Leading Principal Investigator: Professor Jan Karlsson, Umeå University, Sweden
Large amounts of organic carbon (C) are stored in permafrost soils at high latitudes. Climate change and the consequent thawing of permafrost cause mobilization and decomposition of these old C stocks and, hence, the release of significant amounts of greenhouse gases from land to the atmosphere. Permafrost thawing may also increase the lateral export of terrestrial C to aquatic systems altering flow pathways in the landscape. Streams and lakes play here an important role by burying C in sediments and
emitting C to the atmosphere and, by that, affect the continental greenhouse gas balance and the amount of C delivered to coastal regions. Still, the current knowledge of climate impact on C cycling in inland waters at high latitudes is in many important aspects incomplete, preventing accurate quantification and predictions of their role in the C cycle and climate system. Siberia contains vast C stocks potentially vulnerable to mobilization following permafrost thawing, and inland waters draining these regions are largely understudied. Thus, research on inland waters of Siberia is of particular importance for understanding climate change. We will carry out a comparative study of lake-stream networks across a climate gradient in western Siberia covering a large range of permafrost conditions. We will test the hypothesis that the role of the inland waters show fundamental differences across the climate gradient, with increasing emission:export ratios in a transition from cold permafrost to warm permafrost-free conditions, and that this change is mainly driven by a combination of differences in temperature dependent loss rates and differences in hydrological transit time in the inland waters along this gradient. The project is important by providing knowledge of the role of Russian inland waters in emitting C to atmosphere and in exporting C to downstream coastal regions and how this varies between different climate regimes.