Larry Summers, the Harvard professor, former Treasury secretary, and National Economic Council director, has a piece in Monday’s Washington Post that that makes a very big claim: The steady progress of human civilization could now stop and go into reverse.

In the last three-quarters of a century, the world has steadily become a safer, healthier, richer place, he writes.

But President Donald Trump may be a tipping point. In particular, his actions in the past two weeks — failing, as Summers writes, “to convincingly reaffirm traditional U.S. security commitments to NATO and abandoning participation in the Paris global climate agreement” — may inflict such severe economic consequences as to alter the course of human progress.

Pulling out of Paris is also such a failure of moral leadership, he writes, that it “is probably our most consequential error since the Iraq War.”

As I wrote last week, Trump’s decision on Paris was cruel in the message it sends about how America values the environment, and how little it now cares about the risks climate change poses to the planet. Though the doomsayers like Summers could turn out to be wrong, many, many experts believe it is likely to prove incredibly damaging to America’s strategic position in the world, our military’s operations, and our standing in international negotiations.

The damage could unfold for years to come not just for US diplomacy but also for US companies that want to do business overseas. Our business partners in Europe, for instance, may decide to penalize US companies with tariffs for the scientific backwardness of our leader.

And national security experts today say they are worried about how the decision creates a “strategic penalty” that will damage US national security in a number of ways.

“This ‘strategic penalty’ will come in terms of strained cooperation with our partners and allies who are dismayed and insulted by the move, as well as in terms of our strategic strength vis-à-vis our competitors and adversaries in the world,” said Francesco Femia, co-president of the Center for Climate and Security, a security think tank. “These competitors and adversaries will likely seize on this decision to expand their influence at our expense, whether that's in the Asia-Pacific, the Arctic, the Middle East and North Africa, or anywhere else the US is engaged. It's a blow to our leadership, and that will take time and great effort to recover from.”

These are not things that Trump is apparently worried about — but they may very well affect people close to him, like Secretary of State Rex Tillerson, in the near future. And more broadly, this move on Paris will be a stain on his presidency and could prevent his ability to do business and expand the Trump brand for years to come.