| Summary: | Biogenic volatile organic compounds play a key role in governing the rate of chemical production and loss of tropospheric ozone and formation of secondary organic aerosol, important atmospheric constituents which affect both climate and air quality. Isoprene is the most important of these compounds, both in terms of quantity emitted and subsequent reactions. The effects of changes in isoprene emissions due to land use change driven by the cultivation of biofuel feedstock crops in the near-future (2020s) have been evaluated. Two realistic biofuel cultivation scenarios were developed, based on current government targets for the replacement of transportation fuel with bio-ethanol and biodiesel. A series of simulations, using isoprene emissions, atmospheric chemistry and climate models, were performed to quantify the impacts. The two biofuel cultivation scenarios yield roughly the same quantity of fuel (180 Mt of oil equivalent per year), in line with projected global demands for biofuel in the 2020s. In each case, global annual isoprene emissions rose by around 1 %. The resulting changes in ground-level ozone concentrations were markedly different, with increases of as much as 10 ppbv over parts of Europe as a result of cultivation in the mid-latitudes, but decreases across much of the tropics due to oil palm cultivation. If co-located emissions of NOx from oil palm processing were included, ozone levels rose by up to 5 ppbv over SE Asia, highlighting the importance of controlling NOx emissions. The increases in ozone over Europe are projected to result in 1300 premature deaths and a 4% reduction r III in the wheat harvest. This is the first time that changes in biogenic emissions resulting from realistic land use changes driven by biofuel cultivation have been considered. The projected impacts on air quality and health indicate that such emissions are important in assessing the overall environmental effect of biofuels.
|
|---|
