David Gergen
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WASHINGTON, DC - JUNE 01: U.S. President Donald Trump arrives to announce his decision regarding the United States' participation in the Paris climate agreement in the Rose Garden at the White House June 1, 2017 in Washington, DC.
Chip Somodevilla/Getty Images
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WASHINGTON, DC - JUNE 01:  U.S. President Donald Trump arrives to announce his decision to withdraw the United States from the Paris climate agreement in the Rose Garden at the White House June 1, 2017 in Washington, DC. Trump pledged on the campaign trail to withdraw from the accord, which former President Barack Obama and the leaders of 194 other countries signed in 2015. The agreement is intended to encourage the reduction of greenhouse gas emissions in an effort to limit global warming to a manageable level.  (Photo by Win McNamee/Getty Images)
Win McNamee/Getty Images North America/Getty Images
WASHINGTON, DC - JUNE 01: U.S. President Donald Trump arrives to announce his decision to withdraw the United States from the Paris climate agreement in the Rose Garden at the White House June 1, 2017 in Washington, DC. Trump pledged on the campaign trail to withdraw from the accord, which former President Barack Obama and the leaders of 194 other countries signed in 2015. The agreement is intended to encourage the reduction of greenhouse gas emissions in an effort to limit global warming to a manageable level. (Photo by Win McNamee/Getty Images)
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WASHINGTON, DC - JUNE 01:  U.S. President Donald Trump announces his decision for the United States to pull out of the Paris climate agreement in the Rose Garden at the White House June 1, 2017 in Washington, DC. Trump pledged on the campaign trail to withdraw from the accord, which former President Barack Obama and the leaders of 194 other countries signed in 2015. The agreement is intended to encourage the reduction of greenhouse gas emissions in an effort to limit global warming to a manageable level.  (Photo by Win McNamee/Getty Images)
Win McNamee/Getty Images
WASHINGTON, DC - JUNE 01: U.S. President Donald Trump announces his decision for the United States to pull out of the Paris climate agreement in the Rose Garden at the White House June 1, 2017 in Washington, DC. Trump pledged on the campaign trail to withdraw from the accord, which former President Barack Obama and the leaders of 194 other countries signed in 2015. The agreement is intended to encourage the reduction of greenhouse gas emissions in an effort to limit global warming to a manageable level. (Photo by Win McNamee/Getty Images)
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US President Donald Trump departs after he announced his decision to withdraw the US from the Paris Climate Accords in the Rose Garden of the White House in Washington, DC, on June 1, 2017.     
"As of today, the United States will cease all implementation of the non-binding Paris accord and the draconian financial and economic burdens the agreement imposes on our country," Trump said. / AFP PHOTO / SAUL LOEB        (Photo credit should read SAUL LOEB/AFP/Getty Images)
SAUL LOEB/AFP/AFP/Getty Images
US President Donald Trump departs after he announced his decision to withdraw the US from the Paris Climate Accords in the Rose Garden of the White House in Washington, DC, on June 1, 2017. "As of today, the United States will cease all implementation of the non-binding Paris accord and the draconian financial and economic burdens the agreement imposes on our country," Trump said. / AFP PHOTO / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)
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Pool/Getty Images North America/Getty Images
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What happens if U.S. pulls out of Paris climate accord?
(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.

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.