Mayor Bill de Blasio wrapped up his visit to the Vatican today and is returning to New York City. The quick trip offered a chance to rub shoulders with mayors from around the world and Pope Francis as he tries to position his administration as a leader in fighting climate change. Our Grace Rauh has been covering the mayor at the Vatican and filed this report.

VATICAN CITY—Italy has been good to Mayor Bill de Blasio. His family roots are here—and on his second trip as mayor, the warm embrace the country offered last summer was still on display.

This time though the focus was climate change, with de Blasio participating in a two-day conference at the Vatican announcing new benchmarks for reducing greenhouse gas emissions in the city.

Seeing Pope Francis speak was a highlight for him, but it was hardly the only one. He got to practice his Italian, hobnob with mayors from around the world—and then there were the pictures. It's a good thing his arms are built to take selfies.

Jeffrey Sachs, who directs the Earth Institute at Columbia University and is a de Blasio ally, says it makes sense to have mayors come together to talk about environmental change and what to do about it.

"The mayors are on the front lines when the cities flood, when the water supply is short, when there's a drought, when there's some kind of epidemic it's the mayors who are handling it," Sachs said.

There was ample time for connections to be made with other politicians. De Blasio ate breakfast with the mayor of Rome and held a private meeting with California Governor Jerry Brown, who has been vocal on environmental causes. 

"Governor Brown, I think, has really been the national leader on these issues," de Blasio said.

The mayor is also talking up the importance of a global climate change meeting in Paris beginning in late November. Advocates hope it leads to an international agreement to reduce emissions. 

"Those of us at the local level have to build momentum toward Paris through local action. That's another thing I think California has been outstanding on. And one of the things I want to emulate in Governor Brown's approach is how we keep raising the bar," the mayor said.

Given the mayor's interest in coming here to the Vatican to participate in the climate change conference, it does seems likely that he would go to Paris to join in at least for part of the summit. He has not, however, been willing to commit to making that trip.