Wildfire seasons are starting to overlap. That spells trouble for firefighting.

“If a fire season is increasing and eventually overlapping, it will shrink the window of opportunity to help each other in terms of firefighting,” said Cong Yin, a climate scientist at the University of California, Merced, who led the new study. “These changes are attributable to climate change, so we need to mitigate climate change if we want to avoid this future.”