In their study, which was published in Global Change Biology, Janssen and Veraverbeke investigated which factors ensure that forest fires in the northern forests of Siberia stop. They analysed satellite observations of more than 27,000 fires, which together burned 80 million hectares of forest between 2012 and 2022. This gave them insight into the factors that contribute to a fire stopping and the influence of climate and landscape factors on the spread of fire. The study is the first to map the limiting factors on fire growth on this scale and in great detail.
Why do forest fires stop?
Fires in Eastern Siberia are virtually uncontained and can rage undisturbed for months. These fires are eventually stopped by a change in the weather or a change in the landscape. For example, a change from dry and hot to wet and cold weather can cause a fire to die out, as can, for example, the presence of a wide river or a road in the landscape. The scientists examined 2.2 million so-called ‘fire stops’, locations where a fire stopped at some point, to determine which factors limit the spread of fire at that specific location. “Understanding what stops fires is as important as knowing what drives them,” says Janssen. “Our study shows clear regional and temporal patterns in the factors that limit fire growth, which is essential for improving fire forecasting.”
Room for growth in wildfires lies further north
The research shows that 87% of all fire stops can be attributed to a change in one or more environmental factors. Of these, 32% is attributed to landscape features, 23% to a change in weather, and 45% to a combination of both. In southeastern Siberia, human landscape features such as roads and land use played a major role in stopping fires, while in the remote northern taiga, weather conditions were the main limiting factor. “This spatial variability shows that forest fires in southeastern Siberia may not grow much larger, even with climate change,” Veraverbeke said. “However, in the vast northern forests, fires can still grow under warmer and drier conditions.”
The methodology developed in this study can be applied to other parts of the world and provides a framework for global fire research. The findings have important implications for improving global climate models and regional fire models, so that policymakers and fire authorities can better predict and respond to extreme wildfires in the future.
This study was supported by a Consolidator project of the European Research Commission, part of the European Union’s Horizon 2020 research and innovation programme.