Global Anthropogenic Emission Inventory Research Articles

Unexpected anthropogenic emission decreases explain recent atmospheric mercury concentration declines.

Anthropogenic activities emit ~2,000 Mg y-1 of the toxic pollutant mercury (Hg) into the atmosphere, leading to long-range transport and deposition to remote ecosystems. Global anthropogenic emission inventories report increases in Northern Hemispheric (NH) Hg emissions during the last three decades, in contradiction with the observed decline in atmospheric Hg concentrations at NH measurement stations. Many factors can obscure the link between anthropogenic emissions and atmospheric Hg concentrations, including trends in the reemissions of previously released anthropogenic ("legacy") Hg, atmospheric sink variability, and spatial heterogeneity of monitoring data. Here, we assess the observed trends in gaseous elemental mercury (Hg0) in the NH and apply biogeochemical box modeling and chemical transport modeling to understand the trend drivers. Using linear mixed effects modeling of observational data from 51 stations, we find negative Hg0 trends in most NH regions, with an overall trend for 2005 to 2020 of -0.011 ± 0.006 ng m-3 y-1 (±2 SD). In contrast to existing emission inventories, our modeling analysis suggests that annual NH anthropogenic emissions must have declined by at least 140 Mg between the years 2005 and 2020 to be consistent with observed trends. Faster declines in 95th percentile Hg0 values than median values in Europe, North America, and East Asian measurement stations corroborate that the likely cause is a decline in nearby anthropogenic emissions rather than background legacy reemissions. Our results are relevant for evaluating the effectiveness of the Minamata Convention on Mercury, demonstrating that existing emission inventories are incompatible with the observed Hg0 declines.

Light oxygenated volatile organic compound concentrations in an Eastern Mediterranean urban atmosphere rivalling those in megacities

Highly resolved measurements of primary and secondary oxygenated volatile organic compounds (OVOCs) by proton-transfer-reaction mass spectrometry (PTR-MS) and the AMOVOC sampler (Airborne Measurements Of VOC) were performed in Beirut, Lebanon, during the ECOCEM (Emissions and Chemistry of Organic Carbon in the East Mediterranean) experiments. The OVOC concentrations (0.15–7.0 ppb) rival those reported for international megacities like Paris, Tokyo, or São Paulo (0.3–6.5 ppb). This study highlights the seasonal variability of OVOCs, the potential role of background pollution on OVOC concentrations, traffic emissions of OVOCs, and the secondary production of OVOCs during both summer and winter.The primary and secondary OVOC fractions were estimated using two methods based on the night-time emission ratio and photochemical age. Our calculations coupled with a correlation analysis revealed the following: firstly, background concentrations contributed significantly, especially for longer-lived OVOCs, such as methanol and acetone (30%–80%). Secondly, secondary production in summer increased up to 60%, except for methanol and isoprene oxidation products, i.e., for methacrolein and methyl vinyl ketone. Thirdly, the secondary production in the Eastern Mediterranean persisted in winter, and finally, strong primary traffic emissions dominated the primary biogenic emissions.Finally, the emission ratios were used to evaluate the global anthropogenic emission inventories downscaled to Lebanon. Although limited to two individual non-lumped species (formaldehyde and acetone), the emission ratios compared well, within a factor of 2. However, the emissions of aldehydes and ketones from the CAMS, Edgar, and MACCITY inventories showed discrepancies of up to three orders of magnitude. This demonstrates a need for improved OVOC representation in emission inventories, considering the atmospheric relevance and abundance of OVOCs and their use in volatile chemical products.

