Analysing seven decades of global wave power trends: The impact of prolonged ocean warming

Wave power results from converting wind energy into kinetic energy on the ocean's surface. Alterations in long-term ocean surface waves can have significant consequences for coastal regions, including erosion and an elevated risk of flooding. Our research has unveiled a discernible and escalating trend in several crucial oceanic parameters, encompassing sea-surface temperature (SST), 10-m wind speed (W10), and significant wave height (SWH), both on a global and regional scale. Importantly, we have established statistically substantial relation-ships between SST and W10 and W10 and SWH. Moreover, our analysis has revealed a temporal lag of one year in the cross-correlation between SST and W10, while no such temporal offset is evident between W10 and SWH. Significantly, our investigation has provided evidence that global wave power (WP) has exhibited an annual increase of 0.54% over the comprehensive 70-year period from 1951 to 2020. This upward trajectory can be primarily attributed to the phenomenon of upper-ocean warming, which serves to enhance W10. Specifically, when SST exceeds the 70-year average by 1 degrees C (1951-2020), a corresponding global increase of 0.8 m/s in W10 is observed. This elevation in W10, in turn, results in a 0.5 m increase in SWH, ultimately culminating in a substantial 32.8 kW/m boost in WP. Our comprehensive analysis of the 70-year dataset underscores the pre-dominant role played by the oceanic region situated between latitudes 30 degrees S and 60 degrees S, contributing a substantial 52.3% share to global WP. Closely following is the South Pacific region, contributing 28.3% to the cumulative WP, followed by the South Atlantic (23.3%), the Indian Ocean (15.1%), and the North Atlantic and North Pacific regions, each contributing approximately 9.6% and 9.3%, respectively. The findings derived from our study cast a spotlight on the intensification of W10, the amplification of SWH, and the significant escalation in WP since the 1970s. These trends are intrinsically linked to the phenomenon of upper-ocean warming. Importantly, they portend a scenario in which the world's oceans will manifest even greater energy levels should current warming trends continue unabated.