18 June 2021
Sudden storms shear Antarctic ice shelves
Published online 6 May 2021
Antarctic cyclone activity may be accelerating the breakdown of ice shelves, fuelling faster sea level rise.
When Antarctica’s Amery Ice Shelf shed a massive iceberg in September 2019, it represented the largest such calving event in half a century—and a warning that the effects of climate change may be outpacing researchers’ projections.
This calving event occurred roughly a decade earlier than expected, says atmospheric scientist Diana Francis of Khalifa University of Science and Technology in Abu Dhabi. She and her colleagues set out to find an explanation for this accelerated breakdown of the ice shelf. Most investigations of ice shelf calving have focused on the ice itself or the ocean beneath, but Francis was more interested in the potential contributions of atmospheric forces, based on a recent uptick in cyclone activity.
Satellite readings and atmospheric data revealed that a class of fast-forming, long-lasting storms known as explosive cyclones were the likely culprit. “Previously, these have only been identified in the tropics and extra-tropical regions,” says Francis. But multiple such storms occurred in rapid succession near the Amery Ice Shelf in late 2019. “These explosive cyclones can have a powerful effect on ice shelves that are hundreds of kilometres thick by modifying the ocean slope and generating powerful waves,” she says.
Similar storms could potentially hasten calving events elsewhere, which could in turn accelerate sea-level rise by allowing inland ice to flow freely into the ocean. “To better understand complex ice dynamics, we certainly need to look up to the atmosphere,” says Francis. She and her team are performing year-round monitoring at the Amery Ice Shelf to better understand the interplay between weather and sea ice.
Francis, D. et al. Atmospheric extremes caused high oceanward sea-surface slope triggering the biggest calving event in more than 50 years at the Amery Ice Shelf. The Cryosphere 15, 2147–2165 (2021).