Regional patterns of future runoff changes from Earth system models constrained by observation. Issue 11 (12th June 2017)

• Record Type: Journal Article
• Authors: Yang, Hui; Zhou, Feng; Piao, Shilong; Huang, Mengtian; Chen, Anping; Ciais, Philippe; Li, Yue; Lian, Xu; Peng, Shushi; Zeng, Zhenzhong
• Is Part Of: Geophysical research letters. Volume 44:Issue 11(2017)
• Page Start: 5540
• Page End: 5549
• Publication Date: 2017-06-12
• Subjects: runoff change -- future projection -- Earth system model -- multimodel ensemble -- Bayesian model averaging; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL073454
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: In the recent Intergovernmental Panel on Climate Change assessment, multimodel ensembles (arithmetic model averaging, AMA) were constructed with equal weights given to Earth system models, without considering the performance of each model at reproducing current conditions. Here we use Bayesian model averaging (BMA) to construct a weighted model ensemble for runoff projections. Higher weights are given to models with better performance in estimating historical decadal mean runoff. Using the BMA method, we find that by the end of this century, the increase of global runoff (9.8 ± 1.5%) under Representative Concentration Pathway 8.5 is significantly lower than estimated from AMA (12.2 ± 1.3%). BMA presents a less severe runoff increase than AMA at northern high latitudes and a more severe decrease in Amazonia. Runoff decrease in Amazonia is stronger than the intermodel difference. The intermodel difference in runoff changes is mainly caused not only by precipitation differences among models, but also by evapotranspiration differences at the high northern latitudes. Key Points: We use a Bayesian model ensemble, where higher weights are given to models with better historical performance, to predict runoff changes Our results suggest a more pronounced runoff decrease in Amazon and a weaker increase in northern high latitudes The large intermodel spread of runoff changes is mainly due to differences in modeled precipitation changes