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.