Unprecedented Canadian forest fire carbon emissions during 2023

Abstract The 2023 Canadian forest fires have been unprecedented in scale and intensity. Here, we quantify the carbon emissions from these fires to be 639 TgC (range: 572–705 TgC) over a five-month period (May-Sep) based upon inverse modeling of satellite carbon monoxide observations. This magnitude is comparable to the annual fossil fuel emissions of large nations, with only India, China and the U.S.A. releasing more carbon. Widespread fire weather was a major driver of fire spread, as 2023 was the warmest and driest year since at least 1980. Although extreme relative to the historical record, climate projections indicate that these temperatures will be typical during the 2050s, even under a moderate climate mitigation scenario (SSP2-4.5). Such conditions are very likely to drive increased fire activity and suppress carbon uptake by Canadian forests, calling into question the long-term durability of these forests as a carbon sink.