The World Resources Institute (WRI) Ross Center for Sustainable Cities today launched Cool Cities Lab, a first-of-its-kind global data platform that maps – down to individual city blocks and streets – where residents face the highest heat risk and which solutions can lower temperatures most effectively. The tool provides cities with detailed, actionable data to help guide heat planning, infrastructure investment and climate resilience strategies. This free, open-source platform currently includes data for 20 cities across five continents, including Cape Town, Johannesburg, Durban, Jakarta, Boston, Nairobi, London, Rio de Janeiro, Mexico City and more, with additional cities planned.
Extreme heat is already straining cities worldwide, contributing to an estimated 489,000 deaths each year while driving up hospital visits and disrupting work and economic activity. The threat is intensifying: 2023, 2024 and 2025 were the three hottest years ever recorded globally. Yet most governments lack the granular data needed to plan effective local heat responses and target strategic infrastructure investments.
“Cities can’t afford to treat heat as a future problem – it’s already reshaping daily life and putting people in danger,” said Rogier van den Berg, Global Director for WRI Ross Center for Sustainable Cities. “Actionable data is essential for responding to this growing threat. It shows where risks are greatest and helps leaders direct solutions to the communities that need them most.”
Cool Cities Lab addresses critical data gaps that cities face when planning responses to extreme urban heat. The platform, co-developed with city decisionmakers, allows users to model how measures such as trees, shade structures and cool roofs could reduce heat stress and air temperatures in nearby areas. Because Cool Cities Lab is built on globally available open data, the platform can scale to cities worldwide. It enables city leaders to test different infrastructure scenarios, prioritize the most effective interventions and make an evidence-based case for investments in cooling solutions.
The platform reveals how heat exposure varies within cities and which communities face the greatest risks – often low-income and densely built neighborhoods with the least access to green space. By combining heat data with information on population and the built environment, Cool Cities Lab empowers planners and leaders to prioritize the needs of the most vulnerable people in their resilience planning efforts from the neighborhood to the entire city – and design context-specific, effective solutions.
Early applications of Cool Cities Lab data show how targeted interventions can deliver significant benefits:
- In Campinas, Brazil, increasing street trees by just 20% in a residential neighborhood could lower felt temperatures by 1.7-8 degrees C (3.1-11.4 degrees F), transforming heat-exposed routes into cooler, more walkable corridors for residents.
- In Cape Town’s central business district, combining street trees with reflective rooftops could nearly double the cooling that people experience compared to using either measure alone.
- In Hermosillo, Mexico, officials have already used the data to design a new park in one of the city’s hottest, least shaded areas, creating a cooler refuge for residents with few places to escape the heat.
- In Atlanta, data on the heat-mitigation potential of reflective roofs helped spur the city’s 2025 Cool Roof Ordinance. The policy, informed by Cool Cities Lab data from WRI and technical assistance from the Smart Surfaces Coalition, is expected to lower citywide temperatures by 1.4 degrees C (2.4 degrees F), and cool the city’s hottest and most vulnerable neighborhoods by up to 3.5 degrees C (6.3 degrees F).
To further expand adoption, WRI is collaborating with a range of initiatives supporting sub-national action on urban cooling, including the UN Environment Programme-led Cool Coalition’s Beat the Heat Implementation Drive, C40 Cities’ Cool Cities Accelerator and Smart Surfaces Coalition’s Cities for Smart Surfaces programme, to make Cool Cities Lab data, analysis and targeted support available to cities within their networks to inform their cooling strategies.
Cool Cities Lab was developed by WRI Ross Center for Sustainable Cities in partnership with WRI’s Data Lab, with support from Google.org and direct input from city officials and technical experts.
To learn more about Cool Cities Lab, visit: https://coolcities.wri.org/
