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LETTER • OPEN ACCESS Rapid decline in carbon monoxide emissions and export from East Asia between years 2005 and 2016 To cite this article: Bo Zheng et al 2018 Environ. Res. Lett. 13 044007 View the article online for updates and enhancements. Related content Uncertainties in emissions estimates of greenhouse gases and air pollutants in India and their impacts on regional air quality-Recent reduction in NO x emissions over China: synthesis of satellite observations and emission inventories-Exceedances of air quality standard level of PM 2.5 in Japan caused by Siberian wildfires-This content was downloaded from IP address 157.136.75.78 on 16/09/2020 at 15:17 Environ. Res. Lett. 13 (2018) 044007 Abstract Measurements of Pollution in the Troposphere (MOPITT) satellite and ground-based carbon monoxide (CO) measurements both suggest a widespread downward trend in CO concentrations over East Asia during the period 2005-2016. This negative trend is inconsistent with global bottom-up inventories of CO emissions, which show a small increase or stable emissions in this region. We try to reconcile the observed CO trend with emission inventories using an atmospheric inversion of the MOPITT CO data that estimates emissions from primary sources, secondary production, and chemical sinks of CO. The atmospheric inversion indicates a ∼ −2% yr −1 decrease in emissions from primary sources in East Asia from 2005-2016. The decreasing emissions are mainly caused by source reductions in China. The regional MEIC inventory for China is the only bottom up estimate consistent with the inversion-diagnosed decrease of CO emissions. According to the MEIC data, decreasing CO emissions from four main sectors (iron and steel industries, residential sources, gasoline-powered vehicles, and construction materials industries) in China explain 76% of the inversion-based trend of East Asian CO emissions. This result suggests that global inventories underestimate the recent decrease of CO emission factors in China which occurred despite increasing consumption of carbon-based fuels, and is driven by rapid technological changes with improved combustion efficiency and emission control measures.