van der Pol Thomas D, van Ierland Ekko C, Gabbert Silke
Environmental Economics and Natural Resources Group, Wageningen University, Hollandseweg 1, 6706 KN Wageningen, The Netherlands.
Mitig Adapt Strateg Glob Chang. 2017;22(2):267-285. doi: 10.1007/s11027-015-9637-0. Epub 2015 Mar 1.
Climate change requires reconsideration of flood risk management strategies. Cost-benefit analysis (CBA), an economic decision-support tool, has been widely applied to assess these strategies. This paper aims to describe and discuss probabilistic extensions of CBA to identify welfare-maximising flood risk management strategies under climate change. First, uncertainty about the changes in return periods of hydro-meteorological extremes is introduced by probability-weighted climate scenarios. Second, the analysis is extended by learning about climate change impacts. Learning occurs upon the probabilistic arrival of information. We distinguish between learning from scientific progress, from statistical evidence and from flood disasters. These probabilistic extensions can be used to analyse and compare the economic efficiency and flexibility of flood risk management strategies under climate change. We offer a critical discussion of the scope of such extensions and options for increasing flexibility. We find that uncertainty reduction from scientific progress may reduce initial investments, while other types of learning may increase initial investments. This requires analysing effects of different types of learning. We also find that probabilistic information about climate change impacts and learning is imprecise. We conclude that risk-based CBA with learning improves the flexibility of flood risk management strategies under climate change. However, CBA provides subjective estimates of expected outcomes and reflects different decision-maker preferences than those captured in robustness analyses. We therefore advocate robustness analysis in addition to, or combined with, cost-benefit analysis to support local investment decisions on flood risk reduction and global strategies on allocation of adaptation funds for flood risk management.
气候变化要求重新考虑洪水风险管理策略。成本效益分析（CBA）作为一种经济决策支持工具，已被广泛应用于评估这些策略。本文旨在描述和讨论CBA的概率扩展，以确定气候变化下福利最大化的洪水风险管理策略。首先，通过概率加权气候情景引入水文气象极端事件重现期变化的不确定性。其次，通过了解气候变化影响来扩展分析。学习是在信息的概率性到来时发生的。我们区分从科学进展、统计证据和洪水灾害中学习。这些概率扩展可用于分析和比较气候变化下洪水风险管理策略的经济效率和灵活性。我们对这种扩展的范围以及提高灵活性的选项进行了批判性讨论。我们发现，科学进展带来的不确定性降低可能会减少初始投资，而其他类型的学习可能会增加初始投资。这需要分析不同类型学习的影响。我们还发现，关于气候变化影响和学习的概率信息是不精确的。我们得出结论，基于风险的带有学习的CBA提高了气候变化下洪水风险管理策略的灵活性。然而，CBA提供了预期结果的主观估计，并且反映了与稳健性分析中所体现的不同决策者偏好。因此，我们主张除成本效益分析之外或与之结合进行稳健性分析，以支持关于减少洪水风险的地方投资决策以及关于洪水风险管理适应资金分配的全球策略。