Development and evaluation of the Aerosol Forecast Member in the National Center for Environment Prediction (NCEP)'s Global Ensemble Forecast System (GEFS-Aerosols v1)

Abstract. The National Oceanic and Atmospheric Administration (NOAA)'s National Weather Service (NWS) is on its way to deploying various operational prediction applications using the Unified Forecast System (https://ufscommunity.org/, last access: 18 June 2022), a community-based coupled, comprehensive Earth modeling system. An aerosol model component developed in collaboration between the Global Systems Laboratory, Chemical Science Laboratory, Air Resources Laboratory, and Environmental Modeling Center (GSL, CSL, ARL, EMC) was coupled online with the FV3 Global Forecast System (FV3GFS) using the National Unified Operational Prediction Capability (NUOPC)-based NOAA Environmental Modeling System (NEMS) software framework. This aerosol prediction system replaced the NEMS GFS Aerosol Component version 2 (NGACv2) system in the National Center for Environment Prediction (NCEP) production suite in September 2020 as one of the ensemble members of the Global Ensemble Forecast System (GEFS), dubbed GEFS-Aerosols v1. The aerosol component of atmospheric composition in the GEFS is based on the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). GEFS-Aerosols includes bulk modules from the Goddard Chemistry Aerosol Radiation and Transport model (GOCART). Additionally, the biomass burning plume rise module from High-Resolution Rapid Refresh (HRRR)-Smoke based on WRF-Chem was implemented. The GOCART dust scheme was replaced by the FENGSHA dust scheme (developed by ARL). The Blended Global Biomass Burning Emissions Product (GBBEPx version 3) provides biomass burning emission and fire radiative power (FRP) data. The global anthropogenic emission inventories are derived from the Community Emissions Data System (CEDS). All sub-grid-scale transport and deposition are handled inside the atmospheric physics routines, which required consistent implementation of positive definite tracer transport and wet scavenging in the physics parameterizations used by the NCEP's operational FV3GFS. This paper describes the details of GEFS-Aerosols model development and evaluation of real-time and retrospective runs using different observations from in situ measurement and satellite and aircraft data. GEFS-Aerosols predictions demonstrate substantial improvements for both composition and variability of aerosol distributions over those from the former operational NGACv2 system with the fundamental updates (e.g., dust and fire emission) in the atmospheric and chemical transport model.

An integrated analysis of contemporary methane emissions and concentration trends over China using in situ and satellite observations and model simulations

Abstract. China, being one of the major emitters of greenhouse gases, has taken strong actions to tackle climate change, e.g., to achieve carbon neutrality by 2060. It also becomes important to better understand the changes in the atmospheric mixing ratios and emissions of CH4, the second most important human-influenced greenhouse gas, in China. Here we analyze the sources contributing to the atmospheric CH4 mixing ratios and their trends in China over 2007–2018 using the GEOS-Chem model simulations driven by two commonly used global anthropogenic emission inventories: the Emissions Database for Global Atmospheric Research (EDGAR v4.3.2) and the Community Emissions Data System (CEDS). The model results are interpreted with an ensemble of surface, aircraft, and satellite observations of CH4 mixing ratios over China and the Pacific region. The EDGAR and CEDS estimates show considerable differences reflecting large uncertainties in estimates of Chinese CH4 emissions. Chinese CH4 emission estimates based on EDGAR and natural sources increase from 46.7 Tg per annum (Tg a−1) in 1980 to 69.8 Tg a−1 in 2012 with an increase rate of 0.7 Tg a−2, and estimates with CEDS increase from 32.9 Tg a−1 in 1980 and 76.7 Tg a−1 in 2014 (a much stronger trend of 1.3 Tg a−2 over the period). Both surface, aircraft, and satellite measurements indicate CH4 increase rates of 7.0–8.4 ppbv a−1 over China in the past decade. We find that the model simulation using the CEDS inventory and interannually varying OH levels can best reproduce these observed CH4 mixing ratios and trends over China. Model results over China are sensitive to the global OH level, with a 10 % increase in the global tropospheric volume-weighted mean OH concentration presenting a similar effect to that of a 47 Tg a−1 decrease in global CH4 emissions. We further apply a tagged tracer simulation to quantify the source contributions from different emission sectors and regions. We find that domestic CH4 emissions account for 14.0 % of the mean surface mixing ratio and drive 66.7 % of the surface trend (mainly via the energy sector) in China over 2007–2018. We emphasize that intensive CH4 measurements covering eastern China will help us better assess the driving factors of CH4 mixing ratios and support the emission mitigation in China.

