The purpose of the San Francisco Communitywide Greenhouse Gas Inventory is to measure and track greenhouse gas emissions to determine progress towards meeting the City's climate action goals. The Department of the Environment collects this data from various sources and calculates the emissions per current greenhouse gas protocols. This data supports San Francisco's climate change planning and mitigation strategies.

Note: Greenhouse gas emissions were calculated based on the ICLEI 2012 U.S. Community Protocol Version 1.0. San Francisco inventories are completed in accordance with the ICLEI U.S. Community Protocol (USCP) for Accounting and Reporting of Greenhouse Gas Emissions. The methodology and sectors tracked were third party verified in inventory year 2012. The subsequent inventories are completed according to the guidance of the verifiers. The third-party verification memo for 2010 is available at http://sfenvironment.org/download/2010-community-greenhouse-gas-inventory-3rd-party-verification-memo-march-2013 and for 2012 at http://sfenvironment.org/download/2012-community-greenhouse-gas-inventory-3rd-party-verification-memo-january-2015. In 2015, the City began reporting its emissions to C40 to improve its GHG emissions inventory by using a newer protocol to estimate emissions referred to as the Global Protocol for Community-Scale Greenhouse Gas Emissions Inventories (GPC). GPC is a framework unifying emissions inventories globally while incorporating new categories to track. San Francisco has been tracking its emissions since 1990; hence, it continues to use the ICLEI USCP. Today, San Francisco continues to disclose emissions under the GPC framework for reporting purposes to and compliance with the Global Covenant of Mayors (GCOM).