Since the 1990s, satellites have shown accelerating ice-loss driven by ocean change in five neighbouring glacier basins that drain more than one-third of West Antarctica. The rate of ice-loss here doubled in just six years and now accounts for ~10% of global sea-level rise. However, considerable uncertainty remains in projections of future ice-loss from West Antarctica, making it difficult to predict future sea-levels.
iSTAR is the Natural Environment Research Council’s (NERC) strategic five-year programme of research and discovery that will focus on Pine Island Glacier – a glacier that in recent years has lost more ice than any other. Drawn from 11 UK universities, 2 NERC research centres and a number of international collaborators, iSTAR participants aim to improve our understanding about the stability of the glacier, and put recent, rapid changes in the context of longer-term climate. These and other advances will be critical for making better predictions about how the ocean and ice will respond to future environmental change, and what impact this may have on global sea level.
iSTAR is now a little more than half-way through. The programme has completed its first phase, an ambitious sequence of ship-borne, over-snow, and airborne fieldwork on Pine Island Glacier and in the Amundsen Sea into which it flows. The second phase of the programme is now underway; this will incorporate the new understanding of the role of the coastal seas around Antarctica in driving ice-loss from Pine Island Glacier and analyses that will answer important questions about recent and current changes, and how to deliver improved projections of future change.
iSTAR has already achieved considerable success across a range of environmental science:
– iSTAR researchers deployed oceanographic moorings in the Amundsen Sea. These instruments have established a programme of year-round monitoring of the changing oceanographic conditions that are driving ice-loss on Pine Island Glacier.
– Using oceanographic instruments temporarily attached to seals, iSTAR researchers have increased the volume of oceanographic data by a factor of 10, demonstrating the temporal and spatial variability of the routes that warm ocean water takes to reach the glacier.
– Working on Pine Island Glacier geophysicists have acquired unprecedented understanding of the interface between the ice and the bed beneath – this interface controls both ice-flow and the rate at which changes are transmitted up-glacier, and ultimately how rapidly the glacier can respond to change.
– Analysis of 10 ice cores together with several radar data sets, which capture the inter-annual variability of snowfall over large areas, will show the degree to which increased snowfall across Pine Island Glacier has partially offset increased rates of ice-loss.
– Satellite data have shown ongoing change across Pine Island Glacier, from the floating ice shelf, the glacier trunk and its tributaries.
– The interpretation of CryoSat-2 satellite observations of ice loss will be improved in the scope of iSTAR by implementing a model for microwave backscattering and testing it on densely observed Pine Island Glacier.
– In parallel to the data-gathering activities in Antarctica, iSTAR has developed new ice-sheet and oceanographic models that will allow incorporation of the newly acquired data into projections of the contribution of Pine Island Glacier to future sea-level rise.
As part of these scientific achievements, iSTAR has deployed newly-developed, innovative technologies to observe and measure change in ice and ocean, and has established a new community of young researchers with first-hand experience in working in challenging polar environments and the skills to take research forward in coming decades.
The success of the first phase of iSTAR, and the integrated nature of the programme means it is now set to provide a step change in our understating of the causes of ice-loss from Pine Island Glacier, the most rapidly changing glacier in West Antarctica. This, in turn, will help improve confidence in future projections of global sea-level rise.