Strong future increases in Arctic precipitation variability linked to poleward moisture transport

Abstract

<p>The Arctic region is projected to experience amplified warming as well as strongly increasing precipitation rates. Equally important to trends in the mean climate are changes in interannual variability, but changes in precipitation fluctuations are highly uncertain and the associated processes unknown. Here we use various state-of-the-art global climate model simulations to show that interannual variability of Arctic precipitation will likely increase markedly (up to 40% over the 21<sup>st</sup> century), especially in summer. This can be attributed to increased poleward atmospheric moisture transport variability associated with enhanced moisture content, possibly modulated by atmospheric dynamics. Because both the means and variability of Arctic precipitation will increase, years/seasons with excessive precipitation will occur more often, as will the associated impacts.</p>

Contribution of climatic changes in mean and variability to monthly temperature and precipitation extremes

“…4a). In contrast, changes in extreme heavy-precipitation events in these near-Arctic regions are much less affected by increasing precipitation variability 17 ( Fig. 4b), showing the importance of understanding the effectivity of these changes to extreme event occurrence.…”

“…Importantly, changes in mean and variability can generally be attributed to different climate mechanisms [14][15][16][17] , and, as a result, may have opposing effects on extreme event frequency. The combined effect on changes in regional extreme event occurrence thus depends on the balance between, and effectivity of, the associated driving mechanisms.…”

“…The individual contributions to the occurrence of hightemperature events are thus of opposite sign, the total effect of climate change on high-temperature event frequency therefore depends on the balance between the two mechanisms. Another example concerns Arctic precipitation, for which mean changes are driven mainly by sea ice retreat and surface evaporation 23 , whereas changes in variability are governed by atmospheric poleward moisture transport 17 . Even though both are projected to increase as a result of climate change, and thus contribute to more and more extreme heavy-precipitation events, the mechanisms behind enhanced Arctic downpours crucially depend on the relative importance of increases in mean precipitation and in precipitation variability.…”

Thermo‐erosional valleys in Siberian ice‐rich permafrost

“…In a warming Arctic with active‐layer deepening 94 and precipitation regime shifts, 95 permafrost degradation is expected to increase. The consequences of this increase include more thermal erosion and thermokarst, intensified organic matter cycling, and release as well as shifts in the seasonality and intensity of the hydrological regime 10,96 .…”

Snowdrift Landscape Patterns: An Arctic Investigation

“…Finally, if our view is correct that the current Arctic Alaskan winter weather system is climatologically convergent with the landscape controlling drift formation, it suggests an important follow‐on question: “How much would the climate system need to change before the drifts of the Arctic begin to change and drift fidelity begins to fall off?” The Arctic is warming rapidly (Cohen et al, 2014; Huang et al, 2017; Johannessen et al, 2004; Räisänen, 2008), with large changes in winter precipitation predicted (Bintanja et al, 2020; Bintanja & Selten, 2014), though these have yet to be documented widely through measurements. While more winter snow should in principle produce larger drifts, several predictions (Bieniek et al, 2016; Bintanja & Andry, 2017) suggest that the increase in winter precipitation could come in the form of rain‐on‐snow (ROS).…”