Abstract
By means of a 21-year simulation of a coupled regional pan-Arctic atmosphere-ocean-ice model for the 1980's and 1990's and comparison of the model results with SSM/I satellite-derived sea-ice concentrations, the patterns of maximum amplitude of interannual variability of the Arctic summer sea-ice cover are revealed. They are shown to concentrate beyond an area enclosed by an isopleth of barotropic planetary potential vorticity that marks the edge of the cyclonic rim current around the deep inner Arctic basin. It is argued that the propagation of the interannual variability signal farther into the inner Arctic basin is hindered by the dynamic isolation of upper Arctic Ocean and the high summer cloudiness usually appearing in the central Arctic. The thinning of the Arctic sea-ice cover in recent years is likely to be jointly responsible for its exceptionally strong decrease in summer 2007 when sea-ice decline was favored by anomalously high atmospheric pressure over the western Arctic Ocean, which can be regarded as a typical feature for years with low sea-ice extent. In addition, unusually low cloud cover appeared in summer 2007, which led to substantial warming of the upper ocean. It is hypothesized that the coincidence of several favorable factors for low sea-ice extent is responsible for this extreme event. Owing to the important role of internal climate variability in the recent decline of sea ice, a temporal return to previous conditions or stabilization at the current level can not be excluded just as further decline.
Highlights
The possible disappearance of the Arctic summer sea-ice cover and its time are currently discussed among climate researchers in view of the rapid decrease of summer sea ice in recent years [1, 2]
Since the observed downward trend is much greater than in most simulations of the climate models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) [3], it is often argued that the Arctic Ocean will possibly become ice free during summer already within the few decades
At least the fact that all IPCC AR4 climate models show longterm decline of Arctic sea ice from the 1990s onwards [3] indicates that greenhouse gases are an important factor for ongoing changes in the Arctic climate system
Summary
The possible disappearance of the Arctic summer sea-ice cover and its time are currently discussed among climate researchers in view of the rapid decrease of summer sea ice in recent years [1, 2]. An ice free Arctic Ocean would definitely have broad implications for Arctic ecosystems, indigenous people, transportation, etc., and significant feedbacks on the global atmospheric and oceanic circulations are very likely [13,14] and indicate the prime importance of knowing the fate of the Arctic sea-ice cover. It is still unclear whether the decrease of summer sea ice will continue at the same or even higher rate, or whether there are some physical factors which could counteract this process. The typical atmospheric circulation patterns in “high-ice” and “low-ice” phases are compared and semi-quantitative arguments for a potential limitation of the area of summer sea-ice variability are discussed and linked to recent changes in summer sea-ice cover
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
