Past Warming Triggered Rapid Runaway Ice Loss in West Antarctica

Nature Geoscience, 8 February 2024

Scientists have uncovered for the first time direct evidence that the West Antarctic Ice Sheet dramatically thinned during a warm period at the end of the Last Ice Age, revealing how quickly this region could experience widespread ice loss if temperatures continue to rise as a result of today’s fossil fuel emissions. In one location, the ice thinned by 450 meters within two centuries. This is the fastest ice loss ever documented in Antarctica. To obtain these findings, researchers drilled a 650-meter ice core near the Ronne Ice Shelf and analyzed the frozen layers to construct a historical record of the ice sheet’s thickness. Around 8,000 years ago, as temperatures began to warm at the end of the last ice age, the West Antarctic Ice Sheet crossed a threshold; and entered a period of runaway ice loss. (Notably, the rate of warming then was less than that of today.) Warm water crept under the edge of the ice sheet, detaching a large section of ice from the bedrock; and that ice floated upward to form today’s Ronne Ice Shelf. This shift triggered rapid thinning and retreat of surrounding ice before it eventually stabilized at a considerably smaller size and thickness. Researchers raise concerns that today’s rising temperatures could trigger similar runaway ice loss across this and similarly vulnerable portions of Antarctica over coming decades and centuries, initiating a new period of rapid thinning and mass loss, with related sea-level rise globally.

https://www.nature.com/articles/s41561-024-01375-8