PNNL

Abstract

Complex interactions between hydroclimate-related physical processes that exert significant impacts on regional fuel aridity and fire activity make it difficult to directly connect anthropogenic climate change and wildfire changes over fire-prone regions like the western United States (U.S.). Here we show that increasing large wildfires over that region appears closely related to more fire-favorable weather associated with rapid declines in Arctic sea ice during the past few decades. Our analysis (based on observations, climate model sensitivity experiments, and a multi-model ensemble of climate simulations) demonstrates and explains the teleconnection. The amplitude of the Arctic-driven fire weather change appears to be of similar magnitude to other leading modes of climate variability such as the El Niño-Southern Oscillation that also influence fire weather in the western U.S.