Understanding conditions leading to WAIS collapse, from the Last Interglacial to the modern

It is virtually certain that the West Antarctic Ice Sheet (WAIS) collapsed during past warm periods in Earth’s history, prompting concerns about the potential recurrence under anthropogenic climate change. Despite observed ice shelf thinning in the region, the combination of climate forcing and ice sheet sensitivity driving these changes remains unclear. Here, we investigate the joint effects of climate forcing and ice sheet sensitivity to evaluate conditions leading to WAIS collapse. We run ensembles of the Community Ice Sheet Model (CISM), spun up to a pre-industrial state, and apply climate anomalies from the Last Interglacial (LIG, 129 to 116 yr ago), and the future (SSP2-4.5).  Forcing is derived from Community Earth System Model (CESM2) global simulations. We find that only modest ocean warming is required to cause significant WAIS mass loss, though such loss takes multiple centuries to millennia to manifest.