Assessment of potential changes in the fire danger in the Ukrainian forests under the climate change

Abstract

Introduction

The primary factors contributing to increased fire risk and wildfires occurrence include regional climatic conditions, socio-economic and anthropogenic influences – such as warfare – and the specific characteristics of vegetation in a given area. Abnormal weather conditions conducive to catastrophic wildfires, as observed in 2015 and 2020, are expected to become more frequent, while the war initiated by Russian Federation is likely to further exacerbate this trend. Ongoing climate change is projected to elevate fire risk in Ukraine's forests and increase wildfire density. This study aims to assess future projections of key fire-prone weather indicators under different climate change scenarios and their potential impact on forest flammability.

Materials and Methods

A nationwide database of forest fires in Ukraine, covering the period from 2007 to 2021 at the regional level, was analysed. Using statistical data of forest fires, we calculated temporal and spatial trends in fire occurrence, forest flammability, and fire density in different regions of Ukraine. The initial analysis of the influence of specific climatic factors was conducted by examining the baseline period at the regional level (including both climatic indicators and indicators of fire density and forest flammability) for 1981–2010. The analysis included the following indicators: the duration of rainless periods, the number of days with maximum temperatures exceeding 35°C, average air temperature (°C), wind speed (m/s), precipitation per rainfall event (mm), and the Fire Weather Index (FWI). As the climatic basis, data from the EURO-CORDEX initiative, the European branch of the international CORDEX climate modeling project, were used.

Results

The relationship between climatic variables and forest fire trends – expressed through fire density and forest flammability – was analysed using correlation analysis, with highly correlated variables filtered out. Regression models were developed across administrative regions to quantify the impact of specific climatic indicators on fire occurrence (fire density) and fire extent (forest flammability). Our findings indicate that an increase in the number of days classified as a high fire danger (FWI > 30) relative to the baseline period (1980–2010) is observed only under the RCP8.5 scenario. This scenario projects a global mean annual temperature increase of 2°C by the mid-21st century compared to the late 20th century. The highest increase in fire danger is expected in the southeastern Ukraine and along the southern border of the Left-Bank Forest-Steppe, as well as in the Ukrainian Carpathians and the Crimean Mountains. A slight decrease in fire danger, attributed to increased precipitation, is expected in the Volyn region and the western part of the Right-Bank Forest-Steppe.

Conclusions

Our analysis identifies the most fire-prone and vulnerable regions under specific climate change scenarios, providing a foundation for developing thematic layers based on factors directly or indirectly influencing wildfire occurrence. According to our findings, the highest wildfire risks will persist in the Kherson, Luhansk, Dnipropetrovsk, and Zaporizhzhia regions. Significant fire density was also identified in the Kyiv region, likely influenced by its high population density.

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