Funeral Pyres in South Asia: Brown Carbon Aerosol Emissions and Climate Impacts

Abstract

Atmospheric heating caused by anthropogenically emitted carbonaceous aerosols contributes to one of the largest uncertainties in climate forcing over south Asia (SA). Past studies have identified the combustion of fossil fuels and residential biofuels as being the dominant emitter of light-absorbing black carbon aerosols over this region. Here, we measure emissions from open-air burning of funeral pyres, a deep-rooted and widely prevalent custom in SA, and find that large amounts (≈98% by mass) of light-absorbing organic carbon (OC) aerosols, optically defined as brown carbon (BrC), are emitted per kilogram of feedstock burned. The emitted OC contributes an average 40% to the smoke particulate matter absorption of the visible solar radiation. We calculate funeral pyres in SA contribute approximately 92 Gg of light-absorbing OC annually, which is equivalent to ≈10 and 23% of the carbonaceous aerosol mass from regional biofuels and fossil fuels, respectively. Our findings underscore the importance of accounting for cultural burning practices as aerosol sources in emission inventories and BrC aerosols in climate models, as well as the development of mitigation strategies.

Mass absorption efficiency of light absorbing organic aerosols from source region of paddy-residue burning emissions in the Indo-Gangetic Plain

“…A more recent study by Srinivas and Sarin (2014a) has documented that the MAE of BrC could account for~40e60% relative to that of EC in PM 2.5 samples collected during early winter months (NoveDec) from a downwind sampling site in the IGP. Our results are also consistent with that documented for water-soluble BrC emissions from biofuel burning, which show the relative contribution of MAE of BrC at 300 and 500 nm compared to EC are 70 and 26%, respectively (Chakrabarty et al, 2014).…”

Filter-based measurements of UV–vis mass absorption cross sections of organic carbon aerosol from residential biomass combustion: Preliminary findings and sources of uncertainty

“…In this study, the estimated EC mass in aerosol samples has been approximated to be the BC mass [40,41]. This approximation, while having found wide usage in the aerosol community, has its limitations.…”

Source-diagnostic dual-isotope composition and optical properties of water-soluble organic carbon and elemental carbon in the South Asian outflow intercepted over the Indian Ocean

“…This effect is much higher over South Asia. In contrast to BC, the organic carbon (OC) aerosol has been traditionally considered as purely light-scattering particles but studies have shown OC to also absorb light, predominantly at shorter wavelengths [Alexander et al, 2008;Andreae and Gelencser, 2006;Chakrabarty et al, 2014;Kirchstetter and Novakov, 2004;Moosmüller et al, 2011;Sun et al, 2007]. These light-absorbing organic aerosols, termed brown carbon (BrC), may thus, next to BC, also contribute to a positive direct radiative effect on climate (+0.04 to +0.11 W m À2 [e.g., Bahadur et al, 2012;Chung et al, 2012;Feng et al, 2013]).…”