| West Siberia is delicately poised with respect to future climate change scenarios, such that perturbations to its unique climatological, ecological and hydrological features may amplify such change both regionally and globally through several feedback mechanisms. West Siberia contains the world's largest stores of peat carbon, exports massive volumes of freshwater to the Arctic Ocean, currently encompasses portions of the climatically sensitive northern treeline and southern limit of permafrost, and is warming faster than the Arctic as a whole. Taken collectively, these features place West Siberia at the forefront of numerous critical global change issues. However, in order to assess potential changes in West Siberia, it is necessary to first establish certain climatological, ecological and hydrological baselines for the region. To this end, my research examines recent meteorological trends, the accuracy of current land cover classification databases, and the present-day distribution of dissolved organic carbon (DOC) and inorganic solute concentrations in streams of West Siberia. Results show that West Siberia has experienced significant warming and notable increases in precipitation over recent decades, driven in part by large-scale arctic atmospheric variability. With further warming, globally significant changes to the region's ecology, hydrology, carbon cycling and land-atmosphere exchange may occur. However, through collection of a unique field-based database of land cover observations, I show that many of the currently available land cover databases are of insufficient quality to model such changes or even ascertain present-day conditions. Finally, my studies of stream biogeochemistry show that cold, permafrost-influenced watersheds release little DOC and inorganic solutes to streams, but considerably higher concentrations occur in warm, permafrost-free watersheds. Noting the observed recent warming trends and accuracy of land cover maps found in this research, I estimate that (i) the flux of DOC from West Siberia to the Arctic Ocean may increase ∼29--46% by 2100; and (ii) the flux of inorganic solutes from West Siberia to the Arctic Ocean may increase ∼59% should permafrost in the region completely disappear. These impacts of warming on West Siberian stream biogeochemistry could have important implications for carbon cycle dynamics in arctic Eurasian shelf waters, the Arctic Ocean and the atmosphere. |
