Many researchers like to look to the Mid-Pliocene as a paleo-example of what the GCMs estimate the Earth could be like in the late 21st century, with regard to surface temperatures ( but not with regard to sea level which was at least 15 to 25 meter above modern levels, as the sea/ice responds more slowly than the atmosphere). The following quote from the IPCC puts the Mid-Pliocene into context:http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-3-2.html
Quote: "The Mid-Pliocene (about 3.3 to 3.0 Ma) is the most recent time in Earth’s history when mean global temperatures were substantially warmer for a sustained period (estimated by GCMs to be about 2°C to 3°C above pre-industrial temperatures; Chandler et al., 1994; Sloan et al., 1996; Haywood et al., 2000; Jiang et al., 2005), providing an accessible example of a world that is similar in many respects to what models estimate could be the Earth of the late 21st century. The Pliocene is also recent enough that the continents and ocean basins had nearly reached their present geographic configuration. Taken together, the average of the warmest times during the middle Pliocene presents a view of the equilibrium state of a globally warmer world, in which atmospheric CO2 concentrations (estimated to be between 360 to 400 ppm) were likely higher than pre-industrial values (Raymo and Rau, 1992; Raymo et al., 1996), and in which geologic evidence and isotopes agree that sea level was at least 15 to 25 m above modern levels (Dowsett and Cronin, 1990; Shackleton et al., 1995), with correspondingly reduced ice sheets and lower continental aridity (Guo et al., 2004)."
Furthermore, I discuss the following linked reference (with a free access pdf) in both the "Forcing" thread (Reply #197) and the "PIG/Thwaites 2012 to 2040-2060" thread in the Antarctic folder, and the first attached image from Hill et al 2014 shows that polar amplification results in about 10 degrees C higher Surface Air Temperatures (SAT) in the Amundsen Sea Embayment, ASE, during the Mid-Pliocene than today, and that this amplification was largely related to reductions in clear sky albedo (see the second attached image), due to such factors as reduction in sea ice.
Hill, D. J., Haywood, A. M., Lunt, D. J., Hunter, S. J., Bragg, F. J., Contoux, C., Stepanek, C., Sohl, L., Rosenbloom, N. A., Chan, W.-L., Kamae, Y., Zhang, Z., Abe-Ouchi, A., Chandler, M. A., Jost, A., Lohmann, G., Otto-Bliesner, B. L., Ramstein, G., and Ueda, H.: Evaluating the dominant components of warming in Pliocene climate simulations, Clim. Past, 10, 79-90, doi:10.5194/cp-10-79-2014, 2014.http://www.clim-past.net/10/79/2014/cp-10-79-2014.html
To emphasize that while currently Antarctic sea ice extent is trending upward (a trend that is projected to reverse after 2080), currently the austral summer sea ice extent in the ASE is actually trending downward as illustrated by the third attached image of an Antarctic sea ice extent map for January 29 2014, and while the fourth attached image shows that solar insolation in Antarctic in January is actually higher than in the Arctic in July.
Taken together, this evidence indicates that by the late 21st century that we can expect extensive ice surface melting in the ASE during the austral summer; which will not only contribute to ice mass loss due to austral summertime runoff, but more importantly preliminary findings indicate that the presence of surface water can markedly accelerate ice mass loss due to the Jakobshavn Effect. This is a very serious matter that could significantly accelerate SLR after about 2070.