Global climate forcing driven by altered BVOC fluxes from 1990–2010 land cover change in maritime Southeast Asia

Abstract

Abstract. Over the period 1990-2010, maritime Southeast Asia experienced large-scale land cover changes, including expansion of high-isoprene-emitting oil palm plantations and contraction of low-isoprene-emitting natural forests. The ModelE2-Yale Interactive Terrestrial Biosphere global chemistry-climate model is used to quantify the atmospheric composition changes and, for the first time, the associated radiative forcing induced by the land-cover-change-driven 10 biogenic volatile organic compound (BVOC) emission changes (+6.5 TgC y -1 isoprene, -0.5 TgC y -1 monoterpenes).Regionally, surface-level ozone concentrations largely decreased (-3.8 to +0.8 ppbv). The tropical land cover changes occurred in a region of strong convective transport, providing a mechanism for the BVOC perturbations to affect the composition of the upper troposphere. Enhanced concentrations of isoprene and its degradation products are simulated in the upper troposphere, and, on a global-mean basis, land cover change had a stronger impact on ozone in the upper troposphere 15 (+0.6 ppbv) than in the lower troposphere (< 0.1 ppbv increase). The positive climate forcing from ozone changes (+9.2 mW m -2 ) was partially offset by a negative forcing (-0.8 mW m -2 ) associated with a regional enhancement in secondary organic aerosol concentrations. The global-mean ozone forcing per unit of regional oil palm expansion is +1 mW m -2 Mha -1 . In light of expected continued expansion of oil palm plantations, regional land cover changes may play an increasingly important role in driving future global ozone radiative forcing. 20

Identifying the Drivers of Modeling Uncertainties in Isoprene Emissions: Schemes Versus Meteorological Forcings

“…Isoprene emissions are highly dependent on vegetation characteristics and weather conditions. Forest emissions are usually much larger than farmland (Hantson et al., 2017; Harper & Unger, 2018; Unger, 2014). Higher temperature and more light promote isoprene emissions (Hantson et al., 2017; Penuelas & Llusia, 2003; Zhang et al., 2008).…”

Responses of isoprene emission and photochemical efficiency to severe drought combined with prolonged hot weather in hybrid Populus

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