The West Antarctic Ice Sheet is a candidate to have supplied about 3 meters of that sea level rise. Unfortunately, evidence of its history is hard to come by, as the regrowth of the ice sheet destroyed some of it and now conceals even more. Sediment cores show the ice sheet shrank drastically in the past, but it’s unclear when in the past.
A new study led by University of Washington researcher Eric Steig applies a suitably clever work-around to get at the ice sheet’s history. It’s based on the impact a collapse of the ice sheet (if it shrank down to a small remnant) would have had on local atmospheric circulation. Losing the ice sheet, after all, is like deflating an entire landscape. There are good reasons to expect that thickening the atmosphere by lowering the surface in that area would have consequences.