the rate of springtime advance is roughly three times greater than what previous studies have indicated. ... read more