Climate change: Declining Arctic sea ice may increase wildfires in the western US

Declining sea ice in the Arctic may contribute to increased wildfire activity in the western United States, suggests a modelling study published in Nature Communications. The finding demonstrates the influence that human-induced climate change can have on extreme weather events in the region.

Wildfires in the western US have become more frequent and severe in recent years. Although there is some evidence that Arctic sea ice declines can influence extreme weather conditions in temperate and subtropical regions, the impact on wildfires has been unclear.

Yufei Zou, Hailong Wang and colleagues combined data on wildfire incidence, sea ice concentrations and weather conditions over the past 40 years and conducted model simulations to investigate the relationship between these factors. The authors identified an association between declining Arctic sea ice concentrations from July to October and the increasing probability of large wildfires in the western US during the following September to December. The model simulations indicate that declines in Arctic sea ice are linked to air circulation changes that cause hotter and dryer weather conditions, which increase the likelihood of wildfires.

The authors conclude that the influence of Arctic sea ice concentrations on wildfires is of similar magnitude to that of the tropical El Niño Southern Oscillation, which can also modulate regional wildfire conditions. As Arctic sea ice is projected to continuously decline, this could further increase the susceptibility of the western US to wildfires in the future, they suggest.