Milan, Phoenix and Paris mayors share heat crisis lessons

The mayors of Milan, Paris and Phoenix have jointly written that the heat crisis confronting their cities is fundamentally a public health question, as they compare strategies for protecting residents during record-breaking summer temperatures. Writing in the Guardian, Emmanuel Grégoire of Paris, Giuseppe Sala of Milan and Kate Gallego of Phoenix described meeting in London during a heatwave that ironically threatened to derail London Climate Action Week, where they discussed how their three very different cities are learning from one another about heat resilience.

The three mayors argue that climate policies — from cooling shelters to urban greening — must be understood not merely as environmental measures but as essential public health interventions. Their joint intervention comes as European cities face increasingly severe summer heat, with the continent already experiencing record-breaking temperatures and extreme weather episodes this year.

For Milan, Sala's participation is significant: the Lombard capital is one of the most heat-exposed cities in northern Italy, with its dense urban fabric and limited green space intensifying the urban heat island effect. The city has been experimenting with cooling strategies that the mayors say could offer a model for other European cities facing similar pressures, though the Guardian article does not detail specific Milanese measures.

The collaboration between the three cities is notable for its geographic spread — from the arid American Southwest to the humid Po Valley — suggesting that heat adaptation requires locally tailored responses rather than a one-size-fits-all approach. Phoenix, one of the hottest large cities in the United States, has developed extensive cooling infrastructure, while Paris has pursued ambitious urban greening under its climate plans.

For Emilia-Romagna, the mayors' framing of heat as a public health issue resonates with the region's own recent climate experience. While the 2023 floods that devastated parts of the region were a water event rather than a heat event, they underscored the same underlying vulnerability: the Po Valley's climate is shifting, and civic infrastructure must adapt. Bologna, with its medieval centre and limited tree canopy in some quarters, faces heat pressures similar to Milan's, though on a smaller scale.

The mayors' joint statement stops short of proposing specific EU-wide policies, but their collaboration hints at a broader pattern of city-to-city knowledge sharing on climate adaptation. As European summers trend hotter — with the supersized El Niño phenomenon expected to influence the continent's climate in coming months — such exchanges are likely to become more common among cities that have traditionally competed rather than cooperated on environmental policy.