Rising Temperatures Prevent Layers of Snow from Stabilizing Antarctic Ice Shelves

Nature Climate Change, 26 January 2023

Future atmospheric warming will likely overpower the ability of snow to protect Antarctic ice shelves from surface meltwater ponding, increasing their vulnerability to collapse. Ponds of meltwater can generate enough pressure to crack the surface of the ice. When these cracks propagate downward to the base of a floating ice shelf, a process termed “hydrofracture,” the entire shelf can collapse and disintegrate. This unleashes ice flow from the Antarctic ice sheet, previously held back by the now-collapsed shelf, into the ocean. Layers of snow on the ice can minimize the risk of hydrofracture by absorbing meltwater before it forms ponds. This study analyzes temperature thresholds for meltwater pond formation and finds that ice shelves with relatively low snowfall (such as Amery, Ross and Filchner-Ronne) are more susceptible to meltwater ponding than previously thought. Continued warming will push many Antarctic ice shelves past these temperature thresholds by the end of this century even under moderate warming scenarios. While surface ice melt is nowhere near as extensive in Antarctica as in Greenland today, these findings underscore that even the coldest and most remote places in Antarctica are not safe from human-induced climate change. Reducing emissions to remain within the 1.5 °C limit of the Paris Agreement will help prevent Antarctic ice shelves from crossing these thresholds, and reduce the risk of rapid ice sheet loss and accelerated sea level rise for future generations.

https://www.nature.com/articles/s41558-022-01577-1