Abstract
AbstractArctic precipitation is projected to increase more rapidly than the global mean in warming climates. However, warming‐induced changes in the variability of Arctic precipitation, which are related to surface evaporation and poleward moisture transport (PMT), are currently largely unknown. This study compares the precipitation variability in different quasi‐equilibrium climates simulated by a global climate model (EC‐Earth) and studies the underlying mechanisms. Five quasi‐equilibrium simulations of 400 years length forced with a broad range of CO2 concentrations (0.25, 0.5, 1, 2, and 4 times the current global mean) were analyzed. PMT is the dominant source of Arctic precipitation variability in colder climates when the ocean in the Arctic basin is completely covered by sea ice year‐round. Arctic precipitation variability increases from colder to warmer climates, primarily in summer. In summer, the increasingly stronger relation between Arctic sea level pressure variability and precipitation variability toward warmer climates enhances variability. In winter, the severe increase in mean precipitation (due to enhanced evaporation) exerts a comparatively small increase in variability, and precipitation variability is modulated by both PMT and evaporation, which oppose each other as they both affect the vertical and meridional moisture gradients.
Highlights
Global warming will affect the Earth's hydrological cycle mainly because of the increasing moisture‐holding capacity of the atmosphere
Mean Precipitation The average precipitation in both winter and summer for the EC‐Earth control climate and the reanalyses is shown in Figure 1, together with the respective differences
Little is known about the variability in the hydrological cycle of the Arctic region and especially about how it will change toward other climates
Summary
Global warming will affect the Earth's hydrological cycle mainly because of the increasing moisture‐holding capacity of the atmosphere. The increase in precipitation in the Arctic region is relatively large (4.5% K−1) compared to the global value of ~2% K−1 (Held & Soden, 2006). This strong increase can be attributed mainly to sea ice retreat, causing enhanced surface evaporation (Bintanja & Selten, 2014), with the increased poleward moisture transport playing a secondary role. The moisture holding capacity of the Arctic atmosphere increases relatively quickly because the Arctic region warms more strongly than other parts of the world (i.e., Arctic amplification) due mainly to local feedbacks (Manabe & Stouffer, 1980; Serreze & Francis, 2006)
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