Increased Atmospheric Aridity and Reduced Precipitation Drive the 2023 Extreme Wildfire Season in Canada

Abstract

Canada experienced an unprecedented wildfire season in 2023. Here, we analyzed the exceptional scale, dominant driving factors, and potential impacts on permafrost of these wildfires using Moderate Resolution Imaging Spectroradiometer burned area (BA) observations and machine learning methods. We found that the 2023 coast-to-coast wildfires raged a staggering area of 13.02 Mha, more than seven times the historical average (2001–2022). The extreme wildfires were predominantly driven by record-breaking drought, characterized by heightened atmospheric aridity and reduced precipitation, with specific water deficit thresholds triggering sharp increases in BA. Over 80% of the 2023 wildfires occurred in Canada's permafrost regions, with burned areas increasing more than six-fold across extensive permafrost, including Arctic regions. These wildfires are expected to accelerate permafrost degradation and considerable carbon release from thawing, presenting previously overlooked risks. Our results emphasize the urgent need for immediate climatic action to mitigate climate change and pressures from wildfire and permafrost degradation.