New Manchester Study Highlights Role of Traffic in Urban Heat Rise

Researchers at the University of Manchester have developed a new modelling tool that reveals how vehicle traffic contributes to rising temperatures in urban areas.

Published in the Journal of Advances in Modeling Earth Systems, the physics-based model uses real-world traffic data from Transport for Greater Manchester (TfGM) and has been validated against historical datasets from both Manchester and Toulouse. The tool is designed to integrate with the Community Earth System Model (CESM), a widely used platform for global climate analysis.

By incorporating traffic data into large-scale climate modelling, the research demonstrates how vehicles contribute to anthropogenic heat flux (AHF), intensifying the urban heat island effect. The study found that traffic-related heat increased average annual temperatures by around 0.25°C in Manchester and 0.4°C in Toulouse.

While these increases may appear modest, researchers warn they can have a significant impact during extreme weather events. The findings suggest that traffic-generated heat can extend periods where temperatures feel dangerously high, increasing risks to public health.

Lead author Dr Zhonghua Zheng explained that transport has often been overlooked in urban heat research: “Much of the focus has traditionally been on buildings and land surfaces, but the heat emitted directly by vehicles has not been fully captured in climate models. Our approach allows us to better understand how this heat interacts with the urban environment.”

The model also indicated that during the UK heatwave in July 2022, vehicle-related heat contributed to elevated “feels like” temperatures, increasing levels of heat stress. It further showed that heat generated at street level can transfer into buildings, potentially raising indoor temperatures and increasing demand for cooling.

A key feature of the model is its ability to simulate different vehicle types—including petrol, diesel, hybrid and electric—and assess how changes in traffic patterns or transport policies could influence urban temperatures.

Co-author Yuan Sun said the findings highlight the need to factor transport into climate strategies: “Understanding the role of traffic in urban heat is essential for designing effective cooling measures, improving resilience and supporting the transition to net zero.”