Recent Eurasian river discharge to the Arctic Ocean in the context of longer-term dendrohydrological records

Abstract

Mapped correlations between annual discharges (AD 1938–1990) of the major Eurasian rivers entering the Arctic Ocean (Severnaya Dvina, Pechora, Ob', Yenisey, Lena, and Kolyma) demonstrate a positive relationship between discharge and the Palmer Drought Severity Index (PDSI) within the individual basins and more distant areas. The relationship between recent discharge and PDSI supports the application of dendrohydrological modeling to produce reconstructions of discharge extending back before the 20th century. The dendrohydrologic models explain from 41% (Yenisey) to 55% (Pechora) of the observed variability of flow in the individual basins and 39% of the total combined discharge. Discharge reconstructions for the period AD 1800–1990 indicate that there is no long-term monotonic trend toward higher discharge over the past 200 years. Reconstructed annual discharge for the individual rivers and the total discharge from all the rivers experienced in the 20th century are within the bounds of natural variability experienced over the past 200 years. The S. Dvina, Pechora, Ob, and Kolyma reconstructions do display significant multidecadal variability in discharge similar to that observed in the North Atlantic, North Pacific, and Northern Hemisphere climatic parameters. Although the translation of such variability to the river discharges remains uncertain, the presence of multidecadal variability makes it more difficult to detect or ascribe annual discharge changes that may be attributable to global warming.