The Paris Climate Agreement and future sea-level rise from Antarctica
The Paris Climate Agreement and future sea-level rise from Antarctica
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DOI：
10.1038/s41586-021-03427-0
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发表时间：
2021-05-06
期刊：
影响因子：
64.8
通讯作者：
Dutton, Andrea
中科院分区：
文献类型：
--
作者：
DeConto, Robert M.;Pollard, David;Dutton, Andrea
一个经过观测校准的冰盖模型表明，全球变暖3摄氏度将引发南极冰的快速流失，到2100年，每年将导致海平面上升约0.5厘米。《巴黎协定》旨在将21世纪的全球平均变暖限制在比工业化前水平高出2摄氏度以内，并推动进一步努力将变暖限制在1.5摄氏度以内（1）。未来几十年的温室气体排放量将通过海洋热膨胀和陆地冰损失的结合，在世纪和更长的时间尺度上对全球平均海平面（GMSL）产生影响（2）。南极冰盖（AIS）是地球上最大的陆地冰库（相当于57.9米的GMSL）（3），其冰损失正在加速（4）。AIS的大部分区域位于海平面以下，易受动力学不稳定性影响（5-8），这能够产生非常快速的撤退（8）。然而，实施《巴黎协定》温度目标以减缓或阻止这些不稳定性发生的潜力尚未通过基于物理学的模型进行直接测试。在这里，我们使用一个观测校准的冰盖模型来表明，随着全球变暖限制在2摄氏度或更低，南极冰损失将继续以类似于今天的速度在整个世纪。然而，与当前政策更一致的情景（允许3摄氏度的变暖）在2060年左右之后，南极冰损失的速度会突然增加，到2100年，每年约有0.5厘米的GMSL上升-比今天快一个数量级。更多的化石燃料密集型情景（9）导致更大的加速。无论基岩和海平面反馈机制（10-12）或地球工程二氧化碳减少，由支撑冰架变薄和丧失引发的冰盖退缩持续了几个世纪。这些结果表明，如果超过《巴黎协定》的目标，可能会引发南极海平面迅速和不可阻挡的上升。
An observationally calibrated ice sheet-shelf model suggests that global warming of 3 degrees C will trigger rapid Antarctic ice loss, contributing about 0.5 cm per year of sea-level rise by 2100.The Paris Agreement aims to limit global mean warming in the twenty-first century to less than 2 degrees Celsius above preindustrial levels, and to promote further efforts to limit warming to 1.5 degrees Celsius(1). The amount of greenhouse gas emissions in coming decades will be consequential for global mean sea level (GMSL) on century and longer timescales through a combination of ocean thermal expansion and loss of land ice(2). The Antarctic Ice Sheet (AIS) is Earth's largest land ice reservoir (equivalent to 57.9 metres of GMSL)(3), and its ice loss is accelerating(4). Extensive regions of the AIS are grounded below sea level and susceptible to dynamical instabilities(5-8) that are capable of producing very rapid retreat(8). Yet the potential for the implementation of the Paris Agreement temperature targets to slow or stop the onset of these instabilities has not been directly tested with physics-based models. Here we use an observationally calibrated ice sheet-shelf model to show that with global warming limited to 2 degrees Celsius or less, Antarctic ice loss will continue at a pace similar to today's throughout the twenty-first century. However, scenarios more consistent with current policies (allowing 3 degrees Celsius of warming) give an abrupt jump in the pace of Antarctic ice loss after around 2060, contributing about 0.5 centimetres GMSL rise per year by 2100-an order of magnitude faster than today(4). More fossil-fuel-intensive scenarios(9) result in even greater acceleration. Ice-sheet retreat initiated by the thinning and loss of buttressing ice shelves continues for centuries, regardless of bedrock and sea-level feedback mechanisms(10-12) or geoengineered carbon dioxide reduction. These results demonstrate the possibility that rapid and unstoppable sea-level rise from Antarctica will be triggered if Paris Agreement targets are exceeded.