Assessing the spatiotemporal uncertainties in future meteorological droughts from CMIP5 models, emission scenarios, and bias corrections

Chuanhao Wu, Pat J.F. Yeh, Jiali Ju, Yi Ying Chen, Kai Xu, Heng Dai, Jie Niu, Bill X. Hu, Guoru Huang

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    Abstract

    Drought projections are accompanied with large uncertainties due to varying estimates of future warming scenarios from different modeling and forcing data. Using the standardized precipitation index (SPI), this study presents a global assessment of uncertainties in drought characteristics (severity S and frequency Df) projections based on the simulations of 28 general circulation models (GCMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5). A hierarchical framework incorporating a variance-based global sensitivity analysis was developed to quantify the uncertainties in drought characteristics projections at various spatial (global and regional) and temporal (decadal and 30-yr) scales due to 28 GCMs, three representative concentration pathway scenarios (RCP2.6, RCP4.5, RCP8.5), and two bias-correction (BC) methods. The results indicated that the largest uncertainty contribution in the globally projected S and Df is from the GCM uncertainty (>60%), followed by BC (<35%) and RCP (<16%) uncertainty. Spatially, BC reduces the spreads among GCMs particularly in Northern Hemisphere (NH), leading to smaller GCM uncertainty in the NH than the Southern Hemisphere (SH). In contrast, the BC and RCP uncertainties are larger in the NH than the SH, and the BC uncertainty can be larger than GCM uncertainty for some regions (e.g., southwest Asia). At the decadal and 30-yr time scales, the contributions for three uncertainty sources show larger variability in S than Df projections, especially in the SH. The GCM and BC uncertainties show overall decreasing trends with time, while the RCP uncertainty is expected to increase over time and even can be larger than BC uncertainty for some regions (e.g., northern Asia) by the end of this century.

    Original languageEnglish
    Pages (from-to)1903-1922
    Number of pages20
    JournalJournal of Climate
    Volume34
    Issue number5
    DOIs
    Publication statusPublished - 1 Mar 2021

    Keywords

    • Climate change
    • Climate prediction
    • Drought
    • Ensembles
    • General circulation models
    • Model comparison
    • Precipitation

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