Protecting the UK’s capital city from global mean sea level rise that the IPCC considers plausible over the next centuries would require a combination of a new tidal barrier, high volume pumping and incremental raising of the system of flood walls and embankments. Using a risk and decision analysis methodology that is transferable to other vulnerable coastal cities of high strategic economic and political importance, we quantify sequences of adaptations that would be needed to protect London from flooding by the sea to the year 2300. Two critical adaptation thresholds are identified: (i) when mechanical pumping has to be provided alongside the moveable tidal barrier in order to drain the River Thames and (ii) when a permanently closed barrier with pumping to remove all of the river flow becomes the only viable means of avoiding flooding. We test the sensitivity of the costs and benefits of alternative adaptation pathways to a wide range of sea level rise trajectories. The adaptation pathway that most cost-effectively and robustly maintains risk at a tolerable level involves moving the Thames Barrier 17 km towards the sea if mean sea level rises 2 m above present levels. Our methodology provides a quantitative risk-based implementation of an adaptation pathway.

IPCC认为，要保护英国的首都免受全球平均海平面上升的影响，在接下来的几个世纪中，将需要结合新的潮汐屏障，大流量抽水和逐步提高防洪墙和堤防系统。我们使用一种风险和决策分析方法论，可以将其转移到具有重要战略经济和政治意义的其他易受伤害的沿海城市，从而量化了保护伦敦到2300年所需的适应序列，以保护伦敦。确定：（i）当必须在可移动的潮汐障碍物旁设置机械泵送以排泄泰晤士河时，以及（ii）当永久性封闭的障碍物通过泵送以清除所有河水成为避免洪水的唯一可行方法时。我们测试了各种适应途径对各种海平面上升轨迹的成本和收益的敏感性。最经济有效地将风险保持在可忍受水平的适应途径包括：如果平均海平面比当前水平高2 m，则将泰晤士河屏障向海移动17 km。我们的方法论提供了基于风险的量化适应途径实施。