Contribution of Fire Emissions to the Global Methane Budget

Abstract:

Fire emissions of methane potentially represent a significant but highly uncertain component of the global methane budget with estimates ranging from 14 to 88 Tg / yr. This range of estimates is driven in part by knowledge of dry matter burned, the fuel type, and variations in combustion efficiency. Here we use global estimates of CO emissions based on CO profiles from the NASA Terra MOPITT instrument and CH₄/CO emission ratios from NASA Aura TES data to constrain estimates of the global contribution to atmospheric methane from fires. For the years 2001 to the present we find that fire emissions of methane are approximately 3% (or ~ 15 Tg / yr) of the global methane budget. Furthermore, fire emissions have likely been decreasing during this time period indicating that non-fire methane fluxes have primarily contributed to the recent increase in global atmospheric methane concentrations.