LONDON: Seals found in Antarctic seas are helping scientists to make more accurate predictions about how rapidly the ice sheet is melting.
Scientists tagged two seal species with devices to collect data about the temperature and salinity of waters around vulnerable ice sheets in West Antarctica, according to the findings published in the journal Geophysical Research Letters.
The team at the University of East Anglia (UEA) in the UK has been investigating ways of studying warm, salty, deep water in the Amundsen Sea, in the Southern Ocean.
Understanding more about how this water gets towards the ice shelves by measuring its temperature, salinity and depth, will help climate change modellers make more accurate predictions about how rapidly the Antarctic ice sheet is melting, they said.
As the ice in west Antarctica melts, it has been estimated that sea levels could rise by up to 3.2 metres, with much of the water draining through two glaciers – Pine Island Glacier and Thwaites Glacier – in the Amundsen Sea.
Estimates of future sea level rise vary a lot and scientists need year-round observations to assess and improve climate change models.
Gathering data in summer months is relatively straightforward but getting ships near the area during the winter is impossible because the area is covered in a thick blanket of sea ice.
The only information available is from ‘moorings,” strings of measurement devices anchored to the sea floor.
These can collect data from a few fixed locations, but they cannot measure near the sea surface at all because the huge icebergs would collide with them.
The team set up a collaboration with the researchers at the University of St Andrews in the UK who were interested in recording the feeding behaviours of seals in the region.
The researchers tagged seven southern elephant seals and seven Weddell seals with devices that can send information via satellite.
Measurements of the warmth and saltiness of the water were sent by the seals as they moved around the area and dived from the surface of the ocean down through the water to the sea bed in their hunt for food.
Over a period of nine months, throughout the Antarctic winter, the team collected data from more than 10,000 dives over an area of around 150,000 square km.
The seals continued to send back signals until they moulted and the devices dropped off.
The researchers discovered that not only is the ice layer thicker in winter, it is also warmer and saltier than during summer months.
This suggests that there is likely to be more melting of the ice sheets during the winter months.
The temperature differences were less marked closer to one of the glaciers, in a region called Pine Island Bay, possibly because ocean currents, called gyres, recirculate the water.
“We knew very little about what to expect from this research, since this is the first time that data has been collected in this way in this area,” said Helen Mallett, who led the study at UEA.
“We were able to collect much more information from the seals than all the previous ship-based surveys in the area combined and it was clear that, at least during the seasons we observed, there were substantial differences in temperature between the seasons,” said Mallett. (AGENCIES)
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