What was done
The authors describe and evaluate recent changes in the Ward Hunt Ice Shelf, located at the northern limit of North America [83°N, 74°W], by means of satellite-borne synthetic aperture radar, helicopter overflight transects and in situ profiling measurements.

What was learned
It was determined, in the words of the authors, that the ice shelf "broke in two over the period 2000 to 2002, with additional fissuring and further ice island calving," while "the fracturing caused the drainage of an ice-dammed epishelf lake (Disraeli Fjord)."

What it means
The breakup of the Ward Hunt Ice Shelf was heralded in the press with great fanfare, the headline of the Independent/UK's treatment of the event trumpeting "Climate Change Blamed as Largest Arctic Ice Shelf Breaks in Two After 3,000 Years."  As noted by Mueller et al., however, the Ward Hunt Ice Shelf was merely "a 443 km² remnant of a much larger feature that extended along the northern coast of Ellsmere Island at the beginning of the last century (Peary, 1907)."  They report, for example, that the original ice shelf had already "contracted 90% during the period 1906-1982 by calving from its northern edge (Vincent et al., 2001)."  In fact, during the following two decades of what climate alarmists typically describe as unprecedented global warming, and in a part of the planet (high northern latitudes) that is supposed to amplify this phenomenon, they report that the ice shelf had "remained relatively stable."

So what do we say about the ice shelf's demise?  We say what Mueler et al. say: "The cumulative effects of a long-term warming trend since the Little Ice Age (Overpeck et al., 1997) likely caused the ongoing changes in the Ward Hunt Ice Shelf," including "the abrupt break-up and loss of integrity ? that we observed over the period 2000-2002."

References
Overpeck, J., Hughen, K., Hardy, D., Bradley, R., Case, R., Douglas, M., Finney, B., Gajewski, K., Jacoby, G., Jennings, A., Lamoureux, S., Lasca, A., MacDonald, G., Moore, J., Retelle, M., Smith, S., Wolfe, A. and Zielinski, G.  1997.  Arctic environmental change of the last four centuries.  Science 278: 1251-1256.

Peary, R.E.  1907.  Nearest the Pole.  Hutchinson, London, UK.

Vincent, W.F., Gibson, J.A.E. and Jeffries, M.O.  2001.  Ice shelf collapse, climate change, and habitat loss in the Canadian high Arctic.  Polar Record 37: 133-142.