Reviews & Syntheses: Arctic Fire Regimes and Emissions in the 21st Century

Abstract

Abstract. In recent years, the Pan-Arctic region has experienced increasingly extreme fire seasons. Fires in the northern high latitudes are driven by current and future climate change, lightning, fuel conditions, and human activity. In this context, conceptualizing and parameterizing current and future Arctic fire regimes will be important for fire and land management as well as understanding current and predicting future fire emissions. The objectives of this review were driven by policy questions identified by the Arctic Monitoring and Assessment Programme (AMAP) Working Group and posed to its Expert Group on Short-Lived Climate Forcers. This review synthesises current understanding of the changing Arctic and boreal fire regimes, particularly as fire activity and its response to future climate change in the Pan-Arctic has consequences for Arctic Council states aiming to mitigate and adapt to climate change in the north. The conclusions from our synthesis are the following: (1) Current and future Arctic fires, and the adjacent boreal region, are driven by natural (i.e., lightning) and human-caused ignition sources, including fires caused by timber and energy extraction, prescribed burning for landscape management, and tourism activities. Little is published in the scientific literature about cultural burning by Indigenous populations across the Pan-Arctic and questions remain on the source of ignitions above 70° N in Arctic Russia. (2) Climate change is expected to make Arctic fires more likely by increasing the likelihood of extreme fire weather, increased lightning activity, and drier vegetative and ground fuel conditions. (3) To some extent, shifting agricultural land use, forest-steppe to steppe, tundra-to-taiga, and coniferous-to-deciduous forest transitions in a warmer climate may increase and decrease open biomass burning. However, at the country- and landscape-scales, these relationships are not well established. (4) Current black carbon and PM2.5 emissions from wildfires above 50° N and 65° N are larger than emissions from the anthropogenic sectors of residential combustion, transportation, and flaring, respectively. Wildfire emissions have increased from 2010 to 2020, particularly above 60° N, with 56 % of black carbon emissions above 65° N in 2020 attributed to open biomass burning – indicating how extreme the 2020 wildfire season was and future Arctic wildfire seasons potential. (5) What works in the boreal zones to prevent and fight wildfires may not work in the Arctic. Fire management will need to adapt to a changing climate, economic development, the Indigenous and local communities, and fragile northern ecosystems, including permafrost and peatlands. (6) Factors contributing to the uncertainty of predicting and quantifying future Arctic fire regimes include underestimation of Arctic fires by satellite systems, lack of agreement between Earth observations and official statistics, and still needed refinements of location, conditions, and previous fire return intervals on peat and permafrost landscapes. This review highlights that much research is needed in order to understand the local and regional impacts of the changing Arctic fire regime on emissions and the global climate, ecosystems and Pan-Arctic communities.

Assessing changes in global fire regimes

“…An increase in extreme fire behavior is also predicted in many regions such as the Amazon, western USA, Mediterranean and southern Australia (Bowman et al, 2020). Substantial intensification of fire behavior is projected for higher latitudes through the end of the 21 st century (Abbott et al, 2021;Flannigan et al, 2013;Talucci et al, 2022), though local fire patterns are expected to be heterogeneous (McCarty et al, 2021).…”

“…The copyright holder for this preprint this version posted February 8, 2023. ; https://doi.org/10.1101/2023.02.07.527551 doi: bioRxiv preprint the end of the 21 st century (Abbott et al, 2021;Flannigan et al, 2013;Talucci et al, 2022), though local fire patterns are expected to be heterogeneous (McCarty et al, 2021).…”

“…Not only can fires directly change the albedo of the region by altering land characteristics, but they also affect albedo by the pollutants they produce. For example, enhanced black carbon and soot deposition associated with increased fire disturbance will contribute to accelerated ice melting and decreased albedo (Aubry-Wake et al, 2022;McCarty et al, 2021). Conversely, increased tropical peatland fire can increase albedo (Ohkubo et al, 2021).…”

“…For example, panarctic wildfire emissions have been predicted to increase by 250% by 2100 under RCP8.5 (Abbott et al, 2016). Similarly, fire emissions in Finnish Boreal forests have been predicted to experience a 190% increase, even under RCP4.5 (McCarty et al, 2021). In Europe, burned area is predicted to increase between 180% to 360% until the end of the century under RCP8.5, but less than 60% under RCP2.6 (Wu et al, 2015).…”

Pan-Arctic seasonal cycles and long-term trends of aerosol properties from ten observatories

“…Given the recent increase in fire activity in the Arctic, one might have expected an emerging trend. Reasons for the absence of a trend may be that biomass burning emissions are carried further aloft in the troposphere and are not well captured at the surface, and that station records do not cover the last years, where the strongest emissions in consecutive years occurred (McCarty et al, 2021).…”