Impacts of Current and Projected Oil Palm Plantation Expansion on Air Quality Over Southeast Asia

Over recent decades oil palm plantations have rapidly expanded across Southeast Asia (SEA). According to the 10 United Nations, oil palm production in SEA increased by a factor of 3 from 1995 to 2010. We investigate the impacts of current (2010) and future (2020) oil palm expansion in SEA on surface-atmosphere exchange and the resulting air quality in the region. For this purpose, we use satellite data, high-resolution land maps, and the chemical transport model GEOS-Chem. Relative to a no oil palm plantation scenario (~1990), overall simulated isoprene emissions in the region increase by 13% due to oil palm plantations in 2010 and a further 11% by 2020. In addition, the expansion of palm plantations leads to local 15 increases in ozone deposition velocities of up to 20%. The net result of these changes is that oil palm expansion in SEA increases surface O3 by up to 3.5 ppbv over dense urban regions, and could rise more than 4.5 ppbv above baseline levels by 2020. Biogenic secondary organic aerosol loadings also increase by up to 1 μg m due to oil palm expansion, and could increase a further 2.5 μg m by 2020. Our analysis indicates that while the impact of recent oil palm expansion on air quality in the region has been significant, the retrieval error and sensitivity of the current constellation of satellite measurements 20 limit our ability to observe these impacts from space. Oil palm expansion is likely to continue to degrade air quality in the region in the coming decade and hinder efforts to achieve air quality regulations in major urban areas such as Kuala Lumpur and Singapore.