A recent scientific study of Antarctic and Greenland ice sheets suggests that current modeling efforts have potentially significant shortcomings, as they do not fully assess the positive feedback loop between ice sheet melting and sea level rise. 

• Alley, Richard B. et al. "Ice-Sheet and Sea-Level Changes." Science 310(5747): 456-460. 21 October 2005 at www.sciencemag.org

Ice sheet melting due to a warming climate may contribute further to climate change than earlier studies anticipated, as sea level rise from melting affects ocean circulation, which, in turn leads to additional climate changes. According to Alley et al., few projections fold in the potential interrelatedness of ice sheet melting, ocean circulation, and climate change. Lacking data on these relationships, scientists have not been able to assess the impacts of these feedbacks.

Implications: Theoretical assessments suggest that one critical consequence of adding fresh water to the oceans will be a slowing in ocean circulation. A second consequence of ice melt is sea level rise -- which until recently had been thought to contribute less to ocean levels than thermal expansion but now is assumed to play a more significant role. While existing model projections already suggest  potentially major effects from continued climate change, the results of this study suggest that previous studies understate the consequences, as they do not take into account the full suite of ocean/ice/temperature interactions.