There are several lines of evidence pointing to a WAIS collapse during the last interglacial (MIS 5 / Eemian).
Evidence for a WAIS collapse.
- Oldest ice in WAIS-divide ice core is younger than 70,000 yrs
- Lack of interglacial ice is very suggestive.
- Note however: bottom melting.
- Note however: Total air content from the ice core can inform on past ice sheet elevations and may help with interpretation but there may be complications (see this issue w. total air content interpretation.) - Does anybody have a link to total air content data for the bottom of the WAIS core. What does it say?
- Octopus genetics.
- Sudden sea level rise during the last interglacial (WAIS best candidate). Multiple records show this around the world:
- High global sea level rise / Greenland not deglaciated implies Antarctic contrib.
Counter evidence for a complete collapse:
- Hillenbrand: Sediment cores http://www.sciencedirect.com/science/article/pii/S0277379108003715
- Fogwill et al. Blue Ice moraines… http://www.sciencedirect.com/science/article/pii/S0031018211000423
There have recently been several papers that show that EAIS also reacts to climate change. So the last interglacial sea level highstand may have contributions from EAIS, WAIS and GrIS. It does not have to be a complete collapse to close the budget. But a partial collapse can explain the octopus genetics.
If you have comments or additional evidence either way then please mail or tweet me.