This summer, the mayors of Paris, Milan, and Phoenix gathered in London during a heatwave that - ironically - threatened to derail London Climate Action Week. As temperatures broke records across the UK and Europe, forcing some climate talks to be suspended or cancelled, the trio found themselves seeking shelter and comparing notes on how their cities handle extreme heat: protecting the vulnerable, communicating risk, and redesigning neighborhoods for hotter summers.
Meanwhile, Paris was busy managing its own crisis response as another intense heatwave swept France, where more than 14,000 people lost their lives due to the heat. The mayors all face the same question: how do you protect millions of people when extreme heat is no longer an exception but a regular summer guest? For Phoenix, that question has shaped city government for decades. For Paris and Milan, it's becoming a defining challenge of urban leadership.
It might seem odd that two of Europe's oldest cities are looking to Arizona's desert for inspiration, but rising temperatures are a global problem, and there's no time for each city to reinvent the wheel. Phoenix has learned - sometimes the hard way - that extreme heat isn't just a weather event; it influences decisions about transport, housing, public health, public space, and emergency planning. Preparing for summer starts long before the mercury rises.
Phoenix established one of the world's first city offices dedicated to heat response and mitigation, focusing on both immediate relief for the most vulnerable and long-term resilience through cooling solutions. The city's shade plans require 75% shade coverage in new development areas with high pedestrian activity, and it's applying cool surface treatments to buildings and roadways, including over 300 kilometers of neighborhood streets. Phoenix provides a 24-hour cooling center with wraparound support - housing, medical services, even job placement - and landlords must maintain indoor temperatures at 28C (82F) or lower. City contractors must implement heat safety plans. These measures saved lives: during the summer of 2024 - Phoenix's hottest on record - heat-related 911 calls dropped 20% year-over-year.
Paris and Milan bring their own expertise and challenges. Both are historic cities where streets and buildings were designed for a different climate. Paris now ensures every resident lives within a seven-minute walk of a cool spot - more than 1,400 spaces, including parks and public facilities, with extended hours during heatwaves. The city has mobilized 27,000 climate volunteers to spread awareness and preventive actions. Paris even organized 'Paris at 50°C' in October 2023 to test emergency response, inspiring Barcelona to do the same in 2027.
No city can simply copy another's model, but mayors should gather the best ideas globally. Through the C40 Cities network, nearly 100 major cities share climate solutions. Cities have always learned from each other - transport systems, housing policies, public health - and heat adaptation should be no different. If one city finds a better way to protect outdoor workers or cool public spaces, others shouldn't spend years reinventing it.
Milan is expanding its Piazze Aperte (Open Squares) and School Streets programs, planting trees, replacing hard surfaces with green space, and creating shaded areas. Milano Aiuta (Milan Helps) provides a helpline and support for elderly and vulnerable residents. Milan's Air and Climate Plan sets a binding goal to limit local temperature increases to 2C by 2050 - one of the few cities worldwide with such a target.
Extreme heat already claims over half a million lives annually, making it the deadliest climate hazard. Cities are especially exposed because buildings and pavements absorb heat by day and release it at night, leaving residents with no relief. Older adults, children, outdoor workers, and low-income communities face the greatest risks. Planting trees, cooling schools, redesigning streets, and expanding early warning systems are often labeled climate policies, but they're also public health measures and investments in local economies.
Heating and cooling account for nearly half of Europe's energy use, with about 70% of heating still from fossil fuels. Cities can lead a fair transition to clean heat by investing in renewables and cleaner systems, cutting emissions, improving air quality, and creating jobs. Cities are often first to feel climate impacts but last to get the powers, funding, and flexibility to respond. National governments should work with cities to develop adaptation strategies and ease access to finance.
This summer gave Europe a taste of what desert dwellers know too well - and what may become the new normal. Extreme heat is not an individual burden; it's a political crisis requiring bold action. The responsibility can't fall on isolated pensioners, vulnerable children, or construction workers. We must prepare and fight back. The climate crisis is redefining 'normal' faster than ever, so our ability to learn from each other must move even faster.