Climate Extremes and Community Resilience

Abstract

Climate extremes -- heatwaves, droughts, floods, and compound events combining multiple extreme conditions simultaneously -- are increasing in frequency, intensity, and duration under anthropogenic climate change, and represent qualitatively different ecological stressors than gradual mean climate trends. While community responses to mean climate change are relatively well-characterised through species distribution model projections and long-term monitoring, the ecological impacts of extreme events -- and the mechanisms by which some communities resist or recover from extremes (resilience) while others collapse -- remain poorly understood and even more poorly predicted. This study synthesises the most comprehensive multi-ecosystem, multi-extreme-type dataset on ecological community responses to climate extremes yet assembled, integrating 247 documented extreme events from 84 ecosystem types across 18 biomes, covering ecological impacts on 38,400 species from 18 taxonomic groups with standardised resilience metrics (resistance: community stability during the event; recovery: return to pre-event composition post-event). Functional diversity was the strongest predictor of both resistance (partial R2 = 0.54; p < 0.001) and recovery (R2 = 0.38; p < 0.001): functionally diverse communities resisted and recovered from extremes significantly better than functionally depauperate communities. Compound events (heatwave + drought simultaneously) produced 74.7% larger community impact than single extremes of equivalent magnitude -- the dominant extreme type emerging under high-emissions scenarios.