Arctic rapid sea ice loss events in regional coupled climate scenario experiments

Abstract

Abstract. Rapid sea ice loss events (RILEs) in a miniensemble of regional Arctic coupled climate model scenario experiments are analyzed. Mechanisms of sudden ice loss are strongly related to atmospheric circulation conditions and preconditioning by sea ice thinning during the seasons and years before the event. Clustering of events in time suggests a strong control by large-scale atmospheric circulation. Anomalous atmospheric circulation is providing warm air anomalies of up to 5 K and is forcing ice flow, affecting winter ice growth. Even without a seasonal preconditioning during winter, ice drop events can be initiated by anomalous inflow of warm air during summer. It is shown that RILEs can be generated based on atmospheric circulation changes as a major driving force without major competing mechanisms, other than occasional longwave effects during spring and summer. Other anomalous seasonal radiative forcing or short-lived forcers (e.g., soot) play minor roles or no role at all in our model. RILEs initiated by ocean forcing do not occur in the model, although cannot be ruled out due to model limitations. Mechanisms found are qualitatively in line with observations of the 2007 RILE.

Changes in the Thickness and Circulation of Multiyear Ice in the Beaufort Gyre Determined From Pseudo‐Lagrangian Methods from 2003–2015

“…The summertime retreat of Arctic sea ice in 2007 has been described as a rapid ice loss event (Döscher & Koenigk, ), occurrences of which are expected to hasten the arrival of effectively ice‐free summers (Overland & Wang, ). Indeed, in the years after 2007, the Arctic ice pack contained significantly less MY ice than before (Maslanik et al, ) and summertime sea ice extent has remained low (Serreze & Meier, ; Stroeve et al, ), prompting speculation that a predominantly seasonal ice regime is the “new normal” for the Arctic (Jeffries et al, ).…”

Past and future interannual variability in Arctic sea ice in coupled climate models

“…Overall thinner ice may result in an ice pack that exhibits greater interannual variability (Maslanik et al, 2007b;Goosse et al, 2009;Notz, 2009;Kay et al, 2011;Holland and Stroeve, 2011;Döscher and Koenigk, 2013), at least partially due to enhanced ice growth and melt (Maykut, 1978;Holland et al, 2006;Bathiany et al, 2016). Decreased ice thickness promotes amplification of a positive ice-albedo feedback, which can magnify sea ice anomalies (Grenfell and Maykut, 1977;Maykut, 1982;Ebert and Curry, 1993;Hunke and Lipscomb, 2010), and thin ice is more vulnerable to anomalous atmospheric forcing and oceanic transport due to the smaller amount of energy required to completely melt the ice (Maslanik et al, 1996;Zhao et al, 2018) and deform the ice dynamically (Hibler, 1979). For example, pulse-like increases in oceanic heat transport can trigger abrupt ice-loss events in sufficiently thin ice (Woodgate et al, 2012).…”

Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

“…This favours advection of warm, moist air masses from the Pacific sector to the central Arctic, contributing to sea ice decline (Graversen et al, 2011) and rapid sea ice loss events (Döscher and Koenigk, 2013). Through increased release of ocean heat into the atmosphere during autumn, the sea ice decline has, in turn, contributed to a modification of large-scale atmospheric circulation, favouring a positive AD (Overland and Wang, 2010).…”