Scientists have confirmed that over 40% of the ice shelves in Antarctica have seen a reduction in volume over the past 25 years. This equates to a net loss of 7.5 trillion tons of meltwater entering the oceans between 1997 and 2021.
Ice shelves play a pivotal role in the Antarctic ecosystem. Floating on the seas, they act as buffers, controlling the rate at which ice drains into the oceans. As they diminish, the rate of ice loss from the glaciers accelerates.
The ice shelves on the western side of Antarctica were found to be the most affected. Nearly all of these shelves had experienced significant ice loss.
By contrast, many of the eastern ice shelves either remained consistent or experienced an increase in volume. The total ice exported to the ocean during this period was around 67 trillion tons – offset by 59 trillion tons of ice added to the shelves.
“There is a mixed picture of ice-shelf deterioration, and this is to do with the ocean temperature and ocean currents around Antarctica,” said Dr. Benjamin Davison, a research fellow at the University of Leeds who led the study.
“The western half is exposed to warm water, which can rapidly erode the ice shelves from below, whereas much of East Antarctica is currently protected from nearby warm water by a band of cold water at the coast.”
Dr. Davison believes that human-induced global warming is a significant contributor to the dwindling ice. Without human influence, signs of regrowth would have been observed in the western region.
“We expected most ice shelves to go through cycles of rapid, but short-lived shrinking, then to regrow slowly. Instead, we see that almost half of them are shrinking with no sign of recovery,” said Dr. Davison.
The Getz Ice Shelf reported a loss of 1.9 trillion tons of ice over 25 years, with a mere 5% resulting from calving. The Pine Island Ice Shelf wasn’t far behind, losing 1.3 trillion tons. By comparison, the Amery Ice Shelf, situated in colder waters, gained 1.2 trillion tons.
Launched in 2010, CryoSat-2 was dedicated to observing polar ice sheets and glaciers. The precision of these satellite sensors has enabled year-by-year tracking of Antarctic changes.
Dr. Mark Drinkwater of the European Space Agency emphasized the role of the European Copernicus Programme’s Sentinel-1 satellite mission in revolutionizing our ability to take stock of floating ice shelves.
The melted freshwater entering the oceans could disrupt global ocean circulation. The Southern Ocean, in particular, plays a role in the global ocean conveyor belt, which circulates nutrients, heat, and carbon. An influx of freshwater could weaken this system.
“The study has generated important findings. We tend to think of ice shelves as going through cyclical advances and retreats. Instead, we are seeing a steady attrition due to melting and calving,” said study co-author Professor Anna Hogg.
“Many of the ice shelves have deteriorated a lot: 48 lost more than 30% of their initial mass over just 25 years. This is further evidence that Antarctica is changing because the climate is warming.”
“The study provides a baseline measure from which we can see further changes that may emerge as the climate gets warmer.”
Video Credit: European Space Agency
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