Exacerbating risk in human-ignited large fires over western United States due to lower flammability thresholds and greenhouse gas emissions.

ABSTRACT: Large fires in the western United States become highly probable when dry conditions surpass critical thresholds of vapor pressure deficit (VPD_t). VPD_t likely differs between human- and lightning-ignited fires, potentially leading to ignition-type varied responses of fire weather risk to natural variability and various anthropogenic forcings, yet a comprehensive quantification remains lacking. Here, through fire observations with ignition types and a machine learning method, we found that human-ignited large fires had consistently lower thresholds (VPD_t) across western US ecoregions. Consequently, the annual number of flammable days (when VPD > VPD_t) for human-caused large fires was 93% higher on average and increased 21% more rapidly than those c

SUBMITTER: Li F 

PROVIDER: S-EPMC11812050 | biostudies-literature | 2025 Feb

REPOSITORIES: biostudies-literature