• oxygenated volatile organic compounds;
  • atmospheric methanol and acetaldehyde;
  • biomass burning

[1] We present carbon isotopic signatures of methanol and acetaldehyde emitted from biomass burning sources using laboratory experiments. The respective δ13C of methanol and acetaldehyde emitted from burning experiments of five plant materials (three C3 and two C4 plants) were −20–−46‰ and −11–−25‰. The variation in δ13C of methanol depends on the δ13C of the fuel biomass and burning conditions, but the variation in δ13C of acetaldehyde depends on the δ13C of fuel biomass and is independent of burning conditions. Combining these observations with previously reported global distributions of fire types, burning conditions, amounts of biomass burned, vegetation types, and emission factors, we estimated the global isotopic signature for biomass burning source as −33 ± 16‰ for methanol.