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A Status Report: Global, Gridded Inventories of Emissions to the Atmosphere

T.E. Graedel

Computer assessments of the atmospheric chemistry and air quality of the past, present, and future rely in part on inventories of emissions constructed on appropriate spatial and temporal scales and with appropriate chemical species. Accurate inventories are also of substantial utility to field measurement scientists and the regulatory and policy communities.

The production of global emissions inventories is the task of the Global Emissions Inventory Activity (GEIA) of the International Global Atmospheric Chemistry Project (IGAC). This paper presents a status report on the GEIA activity as of June, 1995, featuring the completion and release of a suite of emissions inventories for most of the significant greenhouse-warming, ozone-depleting, and acid-producing species.

Future plans include the completion of inventories not yet represented in the releases, together with a focus on historic inventories and scenario projected inventories for the use of the scientific and policy communities.

The GEIA Effort

Emissions inventories are the basis for studies of the interrelationships of atmosphere and surfaces, and of the interactions of societal development and environmental impact. In certain regions of the world, particularly the more heavily industrialized countries of Western Europe and North America, detailed emissions inventories have been available for a decade or more, though they undergo constant revision and improvement. For other regions, emissions inventories are often unreliable or nonexistent.

In all cases, differences in approach make it difficult to compare local or regional inventories with one another and to merge such inventories to create a larger whole. Yet, it is these merged inventories that are needed by modelers working on continental or global scales, or in regions for which locally-generated emissions inventories are not available. Further, continental or global modelers have often been required to prepare their own inventories and have done so in very different ways, since they are not emissions specialists; as a consequence, comparing model results is confounded by the use of widely-varying emissions scenarios.

Are suitable, reliable emissions inventories generally available, even if many are unaware of them? A survey of then-existing emissions inventories performed in 1992 (Graedel et al., 1993) indicated that only the extant CFC inventory was regarded as good; however, that inventory was not available in gridded form. Inventories for CO2 , CH4 , NOx, SOx , reduced sulfur, and radon were regarded as fair, other inventories as poor or nonexistent. The temporal resolution was considered almost uniformly poor. That survey made it clear that the generation of internally consistent, rigorously developed, gridded inventories with good spatial and temporal resolution would be of considerable value.

These needs were the inspiration for the formation of the Global Emissions Inventory Activity (GEIA) under the auspices of the International Global Atmospheric Chemistry Project. The GEIA activities encompass the following:

The ultimate target of the GEIA effort is to establish emissions inventories for all trace species of interest, incorporating fluxes from both anthropogenic and natural sources. All inventories are generated by international, intercontinental teams of specialists. It is hoped that the resulting authoritative inventories, periodically updated as appropriate, will be adopted as standards by the atmospheric modeling community, thus removing an area of uncertainty from inter-model comparisons and providing a recognized foundation from which emissions inventories can be modified and updated periodically. Every interested party is welcome to be included in the GEIA effort.

Project Status

GEIA inventory activities have been under way since the latter part of 1991. As of late 1994, global, GEIA project teams began to release by for general use gridded emissions inventories ("Version 1" inventories) by the scientific and policy communities. Table 1 presents details about these inventories, which comprise most of the greenhouse-warming, ozone-depleting, and acid-producing species. Additional information appears in the references given below. Completion and release of a number of other inventories is anticipated within the next several years. The pace will be strongly dictated by the amount of funding available to support travel, data entry, and associated activities.

GEIA inventories are available electronically through anonymous file transfer protocol (FTP). The resident source, at least initially, is the Data Center at the National Center for Atmospheric Research, whose email address for GEIA data and documents is ncardata.ucar.edu (128.117.8.111). The FTP file contains documentation on line (a README file) for using the data system. Users without FTP access may order data on tape or diskettes for a small handling fee from the GEIA Data Management Center [1-303-442-6866 or communicate by electronic mail (the preferred technique): paulette@rmii.com or hopkins@rmii.com].

Discussion

Reliable, gridded emissions inventories are now available, or soon will be, for all of the principal atmospheric species. Those inventories will, of course, be improved as more detailed local information becomes available, especially for emissions from the less developed countries. Nonetheless, there is no scientific reason to avoid standardizing on the inventories now available for use in model studies.

Historical estimates of emissions are much less reliable than those for the present epoch, but historical inventories based on unified global statistics and methodologies are beginning to appear. They will be particularly useful in model studies linked to historical data from sediments, ice cores, and other data repositories.

Much effort remains to be done in this regard; in particular, a gridded, global historical inventory of NOx emissions would be a valuable project, and could be accomplished. Scenarios for future emissions are also beginning to be attempted, and will evolve rapidly during the next few years. Thus far only applied to greenhouse gas problems, one can envision the scenarios as tools for the study of future air quality, acid deposition, biodiversity, resource cycling, and the like.

