Cooperative Institute for Climate Science

Scientists working with NOAA’s Cooperative Institute for Climate Science (CICS) have developed a new model for understanding how ice shelves melt. A number of these great floating masses of ice, which act as buttresses preventing the land ice behind them from flowing into the ocean, have recently collapsed along the Antarctic Peninsula. In a study currently in press in the Journal of Physical Oceanography, graduate student Chris Little and NOAA GFDL scientists Anand Gnanadesikan and Robert Hallberg examined the question of what controls the spatial distribution of melting under large ice shelves. It has been suggested that bottom topography could play a key role in making individual ice shelves vulnerable to melting, by creating pathways by which warm water can be funneled to the ice shelf base. This paper argues that it is not the topography associated with the ocean floor but rather that associated with the ice shelf itself that controls the melt distribution. The sloping bottom of the ice shelf steers the flow of fresh meltwater, which in turn acts to protect the ice shelf from melting from below. This work suggests that knowledge of the thickness of ice shelves is particularly important for monitoring where they melt, and how vulnerable they are to climate change.

Background: CICS is a cooperative institute at Princeton University. CICS conducts collaborative research with the Geophysical Fluid Dynamics Laboratory on biogeochemistry, physical oceanography, paleoclimate, hydrology, ecosystem ecology, climate change mitigation technology, economics and policy as well as fundamental work in modeling the oceans, atmosphere and climate.

Significance: The vulnerability of the large Antarctic Ice Shelves to climate change is one of the key uncertainties in predicting sea level under global warming. This research supports NOAA’s strategic goal to understand climate variability and change.