Historical and projected extreme climate changes in the upper Yellow River Basin, China.

Considering plateau climate and complex terrain of the upper Yellow River Basin, understanding changes in climate extremes has become increasingly urgent. This study has highlighted the historical changes in climate extremes from 1960 to 2022 based on 20 extreme climate indices, and future changes in climate extremes until 2100 under two Shared Socioeconomic Pathways (SSP126 and SSP585) based on the Coupled Model Intercomparison Project phase 6 (CMIP6) models. We found that historical spatial and temporal evolutions of precipitation extremes (PEs) and temperature extremes (TEs) primarily exhibit increasing trends. The frequency and intensity of PEs primarily show an increasing trend, while the duration of PEs primarily shows a decreasing trend. Both the frequency and duration of cold extremes primarily show a decreasing trend, while the intensity of cold extremes, as well as the intensity, frequency, and duration of warm extremes, primarily show an increasing trend. Future PEs and TEs are expected to continue to intensify even under the most ideal scenario (i.e., SSP126), and these are anticipated to further intensify with increasing radiative forcing levels and greenhouse gas concentrations. Results could provide scientific references for better coping with extreme climate changes in regions of complex terrain and scarce observation station.