A network of city mayors delivering urgent climate solutions. Protecting the people and places we love. 🌳🌍🌆💚

Global
We're at #COP31. Here’s why cities need to be part of the conversation ➡️
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⭐ The Yearly Offer of Action is back, and more mayors are involved than ever before. From cleaner energy to greener public spaces, C40 and @Mayors4Climate cities are turning climate targets into real results, year after year. c40.org/yooa/
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Brazil is showing what climate action looks like 🇧🇷 Cities are bringing climate action into public budgets and building on the momentum of COP30. c40.org/news/brazilian-citie…
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Huge opportunities await businesses investing in green tech and infrastructure. In @ClimateHome, @LordMayorMelb Nick Reece & Mayor of Renca @cn_castro detail why C40 cities are generating a green investment boom. climatechangenews.com/2026/1…
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Londonmaxxing at its finest. Under the leadership of C40 Co-Chair and @MayorofLondon, one of the world's most famous shopping streets is putting people first. @SadiqKhan
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Mayor Sadiq Khan's transformation of Oxford Street shows what is possible when mayors put people at the heart of their cities.
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Water = life 💧 By introducing clean drinking water kiosks in underserved communities, C40 Co-Chair and Mayor of Freetown @yakisawyerr is tackling climate challenges, creating new jobs and protecting people from unsafe water. @FCC_Freetown
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More trees, cooler streets and a city better prepared for extreme heat. 🌳 Through ‘Freetown the Treetown’, C40 Co-Chair @yakisawyerr is showing how a simple solution can make a big difference in the fight against rising temperatures in Freetown, Sierra Leone. @FCC_Freetown
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Transforming the Seine River and making it clean and swimmable was one of the boldest moves Paris took to tackle the climate crisis. Hear from the Mayor of Paris, Emmanuel Gregoire, about how restoring the Seine is future-proofing the city for generations to come.
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GOOD NEWS: Cities are taking bigger, bolder steps to tackle the climate crisis. Across C40 cities, climate action is already delivering real results. From cleaner air and greener transport to cooler neighbourhoods and more renewable energy ⬇️🧵
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🇨🇳 Shenzhen is making global shipping greener with cleaner energy at ports. 🇧🇷 Curitiba is improving waste services six years ahead of its target timeline. 🇺🇸 New York City is cutting food emissions by serving more plant-based meals across hospitals.
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🇲🇾 Kuala Lumpur is helping communities stay cool as temperatures rise. 🇮🇳 Bengaluru is turning rooftops into a major source of clean energy. Explore the progress and learn more about the data in our 2025 annual report: bit.ly/C40AnnualReport2025
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Cities are already feeling the impact of a hotter, more unforgiving climate. From opening public areas 24/7 for people to cool down to creating more shade and green spaces, cities like Paris are finding practical ways to protect residents from extreme heat. @egregoire
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Listen up 🗣️🗣️🗣️
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Over the last 4 years, global emissions rose by 2%. Meanwhile, C40 cities cut emissions per person by 3.5%. Cities have the power to drive change. Dive into the work mayors and cities are putting in every day to protect the people and places we love: bit.ly/C40AnnualReport2025
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36 cities in C40’s Cool Cities Accelerator are helping millions of people stay safe as temperatures rise. In New York, cooling pop-ups are being expanded across all five boroughs. In Miami, Mayor Eileen Higgins is using data from heat sensors to help improve heat safety.
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Extreme weather is being felt in cities everywhere, and sessions during #ClimateWeekNYC are exploring how cities can get prepared: Phoenix is expanding shade, Austin is making homes cooler and safer, and New York City is improving access to essential cooling for tenants.
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Governor of California @GavinNewsom speaking at the United Nations on the power of local climate action.
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