After more than a year of waiting, Barack Obama this week unveiled the final iteration of the Clean Power Plan, the EPA’s biggest environmental regulation issued to date. According to EPA Administrator Gina McCarthy, the estimated annual cost by 2030 will be $8.4 billion. But as with all government estimates, that number largely omits a comprehensive examination of the economic toll. When it comes to Obama’s agenda, we’re usually talking figures in the trillions of dollars, and this particular regulation is no different. A Heritage Foundation study published last month found that, by 2030, the Clean Power Plan will result in “[a] loss of more than $2.5 trillion (inflation-adjusted) in aggregate gross domestic product (GDP).” On the one hand, you have McCarthy advertising $8.4 billion in annual costs — a relatively minor expense all things considered — while on the other hand, an independent study puts that figure at $2.5 trillion over the next 15 years. The disparity is huge, and it can’t be blamed on a rounding error. Nor is it right-wing think-tank conspiracy. Take ObamaCare, for instance. What was originally calculated by the Congressional Budget Office to cost American taxpayers less than $1 trillion over a decade ballooned to more than $2 trillion, according to new CBO figures. You’ll discover a familiar trend with any government program. That’s why the most important thing Republicans can do is put a stop to the Clean Power Plan before it truly gets started.