President George W. Bush punted on the issue. President Obama's team tried but failed. President Trump might be the first chief executive to regulate power plants' greenhouse gas emissions.
The Trump administration is expected to soon release its much-anticipated plans for tearing down the Obama administration's Clean Power Plan. That rule would have set nationwide limits for greenhouse gases from utilities—the largest U.S. source of heat-trapping gases. But it was halted by the Supreme Court last year—well before states would have been required to write plans to comply and years before actual reductions were mandated. Trump's election was its death knell.