Project description:

Heinrich events are episodes of rapid and massive ice discharges from the North American ice sheet during the last glacial period. One hypothesis to explain these events is the binge-purge mechanism. A second hypothesis is that ocean-induced melting triggered ice sheet instabilities (i.e., sudden increase in ice flow velocity and/or mass transport). In this context, two major mechanisms of instabilities are the Marine Ice Sheet Instability (MISI) and the Marine Ice Cliff Instability (MICI), whereby tall ice cliffs become mechanically unstable and collapse. MICI may contribute to Heinrich events in response to subsurface ocean warming, as suggested by simulations using an idealized ice- stream model (Bassis et al., 2017). This internship will investigate to what extent MICI can provide a mechanism for Heinrich events in a 3D thermomechanical ice sheet model (GRISLI). The intern will implement a MICI parameterization (e.g., Pollard et al., 2015; Morlighem et al., 2024) and assess its ability to reproduce past abrupt ice discharge events. If time permits, the development of ice sheet instabilities could also be investigated using a fully coupled climate-ice sheet model (iLOVECLIM- GRISLI).

Bassis, Jeremy N., Sierra V. Petersen, and L. Mac Cathles. « Heinrich events triggered by ocean forcing and modulated by isostatic adjustment. » Nature 542.7641 (2017): 332-334.

Morlighem, Mathieu, et al. « The West Antarctic Ice Sheet may not be vulnerable to marine ice cliff instability during the 21st century. » Science Advances 10.34 (2024): eado7794.

Pollard, David, Robert M. DeConto, and Richard B. Alley. « Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure. » Earth and Planetary Science Letters 412 (2015): 112-121.