Impermanent permafrost

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Science  31 Aug 2018:
Vol. 361, Issue 6405, pp. 889-890
DOI: 10.1126/science.361.6405.889-f

Permafrost constitutes a quarter of Earth's surface and about half the buried ancient carbon. Thaw releases water, and, together with higher temperatures, this promotes microbial respiration. Thus, permafrost melt during global warming represents a threat for escalating greenhouse gas release. Müller et al. extracted 2-meter core samples from Svalbard permafrost in Norway for 16S ribosomal RNA gene analysis. Sampling at 3-centimeter intervals, they noted distinctive strata of microbial communities. On thawing and subsequent incubation, each community showed different metabolic rates and different CO2 fluxes. Within 24 hours, thawing the deepest permafrost layers released most CO2, but over a longer term, most CO2 was produced under shallow aerobic conditions. These Svalbard mineral soils also have high iron availability. Intimate knowledge of the microbial, as well as the physicochemical, conditions prevailing in any specific permafrost area is needed to accurately estimate CO2 emission during anthropogenic climate warming.

Environ. Microbiol. 10.1111/1462-2920.14348 (2018).

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