In a significant move ahead of the U.N. climate conference in Brazil, 300 mayors from around the world convened in Rio de Janeiro on Monday to pledge coordinated climate action. Organized by C40, a network of mayors from major cities, the summit emphasized the urgent need to address the escalating impacts of global warming, particularly rising temperatures that are severely affecting urban populations. Selwyn Hart, the U.N. special adviser and assistant secretary-general for climate change, highlighted the critical role of mayors in the climate crisis, stating that local leaders are essential as the world enters the second decade of implementing the 2015 Paris Agreement. The Paris Agreement aims to limit global temperature rise to 1.5 degrees Celsius above pre-industrial levels, requiring drastic reductions in greenhouse gas emissions. Ana Toni, Brazil’s climate change chief and CEO of COP30, stressed that achieving these goals depends heavily on the active involvement of mayors, who make crucial daily decisions impacting their communities. The summit also addressed the U.S. withdrawal from the Paris Agreement, with London Mayor Sadiq Khan criticizing the Trump administration for its climate policies, labeling the president as a ‘climate wrecker.’ Phoenix Mayor Kate Gallego announced ambitious climate actions from 50 U.S. cities, despite federal setbacks, including initiatives to combat extreme heat through tree planting, cool-surface technology, and heat-relief training. The event concluded with the launch of the Cool Cities Accelerator, a global coalition of 33 cities committed to implementing emergency measures to protect residents from extreme heat, supported by various foundations and organizations.