A global anthropogenic emission inventory of atmospheric pollutants from sector- and fuel-specific sources (1970–2017): an application of the Community Emissions Data System (CEDS)

Abstract. Global anthropogenic emission inventories remain vital for understanding the sources of atmospheric pollution and the associated impacts on the environment, human health, and society. Rapid changes in today's society require that these inventories provide contemporary estimates of multiple atmospheric pollutants with both source sector and fuel type information to understand and effectively mitigate future impacts. To fill this need, we have updated the open-source Community Emissions Data System (CEDS) (Hoesly et al., 2019) to develop a new global emission inventory, CEDSGBD-MAPS. This inventory includes emissions of seven key atmospheric pollutants (NOx; CO; SO2; NH3; non-methane volatile organic compounds, NMVOCs; black carbon, BC; organic carbon, OC) over the time period from 1970–2017 and reports annual country-total emissions as a function of 11 anthropogenic sectors (agriculture; energy generation; industrial processes; on-road and non-road transportation; separate residential, commercial, and other sectors (RCO); waste; solvent use; and international shipping) and four fuel categories (total coal, solid biofuel, the sum of liquid-fuel and natural-gas combustion, and remaining process-level emissions). The CEDSGBD-MAPS inventory additionally includes monthly global gridded (0.5∘ × 0.5∘) emission fluxes for each compound, sector, and fuel type to facilitate their use in earth system models. CEDSGBD-MAPS utilizes updated activity data, updates to the core CEDS default scaling procedure, and modifications to the final procedures for emissions gridding and aggregation. Relative to the previous CEDS inventory (Hoesly et al., 2018), these updates extend the emission estimates from 2014 to 2017 and improve the overall agreement between CEDS and two widely used global bottom-up emission inventories. The CEDSGBD-MAPS inventory provides the most contemporary global emission estimates to date for these key atmospheric pollutants and is the first to provide global estimates for these species as a function of multiple fuel types and source sectors. Dominant sources of global NOx and SO2 emissions in 2017 include the combustion of oil, gas, and coal in the energy and industry sectors as well as on-road transportation and international shipping for NOx. Dominant sources of global CO emissions in 2017 include on-road transportation and residential biofuel combustion. Dominant global sources of carbonaceous aerosol in 2017 include residential biofuel combustion, on-road transportation (BC only), and emissions from the waste sector. Global emissions of NOx, SO2, CO, BC, and OC all peak in 2012 or earlier, with more recent emission reductions driven by large changes in emissions from China, North America, and Europe. In contrast, global emissions of NH3 and NMVOCs continuously increase between 1970 and 2017, with agriculture as a major source of global NH3 emissions and solvent use, energy, residential, and the on-road transport sectors as major sources of global NMVOCs. Due to similar development methods and underlying datasets, the CEDSGBD-MAPS emissions are expected to have consistent sources of uncertainty as other bottom-up inventories. The CEDSGBD-MAPS source code is publicly available online through GitHub: https://github.com/emcduffie/CEDS/tree/CEDS_GBD-MAPS (last access: 1 December 2020). The CEDSGBD-MAPS emission inventory dataset (both annual country-total and monthly global gridded files) is publicly available under https://doi.org/10.5281/zenodo.3754964 (McDuffie et al., 2020c).

Development and application of an updated geospatial distribution model for gridding 2015 global mercury emissions

Mercury is a global pollutant that poses threats to ecosystems and to human health. Due to its global transport, mercury contamination is found in regions of the Earth that are remote from major emissions areas, including the Polar regions. Global anthropogenic emission inventories identify important sectors and industries responsible for emissions at a national level; however, to be useful for air transport modelling, more precise information on the locations of emission is required. This paper describes the methodology applied, and the results of work that was conducted to geospatially distribute anthropogenic mercury emissions as part of the global anthropogenic mercury emissions inventory for 2015 prepared by AMAP/UNEP for the Global Mercury Assessment (GMA) 2018 (UN Environment, 2019). This work includes the identification and use of emission point sources as well as distributing diffuse emissions for 21 emission (industry) sectors. The basic approach involves assigning emission estimates to geo-located point sources, using reported emissions information where available, and otherwise assigning a modelled emission to the point. Emissions which cannot be assigned to point sources are distributed using sector-specific proxies. Mercury speciation highly depends on industry processes and air pollution control technology. Different Hg speciation ratios are therefore applied per sector and country technology level. The resulting global emission datasets include total mercury (HgT), gaseous elemental mercury (Hg0), divalent mercury (Hg2+) and particulate mercury (HgP) in kg per year per raster cell (kg/a). The spatial resolution is flexible and the vertical resolution of the data is based on a set of predefined height classes. The resolution of the GMA2018 emission data is 0.25° × 0.25° with three (physical emission) height classes (0–50, 50–150 and > 150m). A comparison with the EMEP European mercury emission was made based on spatial correlation between the two datasets. Suggested improvements for future work include the further development of proxy data and the implementation of a more structured reporting of emissions by countries.

