Projections of large-scale greenhouse gas emissions from degrading Siberian permafrost and the effect on climate
Work package 2 works on improving and advancing different modeling approaches to project large-scale greenhouse gas emissions from degrading Siberian permafrost and the effect on climate. Both process-orientated and data driven models of large-scale greenhouse gas exchanges between the Earth’s surface and the atmosphere will be implemented. Especially the description of cold-regions specific physical processes and permafrost-carbon dynamics shall be improved. There are two main foci.
The Max Planck Institutes for Meteorology in Hamburg and Biochemistry in Jena work on improving the land-surface model JSBACH. In particular, the implementation of updated carbon pool data in permafrost-affected soils will lead to a more realistic representation of soil organic carbon contents and thus a better initialization of the models. A data-based process understanding will be developed in close cooperation with work package 3, which will decrease the large uncertainties concerning the temporal carbon pool dynamics. Together with work package 4, vegetation trends shall be derived from remote sensing data and incorporated into the model runs. This will give an indication of if and when the current carbon sink of northern regions, especially Siberian permafrost, can turn into a future carbon source.
Furthermore, the atmospheric inverse modelling approaches will be further developed and optimized. Large-scale greenhouse gas exchange between the land surface and the atmosphere will be modeled based on atmospheric greenhouse gas concentrations and gas transport models. The coupling of inverse modeling with the process-orientated JSBACH model and the inclusion of geo-statistical methods allows the calculation of spatially- and temporally highly resolved scaling factors. The modeled carbon fluxes can then be optimized with the atmospheric reference measurements.
© J. Walz: Heterogeneous polygonal tundra
Goals and milestones:
- Improvement of permafrost-carbon dynamics in the JSBACH land-surface model
- Sensitivity analyses of organic carbon decomposition rates to greenhouse gas release
- Compilation of regional greenhouse gas budgets from atmospheric inverse modeling
- Model evaluation of JSBACH with inverse model results
- Model evaluation of JSBACH with vegetation dynamics derived from remote sensing data
- Model projections of greenhouse gas release from thawing permafrost under different warming scenarios
- Prof. Dr. Victor Brovkin (Max Planck Institute for Meteorology)
- Dr. Mathias Göckede (Max Planck Institut for Biogeochemitry)
- Prof. Dr. Martin Heimann (Max Planck Institut for Biogeochemitry)
- Dr. Thomas Schneider-von Deimling (Max Planck Institute for Meteorology)
- Scientist (Max Planck Institut for Biogeochemitry)
- Prof. Igor Mokhov (Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow)
- Dr. Alexey Eliseev (Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow)
- Sergey Zimov (Northeast Science Station in Chersky)
- Nikita Zimov (Northeast Science Station in Chersky)
- Dr. Victor Stepanenko (Lomonosov Moscow State University)
The decomposition of eddy covariance-based CO2 fluxes into respiration and photosynthesis was not only applied for the overall footprint as commonly carried out, but instead for each of two vegetation classes. In this way, a differing seasonality in the net uptakes of bushes and sedges could be unveiled. Therefore, the flux decomposition proved to be a useful tool for gaining insights into both the phenological dynamic of individual vegetation classes, plus their respective functional flux to flux driver relationships with the aid of ecophysiologically interpretable parameters (Rößger et al., 2019, Biogeosciences Discuss).
20 Years Lena Expedition
German and Russian scientists, technicians, and students will meet in Saint Petersburg from October 17-19 to celebrate 20 years of successful cooperation in the Lena River Delta and Laptev Sea region. Future expeditions and joint research strategies will also be discussed. The meeting is organized by the Arctic and Antarctic Research Institute in Saint Petersburg, the Alfred Wegener Institute in Potsdam, the Melnikov Permafrost Institute in Yakutsk, and the Institute of Soil Science in Hamburg.
© T. Eckhardt: The "old" research station on Samoylov Island
Partitioning of CO2 net ecosystem exchange on the microsite scale in the Lena River Delta shows that both polygon centers and polygon rims were sinks for atmospheric CO2 during a growing season, but the sink strengths varied between the two microsites. Furthermore, it was shown that autotrophic and heterotrophic respiration fluxes react differently to changing hydrologic conditions (Eckhardt et al. Biogeoscience Discuss. 2018)
Greenhouse gas production in degrading ice-rich permafrost deposits in northeast Siberia depends on the climate conditions during deposition. Late Pleistocene Yedoma deposits generally produced more CO2 than Holocene deposits. Thus, organic matter decomposability needs to be interpreted against the paleo-environmental background. However, organic matter decomposability cannot be generalized solely based on the stratigraphic position (Walz et al. Biogeoscience 2018)