The 4 main environmental problems in Spain are air pollution from traffic, industry and Saharan currents which causes acid rain, ozone layer destruction, and the greenhouse effect; deforestation from farming, urban development, and forest fires; pollution, erosion, and land desertification caused by industrial discharges and exacerbated by climate change; and overfishing and water pollution from increased water consumption and waste disposal, affecting areas like southern Huelva, the River Nervion, and Galicia.