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Revisiting Community-Scale Greenhouse Gas Inventories Peter Erickson* and Michael Lazarus Stockholm Environment Institute (U.S. Center), 11 Curtis Avenue, Somerville, Massachusetts 02144-1224, United States How a community counts these emissions can have significant implications for the usability and relevance of its GHG inventory. Historically, as well as in recent draft community-scale protocols, communities have counted all emissions associated with producing goods and materials in the community. For example, a cement plant’s emissions are included even if the cement is used largely outside the community. Communities typically report total emissions estimates that combine these goods-producing emissions with emissions from other sources, such as vehicles and homes. A key goal of inventories is to help communities set targets and measure progress. From this perspective, lumping emissions associated with producing goods together with other sources (such as vehicles and homes) brings three potentially significant problems: • Introduces noise to the signal of climate policy. Many industrial facilities largely serve demand, and respond to economic signals, from outside the community. As a result, their absolute emissions can fluctuate dramatically from year to year, with little relationship to their emission intensity or to demand within the community, factors that communities may seek to influence. Such INTRODUCTION fluctuations can be significant, and can swamp the yearIncreasing urbanization, together with a lack of ambitious to-year impact of local climate-related policies, thereby climate action at national levels, has positioned local governconfounding efforts to track community progress over ments (towns, cities, and counties) to take a leadership role on time. climate change mitigation. However, no broadly accepted • Obfuscates differences among communities. In addistandard yet exists to measure a community’s contribution to tion, comparing GHG inventories across communities global greenhouse gas (GHG) emissions, and thus to track with substantially different industrial facilities obfuscates progress toward meeting ambitious climate goals. the important differences in other sources that are The last year has seen a surge of interest in methods for arguably more under the control of communities: namely measuring and tracking community-wide GHG emissions. local vehicle travel and building energy use. Internationally, the C40 Cities Climate Leadership Group • Allows communities to appear to reduce emissions by and ICLEI−Local Governments for Sustainability released a virtue of decreases in local production. A community new draft community-scale protocol.1 In the United States, that includes significant producers in its GHG inventory ICLEI-USA also released a draft “framework” and will soon be could appear to reduce emissions if production decreases 2 releasing a full draft protocol. Numerous academic journals, or is relocated outside of the community boundary, including this one, have also recently published articles on the giving the false illusion that global GHG emissions have topic of community-scale GHG inventory methods.3 decreased, even as production (and associated GHG
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emissions) would increase elsewhere as a result. This is called emissions leakage and is discussed extensively in the literature. Existing community GHG protocol efforts have yet to seriously address these issues. Both the recent C40/ICLEI1 and ICLEI-USA2 efforts include industrial producers in their mandatory standards on reporting total emissionsstandards that are intended to facilitate comparisons over time and among communities. Both these efforts provide the option of also reporting emissions associated with goods and materials
PRODUCTION AND CONSUMPTION: A VEXING QUESTION One of the most vexing questions in assessing a community’s contribution to global GHG emissions is how to account for the emissions associated with goods and materials consumed and/or produced in the community. Most communities import and consume a large number of goods and materials (such as food, clothing, and construction materials) that are produced elsewhere. Some communities produce significant quantities of goods and materials, including energy-intensive goods or materials such as cement or steel, that are largely consumed or used elsewhere. © 2012 American Chemical Society
Published: April 17, 2012 4693
dx.doi.org/10.1021/es301366b | Environ. Sci. Technol. 2012, 46, 4693−4694
Environmental Science & Technology
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Figure 1. Framework for assessing GHG emissions sources and activities (as applied to King County, Washington).
imported into, or consumed, within the community. Looking at goods and materials from a consumption-based perspective is largely free of the problems above,4 and furthermore, it provides a more holistic picture of a community’s emissions. However, doing so does not correct the three concerns listed above.
buildings and transportation systems, the implications of including industry (and associated goods and materials) are less clear. We suggest that pulling industry out of communityscale inventoriesand looking at it separately from both a production and consumption perspectivecould help avoid significant problems and bring substantial benefits, including helping to bring a greater focus on the GHG emission sources over which local governments have unique and direct influence.
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SEPARATE TREATMENT FOR PRODUCTION AND CONSUMPTION OF GOODS AND MATERIALS To address the issues above, communities can assess a wide range of possible emissions sources and activities, sorting them into distinct approaches or “scopes” based on how much influence the communities have and how measurable the emissions are. As an example of such an approach, Figure 1 presents an assessment for King County (WA) that defines three distinct “scopes”.5 A “core” scope focuses on sources where the County and its local government partners have the most direct influence and also the greatest ability to measure progress. A supplemental “production” scope focuses on goods and materials produced in-region (largely industry), where emissions could be normalized to output (e.g., tons of cement or steel) to help track local actions to reduce emissions intensity of industrial production (independent of output and the broader fluctuations in regional demand discussed above). A supplemental “consumption” scope would track emissions associated with goods and materials consumed within the community, and help illuminate opportunities for low-GHG consumption among community residents. This approach provides a rational basis for how to track and report emissions, but the boundaries between scopes are still not perfect: for example, emissions from commercial building use might also be subject to external forces, such as demand for services (e.g., software made in the buildings), as well as be subject to leakage. However, since commercial services are much less emissions intensive than industry, these issues are less of a concern.
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AUTHOR INFORMATION
Corresponding Author
*Phone: +1 (206) 547-4000; fax: +1 (206) 312-4720; e-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) C40; ICLEI. Global Protocol for Community-Scale GHG Emissions: Version 0.9; C40 Cities Climate Leadership Group and ICLEI Local Governments for Sustainability, in collaboration with World Bank, UNEP, UN-HABITAT, World Resources Institute, 2012. (2) ICLEI-USA. Community-Scale GHG Emissions Accounting and Reporting Protocol: DRAFT Protocol Framework for Public Comment; ICLEI - Local Governments for Sustainability, 2011. (3) Chavez, A.; Ramaswami, A. Progress toward low carbon cities: Approaches for transboundary GHG emissions’ footprinting. Carbon Manage. 2011, 2, 471−482. (4) Erickson, P.; Allaway, D.; Lazarus, M.; Stanton, E. A. A Consumption-Based GHG Inventory for the U.S. State of Oregon. Environ. Sci. Technol. 2012, 46, 3679−3686. (5) SEI. Greenhouse Gas Emissions in King County; Stockholm Environment Institute-U.S. Center for the King County Department of Natural Resources and Parks, with support from Cascadia Consulting, Ecofor LLC, and Michael Gillenwater: Seattle, WA, 2012.
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CONCLUSION Nearly all efforts to assess community-scale GHG emissions focus on emissions associated with in-boundary energy use. Although such efforts help bolster local government actions on 4694
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