The impact of historical land use change from 1850 to 2000 on secondary particulate matter and ozone

• Published in: Atmospheric chemistry and physics 2016-12, Vol.16 (23), p.14997-15010
• Main Authors: Heald, Colette L, Geddes, Jeffrey A
• Format: Article
• Language: English
• Subjects: Aerosol concentrations; Aerosols; Agricultural land; Agricultural management; Air pollution; Air quality; Air quality assessments; Ammonia; Ammonia emissions; Anthropogenic factors; Atmosphere; Atmospheric chemistry; Biosphere; Climate; Climate change; Climate studies; Dry deposition; Ecosystem management; Ecosystems; Emissions; Environmental changes; Estimates; Human influences; Land use; Land use controls; Meteorology; Nitrates; Nitrogen; Nitrogen oxides; Organic compounds; Outdoor air quality; Oxidation; Ozone; Ozone formation; Particulate emissions; Particulate matter; Photochemicals; Radiative forcing; Secondary aerosols; Soil; Suspended particulate matter; Troposphere; Tropospheric ozone; Vegetation; Vegetation distribution; VOCs; Volatile organic compound emissions; Volatile organic compounds; Volatility
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-16-14997-2016

Anthropogenic land use change (LUC) since preindustrial (1850) has altered the vegetation distribution and density around the world. We use a global model (GEOS-Chem) to assess the attendant changes in surface air quality and the direct radiative forcing (DRF). We focus our analysis on secondary particulate matter and tropospheric ozone formation. The general trend of expansion of managed ecosystems (croplands and pasturelands) at the expense of natural ecosystems has led to an 11 % decline in global mean biogenic volatile organic compound emissions. Concomitant growth in agricultural activity has more than doubled ammonia emissions and increased emissions of nitrogen oxides from soils by more than 50 %. Conversion to croplands has also led to a widespread increase in ozone dry deposition velocity. Together these changes in biosphere–atmosphere exchange have led to a 14 % global mean increase in biogenic secondary organic aerosol (BSOA) surface concentrations, a doubling of surface aerosol nitrate concentrations, and local changes in surface ozone of up to 8.5 ppb. We assess a global mean LUC-DRF of +0.017, −0.071, and −0.01 W m−2 for BSOA, nitrate, and tropospheric ozone, respectively. We conclude that the DRF and the perturbations in surface air quality associated with LUC (and the associated changes in agricultural emissions) are substantial and should be considered alongside changes in anthropogenic emissions and climate feedbacks in chemistry–climate studies.