A coalition of 236 mayors of U.S. cities, collectively representing more than 51 million residents in 47 states and territories, urged the Environmental Protection Agency (EPA) to halt its plans for a complete repeal of the Clean Power Plan (CPP).

In a letter Tuesday to EPA Administrator Scott Pruitt, the mayors said they “strongly oppose” the proposed repeal, which they said would put their citizens at risk and damage efforts to address climate change.

The mayors cited a peer reviewed study, Climate Change Impacts and Risk Analysis (CIRA), which was conducted by the EPA in 2015. According to the mayors, CIRA portends that if global warming goes unchecked and increases by an average of four degrees Celsius by the year 2100, 50 cities in the U.S. would face up to $6.4 billion in annual adaptation costs for severe precipitation. Under that scenario, cities would also face $3.1 billion in annual damage and adaptation costs from rising sea levels and storm surges along the coasts, and up to $2.5 billion in damages from inland flooding.

“No one is insulated from the impacts of climate change — people in cities of all sizes, along with suburban and rural communities are all at risk,” the mayors wrote. “Residents of our communities have experienced harmful impacts of climate change such as dirtier air, increased heat-related illnesses and deaths, damaged and disappearing coastlines, longer droughts and other strains on water quantity and quality, and increasingly frequent and severe storms and wildfires.”

Signatories of the letter include New York City Mayor Bill de Blasio, Los Angeles Mayor Eric Garcetti, Chicago Mayor Rahm Emanuel, Houston Mayor Sylvester Turner and Philadelphia Mayor Jim Kenney.

The Trump administration first targeted the CPP last March, when the president issued an executive order calling for, among other things, a review of the CPP. EPA followed up with an announcement last October that it would ultimately repeal the CPP. Two months later, a biannual plan listing hundreds of rules in various stages of rulemaking at many federal agencies, including the EPA, showed a final rule to repeal the CPP is set for October 2018.

Last March, two organizations representing major U.S. cities — the Mayors National Climate Action Agenda (MNCAA) and the United States Conference of Mayors (USCM) — issued separate statements in support of the CPP. While the MNCAA took the additional step of condemning the Trump administration for targeting the CPP, the USCM did not do so.

The Obama administration unveiled the final version of the CPP in August 2015. The plan, which embraces renewables, solar and wind power, but not so much natural gas, calls for states to reduce emissions 32% below 2005 levels by 2030.

The CPP would require that states develop and implement plans to ensure power plants — either as single plants or as a collective group — achieve goals for reducing carbon dioxide (CO2) emissions between 2022 and 2029, and final CO2 emission performance rates by 2030. The CPP gave states the option of choosing between either an emissions standards plan or a state measures plan to reduce emissions. They also would have the option of trading emissions rate credits with other states.