The following set of graphs (provisional information, courtesy of Dr Luke Skinner) records some of the major events of the last deglaciation. See for instance Le Quéré et al. (2007), Shakun et al. (2012), Skinner et al. (2014) and Watson et al. (2015), in the Postlude references, for more detail supporting our state of knowledge of the mechanisms behind these events. The sea-level change is subject to uncertainties of the order of 10 metres but there is no significant uncertainty as to its overall order of magnitude, well over 100 metres.
Time, in millennia, runs from right to left up to the present day. The atmospheric carbon dioxide (CO2) values and the temperature estimates come from ice-core measurements. The temperature estimates come from high-precision measurements of isotope ratios. The light pink curve marked "Antarctic sea ice" is a qualitative indicator of sea-ice area (further notes below). It is consistent with the strong expectation that the sea-ice area must have been largest (the curve dips lowest) in the coldest conditions. It is clear from many indicators that on average those coldest conditions occurred around the time of the Last Glacial Maximum, or maximum land-ice volume, just over 20 millennia ago.
`EDML' and `EDC' refer to data from ice cores taken at high altitude on the East Antarctic ice sheet, respectively in Dronning Maud Land and at `Dome C'; `NGRIP' refers to an ice core from a high-altitude location in Greenland.
The bottom curve estimates Greenland temperatures from ice-core data. The sudden warming events around 11.5, 14.7, and 24 millennia ago are conventionally designated as numbers 0, 1, and 2 in the sequence of Dansgaard-Oeschger warming events; see also main text, Figure 4. The time resolution is coarse. These warmings were far more abrupt than the curve suggests; see Alley (2000) and also, e.g., Severinghaus and Brook (1999, Science, 286, 930-934).
The light pink curve comes from measuring the concentration of sea salt in the EDML ice core. The concentration is divided by the estimated time of snow accumulation corresponding to the thickness of the layer measured -- hence `flux' or rate of arrival, rather than `concentration'. The reasons why this measurement correlates to the area of sea ice surrounding the continent are rather subtle. They are thought to be connected with the long-range transport of airborne, sea-salt-bearing powder snow blown off the surface of the sea ice. A careful discussion is given in the recent review by Abram, N.J., Wolff, E.W., and Curran, M.A.J., 2013: Review of sea ice proxy information from polar ice cores, Quaternary Science Reviews 79, 168-183.
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Last updated 12 February 2020
