On December 4, 2015, hundreds of mayors gathered at the Paris City Hall for the Climate Summit for Local Leaders, as part of the largest global gathering of mayors, governors, and local leaders focused on climate change.

The afternoon general session began with opening remarks from hosts Anne Hidalgo, Mayor of Paris, and Michael Bloomberg, UN Secretary-General’s Special Envoy for Cities and Climate Change, who emphasized the strong knowledge base that exists among cities worldwide. Mayor Hidalgo noted that cities represent fifty percent of the solution to climate change and must share ideas and practices to ensure that cities create better environments for their citizens.

Park Wonsoon, Mayor of Seoul, South Korea and President of ICLEI – Local Governments for Sustainability, spoke about the role of local and regional government networks in advancing sustainability goals, explaining that ICLEI's more than 1,000 members agreed to implement the Seoul Action Plan, which includes specific measures for sustainable growth. He asked participants to “keep in mind the saying, ‘'Think globally, act locally'“, A theme that resonates powerfully at an event that highlighted the power and potential of local climate ambitions amid ongoing international negotiations in Paris.

Hoesung Lee, Chair of the IPCC, emphasized the need to focus on solutions to climate change, not just the problems. Science clearly shows that we face disastrous consequences without action, meaning that the world must now use innovative and disruptive technologies that can give rise to a new economy and job creation.

Leonardo DiCaprio echoed Mayor Hidalgo in emphasizing the importance of knowledge, exchange, and collaboration, stating that "one thing is fundamentally clear: we need to find the will to work together," highlighting the importance of strong networks like the Compact of Mayors, which recently reached [a milestone]. 400 cities committed worldwide. DiCaprio also called attention to more ambitious and rapid actions by local and regional leaders towards goals such as 100% of renewable energy, which are achievable even if they seem out of reach.

Following remarks from several officials, a panel composed of the Mayors of New Orleans (USA), Barcelona (Spain), and Amman (Jordan) joined the top-level representatives to discuss how to address the risks of climate change, agreeing that cities and people must adapt and respond to signals from the natural environment. New Orleans, a city surrounded by water, has decided to work with its water resources, not against them, while the Mayor of Barcelona, Ada Colau, acknowledges that "if we don't want climate change, then we have to change ourselves."“