(CNN)As the reaction to President Donald Trump's decision to pull out of the Paris climate accord splits largely along party lines, one man who has advised presidents from both parties accused Trump Thursday night of committing "one of the most shameful acts" in America's history.
Gergen: Why Trump committed one of US's most shameful acts
Defending the decision during a speech at the White House, Trump said, "As someone who cares deeply about our environment, I cannot in good conscience support a deal which punishes the United States," and "the Paris accord is very unfair at the highest level to the United States."
But David Gergen, who advised former Presidents Richard Nixon, Gerald Ford, Ronald Reagan and Bill Clinton, strongly called out Trump's decision during an appearance on CNN's "Erin Burnett Outfront."
"Some 70 years ago, the United States entered an international agreement called the Marshall Plan, when we came to the aid of Europe, and it was one of the noblest acts in human history," he said. "Today we walked away from the rest of the world, and it's one of the most shameful acts in our history."
Gergen added that "we're the largest contributor to carbon dioxide in the world, and for us to walk away as this carbon dioxide threatens the future of our grandchildren -- for us to walk away from that, it's grotesquely irresponsible."
He also predicted that the decision "will widely be seen around the world as a terrible, terrible setback for the planet," and that poor nations will pay the greatest price for global warming, even though the US has contributed the most to global warming while poor nations have contributed the least.