Why is the president so sanguine about clean energy? He lays out four reasons.

First, he says that the United States has proven that an advanced economy can grow without greenhouse gas emissions growing too—a phenomenon that in energy jargon is called decoupling.

“CO2 emissions from the energy sector fell by 9.5 percent from 2008 to 2015, while the economy grew by more than 10 percent,” he writes. (This decline has been due in some part to the replacement of coal-generated electricity with natural-gas burning, but more on that in a bit.)

Second, many businesses will continue to make energy-efficiency investments, he says—though he adds that some of these investments were only possible thanks to federal energy-efficiency standards. Third, the power sector is already switching electricity plants from coal to natural gas and is unlikely to migrate back to coal. Finally, the entire world is moving toward clean energy and investing in renewable development, he says. If nothing else, it will tug the United States along with it. (Just last week, China committed to spending at least $360 billion on renewable energy by 2020.)

It’s the third time in a week that Obama has taken to a preeminent journal to defend his legacy. On Thursday, he wrote a commentary for the Harvard Law Review on the chief executive’s role in criminal-justice reform. The next day, he warned in The New England Journal of Medicine against repealing the Affordable Care Act without a replacement.

You could understand this publishing streak as the wonk president taking a final, well-credentialed bow—or as Obama, the great establishmentarian, making one last appeal to the institutions that made him and bolstered his presidency.

To my eye, the most interesting part of the president’s paper is his point about natural gas and power generation. In 2016, natural gas surpassed coal and became the largest generator of electricity in the United States. Obama argues, basically, that the fuels won’t switch back. In this argument he makes two different references to “near-term federal policy.” It seems he is talking about Trump without ever actually saying “Trump”:

Because the cost of new electricity generation using natural gas is projected to remain low relative to coal, it is unlikely that utilities will change course and choose to build coal-fired power plants, which would be more expensive than natural gas plants, regardless of any near-term changes in federal policy. Although methane emissions from natural gas production are a serious concern, firms have an economic incentive over the long term to put in place waste-reducing measures consistent with standards my Administration has put in place, and states will continue making important progress toward addressing this issue, irrespective of near-term federal policy.

The president is making two arguments by allusion here. First, he is warning that even if the Trump administration soon subsidizes coal mining, those subsidies will not last long enough to justify new coal power plants. Second, he is asserting that the EPA’s recent restrictions on natural-gas leaks—a regulation that Republicans in Congress have sworn to repeal— are in the best interest of the entire energy industry.