Decline in Arctic sea ice thickness from submarine and ICESat records: 1958-2008

The decline of sea ice thickness in the Arctic Ocean from ICESat (2003-2008) is placed in the context of estimates from 42 years of submarine records (1958-2000) described by Rothrock et al. (1999, 2008). While the earlier 1999 work provides a longer historical record of the regional changes, the latter offers a more refined analysis, over a sizable portion of the Arctic Ocean supported by a much stronger and richer data set. Within the data release area (DRA) of declassified submarine sonar measurements (covering similar to 38% of the Arctic Ocean), the overall mean winter thickness of 3.64 m in 1980 can be compared to a 1.89 m mean during the last winter of the ICESat record-an astonishing decrease of 1.75 m in thickness. Between 1975 and 2000, the steepest rate of decrease is -0.08m/yr in 1990 compared to a slightly higher winter/summer rate of 00.10/-0.20 m/yr in the five-year ICESat record (20032008). Prior to 1997, ice extent in the DRA was >90% during the summer minimum. This can be contrasted to the gradual decrease in the early 2000s followed by an abrupt drop to <55% during the record setting minimum in 2007. This combined analysis shows a long-term trend of sea ice thinning over submarine and ICESat records that span five decades. Citation: Kwok, R., and D. A. Rothrock (2009), Decline in Arctic sea ice thickness from submarine and ICESat records: 1958-2008, Geophys. Res. Lett., 36, L15501, doi: 10.1029/2009GL039035.