Reviews and syntheses: Arctic fire regimes and emissions in the 21st century
Authors: McCarty Jessica L. , Aalto Juha , Paunu Ville-Veikko , Arnold Steve R. , Eckhardt Sabine , Klimont Zbigniew , Fain Justin J. , Evangeliou Nikolaos , Venäläinen Ari , Tchebakova Nadezhda M. , Parfenova Elena I. , Kupiainen Kaarle , Soja Amber J. , Huang Lin , Wilson Simon 
Published: September 2021

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 synthesizes 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 have 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 and forest transitions from forest–steppe to steppe, tundra to taiga, and
coniferous to deciduous in a warmer climate may increase
and decrease open biomass burning, depending on land use in addition to
climate-driven biome shifts. 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 and 65∘ N are larger than emissions from the anthropogenic sectors of residential
combustion, transportation, and flaring. 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 how severe future Arctic wildfire seasons can potentially be. (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.