(ABC NEWS) -- President Trump will pull the United States out of the Paris climate accord, he said this afternoon.
The decision fulfills a key promise Trump made on the campaign trail and overturns a major accomplishment by his predecessor, Barack Obama.
The accord, which is sponsored by the United Nations, aims to slow the globe's rising temperature. Under Obama, the United States committed to cutting its carbon emissions by 26 percent to 28 percent from 2005 levels by 2025.
The United States officially entered the Paris agreement along with China on Sept. 3, 2016. Only 31 percent of respondents in an ABC News/Washington Post pre-inauguration poll in January said they supported withdrawing from the pact.
For many, Trump's decision is an indicator that the United States is pushing off inevitable work necessary to combat climate change.
"It means that that country that's most responsible for climate change has reneged on its promise to be part of the solution," said Timmons Roberts, a professor of environmental studies at Brown University. "It's very worrisome that we're delaying the inevitable work we need to do on this issue."
International policy experts say that the decision will also affect U.S. standing abroad.
"It will threaten our credibility in the world," said Nicholas Burns, a former U.S. diplomat and professor of international politics at Harvard University. "It may begin to create the impression that China is a more responsible country than the United States, and it might give a real boost to the Chinese because we will be seen as not doing our part on the biggest global problem."
On the Hill, some Senate Republicans had been calling for an exit. Senate Majority Leader Mitch McConnell of Kentucky and Sens. Rand Paul of Kentucky, Mike Lee of Utah and Ted Cruz of Texas, among others, sent a letter to Trump May 25 requesting he withdraw.
But other top Republicans in both the House and the Senate had urged the president to stay in the agreement.
"It would be taken as a statement that climate change is not a problem; is not real," Sen. Lindsey Graham of South Carolina said on CNN last week. "So that would be bad for the party, bad for the country."