Australia: The Land Where Time Began

A biography of the Australian continent 

Methane Emissions Proportional to Carbon from Permafrost Thawed in Arctic Lakes Since the 1950s

Organic matter in soil that has been frozen in permafrost is being exposed as the permafrost thaws to microbial decomposition. A positive feedback process is being fuelled by the methane and carbon dioxide that is generated by this decomposition which leads to further warming and thaw (Romanovsky, Smith & Christiansen, 2010). The degree to which the thawing of permafrost may be contributing to a feedback between warming and thaw in recent decades is not well known, in spite of the widespread degradation of permafrost over about the last 40 years (Romanovsky et al., 2010; Romanovsky, Smith & Christiansen, 2010). There is also little known radiocarbon evidence of modern emissions of ancient carbon from permafrost (Schuur et al., 2009). In this paper Anthony et al. have combined the radiocarbon dating of bubble trace-gas methane, from 113 samples, and soil organic carbon, 289 measurements, from lakes in Alaska, Canada, Sweden and Siberia with the results of numerical modelling of thaw and remote sensing of thermokarst shore expansion. Methane being emitted from thermokarst areas of lakes that have been expanding over the last 60 years was found to be directly proportional to the mass of the inputs of soil carbon from the erosion of thawing permafrost into the lakes. It is indicated by radiocarbon dating that the age of methane from lakes is almost identical to carbon in permafrost soil that is thawing around them. Anthony et al. have estimated 0.2-2.5 Pg of permafrost carbon that was released as methane and carbon dioxide in zones of thermokarst expansion of pan-Arctic lakes during the last 60 years.

Sources & Further reading

1. Walter Anthony, K., R. Daanen, P. Anthony, T. Schneider von Deimling, C.-L. Ping, J. P. Chanton and G. Grosse (2016). "Methane emissions proportional to permafrost carbon thawed in Arctic lakes since the 1950s." Nature Geosci 9(9): 679-682.