By John Light / Moyers and Company

Last week, President Donald Trump delivered on years of promises to his supporters and spat in the face of the world by pulling out of the Paris Agreement on climate change. After the announcement, many of our allies publicly denounced the US — but, privately, reacted with relief that the US had cleared the field for countries who take climate change seriously to ramp up their efforts.

In his Rose Garden speech to announce America’s withdrawal, Trump said his administration hoped to “begin negotiations to re-enter either the Paris accord, or a really entirely new transaction with terms that are fair to the United States.”

America’s European allies issued a statement almost immediately, saying they had no interest in renegotiating with Trump.

“I was elected to represent the citizens of Pittsburgh, not Paris,” Trump said.

Pittsburgh Mayor Bill Peduto promptly replied, “Pittsburgh stands with the world and will follow Paris agreement.” The city was one of 83 to sign onto a agreement promising to uphold the Paris Agreement.

As many have noted, Trump’s decision seems to have been based entirely on ideology — his need for “wins,” his need to cater to his base’s tribalism, his love of trolling. The facts and figures in his speech were handed to him by the National Economics Research Associates (NERA), a consulting firm that produces lobbying materials for fossil fuel companies.

But there was a silver lining to Trump’s decision. Trump chose to withdraw from the Paris Agreement in a way that will take four years. That means if another candidate manages to defeat him in the 2020 presidential election, the ultimate decision of whether or not to pull out will fall to that individual.

Under the deal, no country can pull out until three years after the agreement went into effect, which happened in November 2016. That means the US cannot officially begin the process of leaving the agreement until November 2019. From that point, it takes a year for withdrawal to be complete.

In the meantime, he said in his speech, and a senior White House adviser confirmed, he will ignore President Barack Obama’s promises under the agreement. Even though the US won’t be officially out until 2020, we will begin acting as if we have left immediately by abandoning Obama’s emission-reducing policies. Trump has also made clear he will not fulfill Obama’s promises to provide billions to help developing countries prepare for climate change. An initial promise of $3 billion has only been partially fulfilled, and the remaining payments won’t be coming under Trump.

US emissions had been declining in recent years, but that will stop — according to an analysis by the Rhodium Group, they’ll hold steady around 14 percent below 2005 levels, a far cry from the reduction of at least 26 percent Obama promised.

The White House was reportedly considering more drastic options for US withdrawal that would have been faster but even more damaging to US involvement in global climate efforts. Trump could have declared the Paris Agreement a treaty, which would require the ratification in the Senate, where US involvement would die a slow death at the hands of fossil fuel industry-financed politicians.

Likewise, Trump could have pulled out of the United Nations Framework Convention on Climate Change, the legal agreement that undergirds the Paris Agreement, signed by George H.W. Bush in 1992. That drastic move would have been an even more dramatic rebuke to the rest of the world. “Leaving the Paris Agreement is a bridge too far,” Wendel Trio, director of Climate Action Network Europe, told us — but pulling out of the UNFCCC “would be almost a declaration of war.”

Trump chose not to take those more dramatic pathways and instead opted to leave the Paris Agreement through the four-year-long withdrawal process. And in doing so, Trump has given voters the opportunity to speak out on climate change in a way they rarely have.

While polls show that Americans in every state support the Paris Agreement, and voters — including about half of Republicans — support government action on climate change, the issue rarely motivates who Americans vote for, in part because the issue is a complicated one and the solutions to it so abstract.

In 2020, voters will have something concrete to vote on: Does the US engage with the rest of the world on climate change, or remain a pariah? Specifically: Does the US stay in the Paris Agreement, or quit?