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📰 The quick summary: New research shows that over 90% of buildings in London, Paris, and Madrid lack adequate tree shade, but cities can cut urban temperatures by up to 4.5°C by planting more trees close to homes.
📈 One key stat: Tree shade can reduce the heat absorbed by pedestrians by up to 18°C, making it one of the most powerful tools cities have to fight dangerous urban heat islands.
💬 One key quote: “A lush shady park 800m away isn’t going to prevent dangerous localised heat island effects for you and your neighbours.”

1️⃣ The big picture: Heatwaves across Europe this summer killed tens of thousands of people and pushed cities like London, Paris, and Madrid to record temperatures above 40°C. A key driver of these extreme conditions is the urban heat island effect, where asphalt and concrete absorb and radiate heat, pushing local temperatures several degrees above surrounding areas. New research found that in London, Paris, and Madrid, more than 90% of buildings lack enough tree shade to prevent this effect. Trees are one of the most effective solutions available, blocking solar radiation, cooling the air through evaporation, and reducing surface temperatures by up to 18°C in shaded areas. However, research shows that trees only provide meaningful protection when planted close to homes, and when shade cover reaches at least 30 to 40% within 60 meters of where people live and work.

2️⃣ Why is this good news: Planting trees near homes offers cities a proven, nature-based way to dramatically reduce dangerous heat exposure for millions of people. Medellin, Colombia, already demonstrated what is possible: after adding millions of plants and over 12,500 trees along city streets, some neighborhoods cooled by 4.5°C, with a 2°C drop recorded across the entire city. Paris and London are both showing signs of action, with London launching its Heat Ready London plan and Paris already rolling out greener school streets that are 5°C cooler than traffic-heavy roads nearby. Beyond cooling, urban trees deliver wide-ranging mental and physical health benefits to residents, making investments in city greenery beneficial well beyond heatwave seasons. Scaling up tree planting close to homes gives cities a powerful tool to protect their most vulnerable residents as summers continue to get hotter.

3️⃣ What’s next: London and Paris are already taking early steps, with greening initiatives embedded in new climate adaptation plans. Researchers are calling for cities to prioritize planting trees within 60 meters of homes and workplaces, and to select species able to thrive in increasingly hot European summers. As extreme heat becomes a recurring reality, urban planners across Europe face growing pressure to make tree planting near homes a central part of city policy.

Read the full story here: The Conversation – More trees are needed to cool down European cities in heatwaves – but they must be planted nearer to homes