This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Green and blue spaces, such as woodlands and riversides, could provide a vital line of defense for cities facing increasingly hot summers, according to new research from the University of Surrey. In a study published in Environment International, researchers from Surrey's Global Centre for Clean Air Research (GCARE) monitored temperatures across Guildford for three years to understand how different urban environments cope with heat.
The team compared six types of green and blue infrastructure—woodland, lakeside, grassland, a pocket park, riverside and a green wall. They then compared temperatures at those sites with temperatures in a built-up area between June 2023 and August 2025. During peak summer hours, all six green and blue sites were cooler than the built-up location.
The woodland site recorded the greatest difference, at around 2.5°C cooler, followed by grassland at 2.3°C and lakeside at 2.1°C. Across 10 extreme heat events analyzed during the study, the woodland site was on average 4.5°C cooler during the daytime than the built-up site, with differences frequently exceeding 5–6°C during the most severe heat waves. Grassland and lakeside were around 4°C cooler on average.
Researchers also compared how often each location experienced heat wave conditions, defined in Surrey as temperatures reaching at least 28°C (82°F) for three consecutive days. Over the three summers, the built-up site experienced 54 heat wave days, with heat wave conditions accounting for 19.6% of summer daytime observations. In comparison, all six green and blue spaces experienced significantly less exposure to extreme heat.
The green wall recorded the highest exposure of the six at 8.7%, while the woodland area recorded no heat wave periods at all. Professor Prashant Kumar, founding director of GCARE at the University of Surrey and corresponding author of the study, said, "Summer 2026 has felt like a wake-up call for the impact of increasingly hot summers, and we now have three years of evidence showing the difference nature can make. What was most surprising was the woodland site, where we recorded no heat wave conditions—compared with almost a fifth of summer daytime observations at the built-up location.
"There is no one-size-fits-all solution, but our findings show why trees, green spaces and water should be an important part of how we design towns and cities to cope with a warmer climate." As part of GCARE's Guildford Living Lab, the study used a network of sensors to record temperature and humidity every minute at the seven locations across Guildford over three years, alongside satellite data to provide a broader picture of urban temperatures. Satellite observations also showed substantial differences in summer surface temperatures, particularly between the built-up, woodland and lakeside areas. While woodland showed some of the largest and most consistent temperature differences, the research team cautioned that each type of green and blue infrastructure was represented by one location, meaning local conditions may have influenced the results.
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