Estimating centennial-scale changes in global terrestrial near-surface wind speed based on CMIP6 GCMs

A global terrestrial stilling in recent decades has been reported, but the centennial-scale changes in global terrestrial near-surface wind speed (NSWS) and the potential contributing factors are yet to be revealed. Consequently, in this study, centennial-scale changes in global terrestrial NSWS are investigated based on Coupled Model Intercomparison Project phase 6 datasets, and that the potential factors causing those changes are detected. The results show that the global annual mean NSWS increased from 1850 to 1967 (+0.0045 m s⁻¹ decade⁻¹, p< 0.01), with significant increases in North America, Europe, Africa, and South Asia. However, the NSWS decreased from 1968 to 2014 (−0.0044 m s⁻¹ decade⁻¹, p < 0.01), significantly so in the mid-to-high latitudes of the Northern Hemisphere. The seasonal mean NSWS also increased before the 1960s and decreased thereafter. However, the NSWS over South America and most of Southern Africa increased during the study period. The changes in NSWS were caused mainly by changes in the number of strong windy days. The increase in NSWS from 1850 to 1967 could be attributed to internal variability, and the decrease in NSWS from 1968 to 2014 could be attributed to natural, aerosol, and greenhouse-gas forcings. However, internal variability acted mainly to increase the NSWS from 1968 to 2014, and so it is suggested that the contributions of external forcings to the global terrestrial stilling after the 1960s were considerable. (letter)