Future increases in Arctic precipitation linked to local evaporation and sea-ice retreat

Abstract

Precipitation changes projected for the end of the twenty-first century show an increase of more than 50 per cent in the Arctic regions. This marked increase, which is among the highest globally, has previously been attributed primarily to enhanced poleward moisture transport from lower latitudes. Here we use state-of-the-art global climate models to show that the projected increases in Arctic precipitation over the twenty-first century, which peak in late autumn and winter, are instead due mainly to strongly intensified local surface evaporation (maximum in winter), and only to a lesser degree due to enhanced moisture inflow from lower latitudes (maximum in late summer and autumn). Moreover, we show that the enhanced surface evaporation results mainly from retreating winter sea ice, signalling an amplified Arctic hydrological cycle. This demonstrates that increases in Arctic precipitation are firmly linked to Arctic warming and sea-ice decline. As a result, the Arctic mean precipitation sensitivity (4.5 per cent increase per degree of temperature warming) is much larger than the global value (1.6 to 1.9 per cent per kelvin). The associated seasonally varying increase in Arctic precipitation is likely to increase river discharge and snowfall over ice sheets (thereby affecting global sea level), and could even affect global climate through freshening of the Arctic Ocean and subsequent modulations of the Atlantic meridional overturning circulation.

A new pattern of the moisture transport for precipitation related to the drastic decline in Arctic sea ice extent

“…Major moisture sources for the Arctic did not provide more moisture for precipitation to the Arctic in summer after 2003, the change point (CP) for Arctic sea ice, than before, although they did provide more moisture in autumn and early winter. Because the enhanced Arctic precipitation projected by most models for the end of the century (Bintaja and Selten, 2014) is partly attributed to enhanced poleward moisture transport from latitudes lower than 70 • N (Bintanja and Andry, 2017), where the major sources studied herein are located, our results raise questions of whether this change has occurred so simply in the current climate, and these questions merit further study.…”

The role of summer precipitation and summer temperature in establishment and growth of dwarf shrub Betula nana in northeast Siberian tundra

“…The large variation of trends in summer precipitation in the Arctic further suggests that shrub expansion might not happen everywhere in the Arctic tundra. However, future precipitation is expected to show an increasing trend as the retreat of sea ice results in strongly increased evaporation and precipitation (Bintanja and Selten 2014).…”

Shifted energy fluxes, increased Bowen ratios, and reduced thaw depths linked with drainage-induced changes in permafrost ecosystem structure

“…Future shifts in hydrologic conditions in the Arctic can be triggered by altered precipitation patterns, where a general trend towards increased rainfall is predicted (Kattsov and Walsh, 2000); however, patterns will vary strongly by region (Huntington, 2006;Bintanja and Selten, 2014); therefore, for some areas also lower precipitation can be expected. Geomorphological processes such as subsidence (Jorgenson et al, 2006;O'Donnell et al, 2012) as well as the formation of a system of connected troughs through the preferential degradation of ice wedges in ice-rich permafrost (Serreze et al, 2000;Liljedahl et al, 2016) can lead to a lateral redistribution of water, and thus can create both wetter and drier microsites within a formerly uniform ecosystem.…”