The overall GEIA effort is guided by the GEIA Steering Committee, which consists of A.F. Bouwman, D.M. Cunnold, T.E. Graedel, P.B. Middleton, and J.M. Pacyna. It is the opinion of the committee that few of the inventories now being released would have been compiled without the focus and organizing efforts of the IGAC program and the GEIA overview, management, and data distribution activities, and that those that would have been produced would not have had standardized formats and distribution mechanisms. We view the continuing GEIA effort as an exemplary example of the quality research that can result from an international collaborative effort in which resources of people, time, and funds are made available largely by participants' host institutions or countries.

Emissions inventories are the base on which many scientific studies rest. Their quality and their availability have improved markedly during the past few years, especially so far as global, gridded inventories are concerned. Nonetheless, emissions inventories are, strictly speaking, never correct and never completed. In a world in which population, economic activity, and technology are constantly evolving, the construction and maintenance of reliable emissions inventories remains an effort in need of continuous financial support and the dedicated participation of outstanding scientists and engineers.

Acknowledgements

This report is based on the work of the GEIA inventory project teams. We are grateful for the contributions of all the participants in these projects; there are too many such to name here.

The activities of GEIA have been greatly assisted by in-kind released time contributions by the institutions of the GEIA participants, and by the financial support of the following institutions and organizations to help facilitate data management activities, workshops, and travel: Chemical Manufacturers Association (USA), Dutch Ministry of Housing, Physical Planning, and Environment (NL), National Aeronautics and Space Administration (USA), National Center for Atmospheric Research (USA), National Institute for Environmental Studies (JPN), National Institute of Public Health and Environmental Protection (NL), National Oceanic and Atmospheric Administration (USA), National Science Foundation (USA), Norwegian Institute of Air Research (NOR), TNO Institute of Environmental and Energy Technology (NL), and World Meteorological Organization (SUI).

Significant Publications

The GEIA Review of Existing Inventories: Graedel, T.E., Bates, T.S., Bouwman, A.F., Cunnold, D., Dignon, J., Fung, I., Jacob, D.J., Lamb, B.K., Logan, J.A., Marland, G., Middleton, P., Pacyna, J.M., Placet, M., and Veldt, C.: 1993, Global Biogeochem. Cycles, 7, 1-26.

The GEIA Announcement of Inventory Availability: Graedel, T.E.: 1994, Global emissions inventories to aid atmospheric modelers, EOS (Trans. AGU), 75, 585, 591.

The GEIA Natural VOC Inventory: Guenther, A., Hewitt, C.N., Erickson, D., et al.: 1995, A global model of natural volatile organic carbon emissions, J. Geophys. Res., 100, 8873-8892.

The GEIA Anthropogenic Aircraft Emissions Inventories: Baughcum, S.L., Metwally, M., Seals, R.K., and Wuebbles, D.J.: 1993, in \f2The Atmospheric Effects of Stratospheric Aircraft: A Third Program Report\f1, edited by R.S. Stolarski and H.L. Wesoky, pp. 185-208, NASA Ref. Pub. 1313, Nat. Aeronautics and Space Admin., Washington, D.C.

The GEIA Anthropogenic CO2 Inventories: Andres, R.J., Marland, G., Fung, I., and Matthews, E.: 1995, Global Biogeochem. Cycles, submitted.

The GEIA Anthropogenic SOx and NOx Inventories: Benkovitz, C.M., Scholtz, M.T., Pacyna, J., Tarrason, L., Dignon, J., Voldner, E.C., Spiro, P.A., Logan, J.A., and Graedel, T.E.: 1995, J. Geophys. Res., submitted.

The GEIA Anthropogenic CFC Inventories: Cunnold, D., et al., Gridded emissions inventories for CFC-11, CFC-12, and CFC-113, manuscript in preparation, 1995.

The GEIA Total Source N2O Inventory: Bouwman, A.F., Van der Hoek, and Olivier, J.G.J.: 1995, Uncertainties in the global source distribution of nitrous oxide, J. Geophys. Res., 100, 2785-2800.

The GEIA Natural NOx Inventory: Yienger, J.J., and Levy, H. II: 1995, Empirical model of global soil-biogenic NOx emissions, J. Geophys. Res., 100, in press.

The GEIA Anthropogenic Black Carbon Inventory: Dignon, J., Eddleman, H.E., and Penner, J.E.: 1994, A Black Carbon Emission Data Base for Atmospheric Chemistry and Climate Studies, Rpt. UCRL-ID-119104, Lawrence Livermore Nat. Lab., Livermore, CA.

The GEIA Asian NH3 Inventory: Dianwu, Z., and Anpu, W.: 1994, Estimation of anthropogenic ammonia emissions in Asia, Atmospheric Environment, 28, 689-694.

(last modified 05/25/03)