Atmospheric emissions, processes, and impacts of tropical peatland fire haze in Equatorial Asia: A review

Abstract

Equatorial Asia, which includes Indonesia, Malaysia, Singapore, and Brunei, developed coastal tropical peatlands, following the last glacial maximum. Recent human activities, especially the agricultural development of the region in the last couple of decades, have enhanced the occurrence of peatland fire haze in the region. This review provides 1) temporal variations in peatland fire haze, 2) emission of gas and particulate matter, 3) chemistry in haze plumes, and 4) environmental and atmospheric impacts of haze. Typically, intense peatland fire in the region occurs during the strong El Niño years. Carbon emissions from tropical peatland burning were estimated to be ∼250 Tg during the event in 2015, which was associated with strong El Niño. Gas- and particle-phase chemical species emitted from tropical peatland fires change atmospheric chemical composition. For instance, since the 1980s, the enhancement of tropospheric ozone has long been observed during peatland fire events. Aerosol particles emitted from tropical peatland fires influenced atmospheric radiation and cloud formation processes over Equatorial Asia and the eastern Indian Ocean. The impact of peatland fire haze on human health has been documented since the intense event in 1997. Recent studies estimated that premature mortality associated with fires in 2015 could range from 10,000–100,000. To date, most studies have been conducted using satellite remote sensing and modeling, while there have been some efforts to conduct field studies. In the future, in situ atmospheric observation and epidemiological studies will need to be better combined with satellite observation and modeling studies to provide a comprehensive understanding of the environmental impacts of peatland fire haze.