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CR 87:117-132 (2022)  -  DOI:

Future changes in aridity in the Upper Indus Basin during the twenty-first century

Xiaoxin Wang1, Xianmei Lang1,2, Dabang Jiang1,3,*

1Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, PR China
2Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, PR China
3National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, PR China
*Corresponding author:

ABSTRACT: The Upper Indus Basin (UIB) supplies water resources for the downstream areas of the Indus Basin, and the associated climate changes have attracted considerable attention. Here, we project the aridity changes in the UIB during the 21st century relative to 1995-2014 based on 12 Coupled Model Intercomparison Project Phase 6 (CMIP6) models under the 3 Shared Socioeconomic Pathway (SSP) scenarios. The aridity index (AI), defined as the ratio of annual precipitation to potential evapotranspiration (PET), is applied to quantify the dry conditions. According to the median of the preferred models, the annual mean temperature is projected to increase continually in the UIB across the 21st century under SSP2-45 and SSP5-85, and it increases before the 2050s and then stabilizes afterwards under SSP1-26. Generally, PET will increase and AI will decrease (a drying trend) in the UIB during the 21st century. The regionally averaged AI over the UIB linearly decreases as global warming intensifies at a slope of 0.1 °C-1 under both SSP2-45 and SSP5-85. Remarkable increases in aridity occur in the northern and northwest parts of the UIB. Seasonally, the largest decrease in AI is seen in December-January-February, and the smallest occurs in June-July-August. Furthermore, PET plays a key role in AI changes, excluding the southeast part of UIB, and the percent contribution of PET to AI changes tends to increase over time in the 21st century. Overall, AI and PET changes are primarily determined by thermodynamic factors in the UIB.

KEY WORDS: Upper Indus Basin · Aridity index · CMIP6 models · Evaluation · Projection

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Cite this article as: Wang X, Lang X, Jiang D (2022) Future changes in aridity in the Upper Indus Basin during the twenty-first century. Clim Res 87:117-132.

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