OBJECTIVE: In this proof-of-concept study, we evaluated the availability of emergency medical services (EMS) system energy consumption data required to calculate a carbon footprint. METHODS: Two diverse North American EMS systems with more than 125,000 combined annual unit responses agreed to report their energy consumption for the last fiscal or calendar year using a data-collection tool based on Carbon Trust recommendations. They also identified the source of information (e.g., bills, logs, receipts), whether the amounts reported were directly measured or estimated, and whether any of the amounts were prorated from shared facilities (e.g., electricity for a shared office building). For this proof-of-concept study, we report only descriptive data about the availability of data and aggregate carbon emissions. RESULTS: Both systems reported diesel fuel, gasoline, and electricity consumption. One system used natural gas; one system used aviation fuel. Direct measurement of consumption using utility bills and statements was possible for these energy types. One system prorated natural gas and electricity usage; one system was able to estimate commercial air travel. Annual carbon dioxide (CO(2)) emissions for these two systems totaled 11.1 million pounds of CO(2). The largest source of CO(2) emissions was diesel fuel (39%), followed by electricity (23%). CONCLUSION: These EMS systems were able to provide the data necessary to determine their carbon footprints. Future research could include broader study to establish EMS-specific norms for carbon emissions, benchmarking of these metrics between different EMS systems, and the assessment of programs designed to reduce EMS carbon emissions.