Direct carbon emissions from Canadian forest fires, 1959-1999

Direct emissions of carbon from Canadian forest fires were estimated for all Canada and for each ecozone for the period 1959-1999. The estimates were based on a data base of large fires for the country and calculations of fuel consumption for each fire using the Canadian Forest Fire Behaviour Prediction System. This technique used the fire locations and start dates to estimate prevailing fire weather and fuel type for each of about 11 000 fires. An average of 2 × 106 ha·year-1 was burned in this period, varying from 0.3 × 106 ha in 1978 to 7.5 × 106 ha in 1989. Ecozones of the boreal and taiga areas experienced the greatest area burned, releasing most of the carbon (C). The mean area-weighted fuel consumption for all fires was 2.6 kg dry fuel·m-2 (1.3 kg C·m-2), but ecozones vary from 1.8 to 3.9 kg dry fuel·m-2. The mean annual estimate of direct carbon emissions was 27 ± 6 Tg C·year-1. Individual years ranged from 3 to 115 Tg C· year-1. These direct fire emissions represent about 18% of the current carbon dioxide emissions from the Canadian energy sector, on average, but vary from 2 to 75% among years. Post-fire effects cause an additional loss of carbon and changes to the forest sink condition.