The C40 Cities Baseline and Opportunities report provides an overview of climate action in 40 megacities, which have a combined population of 297 million and 4,734 climate actions. The report covers various sectors such as transport, existing buildings, waste management, water, energy supply, outdoor lighting, planning and urban land use, food and urban agriculture, information and communication technology, finance and economy, and climate adaptation. The report also highlights the leadership of Michael R. Bloomberg, the Mayor of New York, who chairs the C40 Cities Climate Leadership Group. The report emphasizes that cities are at the forefront of addressing global climate change and are implementing sustainability practices.