One of the biggest questions facing American energy policy is the role of natural gas. The Clean Power Plan swaps gas in for coal, but that has led to higher methane emissions than previously projected. Natural gas can be cheaply had through domestic fracking, and Donald Trump has played up his support for the fossil fuel in states like Pennsylvania. On the other hand, fracking is undeniably a consequence of Obama's controversial "all of the above" energy platform, and though he seems to have moved away from it, the Democratic Party remains split on whether the climate impacts of methane are too dire to keep fracking.

If you do the climate math, the answer is even simpler: we have to stop building new fossil fuel infrastructure right away. 

If the Clean Power Plan is upheld, it will reduce carbon pollution from utilities by 30%. That would require a severe decrease in reliance on coal for electricity. The scheme will raise the cost for utilities to produce electricity, but not the price that consumers pay.

Despite the hold put on the Clean Power Plan, Obama has been able to reduce climate pollution through other domestic instruments. That includes expanding regulation to cover trucks and planes, using existing rules to require states to reduce unhealthy pollution that is cogenerated with carbon dioxide at coal plants, and withholding funding from states that don't comply.

The stay also didn't prevent the EPA from helping some states form carbon cap-and-trade style markets and defining a social cost of carbon that guides how government projects are evaluated.

The legal challenge to the Clean Power Plan essentially contends that the executive branch doesn't have the power to intepret laws passed by Congress in new ways based on new information. It's a sort of specific application of legal originalism that Justice Scalia, may he rest in peace, invoked in joining four other justices in staying the Clean Power Plan last year. 

Environmentalists had hoped a swift resolution to Scalia's death would strengthen the Clean Power Plan against a court challenge, but his ghost continues to haunt Obama: yesterday a judge invoked a Scalia precedent that suggests Congress, not regulators, must be the source of decisions with "economy-wide" impacts.