K061-1516-A

Summary

• As climate warms, the West Antarctic Ice Sheet will retreat, sea level will rise, sea ice extent will change, and the circulation of both the ocean and atmosphere will be modified. 
• The lofty goal of the NZARI Ross Ice Shelf Programme is to understand the physical processes and process interactions that determine the rate at which those changes will unfold.
• As a practical matter, this means coordinated, interdisciplinary research that spans many institutions and many locations in West Antarctica.
• We have to build on what we already know and already do well, which means this programme is as much about what the 22 New Zealand investigators bring to the effort as what they take away.
• Partners in Australia, the U.S., Korea, and Germany bring additional expertise to the team.

Themes

1.            Grounding zone processes

We seek to understand the roles local processes, including sediment distribution and transport, basal melting/freezing in the grounding zone, and feedbacks associated with ice stream variability, play in setting grounding line position. As part of this effort, we must identify the essential temporal and spatial scales associated with these processes and their interactions.

2.            Ice/ocean processes in the sub ice shelf cavity 

We want to understand how processes in the boundary layer between the base of the ice shelf and underlying ocean set limits on the rate of melting at the base of the ice shelf. This will help us assess the likelihood of changes in ice shelf melting in a warming world. 

We want to assess relative importance of atmospheric and ice shelf/ocean processes to sea ice variability and sea ice change.

3.            Surface processes and atmosphere interactions

We want to understand how synoptic-scale circulation in the atmosphere determines patterns of accumulation and ablation on the ice shelf surface.

4.            Ice shelf front 

The position of the ice shelf calving front is both a forcing on and response to other elements of the coupled system. We want to evaluate which aspects of those coupled processes are most important to driving change in the RIS system.

5.            Lessons from the past

Ice sheet retreat at the end of the last glaciation is an example of West Antarctic response to global warming. To make use of this past event, we must add detail to the scant geologic record and use insights from our process studies to guide model simulations of the ice sheet and ice shelf system.

The Project

• Meeting RIS Programme goals requires both field and laboratory work.
• The field component involves two ice shelf locations over the next three years.
• At both locations we plan to drill through the ice shelf, deploy observational instruments in the underlying ocean, and sample sediments on the sea floor.
• We will conduct surface observations at both sites, including  ice penetrating radar, high-precision surveying, satellite remote sensing, and in situ meteorological observations. 
• The first field site is about 350 km away from Scott Base, at a site where oceanic observations will inform us about water circulation under the shelf and about interactions between the base of the ice shelf and the ocean beneath.
• We will also sample sediments on the sea floor, in order to evaluate when the ice sheet retreated past this location as it shrank during the warm up at the end of the last glacial age.
• The second site is close to the Kamb Ice Stream grounding line, where we can observe sedimentary processes in action, as well as the turbulent junction between ice sheet, ice shelf, ocean, and sea floor.