Towards a better assessment of hydrological natural variability as a key adaptation strategy to climate change

尽管关于气候变化对水资源影响的研究已经完成，但很少有利益相关者愿意为遥远而不确定的未来制定适应战略。决策者更愿意适应投资回报较短（<20年）的战略。然而，在20年的时间跨度内，气候在很大程度上受自然变率的支配，而不受人为变化的支配。在许多情况下，基础设施不能很好地适应自然气候变率（更不用说气候变化了），因为在工程设计中通常假设平稳的随机过程，因此基本上忽略了这一点。****因此，适应自然变率将是减少当前和未来气候脆弱性的有效途径。有了对自然变异性的充分认识，就可以设计出强有力的无悔适应策略。这些策略将更容易被利益相关者接受，因为它们不会像气候变化影响研究那样充满不确定性。本研究计划提出了一个深入研究自然气候变化的水文科学，以及如何收获这些知识，以最终改善工程设计实践，并提供强大的适应气候变化的策略。主要目标是：****o更好地描述和理解加拿大流域关键水文变量的自然变率；对比当前和未来气候下自然变率和气候变化对水文脆弱性的相对贡献。******为实现这些长期目标，提出了以下四个具体目标：****-利用现有的最长传统时间序列研究选定流域的自然气候变率；***-利用20世纪再分析项目的输出数据和远程气象网格数据，结合水文模拟，扩展关键站点和流域的历史记录；***-利用三个大型气候模式模拟集合进一步了解自然变率；***-基于1980-2010参考期，对比未来不同时间范围内自然变率和气候变化的影响。******这项研究计划将使利益相关者更好地了解我们对自然气候变化的脆弱性。适应自然变率，而不是适应气候变化，可能会促使决策者采取更迅速的行动，同时为抵御气候变化提供重要保护。考虑到到2050年，加拿大气候变化的成本估计在每年210亿至430亿美元之间，任何成功的适应战略都将为加拿大经济节省大量资金

Despite all the research done on the impacts of climate change on water resources, few stakeholders have been willing to commit to adaptation strategies for a distant and uncertain future. Decision makers are more prepared to adapt to strategies with a shorter return on investment (<20 years). Over a 20-year horizon however, climate is strongly dominated by natural variability and not by human-induced change. In many cases, infrastructures are not well adapted to natural climate variability (let alone climate change), because it is essentially overlooked in engineering design which usually assumes stationary stochastic processes.****Consequently, adaptation to natural variability would be an efficient way to reduce vulnerabilities in the current and future climate. With an adequate knowledge of natural variability, robust no-regrets adaptation strategies could be devised. These strategies would be easier to sell to stakeholders because they would not be as clouded with uncertainties as those derived from climate change impact studies. This research program proposes an in-depth look at natural climate variability in hydrological sciences and how to harvest this knowledge to eventually improve engineering design practices and provide robust adaptation strategies to climate change. The main objectives are to:****o Better describe and understand the natural variability of key hydrological variables over Canadian watersheds; and***o Contrast the relative contributions of natural variability and climate change to hydrological vulnerability in both current and future climates.******To move toward these long term goals, the following four specific objectives are proposed:****- Study the natural climate variability on selected watersheds using the longest available traditional time-series;***- Extend the historical record for key stations and watersheds using output data from the 20th century reanalysis project and long-range meteorological gridded data, combined with hydrological modelling;***- Further our understanding of natural variability using three large ensembles of climate model simulations; and***- Based on the 1980-2010 reference period, to contrast the impacts of natural variability and climate change for various future time horizons.******This research program will provide stakeholders with a better understanding of our vulnerabilities to natural climate variability. Adapting to natural variability, as opposed to climate change, is likely to translate into more rapid actions by decision makers, while affording a significant protection against climate change. Considering that the cost of climate change in Canada is evaluated at between 21 and 43 billion dollars per year by 2050, any successful adaptation strategy will result in a very large saving for the Canadian economy.**