Source: AGU Advances
As the global climate continues to warm, fire seasons have intensified, and large-scale wildfires have become more frequent in many parts of the world. Factors such as vegetation type, land use patterns, and human activity all affect the likelihood of ignition, but wildfire proliferation ultimately depends on two factors: climate and fuel availability.
Kampf et al. studied relationships between fire, fuel, and climate in temperate regions around the world, focusing specifically on western North America, western and central Europe, and southwestern South America. Each of the three regions includes desert, shrub, and forest areas, as well as local climates ranging from arid to humid.
The researchers pulled information on total burned area and wildfire frequency in these regions between 2002 and 2021 from the GlobFire database, and they sourced data on land cover and biomass during the same period from NASA’s Global Land Cover Mapping and Estimation (GLanCE). They also used precipitation and evapotranspiration data from TerraClimate to calculate the mean annual aridity index (mean annual precipitation divided by mean annual evapotranspiration) for each region.
The researchers found that over the 20-year study period and across all three regions, fires burned smaller areas of land in zones with either very dry climates or very wet climates compared with zones of intermediate aridity. They suggest that this trend is explained by the lack of vegetation sufficient to fuel widespread fires in dry zones and, in wet zones, by weather conditions that dampen the likelihood of fires. In contrast, burned areas were larger in the intermediate zones where biomass abundance and weather conditions are more conducive to fueling fires.
Of the three regions studied, North America had the largest total burned area, fraction of area burned, and fire sizes. The researchers note that the fragmentation of vegetated areas in South America (by the Andes Mountains) and in Europe (because of extensive land use) has likely limited the sizes of fires and burned areas in those regions. They also point out that rising temperatures and aridity are increasing the risk of large wildfires in all three regions, suggesting that fire managers need to be flexible and responsive to local changes. (AGU Advances, https://doi.org/10.1029/2024AV001628, 2025)
—Sarah Derouin (@sarahderouin.com), Science Writer
