Abstract
A regional modeling system was applied with inputs from global climate and chemistry models to quantify the effects of global change on future biogenic emissions and their impacts on ozone and biogenic secondary organic aerosols (BSOA) in the US. Biogenic emissions in the future are influenced by projected changes in global and regional climates and by variations in future land use and land cover (LULC). The modeling system was applied for five summer months for the present-day case (1990–1999, Case 1) and three future cases covering 2045–2054. Individual future cases were: present-day LULC (Case 2); projected-future LULC (Case 3); and future LULC with designated regions of tree planting for carbon sequestration (Case 4). Results showed changing future meteorology with present-day LULC (Case 2) increased average isoprene and monoterpene emission rates by 26% and 20% due to higher temperature and solar insolation. However when LULC was changed together with climate (Case 3), predicted isoprene and monoterpene emissions decreased by 52% and 31%, respectively, due primarily to projected cropland expansion. The reduction was less, at 31% and 14% respectively, when future LULC changes were accompanied by regions of tree planting (Case 4). Despite the large decrease in biogenic emission, future average daily maximum 8-h (DM8H) ozone was found to increase between +8 ppbv and +10 ppbv due to high future anthropogenic emissions and global chemistry conditions. Among the future cases, changing LULC resulted in spatially varying future ozone differences of −5 ppbv to +5 ppbv when compared with present-day case. Future BSOA changed directly with the estimated monoterpene emissions. BSOA increased by 8% with current LULC (Case 2) but decreased by 45%–28% due to future LULC changes. Overall, the results demonstrated that on a regional basis, changes in LULC can offset temperature driven increases in biogenic emissions, and, thus, LULC projection is an important factor to consider in the study of future regional air quality.
Highlights
Natural emissions such as those from plants are important components of the Earth System that can significantly affect regional air quality
Under the IPCC SRES A2 emissions and climate scenario (IPCC, 2001; Nakicenovicand Swart, 2000), we further estimated the impacts on regional ground level ozone and biogenic secondary organic aerosols (BSOA) when combined with projected anthropogenic emission changes in the 2050s
Since the model did not consider the effects of BSOA from isoprene and sesquiterpene, the results presented in this study represent lower sensitivity bounds towards biogenic emission changes
Summary
Natural emissions such as those from plants are important components of the Earth System that can significantly affect regional air quality. Wiedinmyer et al (2006) estimated global isoprene to increase in the future by 70% to 873 TgC yearÀ1 with combined climate and LULC changes. This increase in biogenic emissions resulted in higher global surface ozone concentrations with average regional mixing ratios up to 55 ppbv. The global effects of LULC changes on biogenic emissions and BSOA was recently examined by Heald et al (2008) They projected that the global SOA burden to decrease by 14% in 2100 compared to present-day conditions. Under the IPCC SRES A2 emissions and climate scenario (IPCC, 2001; Nakicenovicand Swart, 2000), we further estimated the impacts on regional ground level ozone and BSOA when combined with projected anthropogenic emission changes in the 2050s. This work follows a decadal simulation study described in Chen et al (2009) and an attribution study described in Avise et al (2009)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
