Ice sheet contributions to future sea-level rise from structured expert judgment
Ice sheet contributions to future sea-level rise from structured expert judgment
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DOI：
10.1073/pnas.1817205116
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发表时间：
2019-06-04
影响因子：
11.1
通讯作者：
Cooke, Roger M.
中科院分区：
文献类型：
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作者：
Bamber, Jonathan L.;Oppenheimer, Michael;Cooke, Roger M.
尽管自政府间气候变化专门委员会第五次评估报告（AR5）以来，在过程理解、数值模拟和冰盖对全球平均海平面上升贡献的观测记录方面取得了相当大的进展，但冰盖模式的预测能力仍然存在严重的局限性。因此，在预估未来单反时，冰盖的潜在贡献仍然是最大的不确定性来源。在这里，我们报告了一项结构化专家判断研究的结果，该研究使用了独特的技术来模拟冰盖内部和冰盖内部过程及其尾部依赖性之间的相关性。我们发现，自AR5以来，专家的不确定性增加了，特别是由于不确定的冰动力效应。对于与《巴黎协定》一致的气温+2℃情景，我们得到到2100年SLR贡献的中值估计为26厘米，第95百分位值为81厘米。在温度+5℃的情况下，与不受控制的排放增长更为一致，相应的值分别为51和178厘米。考虑热膨胀和冰川的贡献，全球总SLR估计值在第95个百分位数处超过2米。我们的研究结果支持将21世纪全球总单反超过200米的情景用于规划目的。2100年以后，不确定性和预估单反将迅速增加。在+5摄氏度的情景下，到2200年，由于南极洲西部和东部的不稳定因素，第95百分位冰盖的贡献为7.5米。引入过程相关性和尾部依赖性会使估计增加大约15%。
Despite considerable advances in process understanding, numerical modeling, and the observational record of ice sheet contributions to global mean sea-level rise (SLR) since the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change, severe limitations remain in the predictive capability of ice sheet models. As a consequence, the potential contributions of ice sheets remain the largest source of uncertainty in projecting future SLR. Here, we report the findings of a structured expert judgement study, using unique techniques for modeling correlations between inter-and intra-ice sheet processes and their tail dependences. We find that since the AR5, expert uncertainty has grown, in particular because of uncertain ice dynamic effects. For a +2 degrees C temperature scenario consistent with the Paris Agreement, we obtain a median estimate of a 26 cm SLR contribution by 2100, with a 95th percentile value of 81 cm. For a +5 degrees C temperature scenario more consistent with unchecked emissions growth, the corresponding values are 51 and 178 cm, respectively. Inclusion of thermal expansion and glacier contributions results in a global total SLR estimate that exceeds 2 m at the 95th percentile. Our findings support the use of scenarios of 21st century global total SLR exceeding 2 m for planning purposes. Beyond 2100, uncertainty and projected SLR increase rapidly. The 95th percentile ice sheet contribution by 2200, for the +5 degrees C scenario, is 7.5 m as a result of instabilities coming into play in both West and East Antarctica. Introducing process correlations and tail dependences increases estimates by roughly 15%.