Performance Evaluation of CMIP6 GCMs for the Projections of Precipitation Extremes in Pakistan

Abstract

Abstract Extreme weather events are more detrimental to human culture and ecosystems than typical weather patterns. A multimodel ensemble (MME) of the top-performing global climate models (GCMs) to simulate 11 precipitation extremes was selected using a hybrid method to project their changes in Pakistan. It also compared the benefits of using all GCMs compared to using only selected GCMs when projecting precipitation extremes for two future periods (2020–2059) and (2060–2099) for four shared socioeconomic pathways (SSPs), SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5. Results showed that EC-Earth3-Veg, MRI-ESM2-0 and NorESM2-MM performed best among GCMs in simulating historical and projecting precipitation extremes. Compared to the MME of all GCMs, the uncertainty in future projections of all precipitation indices using the selected GCMs was significantly smaller. The MME median of the selected GCMs showed increased precipitation extremes over most of Pakistan. The greater increases were in one-day maximum precipitation by 6–12 mm, five-day maximum precipitation by 12–20 mm, total precipitation by 40–50 mm, 95th percentile precipitation events by greater than 30 mm, 99th percentile precipitation events by more than 9 mm, days when precipitation ≥ 4 mm by 0–4 days, days when precipitation ≥ 10 mm by 2–6 days, days when precipitation ≥ 20 mm by 1–3 days, and precipitation intensity by 1 mm/day, consecutive wet days by one day, consecutive dry days by 0–4 days in the northern high elevated areas for SSP5-8.5 in the late future. These results emphasize the greater influence of climate change on precipitation extremes in the northern, high-elevation areas, which provide the majority of the country's water. This emphasizes the necessity to adopt suitable climate change mitigation strategies for sustainable development, particularly in the country's northern regions.