United Nations Secretary-General Antonio Guterres, U.S. Rep. Alexandria Ocasio-Cortez and Danish Prime Minister Mette Frederiksen are set to lend their weight to the event. Deputy mayors, local officials, climate experts, business leaders and activists also are attending the conference.
Discussions cover how cities can reduce emissions, transition to green energy and help curb global warming. Paris Mayor Anne Hidalgo is chair of the event. She says she hopes cities share their experiences "so we can accelerate our efforts" to tackle climate change.
Hidalgo said: "The solutions are there."