Pyrogeography of extraordinary wildfires

Calum Cunningham , Grant J. Williamson, John Abatzoglou, Crystal Kolden, Matthew W Jones, Michael Fromm, David A Peterson, Fantina Tedim, Mike Flannigan, Fay H Johnston, Nicolas Borchers-Arriagada, David Bowman

Extraordinary wildfires – defined by anomalous fire behaviour, physical attributes, paleo-ecological context, spatiotemporal scales, or consequences – have emerged as defining features of the global wildfire crisis. Extraordinary wildfires have profound impacts on ecosystems, climate, air quality, and human societies. In this Review, we characterise key dimensions of extraordinary wildfires, contextualise their global distribution and trends, and review causes and consequences. Globally extraordinary fires (highly anomalous in ≥1 dimension) show distinct geographic patterns, being most common in boreal and temperate conifer forests, Mediterranean systems, and deserts, but less so in tropical and subtropical forests and savannas. Upward trajectories in the 21st century are most pronounced in boreal forests and temperate conifer forests. Drought and fire weather are tightly linked to extraordinary fires in cool, moist or fuel-rich extratropical biomes, but weakly associated in deserts, grasslands and savannas. Other additional drivers and amplifiers of extraordinary fires include invasive plants, interruption of Indigenous burning regimes, vegetation mismanagement, and an expanding wildland interface. The primacy of climate and fire weather – which are exacerbated by anthropogenic climate change – highlights the urgency with which we must adapt management of anthropogenic and natural environments in the face of a more fire-prone future.