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.
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.
China’s recent import ban has thrown Western recycling systems into disarray. DCW has participated as CIWM President in three regional open meetings to address the ‘China recycling crisis’. His April column for the CIWM Journal has written up his presentation, providing a personal perspective on how he has seen China’s internal resource and waste management systems develop over the last 40 years. Arguably, its 1970s system could be viewed as an early example of a circular economy. The transition to ‘market -oriented’ operations led to economic growth being prioritised over environmental protection. But the current ‘National Sword’ campaign is just one symptom of a fundamental change, suggesting that, going forward, perhaps China really could lead the world in transitioning to a circular economy.
DCW’s February column for the CIWM Journal focused on the topical subject of marine plastics. He reported back on ‘Oceans 21’, the latest Development Finance Forum organised by the German Development Bank KfW, where he led a workshop on marine litter. The conclusions were clear: the amount of plastics entering the oceans is at least an order of magnitude greater than estimates of the visible quantities in the oceans or on beaches – so the first priority is to ‘turn off the tap’. And the most effective way to do that is to extend municipal solid waste collection in developing countries to all people and to eliminate uncontrolled dumping and burning; our best judgement was that this could reduce the weight of plastics entering the oceans by 50-70%.