Cumulative hydrodynamic impacts of offshore wind farms on North Sea currents and surface temperatures

Abstract Offshore wind farms are increasingly shaping coastal ocean dynamics, yet their cumulative physical impacts remain poorly quantified. Using decade-long, high-resolution simulations of the North Sea, we show that large-scale offshore wind development can reduce current velocities by up to $$20 \%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>20</mml:mn> <mml:mi>%</mml:mi> </mml:math> and reshape local tidal energy distributions. Wind and tidal wakes exert distinct but interacting influences on ocean physics: wind speed anomalies drive far-field hydrodynamic impacts, while structure-induced drag intensifies local turbulence and mixing. Turbine spacing emerges as a key control on wake interactions, governing the formation of high-turbulence hotspots. The near- and far-field wake effects affect vertical mixing and surface heat fluxes – primarily driven by large-scale wind stress reductions – leading to shallower mixed layers and long-term surface warming of up to $$0.2\,^{\circ} \,{{{\rm{C}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>0</mml:mn> <mml:mo>.</mml:mo> <mml:msup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>∘</mml:mo> </mml:mrow> </mml:msup> <mml:mspace/> <mml:mi>C</mml:mi> </mml:math> in wind farm areas. Our findings reveal a basin-scale physical footprint of offshore wind energy and highlight the need to account for hydrodynamic impacts in future offshore wind farm planning.