As most people posting on this topic have already reviewed the Antarctic folder, which has extensively discussed the possible SLR contribution of both the WAIS, and the EAIS, by 2100; I will not bother to repeat those discussions here. Nevertheless, I would like to note that the Antarctic folder cites a considerable amount of evidence that a significant portion of the WAIS became ungrounded/collapsed during the Eemian, and my favorite paper on this topic is the following by O'Leary et al (2013), which shows that around 119 to 120 kya RSLR in Western Australia jump up over 6m in less than 1,000 years (see linked and attached figure/caption):
O'Leary, M.J., Hearty, P.J., Thompson, W.G., Raymo, M.E., Mitrovica, J.X., and Webster, J.M., (2013), "Ice sheet collapse following a prolonged period of stable sea level during the last interglacial", Nature Geoscience; doi:10.1038/ngeo1890.http://www.nature.com/ngeo/journal/v6/n9/fig_tab/ngeo1890_F3.html
Caption for the linked and attached figure is: "A geomorphically defined palaeoMSL datum of +2.5 m 120 kyr ago (Fig. 1c) anchors a predicted relative sea-level curve at Red Bluff, which includes a GIA signal based on the test calculation (see Methods) plus the following ESL history: ESL jumps from 0 to 3.4 m between 127.5 kyr and 127 kyr ago and remains at this level until 120 kyr ago; and 120 kyr ago, ESL jumps ~ 6 m over 1 kyr. Dashed green line is an inferred sea-level curve based on a minimum coral palaeodepth (solid bar above circle) of 0.4 m below palaeoMSL. This palaeodepth calculation is applicable only to highest in situ corals, as corals of the same age found at lower elevations will have a known water depth of at least up to the height of the coral above it. Arrows indicate potential for greater palaeodepth range."
While this paper does not make it clear how much of this RSLR came from the WAIS, and how much faster than 1,000 yrs did it occur over; the researchers are working hard to address these questions and are making progress as indicated in the following recent paper:
Rovere, A., M. E. Raymo, J. X. Mitrovica, P. J. Hearty, M. J. O'Leary, and J. D. Inglis. 2014. “The Mid-Pliocene sea-level conundrum: Glacial isostasy, eustasy and dynamic topography.” Earth and Planetary Science Letters 387: 27-33
My general point is that paleo-evidence indicates that marine ice sheets and marine terminating glaciers appear to be less stable than commonly assumed by most researchers, so no one reading this thread should be too surprised when AR6 has higher SLR projections than AR5; not because this risk of SLR is increasing that fast, but because the more we learn the more we acknowledge the risks that are already dialed into the Earth systems.