Melting of Ice Sheets

Over the past decade, the Antarctic and Greenland Ice Sheets have been losing its mass at an alarming rate. Antarctic ice-shelves are melting by turbulent transport of heat and salt to the ice face, predominantly under the influence of warmer Circumpolar Deep Water entering ice shelf cavities from the surrounding Southern Ocean. This mass loss occurs largely from the underside and fronts of ice shelves where glaciers reach the ocean and from the icebergs that calve from the shelves. The water exiting ice shelf cavities contributes to Antarctic Bottom Water, a crucial component of the global thermohaline circulation. Knowledge of these processes, and the feedbacks between them, is needed to predict future climate change.

We are investigating the physical processes that control these ice-ocean interactions and the resulting circulation at basin scale.  Group research focuses on:

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Laboratory models

The laboratory experiments are being conducted both in our temperature controlled cold room and on one of our rotating tables in the Climate & Fluid Physics Laboratory. The cold room allows us to conduct experiments at conditions that are close to what would be found near actual Antarctic ice shelves. The laboratory experiments let us measure some of the fluid properties a lot closer to the ice surface than a lot of the field studies can as well as in a more controlled environment. They also provide a real data set that can be used to confirm and test theoretical or numerical results. We have previously focused on the effect of ambient ocean temperature and stratification on the melt rate, and are currently investigating the effects of external flow, background rotation, and ice shelf geometry.

Parameterising melt in large-scale numerical ocean models

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Recent developments in regional and global ocean modelling have enabled the inclusion of the ocean cavities beneath ice shelves in models. However, a lack of direct observations in these remote, ice-covered regions have limited our understanding of melt, hampered by complex physical processes that occur at the ice-ocean boundary layer on small temporal and spatial scales. 

Our group uses numerical modelling to understand the oceanic processes which control delivery of heat to the Antarctic coastal region. Example projects within this topic include:

1. Determining which local or remote forcing (e.g. changing winds, surface freshening) controls the warming of Antarctic waters.
2. Quantifying the contribution of ocean processes that govern the fine-scale intrusion of warm water into the Antarctic coastal region, such as eddies, bottom flows and tides.
3. Investigating large-scale feedbacks between Antarctic ice melt and the global overturning circulation.
4. Refining melt parameterisations in global ocean models through incorporation of physical processes from high-resolution numerical models and laboratory studies.