“I am fighting every day for the great people of this country. Therefore, in order to fulfill my solemn duty to protect America and its citizens, the United States will withdraw from the Paris climate accord,” said Trump. He also said he would “begin negotiations to re-enter either the Paris accord or a really entirely new transaction on terms that are fair to the United States, its businesses, its workers, its people, its taxpayers.”

“And if we can’t, that’s fine,” he added.

Despite his decision to withdraw, the president will cohere to the legal terms of Paris. This means that the United States will not be able to give notice of its departure from the agreement until November 4, 2019, three years after the accord entered into force. And the country will not technically leave Paris until November 4, 2020—one day after that year’s presidential election.

What will this actually do to the Earth’s climate? For those of us who have to live with the consequences of global warming—who plan on seeing 2060, or at least expect our children to see it—will this make their lives worse? Or will it have no effect at all?

To fully answer that question, it requires stepping back and looking at other big things: how the Paris agreement works, and how the rest of the international community plans to avoid the worst of global warming.

As I wrote earlier this week, the Paris Agreement works by a delicate consensus mechanism: Instead of mandating restrictions from the top down, it asks every country to submit a nonbinding, voluntary plan to reduce its own emissions. Starting in 2020, and every five years after that, countries will issue new plans describing how they will further decrease emissions.

The nonbinding nature of the treaty allowed powerful but rapidly developing countries like India and China to sign on. Their participation sets the agreement apart from the Kyoto Protocol, an earlier attempt at an international climate-change treaty. Kyoto, whose negotiations were led in part by then-Vice President Al Gore in 1997, faltered after George W. Bush abandoned it during his first months in office.

The Paris Agreement’s voluntary nature also permitted the Obama administration to join the agreement through executive fiat. A Republican-controlled U.S. Senate would never have ratified a climate treaty, much less a binding one. From the U.S. legal perspective, Paris is essentially a UN resolution. Almost every clause describing U.S. involvement says that this country “should,” not that it “will”—a meaningful legal difference.

Now, however, there is a different president, and the international politics of climate change have shifted. More than 140 countries have now ratified the Paris accord, meaning that it will stay in legal force even if the United States leaves. And China, sensing an opportunity, has taken up the mantle of diplomatic leadership on this issue. It has joined with the European Union and promised to uphold the promises they made under the agreement. (Apart from the U.S., China and the EU are the two other major historical emitters of heat-trapping gases.)