Menu
NIWA: New Zealand Scientists Unlock Antarctic Ice Melt Mystery

New Zealand Scientists Unlock Antarctic Ice Melt Mystery

Top image: NIWA
 
A groundbreaking Antarctic research expedition, led by New Zealand scientists, has for the first time directly observed water flowing out from beneath the West Antarctic Ice Sheet—revealing how massive, hidden floods beneath the ice are contributing to the melting of the continent’s largest ice shelves.
 
The findings, recently published in Nature Geoscience, offer dramatic new insights into how meltwater beneath Antarctica flows and affects sea level rise, says expedition lead Victoria University of Wellington Associate Professor Huw Horgan:
 

“Researchers have long suspected that water, from geothermal heat and other sources, flows from under the ice sheets. Satellite observations from elsewhere in West and East Antarctica have revealed active lakes under the ice caps. Our quest was not just to discover the network of hidden lakes and streams that can’t be seen from the surface, but to complete the first close-up observation of these watercourses meeting the ocean in cavities under the ice shelf. These sub-glacial watercourses play a central role in the melting of the ice shelf, so the findings will enable us to predict sea level rise more accurately.”

Supported by New Zealand’s Antarctic Science Platform, the scientists from NIWA, Victoria University, GNS Science and the University of Otago, as well as researchers in the UK and the US including Cornell University, undertook the fieldwork in the autumn of 2021. It took two weeks for the international team to travel from Scott Base 1,200 kilometres towards the Kamb Ice Stream across the Ross Ice Shelf, a floating ice sheet about the area of France.

“The first challenge was just to get there,” says Associate Professor Horgan, who also works in Switzerland for ETH Zurich’s Laboratory of Hydraulics, Hydrology and Glaciology.

“Fortunately, Antarctica New Zealand has developed long-range ice traverse capabilities to safely move people and gear over vast distances. The second challenge was drilling half a kilometre into the Kamb Ice Stream, a major glacier feeding into the Ross Ice Shelf. Vital to the expedition’s success were the skills of the drilling team from the Antarctic Research Centre at the Victoria University of Wellington who, using high-pressure hot water at 80°C, drilled a 500-metre-deep borehole through the Kamb Ice Stream.”
Drilling team from the Antarctic Research Centre at the Victoria University of Wellington. Image: NIWA
Once the team melted through the ice down into the ocean, they were able to film the under-ice watercourse and collect unique data on its temperature, salinity, sediment, and flow behaviour using a range of NIWA’s specialist ocean equipment—as well as Cornell University’s IceFin remotely operated vehicle. 
Camera being lowered down through the ice. Image: NIWA

“With the help of our camera, we even discovered a school of lobster-like (amphipods) creatures, 400 kilometres from the open ocean.”

The measurements provided many surprises for the team, says NIWA and University of Auckland physical oceanographer Professor Craig Stevens:

“Our first discovery was the unique shape of the under-ice cavity where the meltwater was flowing. The size of the watercourse—about 250 metres deep and 150 metres wide—was larger than expected and mostly filled with ocean water, with only a small portion being freshwater from beneath the ice sheet.”

Using sediment cores the team concluded that the water comes from sub-glacial lakes upstream, which fill and empty the lakes in cycles – when they empty, a flood of water rushes towards the sea.

“Understanding these hidden systems is crucial to improving climate models and predicting sea level rise more accurately. The Ross Ice Shelf and others like it play a critical role in slowing the flow of inland glaciers to the sea. Their decline will significantly accelerate global sea level rise.”

“Antarctica may be remote, but what happens there affects us all,” says Professor Stevens. “We need to understand this distant changing environment, so we can prepare for future challenges here at home.”

Related Posts