Wildfire danger under changing climates in the southern Great Plains throughout the 21st century

The southern Great Plains (SGP) has recently experienced wildfires with unprecedented severity and frequency, which significantly threatened human life and property and altered terrestrial ecosystem functions. While it is expected that future climate change will affect wildfire danger levels by altering fire weather and fuel conditions, there remains a significant gap in understanding how these changes will manifest in the SGP. Therefore, our objectives were to (1) simulate the spatial and temporal dynamics of the Burning Index (BI), a widely used fire danger index in the National Fire Danger Rating System (NFDRS), and high fire danger days based on CMIP5 climate simulations, comparing the 1986-2005 historical period and 2006-2099 under two climate change scenarios (RCP4.5 and RCP8.5), and (2) identify important weather variables driving projected BI changes. We found that the BI would increase at 0.1 x 10 ft per decade under RCP4.5 and 0.4 x 10 ft per decade under RCP8.5. By the end of the 21st century, the southwestern SGP is projected to become a hotspot for increased wildfire danger, its annual high fire danger days are projected to increase by over 25 days (50 %) under the RCP8.5 and more than 15 days (30 %) under the RCP4.5 compared to 1986-2005. The BI is projected to increase in all months except April, with the highest increases occurring during the summer. The primary climate factor contributing to future BI increases is a decline in relative humidity. Interestingly, our simulations suggest a potential decrease in BI for April, likely due to earlier vegetation green-up prompted by rising temperature. Overall, our study outlines future patterns of fire danger in the SGP. These findings are essential for developing long-term preparedness strategies to mitigate wildfire risks and adapt to the new wildfire regimes under changing climate conditions.