Predicting climate-driven urban rat release and associated risks across climate zones.

Abstract

Urban rat populations are widely assumed to increase under climate change, largely due to recent studies. This narrative is often extended to cities worldwide, irrespective of their local climate. Yet, this oversimplification obscures complex ecological and social processes that shape commensal rat dynamics. Here, we synthesize evidence across rodent ecology, epidemiology, urbanization, and human behavior to propose a multi‑dimensional framework for urban rat‑release: a climate‑mediated relaxation of seasonal constraints that reduces winter burrow confinement and increases above‑ground activity, dispersal, apparency, and reproductive output in cold‑temperate cities, often producing short‑term population increases before density‑dependent processes stabilize numbers. Warming winters may extend breeding windows and increase winter food availability, but these effects interact with expanding arthropod vectors, shifting pathogen pressures, and the compounding forces of urban architecture, waste management systems, and human activity. Human social responses-sanitation reforms, surges in panic‑driven control, and predictable political attention cycles-can either magnify or suppress populations, often more strongly than ecological factors. We argue that climate change will not produce uniform increases in rat abundance; instead, outcomes will vary predictably across cold‑temperate, mild‑temperate, and tropical cities depending on the alignment of these interacting dimensions. Importantly, rat populations may stabilize or surge depending on how disease dynamics, density-dependent constraints, and public responses converge. This framework provides a foundation for forecasting models and offers practical guidance for urban planning, public health, and policy development in warming climates where rats and vectors reshape urban risks. These dynamics align with the One Health perspective, which emphasizes the interdependence of human, animal, and environmental systems.