Editing IPCC:AR6/WGII/Chapter-2 (section)

===== 2.4.4.2.4 Observed changes in fire seasons globally =====

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The IPCC AR6 WGI assessed fire weather ( [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ), while this chapter assesses the impacts of changes in fire weather: burned area and fire frequency. The global increases in temperature from anthropogenic climate change have increased aridity and drought, lengthening the fire weather season (the annual period with a heat and aridity index greater than half of its annual range) on one-quarter of global vegetated area and increasing the average fire season length by one-fifth from 1979 to 2013 ( [[#Jolly--2015|Jolly et al., 2015]] ). Climate change has contributed to increases in the fire weather season or the probability of fire weather conditions in the Amazon ( [[#Jolly--2015|Jolly et al., 2015]] ), Australia ( [[#Dowdy--2018|Dowdy, 2018]] ; [[#Abram--2021|Abram et al., 2021]] ; [[#van%20Oldenborgh--2021|van Oldenborgh et al., 2021]] ), Canada ( [[#Hanes--2019|Hanes et al., 2019]] ), central Asia ( [[#Jolly--2015|Jolly et al., 2015]] ), East Africa ( [[#Jolly--2015|Jolly et al., 2015]] ) and North America ( [[#Jain--2017|Jain et al., 2017]] ; [[#Williams--2019|Williams et al., 2019]] ; [[#Goss--2020|Goss et al., 2020]] ). In forest areas, the burned area correlates with fuel aridity, a function of temperature; in non-forest areas, the burned area correlates with high precipitation in the previous year, which can produce high grass fuel loads ( [[#Abatzoglou--2018|Abatzoglou et al., 2018]] ). Fire use in agriculture and raising livestock or other factors have generated a second fire season on approximately one-quarter of global land where fire is present, despite sub-optimal fire weather in the second fire season ( [[#Benali--2017|Benali et al., 2017]] ). In summary, anthropogenic climate change, through a 0.9°C surface temperature increase since the pre-industrial period, has lengthened or increased the frequency of periods with heat and aridity that favour wildfire on up to one-quarter of vegetated area since 1979 ( ''robust evidence, high agreement'' ).

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