National Oceanography Centre, Liverpool, UK.
Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL, USA.
Nature. 2022 Mar;603(7903):841-845. doi: 10.1038/s41586-022-04426-5. Epub 2022 Mar 30.
Coastal communities across the world are already feeling the disastrous impacts of climate change through variations in extreme sea levels. These variations reflect the combined effect of sea-level rise and changes in storm surge activity. Understanding the relative importance of these two factors in altering the likelihood of extreme events is crucial to the success of coastal adaptation measures. Existing analyses of tide gauge records agree that sea-level rise has been a considerable driver of trends in sea-level extremes since at least 1960. However, the contribution from changes in storminess remains unclear, owing to the difficulty of inferring this contribution from sparse data and the consequent inconclusive results that have accumulated in the literature. Here we analyse tide gauge observations using spatial Bayesian methods to show that, contrary to current thought, trends in surge extremes and sea-level rise both made comparable contributions to the overall change in extreme sea levels in Europe since 1960 . We determine that the trend pattern of surge extremes reflects the contributions from a dominant north-south dipole associated with internal climate variability and a single-sign positive pattern related to anthropogenic forcing. Our results demonstrate that both external and internal influences can considerably affect the likelihood of surge extremes over periods as long as 60 years, suggesting that the current coastal planning practice of assuming stationary surge extremes might be inadequate.
世界各地的沿海社区已经感受到了气候变化对极端海平面变化的灾难性影响。这些变化反映了海平面上升和风暴潮活动变化的综合影响。了解这两个因素在改变极端事件可能性方面的相对重要性，对于沿海适应措施的成功至关重要。现有的潮汐计记录分析一致认为，自至少 1960 年以来，海平面上升一直是海平面极端变化的一个重要驱动因素。然而，由于难以从稀疏的数据中推断出这一贡献，以及文献中积累的不确定结果，风暴活动变化的贡献仍不清楚。在这里，我们使用空间贝叶斯方法分析潮汐计观测结果，表明与当前的观点相反，自 1960 年以来，极端海平面上升的趋势和海平面上升都对欧洲极端海平面的总体变化做出了相当的贡献。我们确定，极端风暴潮的趋势模式反映了与内部气候变率相关的主导南北偶极子以及与人为强迫相关的单一正相关模式的贡献。我们的研究结果表明，在长达 60 年的时间里，外部和内部因素都可能极大地影响风暴潮的极端可能性，这表明当前假设风暴潮极端稳定的沿海规划实践可能不够充分。
