What was done
Using "the most comprehensive data set presently available to the research community," the author analyzed data pertaining to the thickness of Arctic sea ice obtained from six submarine cruises conducted between 1991 and 1997.  The data were acquired from transects covering the central Arctic Basin from 76° N to 90° N, as well as from two areas that have been particularly densely sampled, one centered around the North Pole (>87° N) and one in the central part of the Beaufort Sea (centered at approximately 76° N, 145°W).

What was learned
Transect data across the entire Arctic Basin revealed that mean Arctic sea ice thickness remained "almost constant" over the period of study.  Data from the North Pole showed little variability, and a linear regression of the data revealed a "slight increasing trend for the whole period."  As for the Beaufort Sea region, annual variability in sea ice thickness was greater than at the North Pole; but once again, "no significant trend" in mean ice thickness was found.  Combining the North Pole results with the results of an earlier study, the author concluded that "mean ice thickness has remained on a near-constant level around the North Pole from 1986 to 1997."

What it means
A couple years ago, Rothrock et al. (1999) published a paper in which they concluded that Arctic sea ice thickness experienced a substantial decline over the 1990s.  Now, however, using the same data as Rothrock et al., but augmented by an additional three years of submarine data, Winsor has come to a vastly different conclusion.  How fast perceptions can change when more facts are at hand!

For related reports that demonstrate the robustness of Winsor's conclusions, see Real-World Data Show No Arctic Warming Over Last 70 Years, Climate Change in the Asian Subarctic, and Arctic Glaciers: Are They Succumbing to Global Warming?

Reference
Rothrock, D.A., Yu, Y. and Maykut, G.A.  1999.  Thinning of the Arctic sea-ice cover.  Geophysical Research Letters 26: 3469-3472.