Hardacre, Catherine and Palmer, Paul I. and Baumanns, Kerstin and Murray-Rust, Dave and Rounsevell, Mark (2012) Probabilistic estimation of future emissions of isoprene and surface oxidant chemistry associated with land use change in response to growing food needs. Atmospheric Chemistry and Physics, 12. pp. 33359-33410. ISSN 1680-7316
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Abstract
We quantify the impact of land use change, determined by our growing need for food and biofuel production, on isoprene emissions and subsequent atmospheric oxidant chemistry in 2015 and 2030, relative to 1990, ignoring compound climate change effects over that period. We estimate isoprene emissions from an ensemble n=1000 of land use change realizations from 1990--2050, broadly guided by the IPCC AR4/SRES scenarios A1 and B1. We also superimpose land use change required to address projected biofuel usage using two scenarios: (1) assuming that world governments make no changes to biofuel policy after 2009, and (2) assuming that world governments develop biofuel policy with the aim of keeping equivalent atmospheric CO2 at 450 ppm. We present the median and interquartile range (IQR) statistics of the ensemble and show that land use change between -1.50 x 10 12 m2 to +6.06 x 10 12 m2 was found to drive changes in the global isoprene burden of -3.5 to +2.8 Tg yr-1 in 2015 and -7.7 to +6.4 Tg yr-1 in 2030. We use land use change realizations corresponding to the median and IQR of these emission estimates to drive the GEOS-Chem global 3-D chemistry transport model to investigate the perturbation to global and regional surface concentrations of isoprene, nitrogen oxides (NO+NO2), and the atmospheric concentration and deposition of ozone (O3). We show that across sub-continental regions the monthly surface O3 increases by 0.1--0.8 ppb, relative to a zero land-use change calculation, driven by increases (decreases) in surface isoprene in high (low) NOx environments. At the local scale (4 x 5) we find that surface O3 increases by 5-12 ppb over temperate North America, China and Boreal Eurasia, driven by large increases in isoprene emissions from short-rotation coppice crop cultivation for biofuel production.