An Ice Pump is a thermohaline mechanism of varying the thickness of an ice shelf.

1. Salt is rejected as water crystallizes so the remaining liquid is saltier.
2. The saltier water is more dense (i.e. has negative buoyancy) and sinks
3. The salty water will melt the ice sheet through contact with it at deeper depths because it has a lower melting point
4. The freshwater melt from the ice shell will be less dense and rise to shallower regions where it will refreeze and/or mix with descending salt water and make it less dense.

One important application of ice pumps in the solar system is their potential to maintain the thickness of Europa’s ice shell despite the localized internal heating¹ and minimize the moon’s polar wander.

 

Credit: Paul A. Cziko Pcziko (Wikimedia Commons)

 

1. Soderlund, K. M., Schmidt, B. E., Wicht, J., Blankenship, D. D. (2014) “Ocean-driven heating of Europa’s icy shell at low latitudes” Nature Geoscience