Fire and climate in the eastern Siberia over the past 500 years (1500-2010 CE)

Abstract:

The year, arctic and subarctic Siberia has experienced a dramatic heat wave and large-scale fire events. Long-term warming under anthropogenic climate change may be amplifying fire frequency and behavior in the region, feeding a positive feedback on climate change through the release of greenhouse gasses from terrestrial and permafrost sources. Whether and to what degree these trends differ from historical processes remains unknown. We used dendrochronologically crossdated fire scars in wood materials from the Sakha Republic of Russia (Yakutia) in subarctic Siberia (62°-63°N) to develop a 500-year (1500-2010 CE) regional fire history. We found that recurrent low- to moderate-severity fires were historically common with mean fire return intervals 25-40 years. Fire activity decreased during 1945-1991 due to Soviet suppression of traditional farming activities and fire-fighting, but has resumed since 1991. Fires were the most widespread across our sites during the last few decades, with 2002 being anomalous in more than 300 years. Comparing the fire-scar recorded fire history with observed climate data (1880s-2011 CE) and tree-ring based temperature records at annual and decadal time-scales, we revealed that fires in Yakutia were driven by summer (June-July) temperature. We found that a double peak in the temperature-fire relationship reveals that two-year heat waves led to more available fuels and thus more fire activity during the 20^th century. Regional fire activity is also related to the Jet stream through amplifying Rossby-wave activity and blocking high-pressure over the region, which results in high temperature and fire risk, such as in 2002 and 2020. Based on the projection of Arctic amplified warming, we expect greater fire activity driven by the Jet Stream leading to further historically uncharacteristic fire activity in the near to long term.