Ice Sheets and Sea-level Rise: How bad will it be?

Sea-level rise in a warming world is almost guaranteed, but the UN IPCC projects that by 2100 the immense Antarctic ice sheet will contribute less than 0.1% of its ability to raise sea level even under the strongest warming considered.  

Not surprisingly, the uncertainties include a long, fat tail on the high side.  The processes that could trigger much faster sea-level rise, including crumbling ice cliffs, make spectacular videos but pose huge challenges to model accurately.  A fascinating history of research on this topic, and ongoing rapid progress, still leave very large difficulties.