After Donald Trump pulled out of the Paris Agreement earlier this month, effectively ignoring the will of the American people, CEOs of the nation's largest companies, and members of his own party, progressive leaders across the country vowed to battle climate change at the local level.

Today many of them will gather in Miami Beach for the 85th-annual meeting of the U.S. Conference of Mayors at the Fontainebleau. And though conference topics include immigration, health care, and the economy, environmental groups hope to get a commitment from the group to transition their cities to 100 percent clean, renewable energy by 2035.

"In light of what's happening at the federal level, mayors and local officials are going to have to drive the movement toward renewable energy," says Shane Levy, press secretary for the Sierra Club's Ready for 100 campaign.

Ready for 100 was launched last year to challenge 100 cities across the nation to commit to using 100 percent renewable energy. Miami Beach Mayor Philip Levine signed on in May, and just this week, Philadelphia Mayor Jim Kenney became the 100th U.S. mayor to come onboard.

To jumpstart the conversation, conference organizers are flying in British artist John Quigley, an environmental advocate who uses human participants to stage powerful aerial photographs. Today at 7 a.m., activists from South Florida and beyond assembled to spell out "100+ Mayors <3 100% Clean Energy" on the beach outside the conference hotel:

photo courtesy of Miami Aerial

"We would like to see the conference pass that resolution, and we know that there are opposing forces trying to kill the bill in committee, so we want to give it a strong show of support," says Emily Gorman, another Sierra Club organizer.

Although Ready for 100 has set a target goal of having cities transition to renewables by 2035, Miami Beach officials are considering ways to power all city buildings with clean energy by 2025. Doing so would greatly reduce the city's carbon footprint — in 2015, electricity accounted for more than three-quarters of all greenhouse emissions by the city government.

Though making the switch would come with a high upfront cost (officials estimate Miami Beach would have to buy at least $24 million worth of solar panels to generate enough energy), three U.S. cities have already made the transition. Burlington, Vermont, in 2015 became the first city to run completely on clean energy, while Greensburg, Kansas; and Aspen, Colorado crossed the finish line last year.

• Environmental