Magnitude of Permafrost Carbon−Climate Feedback
Source: LBNL News Center
As permafrost soils warm, the carbon that is currently locked in them is expected to decompose, increasing the concentrations of CO2 and CH4 in the atmosphere. This process, known as the permafrost carbon-climate feedback, is a potentially strong amplifier of global climate change. As reported this week (March 18, 2015) in the Proceedings of the National Academy of Sciences (PNAS), ESD climate scientists Charlie Koven and Bill Riley have recently developed the mechanistic basis for this process within a land surface model, CLM4.5, the terrestrial component of the CESM Earth system model, and explore the roles of decomposition dynamics and their interactions with ecosystem processes that govern the magnitude of this process.
They found that the magnitude of this effect is highly sensitive to how decomposition dynamics differ at depth from at the surface, and that deep soil processes therefore represent a critical uncertainty on projections of future climate change. Further, they included a model of nitrogen dynamics, which are expected to increase plant growth due to nitrogen released from thawing permafrost. However, they also found that deep nitrogen pools are less effective at stimulating plant growth than surface soil pools, implying that the decomposition of deep permafrost soils is more likely to lead to net carbon losses—and therefore more climate change—than surface soils.
To read more, go to: http://newscenter.lbl.gov/2015/03/18/permafrost-carbon/
Koven, C.D., D.M. Lawrence, and W.J. Riley (2015), Permafrost carbon−climate feedback is sensitive to deep soil carbon decomposability but not deep soil nitrogen dynamics. Proceedings of the National Academy of Sciences (PNAS), DOI: 10.1073/pnas.1415123112.