United States cities will lead the fight against climate change by working harder to reduce emissions, switch to cleaner energy, and protect residents from sea-level rise even as Washington refuses to formally acknowledge global warming as a problem, mayors said this week.

As the US Conference of Mayors wrapped up on Monday in Miami Beach, Fla., a city that's at the forefront of the fight against rising waters, the message was clear: cities aim to ensure the US remains a leading global player in climate policies and innovation, and mayors will sidestep Washington to achieve their goals.

More than 250 mayors at the event signed nonbinding resolutions including a cities-driven plan to slow climate change – though no emissions targets were set – and a target to power their communities with 100 percent renewable energy by 2035.

The growing Climate Mayors movement also saw new mayors signing a letter agreeing to abide by the Paris accord and step up efforts to reach city climate targets. The letter now has 330 mayoral signatures.

"We are creating a groundswell of climate leadership by the mayors because cities large and small, rural and urban, in blue and red states, experience the effects of climate change every single day," Los Angeles Mayor Eric Garcetti said. "Climate change touches us all and unites us."

US cities are scrambling to fill a leadership void and assert their role as a leading force against global warming after President Trump decided to withdraw from the Paris climate accord earlier this month, raising the risk of potential changes to carbon emissions regulations and energy policy.

Under the Paris deal, former President Obama's administration vowed to cut greenhouse gas emissions by 26 percent to 28 percent below 2005 levels by 2025.

In the only pledge that was backed by financing, former New York City Mayor Michael Bloomberg committed $200 million to support city initiatives including projects to combat global warming through a grant program called the American Cities Initiative.

"We are expanding our support to empower mayors so they can meet the challenges of climate change and support what was laid out in Paris, no matter what happens in Washington," Mr. Bloomberg told a cheering crowd on Monday.

"On nearly all issues, Washington has been AWOL, and as further cuts loom, the situation will go from bad to worse," he said.

After Mr. Trump's decision, Bloomberg offered $15 million to support the United Nations' efforts to tackle climate change and has been the loudest voice in the campaign to empower cities, businesses and citizens to take charge to combat global warming.

He took advantage of the rock star treatment he received at the mayors' conference to promote his new book "Climate of Hope: How Cities, Businesses and Citizens can Save the Planet."

A strong message of bipartisanship set the tone of the speeches and committee meetings, and humor was often used in reference to Trump's dismissal of the increasingly clear effects of climate change.

"Politics has almost no influence on science, in case you haven't noticed," former President Bill Clinton told a packed ballroom at Miami Beach's iconic Fontainebleau Hotel on Saturday.

Miami Beach Mayor Philip Levine said Trump should be concerned about sea level rise in front of his Mar-a-Lago resort in Palm Beach.

"I'm not really sure if he wants to turn that into a water park," Mr. Levine said.

As the host of the annual conference, Levine showed off his anti-flooding efforts by taking New York City Mayor Bill de Blasio and others on a tour of Sunset Harbor, considered Miami's ground zero for the fight against climate change.

There streets have been raised and pumps installed to keep water away from luxury condos and upscale restaurants.

Accompanied by his chief engineer Bruce Mowry, whom the mayor calls "Pump Man," Levine bragged about how the thriving economy allowed the city to raise more than $400 million for anti-flooding projects through tax increases.

Though cities appear are showing newfound urgency to tackle climate change after Trump's decision, it remains to be seen if the pledges made in Miami will translate into action.

Skeptics were quick to point out that in 2007 more than a thousand US mayors signed a pledge to meet the emissions cuts mandated under the Kyoto Protocol, but virtually all of them missed the targets.

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Large US cities such as New York and Chicago are currently on track to miss current targets, Washington Policy Center director Todd Myers wrote in a June 15 column for the National Review.

"The failure of these cities to achieve existing goals is a stark demonstration of the gap between environmental rhetoric and results from those who style themselves as environmental heroes," he wrote.