Response of River Runoff in the Cryolithic Zone of Eastern Siberia (Lena River Basin) to Future Climate Warming

Abstract

During the last several decades significant climate warming has been observed in the permafrost regions of Eastern Siberia. Observed environmental changes include increasing air temperature and to a lesser degree precipitation. Changes in regional climate are accompanied by changes in river runoff. Seasonal and long-term changes of river runoff in different parts of the Lena river basin are characterized by distinct differences that can be explained by regional distinctions of climatic conditions, types and properties of permafrost, character of relief, hydrogeological conditions, etc. These factors determine the non-uniform response of river runoff amount and seasonal distribution to contemporary climate changes within the Lena river basin. Over the past 15–20 years river runoff has increased in different parts of the Lena river basin, but the scale of this increase over its territory is quite variable. Hydrological responses to climate warming have been evaluated for the plain part of the Lena river basin based on a macroscale hydrological model featuring simplified descriptions of processes developed at the Institute of Geography of the Russian Academy of Sciences. Two atmosphere-ocean global circulation models used by the IPCC (ECHAM4/OPY3 and GFDL-R30) were used to model scenarios of future global climate. According to the results from hydrological modelling the expected anthropogenic climate warming in the twenty-first century can bring more significant river runoff changes in the Lena river basin compared to the twentieth century.