The biggest terrestrial tipping point or a potential carbon sink? Local and global consequences of thawing permafrost

Ben Abbott (March 29, 2019)

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Arctic tundra and Boreal forest contain approximately half of all terrestrial organic carbon and represent a quarter of the terrestrial habitat in the Northern Hemisphere. As the permafrost region warms, more of this immense carbon pool will be exposed to decomposition, combustion, and hydrologic export. This permafrost carbon feedback has been described as the largest terrestrial feedback to climate change as well as one of the most likely to occur; however, it is not included in current emissions negotiations and estimates of its strength vary by a factor of thirty. Models predict that some portion of this release will be offset by increased Arctic and boreal biomass, but the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets with serious societal and environmental consequences. Because precise empirical or model-based assessments of the critical factors driving carbon balance and biodiversity in the permafrost zone are unlikely in the near future, creative mathematical and methodological approaches are needed. In this talk, I will synthesize recent understanding of the permafrost zone generated by the Permafrost Carbon Network (PCN). The PCN is a coalition of ~450 researchers spanning the natural and social sciences. I will explore sources of uncertainty in current estimates of greenhouse gas release and present several promising approaches for identifying tipping points in biosphere integrity and permafrost-climate coupling.