Air Quality in Southeast Asia: The Growing Threat of Coal Emissions and Land Use Change Fires to Human Health in a Rapidly Evolving Region

air quality;Southeast Asia

Koplitz, Shannon N. ; Mickley, Loretta J.,Jacob, Daniel J.

University:Havard University

Department:Earth and Planetary Sciences

关键词: air quality;    Southeast Asia;   

Others  :  https://dash.harvard.edu/bitstream/handle/1/37365505/KOPLITZ-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: Digital Access to Scholarship at Harvard

【 摘 要 】

Southeast Asia is one of the most densely populated, rapidly developing regions in the world. Despite the extreme rate of economic and population growth, the implications for air quality and human health from the consequent rise in particulate matter (PM) and ozone pollution remain largely unquantified. In this thesis I investigate how anthropogenic activity associated with rapid economic growth in Southeast Asia influences regional air quality and human health, and how these processes are projected to change in the future. In particular, I use the GEOS-Chem chemical transport model (CTM) along with surface and satellite observations to assess 1) the human health implications of projected coal plant expansion across Southeast Asia, and 2) the meteorological and anthropogenic factors contributing to severe haze events stemming from agricultural fires in Indonesia.I first quantify the burden of disease from rapidly expanding coal fired power plant emissions, both in the present day and for projected 2030 levels. Southeast Asia has a very high population density and is on a fast track to economic development, with most of the growth in electricity demand currently projected to be met by coal. From a detailed analysis of coal-fired power plants presently planned or under construction in Southeast Asia, we project in a business-as-usual scenario that emissions from coal in the region will triple to 2.6 Tg a-1 SO2 and 2.6 Tg a-1 NOx by 2030, with the largest increases occurring in Indonesia and Vietnam. Simulations with the GEOS-Chem chemical transport model show large resulting increases in surface air pollution, up to 11 ug m-3 for annual mean fine particulate matter (PM2.5) in northern Vietnam and up to 15 ppb for seasonal maximum 1-h ozone in Indonesia. We estimate 20,000 excess deaths per year from Southeast Asian coal emissions at present, increasing to 70,000 by 2030. 9,000 of these excess deaths in 2030 are in China. As Chinese emissions from coal decline in coming decades, transboundary pollution influence from rising coal emissions in Southeast Asia may become an increasing issue.Next, I assess the contributions of fires in different geographic areas to deteoriated air quality across Equatorial Asia during an extreme haze event in September-October 2015, demonstrating for the first time the utility of a new rapid assessment framework. In September-October 2015, El Nino and positive Indian Ocean Dipole conditions set the stage for massive fires in Sumatra and Kalimantan (Indonesian Borneo), leading to persistently hazardous levels of smoke pollution across much of Equatorial Asia. Here we quantify the emission sources and health impacts of this haze episode and compare the sources and impacts to an event of similar magnitude occurring under similar meteorological conditions in September-October 2006.Using the adjoint of the GEOS-Chem chemical transport model, we first calculate the influence of potential fire emissions across the domain on smoke concentrations in three receptor areas downwind – Indonesia, Malaysia, and Singapore – during the 2006 event. This step maps the sensitivity of each receptor to fire emissions in each grid cell upwind. We then combine these sensitivities with 2006 and 2015 fire emission inventories from the Global Fire Assimilation System (GFAS) to estimate the resulting population-weighted smoke exposure. This method, which assumes similar smoke transport pathways in 2006 and 2015, allows near real-time assessment of smoke pollution exposure, and therefore the consequent morbidity and premature mortality, due to severe haze. Our approach also provides rapid assessment of the relative contribution of fire emissions generated in a specific province to smoke-related health impacts in the receptor areas. We estimate that haze in 2015 resulted in 100,300 excess deaths across Indonesia, Malaysia and Singapore, more than double those of the 2006 event, with much of the increase due to fires in Indonesia’s South Sumatra Province. The model framework we introduce in this study can rapidly identify those areas where land use management to reduce and/or avoid fires would yield the greatest benefit to human health, both nationally and regionally. In the final section of this thesis, I diagnose the meteorological drivers of an unexpected haze event in Singapore during June 2013, and I demonstrate that the conditions responsible for June 2013 are in fact a recurring mechanism for smoke exposure in the Malay Peninsula that has never been identified before. In June 2013, Singapore experienced severe smoke levels, with surface particulate matter concentrations reaching above 300 ug m-3. Unlike other intense haze events in Singapore and Equatorial Asia (e.g., September 1997, October 2006, September 2015), the June 2013 episode occurred in the absence of El Nino-positive Indian Ocean Dipole (pIOD) conditions generally associated with drought. The smoke originated from fires in the Riau province of central Sumatra and was carried to the Malay Peninsula by westerly winds, unlike typical conditions in September-October events when Singapore is affected by smoke from fires in southern Sumatra and Kalimantan transported by southerly winds.We show that June 2013 was not an exceptional event; inspection of the 2005-2015 record identifies two other severe haze events in the Malay Peninsula (August 2005 and October 2010) occurring under the same conditions. Common to all threeevents was a combination of late-phase Madden-Julian Oscillation (MJO) and negative phase of the IOD. Our work suggests that the MJO-IOD combination in medium-range weather forecasts could help predict severe haze events in Singapore and the Malay Peninsula.