Permafrost is so biodegradable that soon after thawing, organic carbon is near-immediately consumed by microbes and released back as carbon dioxide into the air. This exacerbates climate change, a new study has warned.
In a new paper published in the Proceedings of National Academy of Sciences, Florida State University doctoral student Travis Drake and Assistant Professor Robert Spencer investigated this quick conversion of organic carbon into CO2. It is considered the first time that experts quantified the speed at which the conversion occurs.
Samples of permafrost soil found from deep below an Alaskan tunnel ground offered the researchers clues into the effects of warming and thawing in the northern areas of the world.
“Immediately upon thaw, microbes start using the carbon and then it is sent back into the atmosphere,” warned Drake, who examined permafrost that contained 35,000-year-old carbon and had been stored frozen out of the carbon cycle until thawing.
The thawing took 200 hours, after which almost half was gone and eaten up by microbes.
Spencer likened it to feeding the microbes chocolates, considered a food source “they really enjoy and is high in energy.”
Increased CO2 levels in the atmosphere lead to further warming of the planet and trigger more thawing of permafrost. Alaskan permafrost, too, contains one of the largest carbon stores on Earth, making it critical to determine what happens when such vast amounts are released into the air and water.
The research team from the U.S. Geological Survey, Florida State University, and Colorado University Boulder studied the ancient “yedoma” – permafrost soil found in Alaska and Siberia and accounts for a huge part of the permafrost soil carbon pool – and how much CO2 is produced at a newly excavated tunnel near Fairbanks.
A separate study published in the journal Nature Climate Change assessed the metabolism of old carbon stored in soils but now released through global warming.
Based on estimates, the amount of carbon in permafrost soils is almost twice the amount now found in the atmosphere.
According to principal investigator and Northern Arizona University professor Ted Schuur, they aimed to show how warming shifts ecosystems “out of their historic balance” and give a glimpse of tundra conditions as temperature increases.
Carbon continues to be exchanged throughout ecosystems, and its ongoing release suggests an “accelerating feedback loop” that could accelerate additional permafrost thawing and speed up climate change and its pernicious effects.
Photo: Mike Beauregard | Flickr