Identifying and characterizing major emission point sources as a basis for geospatial distribution of mercury emissions inventories

Mercury is a global pollutant that poses threats to ecosystem and human health. Due to its global transport, mercury contamination is found in regions of the Earth that are remote from major emissions areas, including the Polar regions. Global anthropogenic emission inventories identify important sectors and industries responsible for emissions at a national level; however, to be useful for air transport modelling, more precise information on the locations of emission is required. This paper describes the methodology applied, and the results of work that was conducted to assign anthropogenic mercury emissions to point sources as part of geospatial mapping of the 2010 global anthropogenic mercury emissions inventory prepared by AMAP/UNEP. Major point-source emission sectors addressed in this work account for about 850 tonnes of the emissions included in the 2010 inventory. This work allocated more than 90% of these emissions to some 4600 identified point source locations, including significantly more point source locations in Africa, Asia, Australia and South America than had been identified during previous work to geospatially-distribute the 2005 global inventory. The results demonstrate the utility and the limitations of using existing, mainly public domain resources to accomplish this work. Assumptions necessary to make use of selected online resources are discussed, as are artefacts that can arise when these assumptions are applied to assign (national-sector) emissions estimates to point sources in various countries and regions. Notwithstanding the limitations of the available information, the value of this procedure over alternative methods commonly used to geo-spatially distribute emissions, such as use of ‘proxy’ datasets to represent emissions patterns, is illustrated. Improvements in information that would facilitate greater use of these methods in future work to assign emissions to point-sources are discussed. These include improvements to both national (geo-referenced) emission inventories and also to other resources that can be employed when such national inventories are lacking.

Multiannual changes of CO<sub>2</sub> emissions in China: indirect estimates derived from satellite measurements of tropospheric NO<sub>2</sub> columns

Abstract. Multiannual satellite measurements of tropospheric NO2 columns are used for evaluation of CO2 emission changes in China in the period from 1996 to 2008. Indirect top-down annual estimates of CO2 emissions are derived from the satellite NO2 column measurements by means of a simple inverse modeling procedure involving simulations performed with the CHIMERE mesoscale chemistry–transport model and the CO2-to-NOx emission ratios from the Emission Database for Global Atmospheric Research (EDGAR) global anthropogenic emission inventory and Regional Emission Inventory in Asia (REAS). Exponential trends in the normalized time series of annual emissions are evaluated separately for the periods from 1996 to 2001 and from 2001 to 2008. The results indicate that the both periods manifest strong positive trends in the CO2 emissions, and that the trend in the second period was significantly larger than the trend in the first period. Specifically, the trends in the first and second periods are best estimated to be in the range from 3.7 to 8.3 and from 11.0 to 13.2% per year, respectively, taking into account statistical uncertainties and differences between the CO2-to-NOx emission ratios from the EDGAR and REAS inventories. Comparison of our indirect top-down estimates of the CO2 emission changes with the corresponding bottom-up estimates provided by the EDGAR (version 4.2) and Global Carbon Project (GCP) glomal emission inventories reveals that while acceleration of the CO2 emission growth in the considered period is a common feature of both kinds of estimates, nonlinearity in the CO2 emission changes may be strongly exaggerated in the global emission inventories. Specifically, the atmospheric NO2 observations do not confirm the existence of a sharp bend in the emission inventory data time series in the period from 2000 to 2002. A significant quantitative difference is revealed between the bottom-up and indirect top-down estimates of the CO2 emission trend in the period from 1996 to 2001 (specifically, the trend was not positive according to the global emission inventories, but is strongly positive in our estimates). These results confirm the findings of earlier studies that indicated probable large uncertainties in the energy production and other activity data for China from international energy statistics used as the input information in the global emission inventories. For the period from 2001 to 2008, some quantitative differences between the different kinds of estimates are found to be in the range of possible systematic uncertainties associated with our estimation method. In general, satellite measurements of tropospheric NO2 are shown to be a useful source of information on CO2 sources collocated with sources of nitrogen oxides; the corresponding potential of these measurements should be exploited further in future studies.

