Professor Jeff Welker and his international colleagues have just published, in the journal Nature Climate Change, a comprehensive synthesis of the winter state-of-affairs, with a focus as to the patterns and magnitude of CO2 emissions during the snow covered season. The study focuses on the climate feedback consequences, the magnitudes of the emissions as compared to the summer, and the consequences of winter carbon emissions and the underlying biophysical processes governing this unique property of the north today and in the coming centuries.
The most important findings from this study across the permafrost region of the north (Arctic and Boreal) are:
- Today winter CO2 emissions are ~30% more than the CO2 assimilated by these regions during summer. The North is a net emitter of CO2-C adding to a rising CO2 concentration in the atmosphere, a critical feed-forward process associated with warmer winters.
- Continued warming in winter will lead to even greater CO2-C emissions, without corresponding increases in CO2 fixation, thus over the next decades permafrost regions will continue to be net emitters of CO2 to the atmosphere, amplifying the positive feedbacks between climate warming, more CO2 accumulating in the atmosphere and further warming.
- The underlying biophysical processes leading to winter CO2-C emissions are a combination of winter warming leading to more snow, and less cold soils, with higher microbial decomposition and further ecosystem winter respiration.
- One possible means by which these large net CO2-C emissions from permafrost regions may be slowed, is whether tundra become more shrubby and the boreal forest produced more trees, that collectively will assimilate more summer C to counter-act all the C that is being emitted by a warmer, less cold, winter.
- Welker’s long-term snow depth experiments simulating 2050 suggest that winter warming will release ancient CO2 in what is now permafrost as the active layer deepens, creating an even greater winter emission rate than today.
Main photo: Toolik Lake Field Station in North Alaska 68oN, October 2019. Brooks Range Mountains in the distance. Professor Welker´s winter CO2 flux program started here in 1996 and continues today with his NSF Navigating the New Arctic ancient C emissions project.
Last updated: 28.10.2019