United Mine Workers of America International President Cecil E. Roberts slammed the Environmental Protection Agency's proposed new rule calling for a 30 percent reduction in carbon emissions. Roberts said the rules would lead to "long-term and irreversible job losses for thousands" without actually benefitting the environment.

"[N]o one -- no one -- can point to a significant reduction in global greenhouse gas emissions that is guaranteed to come from this rule," Roberts said Monday.

UMW estimated that there would be direct losses of 75,000 jobs in the coal, railroad and power plant industries by 2020.

The ripple effects would be severe, Roberts said: "[I]'s not just that these jobs will be lost, it's that the ability of companies to continue funding pension and retiree health care benefits will be at great risk. That puts hundreds of thousands more -- mostly senior citizens living on already-low fixed incomes -- squarely in the crosshairs of this rule."

UMW has long opposed the EPA's efforts to reduce carbon emissions on these grounds, arguing that the cost to workers far outstrips any benefit to the broader environment. While it endorsed President Obama in 2008, it refused to do so in 2012, citing his coal policy.

Roberts said the union did not dispute the science behind global warming, but said it was unfair for its members to bear the brunt of the policy change.

He also scoffed at the notion that "green jobs" would replace the ones lost by the industry. "I don't know how one can actually count jobs that do not yet exist."

During the 2012 election, AFL-CIO President Richard Trumka made the novel argument President Obama's coal policy was actually the doing of Republican nominee Mitt Romney. Republicans were at the time accusing Obama of waging a "war on coal."