Overview
- The study published Tuesday, July 21, 2026 in Nature Geoscience reports data from four European drill cores including a 640 m UK core and 15,000 pollen and spore color measurements.
- Researchers identified a synchronous 'Dark Zone' of unusually darkened microfossils that lines up with a large fern expansion known as the fern spike and with elevated charcoal and PAH levels.
- The team introduced a Palynomorph Darkness Index, a low‑cost color measure of fossil pollen and spores, to detect charring because charcoal pieces can fragment and PAHs can travel far from fires.
- Authors argue that dense, fast‑regrowing fern mats provided abundant dry fuel that sustained repeated wildfires and created a feedback that prolonged the main extinction interval, which they estimate lasted roughly 40,000 to 300,000 years.
- The findings retain volcanism and rapid warming as the initial driver but add a clear biotic amplifier, showing how vegetation and fire can reinforce ecosystem collapse and offering a cautionary example for modern climate, land use, and fire risk.