Arctic carbon cycle is speeding up

The warning lights are blinking red.

NASA’s Jet Propulsion Laboratory has found that Alaska’s North Slope spends about 13 percent less time locked in frozen soil than it did just 40 years ago.

The tundra holds massive stores of carbon in its permanently frozen soil. Warming temperatures from our changing climate exposes thawing soil to “microbial decomposition,” which in turn releases additional carbon into the atmosphere. 

A new NASA-led study using data from the Arctic Boreal Vulnerability Experiment (ABoVE) shows that carbon in Alaska's North Slope tundra ecosystems spends about 13 percent less time locked in frozen soil than it did 40 years ago. In other words, the carbon cycle there is speeding up -- and is now at a pace more characteristic of a North American boreal forest than of the icy Arctic.

"Warming temperatures mean that essentially we have one ecosystem -- the tundra -- developing some of the characteristics of a different ecosystem -- a boreal forest," said study co-author Anthony Bloom of NASA's Jet Propulsion Laboratory in Pasadena, California. "While various factors regulate how fast this transformation will continue to occur, studies using Landsat and MODIS satellite imagery with field measurements over the past decades have observed a northward migration of shrubs and trees."

And it's not just about the trees. The Arctic carbon cycle is a delicate balance of carbon being released into the atmosphere and carbon being removed from the atmosphere. Disruptions to this balance have implications well beyond the Arctic.

During Arctic summer, warmer temperatures thaw the uppermost layers of permafrost, allowing microbes to break down previously frozen organic matter. This process releases carbon dioxide into the atmosphere. Plant growth also increases during this period - and plants remove carbon dioxide from the atmosphere through photosynthesis. But as temperatures increase, the amount of time carbon is stored in the Arctic soil decreases.

Scientists believe that more open sea water (a result of the loss of sea ice in the Chukchi Sea) in the summer, along with increased summer warmth is driving the thawing process of the tundra. Most of the Arctic’s coastal waters have become increasingly ice-free, with only a few areas experiencing a trend of less open water over the past three decades, according to climate.gov. 

Further reading on the “shrubification” of the Arctic tundra and one man’s bold plan to stop it:

Bison to be flown to Siberia's 'Pleistocene Park' in effort to slow deadly permafrost feedback