水文水资源管理经济中气候变化影响评估的不确定性问题

大多数关于气候变化对水文过程影响评估的文献中,对大气模型中存在的显著的不确定性往往考虑不足.在很多重要的领域,GCM生成的长期预测很少能用于未来水资源规划与管理,因为其结果无法对变化趋势进行准确的描述,也就是对水文变量增加或减少趋势的预测缺乏可信度.一项借助于14个GCM模型以及不同发展情景(包括基准情景)开展的径流预报集合分析研究验证了这一点.GCM的输出情景作为水平衡模型的输入这种方法用于多瑙河上游未来水文变化的预测.如果将这种预测情景用于预测由气候变化引起的水文变化经济成本,更大的不确定性将会在经济数学模型中产生.著名的Stern"气候变化经济学"评论在水资源管理领域被广泛的应用.在经济学文献中对Stern评论的观点存在很多争议,很多专家对方法的使用和结论提出了一些质疑,本文的实例也证明了这一点.因此,进行气候变化对水文和水资源影响评估的学者们应该意识到不仅在GCM中存在很大的不确定性,大气-水文-经济模型的耦合过程可能会导致更大的不确定性.

UNCERTAINTIES OF CLIMATE CHANGE IMPACT ASSESSMENT IN HYDROLOGY AND WATER MANAGEMENT ECONOMY

In most of the many publications on climate change impact predictions for hydrological processes the significant uncertainties of the atmospheric models used is not considered in an adequate way. The paper shows that in many important areas of the globe long-term predictions produced by GCMs are of rather little use for future water resources planning and management since there is not even the sign (+or-) of the changes, I.e. increase or decrease of a hydrological variable can be predicted with acceptable confidence. This is proven along with the results of a thorough scientific investigation which analyses a large runoff prediction ensemble produced with the aid of 14 GCMs and many different development scenarios (including BAU). The GCM output scenarios are used as input to a hydrological water balance model for the Upper Danube River in Europe in order to get insight into future hydrological developments there. If such predicted scenarios are used to predict the economic costs of hydrological changes caused by climate changes further considerable uncertainties are created by the economic mathematical models. The well-known Stem Review "The economics of climate change" is briefly discussed as far as relevant to water management. The extensive discussion of the review in the economic scientific literature shows strongly controversial opinions with a large number of experts expressing severe doubts on the methods applied and the conclusions. Examples thereof are presented. Scientists and practitioners working in the field of climate impact assessment in hydrology and water management should be aware not only of the high uncertainties in the GCMs but also of the even much higher cumulative uncertainties of combined atmospherichydrological-economic modelling.