During his campaign for president, Donald Trump said he hoped to pull the U.S. out of the Paris climate agreement -- the first global treaty to tackle global warming, signed by more than 190 countries. He doubled down on his assertion in the weeks following his inauguration, and many in America and around the world grew troubled that the U.S. may renege on its commitments.

This week former New York City Mayor Michael Bloomberg boarded a trans-Atlantic flight to meet with Paris Mayor Anne Hidalgo and French President Francois Hollande. Perhaps in an effort to ease minds across the pond, the group discussed the progress cities are making on climate change, including in the United States.

Bloomberg insisted that American cities and businesses have no intention of breaking their promise to the world.

“I communicated to President Hollande that American cities, states and businesses will deliver the U.S. commitment to the Paris Agreement,” he said in a press statement. "In the U.S., action by state and local governments and businesses has replaced half the country’s coal-fired power production with cleaner forms of energy and put the country on an irreversible path to meet our Paris commitment -- irrespective of future national policies.”

Analysis by the Sierra Club’s Beyond Coal campaign, supported by Bloomberg Philanthropies, backs up this assertion: Coal retirements and new clean energy through 2025 will reduce U.S. carbon emissions by at least 437 million metric tons. That accounts for 60 percent of America's commitments under the Paris agreement.

And actions already underway by leading U.S. cities, states and businesses are poised to close the gap: 12 American cities alone can deliver up to 131 million metric tons of CO2 savings by 2025, according to C40, a group that connects 90 global cities representing over 650 million people around climate action.

Some of C40's American members are at the top of the pack when it comes to delivering on our stated greenhouse gas reduction targets -- and their mayors quickly rallied behind Bloomberg, saying they have no plans to back down to the Trump administration. Let's take a closer look at the leaders (in alphabetical order).

1. Atlanta

Fun fact: Atlanta Mayor Kasim Reed is the only U.S. city leader on the board of the Global Covenant of Mayors for Climate and Energy. But that's only the start of how Georgia's largest city is taking on climate change.

“The city of Atlanta leads the nation in square footage of commercial building space committed to energy efficiency through the Better Buildings Challenge," Reed said in a press statement. "In addition, we deployed electric vehicles in the city’s fleet and installed solar panels on municipal facilities. Local actions like these show that cities are where hope meets the street."

Atlanta’s citywide sustainability initiative, Power to Change, united more than 300 stakeholders, including residents, schools and businesses.

The resulting Climate Action Plan calls for a 20 percent reduction in GHG emissions by 2020, using 2009 as a baseline. That target increases to 40 percent by 2030. The city set economic, environmental and social targets in its plan -- from educating companies about resource efficiency to increasing renewables and energy efficiency.

“We are engaging in the tough but necessary work to pioneer a cleaner path forward," Reed insisted. "In such a connected and economically competitive world, it is up to cities now to work together to push ahead. We won’t slow down, and we won’t change course.”

2. Austin, Texas

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The capital city of the Lone Star state has big plans for climate action. Austin is targeting carbon neutrality for city operations by 2020, a goal officials set only five years ago but are confident they can meet. Austin is set to hit net zero emissions by 2050 if all goes as planned.

And regardless of what happens in Washington, the city has no plans to back down.

“Austin will not stop fighting climate change," Mayor Steve Adler said in a press statement. "Worldwide, cities will lead in achieving climate treaty goals because so much of what’s required happens at the local level. Regardless of what happens around us, we're still Austin, Texas.”

3. Boston

Boston released its first citywide climate action plan on Earth Day 2011, and it updates the plan every three years. The most recent iteration, launched in 2014, calls for greater climate preparedness and community engagement.

When it comes to the metrics, Boston targeted a 25 percent reduction in GHGs by 2020 -- a goal it reached seven years early. That puts the city well on its way to meeting its whopping emissions 80 percent cut by 2050. The 2014 plan sets sector-specific targets so residents, businesses, institutions and government know what's expected of them.

Boston Mayor Martin J. Walsh joined his peers in "reaffirming" his pledge to support the Paris Agreement. "To compete in a 21st century economy, cities across the country must proactively prepare and reverse the course of our changing climate to safeguard our future," Walsh said in a press statement. We couldn't agree more.

