Black carbon (BC) emissions from the open burning of municipal solid wastes (MSW) and other waste types contribute significantly to global heating but are not yet included in the official (IPCC) inventory of greenhouse gases (GHGs) due to poor data availability. Natalia Reyna has just completed her PhD thesis at Imperial College London, co-supervised by Professors David C Wilson and Stephen R. Smith, with the aim of generating reliable data to plug that gap. Our second and final paper was published last week in the leading journal Atmospheric Environment, providing a reliable methodology for measuring emission factors (EFs) for black carbon from waste burning. i.e. how much black carbon is produced by burning a kilogram of waste. The two papers have been submitted as evidence to the IPCC sixth assessment study due to be published in 2021.
When the measured emission factors are combined with our earlier measurements of the extent of open burning of municipal solid wastes in Mexico; other published estimates of waste composition and activity levels around the world; and a range of estimates of the global warming potential of black carbon as compared to CO₂; our best estimate of the contribution of BC from the open burning of MSW to global heating is in the range 2-10% of global CO₂Eq emissions. Given the associated air pollution and health impacts, urgent global action is essential to eliminate open burning of waste; this will provide a relatively ‘quick win’ in tackling the global climate emergency.
A short article reporting this research appeared in the September/October 2019 issue of CIWM’s new, award-winning magazine Circular.
In his July column, CIWM President David C Wilson makes the case for more investment in resource and waste management as an ‘entry point’ to achieve significant climate mitigation. The sector already has a track record in developed countries, with methane mitigation from landfill since the 1970s, and both methane mitigation and recycling making a major contribution to meeting Kyoto Convention greenhouse gas (GHG) reduction targets between 1990 and 2010. But that early success also means that the IPCC’s 2010 assessment is that the ‘waste’ sector only contributes 3-5% to current GHG emissions. DCW argues that this is a gross underestimate which fails to consider: the current emissions from uncontrolled burning; historical reductions; contributions across the economy from recycling; and waste prevention (particularly food waste). The results suggest that better resource and waste management has the potential for reducing GHG emissions across the World economy by 15, 20 or 25% or even more. Such numbers may be guesstimates, but whatever number we choose to use, the message is still the same. Further investment in this sector, in both developing and developed countries, is a major political priority in order to meet our climate targets.
This article was subsequently re-published by the National Solid Waste Association of India (NSWAI) in their member journal Waste Monitor in July 2019.
To qualify for inclusion in the official (IPCC) inventory of greenhouse gases (GHGs), data for an emission source must meet a quality threshold. This currently excludes black carbon emissions from the open burning of wastes. The relative quantities may be small compared to carbon dioxide from fossil fuels or methane from landfill, but black carbon is around 2,000 more powerful than CO₂ as a GHG and has an even shorter half-life than methane. In the absence of real data, early modelling studies using broad assumptions suggested that black carbon from open burning contributes 5% of total global GHG emissions, causing 270,000 premature deaths a year. DCW’s PhD student at Imperial College London, Natalia Reyna, has been working for the last four years to provide real data which would meet the IPCC requirements. Our first paper, published this month in the leading journal Environmental Research, presents field data from Mexico on how much solid wastes are disposed of by open burning, either by households or at uncontrolled dumpsites. The results suggest a GHG contribution from uncontrolled burning in backyards in Mexico fifteen times larger compared to methane released from the decomposition of equivalent amounts of waste in a disposal site. This suggests that urgent action is needed to reduce domestic open burning of waste and that this would have a significant impact, both on improving local air quality and respiratory health, and on reducing climate change. A future paper will present data on emission factors, i.e. how much black carbon is produced by burning a kilogram of waste.