Past Antarctic Ice Sheet Tipping Points Occurred Within a Single Decade

Nature Communications, November 15

At the end of the last Ice Age, there were eight periods in which elevated global temperatures caused large masses of icebergs to break off from Antarctica. During a majority of these periods, measurements of iceberg discharge show that the Antarctic Ice Sheet reached critical points of destabilization in ten years or less; but that these tipping points then led to several centuries or millennia of sustained ice loss, and relatively rapid sea-level rise.

This apparent past sensitivity of Antarctica has serious implications for the impact from today’s global heating on the West Antarctic Ice Sheet in particular. As the authors conclude, “Emerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries….Our findings are consistent with a growing body of evidence suggesting the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat and substantial global sea level rise.” In other words, the observed response of Antarctica to the warming of recent decades could usher in a similarly self-sustaining and irreversible period of ice sheet retreat, with a corresponding rise in sea level of several meters globally.

The study also suggests that the amount of time required for Antarctica to re-stabilize after passing a tipping point is contingent on the amount of future warming. This underscores the need for immediate reductions in greenhouse gas emissions, in order to lower the risk of many centuries of catastrophic sea-level rise, with loss of major coastlines, cities and infrastructure.

https://www.nature.com/articles/s41467-021-27053-6