The Antarctic Ice Sheet is rapidly melting, posing a major threat of global sea level rise in the coming decades. This stage of rapid ice loss likely began in the mid-20th century, but due to limited instrumental data, the climatic drivers that initiated ice loss remain poorly understood. In West Antarctica — the most rapidly melting region of Antarctica -- the ice sheet melts via wind-driven exposure to warm ocean water. While widely used historical climate simulations suggest that strengthening local westerly winds are responsible for initiating ice loss, I will show in this talk that proxy records (i.e., ice-core and coral records) provide no evidence that local westerly winds strengthened; they instead show that northerly winds strengthened. I will also present results from a new ensemble of high-resolution ocean simulations, which provide evidence that local northerly winds, interacting with coastal polynyas, are the dominant driver of warm water transport toward the ice sheet. Together, the proxy data and ocean simulations point to a new explanation for historical ice loss, triggered by northerly winds. This transformation in our understanding of the drivers of Antarctic ice loss invites many new questions to guide future research, including potential connections to anthropogenic forcing.

*Refreshments: 10:30 AM - 11:00 AM (Atrium)