Wildland fire emissions, carbon, and climate: Emission factors

• Review current knowledge on the chemical composition of emissions from wildland fires in the United States.
• Recommend best estimate emission factors for United States wildland fires.
• Identify key gaps in the current knowledge of emission factors for US wildland fires.

While the vast majority of carbon emitted by wildland fires is released as CO2, CO, and CH4, wildland fire smoke is nonetheless a rich and complex mixture of gases and aerosols. Primary emissions include significant amounts of CH4 and aerosol (organic aerosol and black carbon), which are short-lived climate forcers. In addition to CO2 and short-lived climate forcers, wildland fires release CO, non-methane organic compounds (NMOC), nitrogen oxides (NOx = NO + NO2), NH3, and SO2. These species play a role in radiative forcing through their photochemical processing, which impacts atmospheric levels of CO2, CH4, tropospheric O3, and aerosol. This paper reviews the current state of knowledge regarding the chemical composition of emissions and emission factors for fires in United States vegetation types as pertinent to radiative forcing and climate. Emission factors are critical input for the models used to estimate wildland fire greenhouse gas and aerosol emission inventories.