Major atmospheric emissions from peat fires in Southeast Asia during non-drought years: evidence from the 2013 Sumatran fires.

David L A Gaveau,Martin Wooster,Mohammad A Salim,Robert Nasi,Douglas Sheil,Husna Yaen,Ruth Defries,Peter Holmgren,Daniel Murdiyarso,Kristell Hergoualc'H,Bruno Locatelli,Miriam E Marlier,Sean Sloan,Louis Verchot,Elis Molidena

doi:10.1038/srep06112

Abstract

Trans-boundary haze events in Southeast Asia are associated with large forest and peatland fires in Indonesia. These episodes of extreme air pollution usually occur during drought years induced by climate anomalies from the Pacific (El Niño Southern Oscillation) and Indian Oceans (Indian Ocean Dipole). However, in June 2013 – a non-drought year – Singapore's 24-hr Pollutants Standards Index reached an all-time record 246 (rated “very unhealthy”). Here, we show using remote sensing, rainfall records and other data, that the Indonesian fires behind the 2013 haze followed a two-month dry spell in a wetter-than-average year. These fires were short-lived (one week) and limited to a localized area in Central Sumatra (1.6% of Indonesia): burning an estimated 163,336 ha, including 137,044 ha (84%) on peat. Most burning was confined to deforested lands (82%; 133,216 ha). The greenhouse gas (GHG) emissions during this brief, localized event were considerable: 172 ± 59 Tg CO2-eq (or 31 ± 12 Tg C), representing 5–10% of Indonesia's mean annual GHG emissions for 2000–2005. Our observations show that extreme air pollution episodes in Southeast Asia are no longer restricted to drought years. We expect major haze events to be increasingly frequent because of ongoing deforestation of Indonesian peatlands.

Highlights

Trans-boundary haze events in Southeast Asia are associated with large forest and peatland fires in Indonesia
Forest and peatland fires in Indonesia are a cause of major international concern because of the large greenhouse gas (GHG) emissions associated with these fires[1,2,3,4], and the negative impact of resulting aerosol emissions for human health, transport, tourism, economic activity in the Southeast Asian region[5]
Drought years in Indonesia occur when anomalously cold sea surface temperatures surround Indonesia and warm waters develop in the eastern Pacific Ocean (El Nino Southern Oscillation, ENSO) and in the western Indian Ocean (Positive Indian Ocean Dipole, IOD)[6]

Summary

Introduction

Trans-boundary haze events in Southeast Asia are associated with large forest and peatland fires in Indonesia. These episodes of extreme air pollution usually occur during drought years induced by climate anomalies from the Pacific (El Nino Southern Oscillation) and Indian Oceans (Indian Ocean Dipole). We show using remote sensing, rainfall records and other data, that the Indonesian fires behind the 2013 haze followed a two-month dry spell in a wetter-than-average year These fires were short-lived (one week) and limited to a localized area in Central Sumatra (1.6% of Indonesia): burning an estimated 163,336 ha, including 137,044 ha (84%) on peat. Our objectives were to: (i) examine the pollution levels generated; (ii) assess climatic conditions prior to the fires; (ii) quantify the area burned, (iii) assess prior vegetation cover and land ownership preceding the fires; (iv) estimate associated GHG emissions; (v) and consider the likelihood of such events recurring in the future

Objectives

Methods

Results