ALBERT

Description: In the exploration of the Russian Arctic German-spelling names of scientists occurred since the 18th century. Geographers and geologists like Alexander von Middendorff, Ernst von Bär, Alexander Bunge, Eduard von Toll studied the frozen ground in Siberia and established by doing so permafrost research. Today joint Russian-German research continues in Siberia, mainly hosted by the Mel’nikov Permafrost Institute (Yakutsk), the faculties of Geology, of Geography and of Soil Science of the Moscow State University (Moscow), the Arctic and Antarctic Research Institute (St. Petersburg), the Institute of Physicochemical and Biological Problems in Soil Science (Pushchino), and the Alfred Wegener Institute (Potsdam), the Institute of Soil Science (Hamburg University). The major scientific topics of this long-term research are permafrost archives, paleoclimate and landscape dynamics; coastal dynamics and subsea permafrost; permafrost degradation and modern changes of permafrost landscapes. More than 30 joint expeditions since 1993 took Russian and German scientists to Central and East Siberia.

Description: Water and sediment supply are essential to the health of deltaic ecosystems. Diverse datasets were integrated to better understand how climate change is shifting the supply of water and sediment to the largest polar distributary channel pattern – the Lena River Delta. Here the increase in warming rate from an average air temperature is from 4.1 °C for the period 1950–99 to 6.1 °C during 2000–21, which is higher than in the adjacent polar regions. Streamflow and sediment yield entering the Lena Delta have increased since 1988 by 56.3 km3 and 6.1×106 t, respectively; meanwhile, the Lena River’s increases in water temperature in June, July–August and September were found to be as much as 1.1, 0.6 and 0.05 °C. These changes have a pronounced effect on sediment regimes in particular parts of the delta. Based on analyses of correlations between various hydroclimatic drivers and sediment concentration changes across particular distributaries of the Lena Delta extracted from Landsat datasets, bank degradation driven by thermal erosional processes (which are in turn related to air and soil temperature increases) is proved to be the primary factor of the sediment regime in the delta. The study also highlights that sediment load changes are sensitive to wind speed due to remobilization of bottom sediment. Sums of daily air temperature and wind speed over 3 days are correlated with sediment concentration changes in the delta. The results also indicate that carbon transport across the delta (both POC and DOC) depends on sediment transport conditions and water discharge and might increase by up to 10 %. We conclude that the Lena Delta can be recognized as the global hot spot in terms of the hydrological consequences of climate change, which is altering sediment regimes, stream hydromorphology and carbon transport.