Analysis of a fire danger index over Southeast Europe

In addition to the historically sensitive Mediterranean regions, northern parts of Southeast Europe are increasingly vulnerable to forest fires exacerbated by climate change. Higher temperatures, more frequent heat waves, and erratic rainfall patterns in the region foster conditions conducive to swift wildfire ignition and propagation. Human-induced factors further exacerbate the risk, while the ecological consequences of these fires are far-reaching, affecting biodiversity and human lives.

The Forest Fire Danger Index is a tool for assessing wildfire risk under very dry soil conditions. It incorporates factors besides soil dryness such as daily wind speed, mean temperature, and humidity to assess the potential risk for wildfires. Elevated wind speed can hasten fire propagation, while low humidity and high temperatures increase the likelihood of ignition and accelerate spread in arid regions. To calculate soil dryness specifically developed for fire controls, we analyzed the widely-used Keetch-Byram Drought Index, which relies on daily precipitation, maximum temperature, and effectively captures the soil's evaporation-precipitation balance.

For the calculations, we assessed E-OBS version 29, a state-of-the-art, quality-controlled and interpolated observational dataset on 0.1° horizontal resolution for the reference period of 1971–2023. For the future, we used an ensemble of regional climate model simulations from the Euro-CORDEX initiative, which takes into account future anthropogenic activity through three distinct RCP scenarios until 2100 (RCP2.6, RCP4.5, and RCP8.5).

Results indicate that regions historically experiencing infrequent severe compound wildfire events, such as most of the northern lowland areas in Romania, Bulgaria, Serbia, Hungary, or Croatia, are exposed to significant changes with global warming. Particularly after 2060 in the case of the non-mitigation scenario of RCP8.5 compared to the immediate mitigation of RCP2.6. Consequently, these possibly high impacts require a substantial investment in fire monitoring, education, and a warning system in these countries as well.

Acknowledgments: Research leading to this study has been supported by the European Climate Foundation (G-2309-66801), the Hungarian National Research, Development and Innovation Fund (K-129162), and the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014).