Australia's current wildfire crisis linked to colonial land-use change.

The global wildfire crisis1 is often attributed to climate change, a framing that overlooks crucial historical drivers. Biomes at the forefront of this crisis, such as the temperate eucalypt forests of Australia, have seen alarming increases in large, intense wildfires in recent decades. Yet evidence of how colonial land-use change and the disruption of Indigenous fire use altered vegetation structure and fuel dynamics remains scarce. Here we reconstruct 1,000 years of vegetation and fire change in a temperate eucalypt forest in southeastern Australia. Before the British invasion (from 1788 CE), fire use by the Indigenous Gunaikurnai people maintained stable, open woodlands through frequent, fine-grained, low-temperature cultural burning. Colonial disruption drove cascading changes: increased fire temperature, a fourfold rise in eucalypt cover, a shift from open woodland to forest and increased soil erosion. These transformations preceded anthropogenic warming, indicating that the vulnerability of these forests to wildfire is shaped by colonial land-use legacies. By creating more flammable landscapes, colonial land use amplified the influence of climate change, suggesting a reinforcing feedback (the 'catastrophic wildfire loop') in which high-intensity wildfires raise fuel loads and further increase the likelihood of climate-driven fire. Integrating Indigenous knowledge into fire management is therefore essential to restoring resilience and mitigating future wildfire risk.