The linked article and associated linked reference, indicate that the WAIS grounding lines had retreated further 10,000 years ago (10 kya) than in modern times (see the first image & the following caption for the first image), will not save us from a potential WAIS collapse in the coming decades, due to the difference in time-scale of glacio-isostatic rebound then vs now. However, in this post I note that this difference in time-scales for the glacio-isostatic rebound then & now, is not the only reason such paleo-evidence will not protect modern society from a potential WAIS collapse in the coming decades, including the following considerations:
1. The rate of change of net radiative forcing had essentially stopped by the Holocene Climate Optimum; whereas today the rate of increase of radiative forcing is so fast that numerous decadal-scale positive feedback mechanisms do not have sufficient time to dissipate before other decadal-scale positive feedback mechanism are trigger, which contribute to increased risk of a coming cascade of decadal-scale tipping points. If for no other reason this consideration alone is sufficient to push GMSTA well above that during the Holocene Climate Optimum, which in turn increases the risk that hydrofracturing may collapse key West Antarctic ice shelves in coming decades; which would effectively eliminate the mechanism that allowed the WAIS to grow 10 kya.
2. The Antarctic Ozone Hole (created by anthropogenic emissions), lead to an increase of the velocities of westerly winds over the Southern Ocean (since about 1970); which has increased ocean upwelling; which has caused increased basal ice melting of key West Antarctic ice shelves and accelerated grounding line retreat for key WAIS marine glaciers. As the ozone hole has begun to heal itself, the concurrent increase in regional atmospheric GHG concentrations have kept the westerly wind velocities in a near optimal range for inducing upwelling of warm CDW.
3. The freshening of the surface seawater near Antarctica together with an associated increase in Antarctic sea ice extent, has accelerated the advection of upwelled warm CDW over the local continental shelves where the warm CDW (circumpolar deep water) has accelerated ice mass loss of key ice shelves & marine glaciers.
4. Advanced ESMs have projected the increase in frequency of El Nino events, which Hansen has noted is already observable in the ENSO record (see the second image). Not only will this trend increase the advection/telecommunication of heat energy from the Tropical Pacific Ocean to coastal regions of West Antarctica, but also will contribute eventually to increased regional snowfall; which will increase the gravitational head driving a potential MICI collapse of the WASI.
5. Atmospheric GHG concentrations are currently much higher than during the Holocene Climate Optimum; which will likely lead to still further acceleration of radiative forcing as anthropogenic aerosol emissions are rapidly reduced (and the remaining emission sources shifted to less optimal locations) in coming decades.
6. Finally, I noted that anthropogenic GHG emissions have been increasing since circa 1750, which has activated several positive oceanic feedback mechanisms; and also the AMOC is currently slowing for at least the next several decades, which is a key positive ice-climate mechanism:
Potsdam Institute for Climate Impact Research (PIK). "What saved the West Antarctic Ice Sheet 10,000 years ago will not save it today." ScienceDaily. ScienceDaily, 14 June 2018.
https://www.sciencedaily.com/releases/2018/06/180614101245.htmSummary: "The retreat of the West Antarctic ice masses after the last Ice Age was reversed surprisingly about 10,000 years ago, scientists found. The reason for the rebound is that, relieved from the weight of the retreating ice, the Earth crust lifted. This made the ice re-advance towards the ocean. Unfortunately, this mechanism is much to slow to prevent dangerous sea-level rise caused by West Antarctica's ice-loss in the present and near future."
Caption for first image: "New data indicates that the retreat of the West Antarctic ice masses after the last Ice Age in some parts of the continent was reversed surprisingly about 10,000 years ago. The maximum ice sheet extension is shown in green, the minimum extent in red, and the modern grounding line after the rebound in orange.
Extract: "A number of factors influences the ice-sheet behavior under warming. In the studied region sea mountains turned out to be rather important for the ice dynamics. The peaks of these mountains underneath the floating ice shelves reach up from the bottom of the ocean. When the bottom rises they can become ice rises within the ice shelf. Since they're made of solid rock, they increase the stability of the ice sheet. The scientists call this a buttressing effect. Conditions for ice re-growth might be less favorable in other areas.
Yet it is the time-scale that is key in the end. "What happened roughly 10,000 years ago might not dictate where we're going in our carbon dioxide-enhanced world, in which the oceans are rapidly warming in the Polar regions," says Scherer. "If the ice sheet were to dramatically retreat now, triggered by anthropogenic warming, the uplift process won't help regrow the ice sheet until long after coastal cities have felt the effects of sea level rise.""
See also:
J. Kingslake, R. P. Scherer, T. Albrecht, J. Coenen, R. D. Powell, R. Reese, N. D. Stansell, S. Tulaczyk, M. G. Wearing, P. L. Whitehouse. Extensive retreat and re-advance of the West Antarctic Ice Sheet during the Holocene. Nature, 2018; DOI: 10.1038/s41586-018-0208-x
https://www.nature.com/articles/s41586-018-0208-x