A novel approach for evaluation of CMIP6 GCMs in simulating temperature and precipitation extremes of Pakistan

Ali, Zulfiqar , Hamed, Mohammad Magdy , Muhammad, Mohd Khairul Idlan , Shahid, Shamsuddin

2024-02-01 INTERNATIONAL JOURNAL OF CLIMATOLOGY 2024   44(卷), 2(期), (592-612页)

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The study used a hybrid approach to evaluate the performance of 20 global cli-mate models (GCMs) from CMIP6 in reproducing 20 extreme temperature and precipitation indices over Pakistan. This study first analysed the future simula-tions of extremes and discarded the GCMs whose projections fell outside the 95% confidence interval. The remaining GCMs' performance was evaluated using the Kling Gupta Efficiency-based criteria. The changes in extreme cli-matic events in Pakistan were projected using the multi-model ensemble (MME) median of the selected GCMs for four shared socioeconomic pathways (SSPs) in two future periods, 2020-2059 and 2060-2099. Four GCMs' showed inconsistency in projecting future climatic extremes and were discarded ini-tially. The past performance of the remaining GCMs revealed EC-Earth3-Veg-LR, GFDL-ESM4, MRI-ESM2-0 and NOR-ESM2-MM to be effective in repro-ducing extreme indices for the historical period. The MME median of the selected GCMs showed a gradual increase in most of the temperature and pre-cipitation extreme indices in the future periods for all SSPs across the country. Specifically, it showed a higher increase in daily maximum temperature (TXx) by 4.5-5 degrees C, daily minimum temperature (TNn) by more than 4.5 degrees C, consecu-tive days with a temperature higher than the 95th percentile (WSDI) by >160 days, one-day maximum rainfall by 9-15 mm and days with precipitation above the 95th percentile by >50 mm in northern high-elevated areas during 2060-2099 for SSP585. Similarly, a higher increase in TXx by 4.5-5 degrees C, TNn by >4.5 degrees C, WSDI by 140 days and tropical nights by 40-60 days was also found in the western arid region during 2060-2099 for SSP585. The study highlights that northern high-elevated and western arid regions are at a higher risk of extreme temperatures and precipitation due to climate change.