More than half of Earth's freshwater resources are held by the Antarctic Ice Sheet, which thus represents by far the largest potential source for global sea-level rise under future warming conditions1. Its long-term stability determines the fate of our coastal cities and cultural heritage. Feedbacks between ice, atmosphere, ocean, and the solid Earth give rise to potential nonlinearities in its response to temperature changes. So far, we are lacking a comprehensive stability analysis of the Antarctic Ice Sheet for different amounts of global warming. Here we show that the Antarctic Ice Sheet exhibits a multitude of temperature thresholds beyond which ice loss is irreversible. Consistent with palaeodata2 we find, using the Parallel Ice Sheet Model3-5, that at global warming levels around 2 degrees Celsius above pre-industrial levels, West Antarctica is committed to long-term partial collapse owing to the marine ice-sheet instability. Between 6 and 9 degrees of warming above pre-industrial levels, the loss of more than 70 per cent of the present-day ice volume is triggered, mainly caused by the surface elevation feedback. At more than 10 degrees of warming above pre-industrial levels, Antarctica is committed to become virtually ice-free. The ice sheet's temperature sensitivity is 1.3 metres of sea-level equivalent per degree of warming up to 2 degrees above pre-industrial levels, almost doubling to 2.4 metres per degree of warming between 2 and 6 degrees and increasing to about 10 metres per degree of warming between 6 and 9 degrees. Each of these thresholds gives rise to hysteresis behaviour: that is, the currently observed ice-sheet configuration is not regained even if temperatures are reversed to present-day levels. In particular, the West Antarctic Ice Sheet does not regrow to its modern extent until temperatures are at least one degree Celsius lower than pre-industrial levels. Our results show that if the Paris Agreement is not met, Antarctica's long-term sea-level contribution will dramatically increase and exceed that of all other sources.

中文翻译：

---

南极冰盖的滞后现象

南极冰盖拥有地球上一半以上的淡水资源，因此它是迄今为止在未来变暖条件下全球海平面上升的最大潜在来源 1。它的长期稳定性决定了我们沿海城市和文化遗产的命运。冰、大气、海洋和固体地球之间的反馈会在其对温度变化的响应中产生潜在的非线性。到目前为止，我们缺乏对不同程度的全球变暖的南极冰盖的综合稳定性分析。在这里，我们表明南极冰盖表现出多种温度阈值，超过这些阈值，冰损失将不可逆转。与古数据 2 一致，我们使用平行冰盖模型 3-5 发现，在全球变暖水平比工业化前水平高 2 摄氏度左右时，由于海洋冰盖不稳定，西南极洲将长期部分崩溃。在比工业化前水平升温 6 到 9 度之间，会触发当今冰量的 70% 以上的损失，这主要是由地表高程反馈引起的。在比工业化前水平升高 10 度以上的情况下，南极洲致力于实现几乎无冰。冰盖的温度敏感性是每升高 1.3 米海平面当量，比工业化前水平升高 2 度，每升高 2 到 6 度，几乎翻倍至 2.4 米，并增加到每度约 10 米。温度在 6 到 9 度之间。这些阈值中的每一个都会引起滞后行为：也就是说，即使温度恢复到今天的水平，目前观察到的冰盖构造也不会恢复。特别是，在温度比工业化前水平至少低 1 摄氏度之前，南极西部冰盖不会重新生长到现代程度。我们的结果表明，如果不满足《巴黎协定》，南极洲的长期海平面贡献将急剧增加并超过所有其他来源。