Google Research has released an expanded dataset of building-level rooftop reflectivity covering 50+ global cities through a new Heat Resilience Earth Engine App. The tool helps urban planners implement cool-roof solutions to combat extreme heat, which claims approximately 500,000 lives annually worldwide.

The urban heat island effect drives localized warming in metropolitan areas, heating cities at twice the global average rate. Dark pavements and roofs trap heat while vegetation remains scarce. Cool roofs offer a cost-effective mitigation strategy by increasing rooftop reflectivity to reduce solar energy absorption and lower local surface temperatures.

Google's approach fuses Sentinel-2 satellite data with high-resolution Airbus Pléiades Neo imagery using machine learning models and radiometric calibration. This methodology, detailed in Nature Communications, achieves 30-cm precision with RMSE of 0.04 against ground-truth measurements. Targeted cool-roof planning could reduce extreme urban heat by up to 0.5°C globally.

The Earth Engine App provides building-level visualization tools and census-tract aggregates for municipal planning. Coverage spans major cities across Europe, Brazil, and the United States. This open dataset enables proactive heat resilience planning and supports initiatives like cool roof ordinances and adaptation strategies.