Distributions and regional budgets of aerosols and their precursors simulated with the EMAC chemistry-climate model

Abstract. The new global anthropogenic emission inventory (EDGAR-CIRCE) of gas and aerosol pollutants has been incorporated in the chemistry general circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry). A relatively high horizontal resolution simulation is performed for the years 2005–2008 to evaluate the capability of the model and the emissions to reproduce observed aerosol concentrations and aerosol optical depth (AOD) values. Model output is compared with observations from different measurement networks (CASTNET, EMEP and EANET) and AODs from remote sensing instruments (MODIS and MISR). A good spatial agreement of the distribution of sulfate and ammonium aerosol is found when compared to observations, while calculated nitrate aerosol concentrations show some discrepancies. The simulated temporal development of the inorganic aerosols is in line with measurements of sulfate and nitrate aerosol, while for ammonium aerosol some deviations from observations occur over the USA, due to the wrong temporal distribution of ammonia gas emissions. The calculated AODs agree well with the satellite observations in most regions, while negative biases are found for the equatorial area and in the dust outflow regions (i.e. Central Atlantic and Northern Indian Ocean), due to an underestimation of biomass burning and aeolian dust emissions, respectively. Aerosols and precursors budgets for five different regions (North America, Europe, East Asia, Central Africa and South America) are calculated. Over East-Asia most of the emitted aerosols (precursors) are also deposited within the region, while in North America and Europe transport plays a larger role. Further, it is shown that a simulation with monthly varying anthropogenic emissions typically improves the temporal correlation by 5–10% compared to one with constant annual emissions.

Analysis of aircraft and satellite measurements from the Intercontinental Chemical Transport Experiment (INTEX-B) to quantify long-range transport of East Asian sulfur to Canada

Abstract. We interpret a suite of satellite, aircraft, and ground-based measurements over the North Pacific Ocean and western North America during April–May 2006 as part of the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign to understand the implications of long-range transport of East Asian emissions to North America. The Canadian component of INTEX-B included 33 vertical profiles from a Cessna 207 aircraft equipped with an aerosol mass spectrometer. Long-range transport of organic aerosols was insignificant, contrary to expectations. Measured sulfate plumes in the free troposphere over British Columbia exceeded 2 μg/m3. We update the global anthropogenic emission inventory in a chemical transport model (GEOS-Chem) and use it to interpret the observations. Aerosol Optical Depth (AOD) retrieved from two satellite instruments (MISR and MODIS) for 2000–2006 are analyzed with GEOS-Chem to estimate an annual growth in Chinese sulfur emissions of 6.2% and 9.6%, respectively. Analysis of aircraft sulfate measurements from the NASA DC-8 over the central Pacific, the NSF C-130 over the east Pacific and the Cessna over British Columbia indicates most Asian sulfate over the ocean is in the lower free troposphere (800–600 hPa), with a decrease in pressure toward land due to orographic effects. We calculate that 56% of the measured sulfate between 500–900 hPa over British Columbia is due to East Asian sources. We find evidence of a 72–85% increase in the relative contribution of East Asian sulfate to the total burden in spring off the northwest coast of the United States since 1985. Campaign-average simulations indicate anthropogenic East Asian sulfur emissions increase mean springtime sulfate in Western Canada at the surface by 0.31 μg/m3 (~30%) and account for 50% of the overall regional sulfate burden between 1 and 5 km. Mean measured daily surface sulfate concentrations taken in the Vancouver area increase by 0.32 μg/m3 per 10% increase in the simulated fraction of Asian sulfate, and suggest current East Asian emissions episodically degrade local air quality by more than 1.5 μg/m3.

