Time series of annual area burned at low (blue), moderate (orange), and high (red) severity (top), and the annual proportion burned at low, moderate, and high-severity (bottom).

Fire severity exerts crucial ecological controls in many forests globally. In California, where annual forest-fire area has increased dramatically in recent decades, understanding how burn severity is changing is essential for informing environmental policy and management. We developed remotely sensed high-resolution maps of severity for 4,391 forest fires to assess trends and drivers of burn severity across California's forests from 1985–2024. We observed that historically dominant low-severity fire was increasingly replaced by high-severity stand-replacing fire, which became the most common severity class beginning in 2012. Link to paper.