Speaker: Professor Gary Wilson, Chief Scientist, GNS Science
Understanding the West Antarctic Ice Sheet is key to understanding potential sea level rise. It is stabilised, at least for the time being, by a phalanx of floating ice shelves, that hang off its outer edges—of which the Ross Ice Shelf is by far the largest.
However, the area now covered by 800m thick ice was open sea 400,000 years ago, bathed in life-sustaining sunlight that could support the growth of diatoms. This suggests that the entire Ross Ice Shelf, and much of the ice behind it, had collapsed.
The Ross Ice Shelf Programme is a major three-year NZ scientific research project that sets out to assess the current health of the Ross Ice Shelf, by measuring water temperatures and ocean currents beneath it—thereby determining how quickly ice is melting off its underside.
To access the ocean cavity beneath, over two summer seasons in Antarctica, the team spent days travelling overland to take supplies and heavy equipment to two hot water drilling sites. The first was located in the middle of the shelf, the second site was 850km from Scott Base, on the remote Siple Coast - at the grounding line, where the West Antarctic Ice Sheet starts to float and become the Ross Ice Shelf.
In January this year, Professor Gary Wilson led the science team on the Siple Coast, conducting a seismic survey by detonating explosives. The team spent a month camping in sub-zero temperatures to undertake a geophysical survey of the coast. The results will help to identify a hot water drilling target for this coming summer, in order to drill through the shelf to collect a core of the sedimentary record from beneath the sea floor.