Overview
- Published in Science Advances, the analysis finds days with synchronized extreme fire weather rose from about 22 per year in 1979–1993 to more than 60 in 2023–2024, using a fire‑weather index at the 90th percentile across regions.
- Model comparisons to a no‑warming counterfactual indicate roughly half of the global rise stems from anthropogenic climate change, with natural variability like El Niño also shaping regional patterns.
- The changes are uneven: the continental U.S. averaged about 38 such days per year over the last decade versus 7.7 in 1979–1988, southern South America climbed to 70.6 with 118 in 2023, boreal zones show the highest synchrony, and Southeast Asia declined.
- More overlap in high‑risk days shortens mutual‑aid windows and can limit sharing of crews, aircraft, and equipment across established cooperation networks in the U.S., Canada, Europe, Australia, and South Africa.
- The study tracks weather conditions rather than ignitions, yet it links concurrent high‑risk periods to worse smoke and health impacts, with research tying wildfire smoke to tens of thousands of premature U.S. deaths and sharp pollution spikes in high‑synchrony years.