Understanding future changes in global terrestrial near-surface wind speed (NSWS) in specific global warming level (GWL) is crucial for climate change adaption. Previous studies have projected the NSWS changes; however, the changes of NSWS with different GWLs have yet to be studied. In this paper, we employ the Max Planck Institute Earth System Model large ensembles to evaluate the contributions of different GWLs to the NSWS changes. The results show that the NSWS decreases over the Northern Hemisphere (NH) mid-to-high latitudes and increases over the Southern Hemisphere (SH) as the GWL increases by 1.5 °C–4.0 °C relative to the preindustrial period, and that these characteristics are more significant with the stronger GWL. The probability density of the NSWS shifts toward weak winds over NH and strong winds over SH between the current climate and the 4.0 °C GWL. Compared to 1.5 °C GWL, the NSWS decreases −0.066 m s−1 over NH and increases +0.065 m s−1 over SH with 4.0 °C GWL, especially for East Asia and South America, the decrease and increase are most significant, which reach −0.21 and +0.093 m s−1, respectively. Changes in the temperature gradient induced by global warming could be the primary factor causing the interhemispheric asymmetry of future NSWS changes. Intensified global warming induces the reduction in Hadley, Ferrell, and Polar cells over NH and the strengthening of the Hadley cell over SH could be another determinant of asymmetry changes in NSWS between two hemispheres.
22 February 2021 in Environmental Research Letters
A recovery of near-surface wind speed (SWS) in the last decade has been reported over China; nevertheless, the contributions of large-scale ocean-atmosphere circulations (LOACs) to the SWS changes are rarely investigated. In this study, the turning point (TP) of the terrestrial stilling was validated over eastern China for 1979–2017. Furthermore, a forward stepwise regression algorithm was used to assess the contribution of LOACs to SWS changes. The results revealed that the TP of the SWS reversal occurred in approximately 2011 during the study period. Mean annual and seasonal SWSs exhibited decreases before the TP, with the largest decrease in spring (–0.134 ± 0.014 m s−1 decade−1), while SWSs increased after the TP, most strongly in autumn (0.377 ± 0.053 m s−1 decade−1). The SWS decrease before the TP and increase after the TP were caused by the decreasing and increasing frequencies of strong windy days (>75th percentile of SWS), respectively. The effects of LOACs on the long-term changes of SWS were pronounced. The contributions of LOACs to the decreasing and increasing trends of SWSs were >60.0%, with the exception of autumn. The projected SWSs exhibited increases in the near-term (2021–2040) for the low-emission scenarios (e.g. Shared Socioeconomic Pathway 245). For the mid-term and long-term projections, the SWSs still displayed a downward trend, which was mainly attributed to the reduction of strong windy days. Consequently, the present SWS recovery in the recent decade may be only expected to last for a short amount of time before winds start decreasing again.
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.