News – Antarctic melting water is emerging more than ever before, changing climate, preventing sea ice from forming and boosting marine productivity – according to a new study from the University of East Anglia (UEA).
For the first time, researchers are able to capture glacial meltwater views in winter, using instruments attached to seal heads that live near the Pine Island glacier, in the remote Amundsen Sea. on the west coast of Antarctica.
The poor Antarctic environment limits the use of the most traditional observation systems, such as ships and planes, especially in winter. But sailors working with biologists used data collected by tagged seals to measure water temperature and salinity.
The paper, ‘Seal-based winter scenes reveal the surface of glacial melting water in the south-east Amundsen Sea’, is published today in the magazine Communication: Earth and the Environment.
The researchers found a highly variable meltwater circulation with two layers full of melt water – one in the 250 meters above and another at about 450 meters deep – connected by scattered columns full of melt water. The signature of melt water irrigation is clearer in winter, when its presence can be mapped incomparably; this analysis is only possible in winter.
The emerging meltwater provides near-surface heat that helps maintain areas of open seawater surrounded by sea ice, near glaciers, and it could alter the melting point of these fragile ice shelves. These findings offer important insights into better predicting the future climate system and sea level rise.
The Pine Island glacier is melting rapidly, discharging glacial meltwater into the ocean. Glacial meltwater is thought to play a role in the irrigation and circulation of sea ice, but so far little has been known about it.
The lead author of the study is Yixi Zheng, a postgraduate researcher in the UEA School of Environmental Sciences. She said: “Water temperature and salinity change wherever there is glacial meltwater. Just like looking for ‘fingerprints’ of glacial meltwater, we using temperature and salinity data to monitor glacial melt water.
“The distribution of glacial meltwater is very wide. It does not mix well with the environmental water, instead flowing on two layers full of meltwater in the highest 250 meters and at about 450 meters, connected by columns full of melt water.
“Because the glacial meltwater is warmer and fresher than the environmental water, it is lighter than the environmental water and more likely to rise. It will bring heat and nutrients such as iron to the nearby surface, which sea ice could melt near glaciers and increase nutrient levels near the surface.This strengthens sea-air interactions, and the nutrients associated with meltwater can stimulate plankton growth mara as algae. “
The winter processes revealed by the study appear to be important for nourishing the near-surface stage before spring blooms, and for bringing heat to the surface to prevent sea ice. This action helps maintain the open water bodies, called polynyas, in front of glaciers.
Many glaciers around Antarctica are thinning rapidly, mainly due to basal melting (ie melting that occurs at the interface between the ocean and the glacier of the ice shelf). The strongest melting in the West Antarctic glaciers was reported as the Pine Island Glacier, where the research was conducted.
The amount of meltwater extracted is small compared to the size of the Antarctic shelf seas, but it is believed to have a disproportionate effect on regional circulation and climate.
The heat from the melting water tends to break ice, melting sea ice and thus increasing the area of open water fields in front of glaciers.
Strong offshore winds near the glacier front can also carry warm water near the surface further and expand the area affected by meltwater. These expanded polynyas (open water areas surrounded by ice) can lead to better airborne fluxes and other effects on iceberg calving and glacier melting.
Seven southern elephant seals (Mirounga leonina) and seven Weddell seals (Leptonychotes weddellii) were captured and tagged by CTD-Satellite Revised Data Recorders around the Amundsen Sea in February 2014. The data was collected by Marine Mammals surveying the Pole of the Ocean at pole (MEOP). Researchers from the universities of Gothenburg and Rhode Island also contributed.
The scientists say more research is needed. The study was based on one year of seal tag data from the Pine Island Glacier, so it cannot be used to measure movements over time or to take into account interregional variability such as the El Nino-Southern Oscillation, which could affect the global world. water temperature.
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The paper, ‘Seal-based winter scenes reveal the surface of glacial meltwater in the south-east of the Amundsen Sea’, is published on 5 March 2021 in the journal Communication: Earth and the Environment.