Attribution of the role of climate change in the forest fires in Sweden 2018

• Published in: Natural Hazards and Earth System Sciences
• Other Authors: Krikken, Folmer (author), Lehner, Flavio (author), Haustein, Karsten (author), Drobyshev, Igor (author), van Oldenborgh, Geert Jan (author)
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Northern Sweden
• Online Access: https://doi.org/10.5194/nhess-21-2169-2021

In this study, we analyse the role of climate change in the forest fires that raged through large parts of Sweden in the summer of 2018 from a meteorological perspective. This is done by studying the Canadian Fire Weather Index (FWI) based on sub-daily data, both in reanalysis data sets (ERA-Interim, ERA5, the Japanese 55 year Reanalysis, JRA-55, and Modern-Era Retrospective analysis for Research and Applications version 2, MERRA-2) and three large-ensemble climate models (EC-Earth, weather@home, W@H, and Community Earth System Model, CESM) simulations. The FWI, based on reanalysis, correlates well with the observed burnt area in summer (r = 0.6 to 0.8). We find that the maximum FWI in July 2018 had return times of similar to 24 years (90% CI, confidence interval, > 10 years) for southern and northern Sweden. Furthermore, we find a negative trend of the FWI for southern Sweden over the 1979 to 2017 time period in the reanalyses, yielding a non-significant reduced probability of such an event. However, the short observational record, large uncertainty between the reanalysis products and large natural variability of the FWI give a large confidence interval around this number that easily includes no change, so we cannot draw robust conclusions from reanalysis data. R16AC00039 ATM0856145