Journal Article

Sources of uncertainty in hydrological climate impact assessment: a cross-scale study

Motovilov, Y, Hattermann, F F, Breuer, L, Masaki, Y, Wada, Y, Liersch, S, Yang, T, Samaniego, L, Su, Buda, Hoffmann, P, Stacke, T, Fekete, B, Krysnaova, V, Daggupati, P, Vetter, T, Donnelly, C, Flörke, F, Gosling, S N, Müller, C

2018

Overview

Climate change impacts on water availability and hydrological extremes are major concerns as regards the Sustainable Development Goals. Impacts on hydrology are normally investigated as part of a modelling chain, in which climate projections from multiple climate models are used as inputs to multiple impact models, under different greenhouse gas emissions scenarios, which result in different amounts of global temperature rise. While the goal is generally to investigate the relevance of changes in climate for the water cycle, water resources or hydrological extremes, it is often the case that variations in other components of the model chain obscure the effect of climate scenario variation. This is particularly important when assessing the impacts of relatively lower magnitudes of global warming, such as those associated with the aspirational goals of the Paris Agreement. In our study, we use ANOVA (analyses of variance) to allocate and quantify the main sources of uncertainty in the hydrological impact modelling chain. In turn we determine the statistical significance of different sources of uncertainty. We achieve this by using a set of five climate models and up to 13 hydrological models, for nine large scale river basins across the globe, under four emissions scenarios. The impact variable we consider in our analysis is daily river discharge. We analyze overall water availability and flow regime, including seasonality, high flows and low flows. Scaling effects are investigated by separately looking at discharge generated by global and regional hydrological models respectively. Finally, we compare our results with other recently published studies. We find that small differences in global temperature rise associated with some emissions scenarios have mostly significant impacts on river discharge-however, climate model related uncertainty is so large that it obscures the sensitivity of the hydrological system.

• Publisher: IOP Publishing
• Subject: ANOVA / Chains / Climate change / climate change uncertainty / Climate effects / Climate models / Climate studies / Emissions / Environmental impact / Global temperatures / Global warming / Greenhouse effect / Greenhouse gases / High flow / Hydrologic cycle / Hydrologic models / Hydrology / Low flow / multi-model assessment / open climate campaign / Paris Agreement / Paris climate agreement / River basins / River discharge / River flow / Rivers / Seasonal variations / Sustainable development / Uncertainty / Variance analysis / Water availability / Water discharge / Water resources