He explained mayors are stepping up because there's no consensus from national governments.
Former U.S. President Barack Obama, in Paris on a five-day global trip, had a two-hour private lunch with French President Emmanuel Macron and gave a speech to business leaders.
Obama didn't mention Trump by name, saying only that the USA was in an "unusual" position as the sole country to reject the Paris agreement. The U.S. won't technically back out until 2020 because of legal technicalities.
10 arrests over auto bomb killing of Malta journalist
Malta has a reputation as a tax haven in the European Union and has attracted companies and money from outside Europe as well. A Maltese court has charged three men with the murder of investigative journalist and blogger Daphne Caruana Galizia .
Virginia Tech, UVa bowl destinations announced
The Hokies beat Rutgers 13-10 in overtime in the 2012 Camping World Bowl, then known as the Russell Athletic Bowl. Oklahoma State: The Cowboys average 392.3 yards passing per game to lead all Football Bowl Subdivision teams.
Earlier, Obama also discussed climate issues with Paris Mayor Anne Hidalgo.
The list of confirmed attendees includes British Prime Minister Theresa May and her Spanish counterpart Mariano Rajoy as well as around 10 African heads of state and leaders from under-threat Pacific islands, the French presidency said.
Obama did not mention President Trump by name, but urged officials in attendance to continue efforts to combat climate change, regardless of the current administration's position.
The charter calls for mayors to achieve a percent reduction in greenhouse gas emissions that's equal or more than outlined in the Paris agreement.
San Francisco Mayor Ed Lee says rising water levels and affordable housing are concerns for his city.