Our management of Earth's natural systems is impacting air and water quality around the world. Warmer temperatures associated with climate change increase the formation of tropospheric ozone, a main constituent of smog and contributor to cardiorespiratory disease. Warmer temperatures and higher atmospheric carbon dioxide concentrations are associated with longer pollen seasons and increased pollen production, intensifying allergic respiratory diseases, such as asthma. Biomass burning for agriculture in places like equatorial Asia is driving sharp increases in particulate air pollution and associated morbidity and mortality. In some regions, air pollution has become so pervasive that it obscures the sun, altering regional weather patterns, reducing agricultural yields, and accelerating glacial melting. Man-made pollutants in water bodies pose a threat to drinking supplies. Water-borne pollutants in oceans and terrestrial water systems are also consumed by small organisms and thus enter the food chain.