There is intense interest in the future stability of the West Antarctic Ice Sheet (WAIS).  Models range widely in their predictions and in the physics they include.  Because the timescales for ice sheets are long, our best hope of constraining the solutions is to look at the past behaviour of WAIS. Two periods are of particular interest. The end of the last glacial period is a time when we know that ice was retreating from its glacial extent, so we can study the pace of retreat. The last interglacial (LIG) is a particularly important time because Antarctic temperature was higher than present and some models predict the complete loss of WAIS and of the large ice shelves adjacent to it.

Within the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project, in 2019 we retrieved a 651 metre ice core to the bed of Skytrain Ice Rise. This ice rise is adjacent to the Ronne Ice Shelf and the WAIS, but is expected to have maintained an independent ice flow because of the protection afforded by the Ellsworth Mountains.  The ice core has been processed and analysed continuously for a range of analytes, including water isotopes, methane and major chemistry.

Our analyses show that the core is continuous through the last glacial period, and most of the last interglacial. Folds occur near the base, in the ice at the older end of the LIG, so that although older ice may be present, we can only interpret the core to 125 ka.

Here, I will show what happened to the ice around Skytrain Ice Rise in the Holocene and the LIG, and discuss the implications for the rate and extent of future ice loss.