4. Chicago

Chicago has emerged as a favorite punching bag for the Trump administration.

And while the city's spike in violent crime is troubling to residents and outsiders alike, Chicago is hardly the first major city to have this problem. Its neighbors like Detroit, Cleveland, Baltimore and Newark, New Jersey, make regular appearances on those 'highest murder rate lists,' an unwanted title Chicago didn't even earn last year. (The city ranked No. 8 in the nation.) But like its neighbors, Chicago and its residents do not let struggles with crime define them.

The city is home to North America's largest and longest-running GHG reduction program. From 2003 to 2010, this included a comprehensive cap-and-trade program with offsets. In 2011, the Chicago Climate Exchange launched an official Offsets Registry Program to register verified emission reductions based on established protocols.

Its climate action plan targets improvements for the entire metro area, home to more than 10 million people. The five-pronged plan tackles energy efficiency, renewable energy, improved transportation and more -- and every target includes an estimated greenhouse gas reduction, so leaders and residents know what's necessary to make the math add up.

"Last month I released our most recent emissions report showing a 7 percent decline in Chicago’s carbon footprint while we grow our population and jobs," Chicago Mayor Rahm Emanuel said in a press statement. "We will continue to take bold action locally to reduce our emissions and combat climate change, and to urge mayors and leaders across the country to do the same.”

5. Houston

“For too long, Houston has seen the devastating impacts of climate change, from severe flooding to historic droughts. But Houston is resilient and our city is working harder than ever to build a sustainable economy and future that will shield our community from a changing climate," Houston Mayor Sylvester Turner said in a press statement.

"With hundreds of miles of bike networks, increased energy efficiency in homes and renewable energy sources in city buildings, we’re working with every citizen in Houston to do our part and show our collective commitment to action."

He's not wrong: The city began goal-setting for climate action back in 2008. Its expansive bike network spans 345 miles. And it now meets a little over 10 percent of its energy needs with renewable power, making it one of the nation's top 10 clean energy users. The city is in the process of finalizing its most recent sustainability action plan.

6. Los Angeles

“We will do all we can in Los Angeles to meet the goals of the Paris Climate Agreement, regardless of what happens in Washington. And we are already doing our part," said Mayor Eric Garcetti, who serves as vice-chair of C40 under Hidalgo of Paris.

Los Angeles is home to the largest municipal fleet of pure electric vehicles in the country, as well as the most publicly available EV charging stations, Garcetti claimed. And as of 2013, the city reduced greenhouse gas emissions by 20 percent since 1990 while creating 20,000 green jobs.

Last November, voters overwhelmingly approved a $120 billion investment in public transit, including light rail, subways, bike lanes and "other measures that will drive down emissions," the mayor asserted in a press statement. The city's climate action plan calls for a 45 percent reduction in GHGs by 2035 and an 80 percent cut by 2050.

7. New Orleans

“The city of New Orleans is on the frontlines of climate change and no matter who holds office in Washington, D.C., that fact will not change," Mayor Mitch Landrieu said in a press statement. "Reports of the U.S. pulling out of the Paris Agreement are deeply troubling to our community."

For its part, New Orleans is surging forward. Last year Landrieu partnered with the Trust for Public Land and the Greater New Orleans Foundation to develop a public data and mapping tool to inform green infrastructure decisions. Community groups like the Lower Ninth Ward Center for Sustainable Engagement and Development advocate for sustainable rebuilding methods and for the neighborhood to become carbon-neutral by 2030. The mostly low-income district was among the hardest hit by Hurricane Katrina.

And as the city faces down inevitable flooding, a new resilience plan aims to stop fighting it -- with infrastructure that's built intentionally to let water in.

"It would be an abdication of our commitment to protect and strengthen our communities to do anything less than shield our citizens from the devastating impacts of a changing climate that New Orleans knows all too well," Landrieu said. "As U.S. cities, we stand committed to joining fellow mayors and national leaders on the global stage to let the world know that we are ready to get the job done.”

8. Oakland, California

Adopted by the city council in 2012, Oakland's energy and climate action plan calls for a 36 percent cut in GHG emissions by 2020, using a 2005 baseline. Action items include taking vehicles off city streets, boosting renewable energy and increasing waste diversion.