The representation of emissions from megacities in global emission inventories

We examine the representation of emissions from megacities in three global anthropogenic emission inventories. Despite the many common sources of data between the inventories, and the similarities in their construction methodologies, there are some very large differences (often a factor of two) between the emissions for individual cities, even when the total global emissions are very similar. We find that the geographical distribution of the emissions within countries plays a larger role in explaining the differences between the inventories than differences in the country total emissions. We also find very large differences between the contribution of various sectors to the total emissions from each city, and relate these differences to the respective methodologies used in the inventory construction. By and large, in OECD countries megacity emissions from the global inventories are dominated by road transport, especially for CO and to a lesser degree for NO x . In non-OECD countries, notably in Asia, megacity CO emissions are dominated by residential biofuel use, while industrial emissions predominate for NO x . Non-methane hydrocarbon emissions in OECD megacities are caused by industry and traffic, whereas in non-OECD countries residential biofuel use makes significant contributions. These emission signatures often result from assumptions about the distribution of emissions according to gridded population density maps rather than according to the actual location of the emitting processes. We recommend the use of an ensemble of inventories, that the geographical distribution of emissions receives increased attention, and that local inventories be integrated into global emission inventories.

Mapping the spatial distribution of global anthropogenic mercury atmospheric emission inventories

This paper describes the procedures employed to spatially distribute global inventories of anthropogenic emissions of mercury to the atmosphere, prepared by Pacyna, E.G., Pacyna, J.M., Steenhuisen, F., Wilson, S. [2006. Global anthropogenic mercury emission inventory for 2000. Atmospheric Environment, this issue, doi:10.1016/j.atmosenv.2006.03.041], and briefly discusses the results of this work. A new spatially distributed global emission inventory for the (nominal) year 2000, and a revised version of the 1995 inventory are presented. Emissions estimates for total mercury and major species groups are distributed within latitude/longitude-based grids with a resolution of 1×1 and 0.5×0.5°. A key component in the spatial distribution procedure is the use of population distribution as a surrogate parameter to distribute emissions from sources that cannot be accurately geographically located. In this connection, new gridded population datasets were prepared, based on the CEISIN GPW3 datasets (CIESIN, 2004. Gridded Population of the World (GPW), Version 3. Center for International Earth Science Information Network (CIESIN), Columbia University and Centro Internacional de Agricultura Tropical (CIAT). GPW3 data are available at http://beta.sedac.ciesin.columbia.edu/gpw/index.jsp). The spatially distributed emissions inventories and population datasets prepared in the course of this work are available on the Internet at www.amap.no/Resources/HgEmissions/

Global gridded inventories of anthropogenic emissions of sulfur and nitrogen

Two sets of global inventories of anthropogenic emissions of both oxides of sulfur and oxides of nitrogen for circa 1985 have been produced under the umbrella of the Global Emissions Inventory Activity (GEIA) of the International Global Atmospheric Chemistry Program. The two sets of inventories have different temporal, sectoral, and vertical resolution. Both were compiled using the same data sets; default data sets of global emissions have been refined via the use of more detailed regional data sets. This article reports on the compilation of the annual, one‐vertical‐level inventories, called version 1A; the inventory files are available to the scientific community via anonymous file transform protocol (FTP). Existing global inventories and regional inventories have been updated and combined on a 1° × 1° longitude/latitude grid. The resulting global anthropogenic emissions are 65 Tg S yr−1 and 21 Tg N yr−1; qualitative uncertainty estimates have been assigned on a regional basis. Emissions of both SOx and NOx are strongly localized in the highly populated and industrialized areas of eastern North America and across Europe; other smaller regions of large emissions are associated with densely populated areas with developed industries or in connection with exploitation of fuels or mineral reserves. The molar ratio of nitrogen to sulfur emissions reflects the overall character of sources; its value is generally between 0.33 and 10 for industrialized and heavily populated areas but varies over a wide range for other areas. We suggest that those requiring sulfur or nitrogen emission inventories standardize on the GEIA inventories, which we believe are authoritative and which are freely available to all users by anonymous FTP.