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

摘要

Over the period of 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 biogenic volatile organic compound (BVOC) emission changes ( +6.5 TgC?y sup?1/sup isoprene, ?0.5 TgC?y sup?1/sup 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 ( +0.5 ppbv) than in the lower troposphere ( ?2/sup ) was partially offset by a negative forcing ( ?0.8 mW?m sup?2/sup ) associated with an enhancement in secondary organic aerosol (SOA). The sign of the net forcing is sensitive to uncertainty in the SOA yield from BVOCs. The global-mean ozone forcing per unit of regional oil palm expansion is + 1?mW?m sup?2/sup Mha sup?1/sup . 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.