Abstract. Rapidly retreating thick ice fronts can generate large amounts of mélange(floating ice debris), which may affect episodes of rapid retreat ofAntarctic marine ice. In modern Greenland fjords, mélange providessubstantial back pressure on calving ice faces, which slows ice front calvingrates. On the much larger scales of West Antarctica, it is unknown ifmélange could clog seaways and provide enough back pressure to act as anegative feedback slowing retreat. Here we describe a new mélange model,using a continuum-mechanical formulation that is computationally feasible forlong-term continental Antarctic applications. It is tested in an idealizedrectangular channel and calibrated very basically using observed modernconditions in Jakobshavn fjord, West Greenland. The model is then applied todrastic retreat of Antarctic ice in response to warm mid-Pliocene climate.With mélange parameter values that yield reasonable modern Jakobshavnresults, Antarctic marine ice still retreats drastically in the Pliocenesimulations, with little slowdown despite the huge amounts of mélangegenerated. This holds both for the rapid early collapse of West Antarcticaand for later retreat into major East Antarctic basins. If parameter valuesare changed to make the mélange much more resistive to flow, far outsidethe range for reasonable Jakobshavn results, West Antarctica still collapsesand retreat is slowed or prevented only in a few East Antarctic basins.
A continuum model (PSUMEL1) of ice mélange and its role during retreat of the Antarctic Ice Sheet
Rapidly retreating thick ice fronts can generate large amounts of mélange (floating ice debris), which may affect episodes of rapid retreat of Antarctic marine ice. In modern Greenland fjords, mélange provides substantial back pressure on calving ice faces, which slows ice-front velocities and calving rates. On the much larger scales of West Antarctica, it is unknown if mélange could clog seaways and provide enough back pressure to act as a negative feedback slowing retreat. Here we describe a new mélange model, using a continuum mechanical formulation that is computationally feasible for long-term continental Antarctic applications. It is tested in an idealized rectangular channel, and calibrated very basically using observed modern conditions in Jakobshavn fjord, West Greenland. The model is then applied to drastic retreat of Antarctic ice in response to warm mid-Pliocene climate. With mélange parameter values that yield reasonable modern Jakobshavn results, Antarctic marine ice still retreats drastically in the Pliocene simulations, with little slowdown despite the huge amounts of mélange generated. This holds both for the rapid early collapse of West Antarctica, and later retreat into major East Antarctic basins. If parameter values are changed to make the mélange much more resistive to flow, far outside the range for reasonable Jakobshavn results, West Antarctica still collapses and retreat is slowed or prevented only in a few East Antarctic basins.
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- NSF-PAR ID:
- 10064242
- Date Published:
- Journal Name:
- Geoscientific model development
- Volume:
- 11
- ISSN:
- 1991-959X
- Page Range / eLocation ID:
- 5149-5172
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/gmd-2018-28
