This week President Donald J. Trump may decide to yank the United States out of the Paris climate accord. Because most Americans believe that climate change is real and important, the action will probably further erode his approval ratings. At the same time, it will likely energize his political base, to whom he has repeatedly promised this step. (Trump has said that the Paris agreement simultaneously does nothing and shackles the U.S. economy.) What his decision will not do is have much effect on U.S. greenhouse-gas emissions, at least in the short term. Nor is it clear that it will lead to the United States actually withdrawing from the Paris climate accord. It is an almost purely symbolic gesture—a raised middle finger to the coastal elites whom many Trump supporters identify as their political enemies.

In a sense, this is because the treaty itself is mainly symbolic. Explaining this requires dipping one’s toes into the murky, acronym-filled water of international diplomacy. Under the Paris agreement, every one of the 147 signatories issues what is called an “intended nationally determined contribution” (INDC), which amounts to a promise that the nation will take certain actions to reduce greenhouse-gas emissions by a certain date. Every nation’s INDC is different, but all are alike in one way—they are completely voluntary, and there is no penalty for not fulfilling them.

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The U.S. INDC, for example, sets a “target” of cutting greenhouse-gas emissions by “26-28 percent below its 2005 level in 2025,” with the hope of reaching 28 percent. There are several types of greenhouse gasses, but carbon dioxide is the most important. In 2005, according to the Environmental Protection Agency, the U.S. emitted 6,131 million metric tons of carbon dioxide. Simple arithmetic tells us that under the U.S. INDC, this figure would have to fall to about 4.660 million metric tons by 2025—a drop of 1.471 million metric tons. Between 2005 and 2015, the last year for which good data are available, U.S. emissions fell by .72 million metric tons—a hair less than half of the target. In other words, if the U.S. just keeps doing what it was doing, it will meet (or almost meet) its Paris commitment—even if the President withdraws.

Withdrawing from the treaty is the latter-day equivalent of President Ronald Reagan’s 1980s removal of the solar panels that President Jimmy Carter had installed on the White House—a nose-thumbing token of tribal membership. In an immediate practical sense, the withdrawal may have even less effect than removing the solar panels. Under Article 28 of the Paris agreement, no country can formally announce it is leaving the treaty until “three years from the date on which Agreement has entered into force.” Even then, the actual withdrawal doesn’t occur for another year. Because the climate pact was signed in November 2016, the United States cannot actually exit until November 2020—after the next presidential election. If Trump or some like-minded climate-change denier loses that election, it seems likely that the wizards of international diplomacy will find some way to let his successor cancel the withdrawal.