Military Actions and Climate Change as Drivers of Wildfires in Northern Regions of Ukraine in 2022-2023

Abstract Wildfires are most often caused by human activity, while weather conditions and climate change contribute to the spread of forest fires. This occurs due to the increased frequency of anomalously high temperatures and a significant reduction in precipitation during the warm season. In the spring of 2022 and 2023, a slight increase in the climate norm for near-surface temperatures were recorded. At the same time, a deficit of atmospheric precipitation was observed in March and May, with only 70% of the typical rainfall. In contrast, April saw 30-50% more precipitation than usual. The weather conditions in the spring of 2022 and 2023 were less dry compared to 2020. However, in 2022 and 2023, wildfires in most of in Northern Regions of Ukraine were caused by warfare, including active combat, missile strikes, landmines, and drone crashes. This study analyzed the spatial distribution of fire occurrences in 2022 and 2023, based on satellite data (FIMS), in Northern Regions of Ukraine. 2,360 fire outbreaks per year were recorded in 2022 and 495 in 2023 within this territory. The highest fire recurrence in 2022 was observed in Kyiv and Chernihiv Polissia, while in 2023 it impacted the northern Novhorod-Siversky Polissia. The fires caused gas-aerosol pollution of the atmosphere over these regions. Daily variations in the aerosol absorption index (AAI) in the vertical air column over the Kyiv region and the Chornobyl Exclusion Zone in the spring of 2022 and 2023, based on data from the Sentinel-5P satellite were used in this research. Background AAI values in March-April in the region average about –1.21±0.37. However, the highest AAI values, about +1.87, were recorded on April 14, 2022, in the atmosphere over the Kyiv region. In the Chornobyl Exclusion Zone, the highest AAI values were recorded: +0.83 on April 14, 2022, and +0.85 on March 22, 2022, which indicates the presence of combustion products in the atmosphere. Military actions increased the risk of fires and complicated fire suppression efforts, making the region more vulnerable to large-scale forest fires.