The Antarctic Ice Sheet is the largest block of ice in the world. It covers an area four times larger than China and contains more than 60% of the world’s fresh water. Where the ice cap meets the ocean, it forms floating shelves that cool and refresh the salty waters below as they melt. Due to the vast size of the Antarctic ice sheet and its effects on the ocean, the rate at which its shelves are melting plays a key role in influencing Earth’s climate.
In a new study, Vaňková and Nicholls used 14 ground-based radars to monitor the speed at which the base of the Filchner-Ronne Ice Shelf (FRIS) – the continent’s largest by volume of ice, located in the West Antarctica – melted both seasonally and annually.
The radars collected measurements at least every two hours, with the shortest device active for several months and the longest for six years. At two of the sites, the team used ocean mooring data to extrapolate further back in time, obtaining up to 15 years of melt rate time series, by far the longest such measurement in Antarctica.
The researchers found that the highest melt rates follow episodes of low summer sea ice concentrations outside the pack ice. They also showed that the strength of this melting velocity signal is not spatially uniform across the entire pack ice. By comparing radar time series with satellite data, they found similar average melting rates using both methods.
However, radar data shows that melting under broad areas of FRIS varies to a much smaller extent than indicated by existing satellite estimates. Additionally, they note, the time series can help scientists determine whether ocean models accurately predict melt rate changes and which regions require additional ground-based data collection, the researchers say.
More precise measurements of the melting rate provide a better understanding of the dynamic interactions between the ocean and the Antarctic ice sheet. Understanding ongoing changes and improving the ability to reproduce these changes in Earth system models can, in turn, lead to better constraints on projections of sea level rise and other impacts. of climate change, according to the authors.
The research has been published in Journal of Geophysical Research: Oceans.
Fact check: human-caused global warming has increased the melting of the Larsen sea ice
Irena Vaňková et al, Ocean Variability Under the Filchner‐Ronne Ice Shelf Inferred From Basal Melt Rate Time Series, Journal of Geophysical Research: Oceans (2022). DOI: 10.1029/2022JC018879
Provided by American Geophysical Union
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