Researchers at the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona have found that climate change will weaken sea and land breezes in the Barcelona region, trapping air pollutants near coastal areas and worsening ozone pollution by 2050 and 2100.

Sea and land breezes form when temperature differences between ocean and land drive wind patterns that naturally disperse air pollutants. As climate change reduces these temperature contrasts, the circulation weakens. The ICTA-UAB team used high-resolution climate models to project how these breezes will change under future warming scenarios, then coupled those projections with air quality simulations to forecast ozone concentrations.

Their models show that reduced wind speeds will allow ground-level ozone to accumulate over the Barcelona metropolitan area. Ozone forms when sunlight triggers reactions between nitrogen oxides and volatile organic compounds from vehicle emissions and industry. Higher concentrations increase respiratory problems and cardiovascular events, particularly during summer heat waves.

The study focuses on two time horizons. The 2050 projections show measurable degradation in sea-land breeze circulation. By 2100, under high-emission scenarios, the weakening becomes more pronounced. Both periods show rising ozone levels trapped near the coast where millions of residents live.

Coastal cities worldwide face similar risks. Mediterranean regions depend on sea breezes to ventilate pollutants. As climate change disrupts these natural ventilation systems, air quality deteriorates even if emission sources stay constant or decline. This creates a compounding problem: mitigation efforts to reduce pollutant emissions get partially offset by atmospheric changes that reduce their dispersal.

The findings underscore that addressing air quality requires considering both emissions reductions and climate adaptation. Cities like Barcelona cannot simply cut pollution sources and expect proportional improvements in air quality. They must also plan for altered