Projected changes in sea-land breeze dynamics and pollutant transport under future climate conditions

Sea-land breezes play multiple roles in coastal environments. Among them, they moderate urban temperatures and enhance ventilation, preventing extreme heat and pollution accumulation during extended periods of atmospheric stability. However, they can also transport ozone precursors inland, shifting air quality impacts to rural regions. Despite their importance, high-resolution projections of sea-land breeze and ozone interactions under future climates remain scarce. To address this critical gap, this study provides a high-resolution (1 km) projection of the sea-land breezes response in the Metropolitan Area of Barcelona under the SSP3-7.0 scenario for 2050 and 2100. Here we apply the Pseudo Global Warming approach with the WRF-Chem model and BEP + BEM urban canopy scheme. Our simulations reveal a novel climate-driven shift: an acceleration of the breeze parallel to the coastline, reducing inland penetration and delaying the breeze front by 1-2 h by 2100. These changes, combined with rising temperatures, modify planetary boundary layer dynamics, which substantially alter ozone formation and transport. Consequently, we project significant ozone increases by 2100, trapping this pollutant particularly in densely populated coastal zones, raising new concerns about future health risks and the need for adapted mitigation strategies.