Communications Earth & Environment, 14 April 2022
Over the past two decades, strong “atmospheric rivers” have triggered more than 60% of the major calving events of the Larsen A and Larsen B ice shelves and preceded their main collapses. Atmospheric rivers are long, flowing air currents that carry water vapor from the tropics and deposit it over cooler regions as rain or snow. When these atmospheric rivers terminate over the Antarctic Ice Sheet, they produce intense periods of rainfall that result in extremely high air temperatures and widespread melt and runoff. Together, these factors increase the formation of melt ponds across the surface of ice shelves, which render it vulnerable to fracturing and complete collapse. Ice shelves play a critical role in the Antarctic; they serve as supportive structures that slow the flow of glaciers and ice sheets into the ocean, restraining their contribution to sea-level rise. As global temperatures increase, the remaining ice shelves in the Antarctic Peninsula might enter a new phase of vulnerability to atmospheric rivers, in particular the Larsen C ice shelf. Authors warn that global warming could push additional Antarctic ice shelves beyond a critical threshold, destabilizing them and initiating their collapse.