President Donald Trump declared the end of a "war on coal" Tuesday, as he moved to curb rules that underpin American emissions targets and a major global climate accord.
Following through on an election promise, Trump signed an order to review some of his predecessor Barack Obama's climate legacy, declaring an end to "job-killing regulations."
In a maiden trip to the Environmental Protection Agency, he ordered a review of emission limits for coal-fired power plants and eased up restrictions on federal leasing for coal production.
Trump said the measures herald "a new era in American energy and production and job creation."
Critics say that rolling back Obama's Clean Power Plan is unlikely to result in a boost to production or to create substantial numbers of jobs.
America's coal industry has long been in decline, with natural gas, cheap renewable energy, automation, and tricky geology making the sooty fuel a less lucrative prospect.
In 2008 there were 88,000 coal miners in the United States, according to the US Energy Information Administration.
Today, the number of coal miners has fallen around 25 percent. More people work in Whole Foods, an upscale supermarket chain.
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But some experts and environmental groups warned Trump's order could be the opening salvo of an effort to undermine internationally agreed targets under the Paris Climate Accord.
Curbing emissions from coal-fired power plants was a pillar of America's commitment to cut carbon emissions by 26-28 percent by 2025.
"It will make it virtually impossible" for the US to meet its target said Bob Ward, a climate specialist at the London School of Economics.
The Trump administration has not said whether it will pull out of the Paris deal. "Whether we stay in or not is still under discussion," a senior administration official told AFP.
Veterans of the Obama administration played down the impact of Trump's actions.
Obama's former chief environmental advisor described the executive order as "terrible" but said "it isn't the ball game."
He added that any damage can be mitigated in the courts and in states, which are tasked with coming up with emissions reduction plans.