Last Thursday, President Trump announced that the U.S. would withdraw from the Paris Climate Agreement. What are the implications of this move?

In practical, real-world terms, very little. After all, President Trump has been steadily rolling back Obama-era policies designed to curb climate change, as well as proposing massive budget cuts in scientific research and many environmental programs, so it was unlikely that the U.S. would meet its own ambitious goals that were spelled out in the agreement (reducing greenhouse gas emissions 26 to 28 percent from 2005 levels by the year 2025) … at least in the short term.

Some have even argued that, given Trump’s apparent unwillingness to meet these climate change targets, remaining a party to this agreement with no intention of working toward its goals would be dishonest … and only inspire others to do the same.

But, in another very real sense, the implications of this move are profound. It is sending a signal to the rest...