Nairobi, 2 June 2026 More than 50 cities across the world have joined UNEP's new 50@50 activation to confront one of the worlds fastest-growing and deadliest climate risks: extreme heat.
Launched on Heat Action Day, ahead of World Environment Day, 50@50 brings together cities to strengthen heat preparedness, stress-test systems, share practical solutions, and accelerate action to both protect communities and cut emissions driving rising temperatures.
Diverse cities like Antalya, Lagos, Melbourne, Mendoza, Paris and Yangzhou, are coming together through 50@50 to learn from each others experiences, share tested approaches to extreme heat adaptation and preparedness. Initiated by UNEP and the City of Paris, this activation contributes to the Beat the Heat implementation drive, launched at the UN Climate Change Conference in Belm (COP30) to accelerate local action on extreme heat and sustainable cooling.
50@50 promotes practical, people-centred solutions, including: cooling islands in public spaces, expanding green spaces, installing water fountains, developing cooling centres, setting up early warning systems, improving cycling infrastructure, increasing shaded areas, and using reflective materials to reduce heat absorption and reflective urban design.
Extreme heat is already reshaping daily life in cities around the world, which will face dangerous heat levels under virtually every climate scenario. This is posing a particular risk to small holder farmers and vulnerable members of the community, said Inger Andersen, Executive Director of UNEP. 50@50 helps local leaders move faster by sharing practical solutions that protect people, reducing inequality and strengthening urban resilience.
As global temperatures rise, cities worldwide are experiencing longer, more intense, and more frequent heatwaves. This contributes to nearly half a million deaths each year and makes schools, transport systems, homes, and public spaces unsafe during peak heat hours. It is also driving up energy demand and compounding inequalities, placing increasing strain on public health systems, especially when combined with air pollution, energy infrastructure, and urban economies.
"Extreme heat is becoming a defining challenge for cities worldwide. Building on Paris' own 50C simulation exercise, this initiative reflects a strong conviction: cities must act together to anticipate extreme heat and protect their residents. Cooperation is our most powerful tool, said Emmanuel Grgoire, Mayor of Paris.
Over the next year, a dozen cities will conduct their own extreme heat stress test with support from UNEP, the C40 Cities Climate Leadership Group and the City of Paris, which already carried out such an exercise.
Running through World Environment Day 2026 and beyond, 50@50 brings together a community of cities committed to urban heat resilience, shifting from coping to redesign through peer-to-peer learning to deliver for their citizens wellbeing before heat emergencies strike.
The full list of participating cities will be available on the World Environment Day website.
