Panta Rhei

The loss of permafrost carbon

Permafrost stores large amount of soil carbon that is vulnerable to climate warming. As the warming climate continues, thawed permafrost releases soil carbon in the form of carbon dioxide, methane, or dissolved carbon in fluvial networks. The carbon dioxide and methane, which are greenhouse gases, can potentially enhance the warming and degradation of permafrost. This positive permafrost carbon feedback are making the permafrost region a significant carbon source. Even though increased temperature and carbon dioxide (which is a fertilizer to plant photosynthesis) can make vegetation yield larger primary production, the accumulation of carbon by vegetation are much smaller than the loss of soil carbon. Part of the reason for that is warming environment can also enhance microbe activities, which can decompose organic carbon and release them to the atmosphere.

A recent study by Plaza et al. used a new equivalent ash mass method to quantify permafrost carbon loss in Alaska permafrost. The results show that the total permafrost soil carbon pool significantly declined with time at an average rate of 1.366 kg m-2 yr-1 over five years. That large losses overwhelmed increased plant biomass carbon uptake. Conversely, a study by Ding et al. showed increased soil carbon in Tibetan plateau permafrost region due to enhanced vegetation growth. The carbon loss in pan-arctic permafrost indicates a rapid changing carbon pool, which can be important factors to climate warming.

Reference: Ted Schuur (2016). Thawing Arctic tundra will likely speed up climate change for a century or more. The question is: How drastically? SCIENTIFIC AMERICAN.

Plaza et al. (2018). Rapid changes in the permafrost soil carbon pool in response to warming. unpublished paper.

Ding, J., Chen, L., Ji, C., Hugelius, G., Li, Y., Liu, L., … & Fang, K. (2017). Decadal soil carbon accumulation across Tibetan permafrost regions. Nature Geoscience, 10(6), 420.

Posted on February 1, 2018