President Donald Trump withdrew the United States from the Paris climate agreement, a landmark 2015 accord that seeks to avoid some of the worst effects of climate change. A primer on how the Paris agreement works — and what could happen next.

Q: What does the Paris climate deal actually do?

A: Under the Paris agreement, every country submitted an individual plan to tackle its greenhouse gas emissions and then agreed to meet regularly to review their progress and prod one another to ratchet up their efforts as the years went by.

Unlike its predecessor, the Kyoto Protocol, the Paris deal was intended to be nonbinding, so that countries could tailor their plans to their situations.

Under the deal, the Obama administration pledged to cut domestic greenhouse gas emissions 26 to 28 percent below 2005 levels by 2025 as well as to commit up to $3 billion in aid for poorer countries by 2020. The United States has delivered $1 billion to date.

There is some evidence that the Paris deal's "soft diplomacy" is nudging countries toward greater action. A Grantham Research Institute study found that the mere existence of the accord had prodded dozens of countries to enact new clean-energy laws.

Q: Can the U.S. just withdraw?

A: The withdrawal mechanism takes four years. A future administration could rejoin.

The United States could face serious diplomatic repercussions for leaving. Europe, China and other countries may threaten to withhold cooperation on issues the Trump administration cares about or impose carbon tariffs on the U.S.

Q: What does withdrawal mean for U.S. climate efforts?

A: Pulling out of Paris will not mean the end of all domestic efforts to reduce emissions. States like California and New York plan to keep pursuing their own programs to clean up power plants and vehicles. And the private sector is already shifting toward cleaner energy.

But the U.S. will be doing far less about global warming. A recent analysis by the Rhodium Group estimated that, under Trump's policies, U.S. emissions will most likely fall 15 to 19 percent below 2005 levels by 2025, rather than the 26 to 28 percent that the Obama administration pledged.

New York Times