Spontaneous ice-front retreat caused by disintegration of adjacent ice shelf in Antarctica

- Observation: Larsen B retreat after collapse of Larsen A (prior to disintegration of Larsen B).
- Hypothesis: spontaneous ice-shelf retreat as consequence of neighboring ice-shelf collapse.
- Precondition: ice shelves along the Antarctic coast are in many cases dynamically interconnected.
- Method: numerical model PISM with applied calving parameterization is capable of simulating ice-shelf dynamics.
- Consequence: domino-effect ice-shelf retreat could result in speed-up of ice flow and abrupt sea-level rise.

Antarctic ice-discharge constitutes the largest uncertainty in future sea-level projections. Floating ice shelves, fringing most of Antarctica, exert retentive forces onto the ice flow. While abrupt ice-shelf retreat has been observed, it is generally considered a localized phenomenon. Here we show that the disintegration of an ice shelf may induce the spontaneous retreat of its neighbor. As an example, we reproduce the spontaneous but gradual retreat of the Larsen B ice front as observed after the disintegration of the adjacent Larsen A ice shelf. We show that the Larsen A collapse yields a change in spreading rate in Larsen B via their connecting ice channels and thereby causes a retreat of the ice front to its observed position of the year 2000, prior to its collapse. This mechanism might be particularly relevant for the role of East Antarctica and the Antarctic Peninsula in future sea level.