“Cities across the country are increasingly becoming hubs of change through innovative climate action," Oakland Mayor Libby Schaaf said in a press statement. "Meanwhile, like so many committed communities in the U.S. and around the world, our work is only just beginning."

9. Phoenix

With its drought-prone climate and sky-high temperatures, Phoenix has a lot to contend with when it comes to reducing emissions. But that didn't slow the Arizona city down.

In 2015, Phoenix met its target to reduce GHG emissions by 15 percent from a 2005 baseline. It blew past its previous target, a modest 5 percent cut, three years ahead of schedule. The city will soon set 2025 targets to further reduce emissions.

With plans to bolster public transportation and renewable energy, Phoenix hopes to become a zero-waste, carbon-neutral city by 2050, Mayor Greg Stanton said in a press statement.

“Phoenix will continue to show how swift and ambitious action at the local level, combined with committed partners around the globe, can advance climate progress," Stanton said. "In Phoenix, we can’t afford to wait, and we know that our best defense is offense."

"Our economic vitality and sustainable future depends on action against a fiercely changing climate," Stanton went on. "If we are going to make a global-scale impact, then cities must lead to ensure a successful implementation of the Paris Agreement.”

10. Pittsburgh

Pittsburgh's most recent climate action plan calls for a 20 percent reduction in GHG emissions by 2023, using 2003 as a baseline. And the Pittsburgh Climate Initiative brings stakeholders from across the city together to achieve this goal.

"Regardless of the vision at the national level on climate change, Pittsburgh will continue on our path," Mayor William Peduto said in a press statement. "And we’re not alone."

11. Portland, Oregon

In 1993 Portland introduced America's first city-focused action plan, and "we haven't looked back," said Mayor Ted Wheeler.

Its most recent climate action plan calls for an aggressive 40 percent reduction in carbon emissions by 2030 and an 80 percent cut by 2050, compared to 1990 levels.

"No matter which way the winds are blowing in Washington, Portland has always continued to innovate and implement ambitious new policies to achieve a low-carbon future," Wheeler insisted. "Now our climate leadership is needed more than ever."

12. San Francisco

It's no secret that 3p's home city of San Francisco is serious about climate change. It hopes to cut GHGs by 25 percent below 1990 levels by the end of this year, on the way to a 40 percent cut by 2025. The city is also targeting zero waste and 100 percent renewable energy for residential buildings.

“In the face of national uncertainty, San Francisco is more committed than ever to providing real solutions to climate change,” said San Francisco Mayor Edwin M. Lee. “We know that San Francisco and other cities worldwide must continue to lead by taking bold actions that reduce greenhouse gas emissions."

13. Seattle

Seattle is home to one of the country's most aggressive emissions targets: The city hopes to curb transportation-related emissions by 80 percent by 2030, and reach net-zero emissions citywide by 2050. Its climate action plan also includes provisions to "foster economic prosperity" and "enhance social equity," meaning officials don't intend to let the city's economy or its citizens suffer as a result of its sustainability goals.

"The United States is facing a watershed moment on climate change. In Seattle, we’re committed to being environmental stewards and guardians of our climate progress," Mayor Ed Murray said in a press statement. "To protect our climate progress, we’re delivering boldly on the goals set by the Paris Agreement because now, the future is in our hands.”

14. Washington, D.C.

While Washington, D.C.'s most famous new resident seems hell-bent on deriding America's commitment to the Paris climate agreement, its local government has different ideas.

The city hopes to halve greenhouse gas emissions by 2032, using 2006 as a baseline, on the way to the coveted (and science-based) 80 percent cut by 2050.

“The tides may have turned in Washington, D.C., but one election does not change our values or commitments," insisted Mayor Muriel Bowser. "As mayors, our work to strengthen and protect our communities from the rising impacts of climate change must continue and that commitment matters."

"If all U.S. mayors come together to pursue rapid emissions reductions within our cities, by 2025 we can contribute more than one third of the emissions reductions needed to meet the U.S.'s commitment to the Paris Agreement."

What is your city doing to address climate change? Do a quick Web search to find out. If your city does not have a stated climate action plan, contact your mayor, city council and representatives to change that.

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