For several years, many US cities have been tracking their greenhouse gas emissions in one way or another. That "one way or another" is the devil in the details. There are various ways to measure and report GHG emissions, so it's often difficult to make apples-to-apples comparisons between cities — or occasionally for a given city's data from one year to the next. Also, several cities only publish inventory summaries (not the actual data).
On Aug. 11, 2008, 21 US cities joined the UK-based Carbon Disclosure Project, and nine more are reportedly in the process of joining. Under this arrangement, the cities will all use the same measurement protocol and software tools to assess the greenhouse gas emissions profile for municipal operations. This inventory data will then be disclosed through the CDP's online reporting. Such uniformity of inventory systems and disclosure can help journalists put local emission-reduction efforts in context.
The 21 participating cities announced so far are: Anchorage (AK), North Little Rock (AR), Pacific Grove and Rohnert Park (CA), Denver (CO), West Palm Beach (FL), Dubuque and Fairfield (IA), New Orleans (LA), St. Paul and Edina (MN), Las Vegas (NV), Albuquerque (NM), New York City and Albany (NY), Park City (UT), Arlington (VA), Burlington (VT), Haverford (PA), Portland (OR), and Washougal (WA). The additional cities are expected to be announced soon by ICLEI (founded as the "International Council for Local Environmental Initiatives," now rebranding itself as "Local Governments for Sustainability"), whose Local Government Operations protocol and software the participating cities will use.
While the ICLEI protocol only tracks emissions related to municipal facilities, fleets, and services that the cities provide, or activities under their budgetary control, the cities also will use CDP's methodology to assess and disclose climate change-related risks and opportunities relating to the whole city.
Cities will submit their responses to CDP by October 31, 2008. Responses will be published in CDP's first-ever Cities Report, and in ICLEI's Local Action Network Report, both due out January 2009.
This effort represents a new direction for CDP, which has gathered published corporate emissions data since 2000. It claims to have the world's largest corporate greenhouse gas emissions database. In Fall 2008, CDP will publish its 6th annual report, with new data from more than 3,000 companies around the world.
- US Conference of Mayors Climate Protection Center,  202-861-6700.
- EPA: US Greenhouse Gas Inventory.  Released April 2008, with data through 2006. Also EPA info  on state & local government efforts to combat climate change. Press: Roxanne Smith,  202-564-4455.
- Institute for Local Government's California Climate Action Network:  email. 
- The California Air Resources Board is partnering with ICLEI on the Local Government Operations Protocol. CARB: Dana Papke, 916-324-9615.