Impact of climate change on tropical cyclone wind and wave hazards and structural reliability of offshore wind turbines along the southeast coast of China

Climate change is expected to influence tropical cyclone (TC) activity, posing risks to offshore wind turbine (WT) structural reliability and codified design. However, few studies have assessed the joint TC wind and wave hazards along the southeast coast of mainland China under projected climate change, and their implications for reliability-based offshore WT design have not been explored. This study developed a computationally efficient, physics-based TC modelling framework and applied it to an ensemble of climate projections from six general circulation models (GCMs) under the Shared Socioeconomic Pathway 5–8.5 scenario. Results indicate a robust statistically significant (95% confidence level) upward trend in the annual occurrence rate of strong TCs, although inter-model variability remains substantial. Spatial-temporal analyses of TC track density and 0.75-quantile maximum winds consistently show increasing trends. Regionally averaged 50- and 500-year return period values for both wind and wave are projected to rise by 6% and 5%, respectively, from the near future (2015–2044) to the long-term future (2073–2100). A Gaussian copula is identified as an appropriate model for modelling joint TC wind and wave annual maxima, and the obtained environmental contours reveal escalated multi-hazard risks——primarily driven by increased TC severity rather than changes in correlation strength. Reliability analysis demonstrates that neither current International Electrotechnical Commission-recommended TC design values nor historically derived 50-year site-specific return period values could adequately ensure target offshore WT structural safety. However, implementing long-term future wind and wave hazards for the design can achieve sufficient reliability. This study provides important insights into future TC multi-hazards for the southeast coast of mainland China and establishes a basis for improving reliability-based offshore WT design to mitigate climate change risks.