Received: 04 May 2016 – Accepted for review: 08 May 2016 – Discussion started: 10 May 2016
Abstract. September open water fraction in the Arctic is analyzed using the satellite era record of ice concentration (1979–2014). This analysis suggests that there is a statistically significant breakpoint (shift in the mean) and increase in the variance around 1988 and another breakpoint around 2007 in the Pacific sector. These structural breaks are robust to the choice of algorithm used for deriving sea ice concentration from satellite data, and are also apparent in other measures of open water, such as operational ice charts and the record of navigable days from Barrow to Prudhoe Bay. Breakpoints in the Atlantic sector record of open water are evident in 1988 and 2007 but more weakly significant. The breakpoints appear to be associated with concomitant shifts in average ice age, and tend to lead change in Arctic circulation regimes. These results support the thesis that Arctic sea ice may have critical points beyond which a return to the previous state is less likely.
How to cite: Goldstein, M. A., Lynch, A. H., Arbetter, T. E., and Fetterer, F.: Abrupt transitions in Arctic open water area, The Cryosphere Discuss., https://doi.org/10.5194/tc-2016-108, 2016.
Statistical analysis of the long term satellite record of Arctic open water in September reveals breakpoints in 1988 and 2007, particularly in the Pacific sector. These shifts are supported by independent data sets such as operational ice charts. Hence, open water in the Arctic ice appears to be associated with abrupt shifts rather than a gradual upward trend. These results support the thesis that Arctic sea ice may have critical points beyond which a return to the previous state is less likely.
Statistical analysis of the long term satellite record of Arctic open water in September reveals...