Signs have been increasing for weeks that Trump was heading toward pulling out of the Paris agreement, apparently believing that a continued US presence in the accord would harm the economy; hinder job creation in regions such as the Appalachia and the West, where his most ardent supporters live; and undermine his "America first" message.

At home, he faced urgent pleas from corporate leaders, including Tim Cook, the chief executive of Apple, who told Trump this week that pulling out was wrong for business, the economy and the environment. Elon Musk, the chief executive of Tesla, threatened to resign from two White House advisory boards if the president withdrew from the Paris agreement.

On his recent trip to Europe, Trump waved aside a barrage of private lobbying by other heads of state to keep the US in the agreement.

Trump has shown a willingness to shift direction up until the moment of a public announcement. He met on Wednesday with Secretary of State Rex Tillerson, who has advocated that the US remain a part of the Paris accord. Other advisers pressing Trump to remain were furiously making their case.

David Rowe

"The actions of the United States are bound to have a ripple effect in other emerging economies that are just getting serious about climate change, such as India, the Philippines, Malaysia and Indonesia," said Michael Oppenheimer, a professor of geosciences and international affairs at Princeton, and a member of the Intergovernmental Panel on Climate Change, a United Nations group that produces scientific reports aimed at informing global policymakers.

Once the fallout settles, he added, "it is now far more likely that we will breach the danger limit of 3.6 degrees", the average atmospheric temperature increase above which a future of extreme conditions is considered irrevocable.

The aim of the Paris agreement was to lower planet-warming emissions enough to avoid that threshold.


"We will see more extreme heat, damaging storms, coastal flooding and risks to food security," Oppenheimer said. "And that's not the kind of world we want to live in."

Donald Trump denies he had any help from Russia. Bloomberg

Foreign policy experts said the move could damage the US's credibility and weaken Trump's efforts to negotiate issues far beyond climate change, like trade and terrorism.

"From a foreign policy perspective, it's a colossal mistake, an abdication of American leadership," said Nicholas Burns, a retired career diplomat and an undersecretary of state for President George W. Bush.

"The success of our foreign policy - in trade, military, any other kind of negotiation - depends on our credibility," Burns said. "I can't think of anything more destructive to our credibility than this."

But Trump's supporters, particularly coal-state Republicans, have cheered the move, celebrating it as a fulfillment of a signature campaign promise. Speaking to a crowd of oil rig workers a year ago, Trump vowed to "cancel" the agreement. Stephen Bannon, Trump's chief strategist, has pushed the president to withdraw from the accord as part of an economic nationalism that has so far included pulling out of the Trans-Pacific Partnership, a multilateral trade pact, and vowing to renegotiate NAFTA.

Coal miners and coal company executives in states such as Kentucky and West Virginia have pushed for Trump to reverse all of President Barack Obama's climate change policies, many of which are aimed at reducing the use of coal, considered the largest contributor to climate change.

The New York Times