Spatiotemporal distribution, evolution, and complementarity of wind and waves in China’s offshore waters and its implications for the development of green energy

•Long-term evolution trend of wind and waves in China’s offshore was investigated.•A novel approach was proposed to evaluate wind-wave joint exploitation potential.•Joint utilization guarantee rate of wind and waves in China’s offshore was 67 %–87 %.•AO, AMO and Niño 3.4 affected WS and Hs from high to low latitudes, respectively.•Impact of ENSO on WS and Hs in SCS could reach 3.92 m/s and 1.15 m, respectively. Assessing wind and waves resources and analyzing their evolution are crucial for the exploitation of wind and wave energy. This paper utilized ERA5 reanalysis data to investigate the distribution characteristics, long-term evolution, and influencing factors of wind speed (WS) and significant wave height (Hs) in China’s offshore regions. It showed that over the past 60 years, the Bohai Sea experienced a significant downward trend in WS (−0.632 cm/s/yr) and Hs (−0.135 cm/yr). The Yellow Sea exhibited a downward trend in WS, but no change trend was observed in Hs (p > 0.05). The Hs in the East China Sea (ECS) and South China Sea (SCS) showed upward trends, increasing by 0.191 cm/yr and 0.262 cm/yr, respectively. The concept of energy utilization guarantee rate (EUGR) was introduced to evaluate the complementarity and synergy between wind and wave resources. The ECS and SCS were found to possess ample wind resources, with an EUGR of approximately 80 %. The combined EUGR of wind and wave energy in the Bohai Sea, Yellow Sea, ECS, and SCS amounted to 67.41 %, 72.29 %, 86.86 %, and 84.10 %, respectively. The southeastern coastal waters of China exhibited significant complementary and synergistic effects between wind and waves, making them suitable for the joint utilization of wind and wave energy. The distribution and evolution of wind and waves in China’s offshore varied due to diverse climate conditions prevailing in different regions. From high to low latitudes, the Bohai Sea was mainly controlled by AO, while the Yellow Sea was jointly affected by AO and AMO; The ECS and SCS were mainly affected by AMO and Niño 3.4, respectively. During El Niño/La Niña years, the SCS exhibited a decrease/increase in WS and Hs, with a lag of ∼3 months in response to ENSO. The variation amplitude of WS and Hs could reach 3.92 m/s and 1.15 m, respectively.