The United States will become a "rogue country" if it decides to pull out of the Paris climate agreement, a former Irish president said.

"It would be a tragedy for the United States and the people of the United States if the U.S. becomes a kind of rogue country," Mary Robinson, former president of Ireland and human rights advocate, told Reuters on Sunday. "The only country in the world that is somehow not going to go ahead with the Paris Agreement."

U.S. President-elect Donald Trump is not a big fan of the international accord, even threatening to pull the United States out of the global climate pact. During his campaign, Trump openly denied climate change and even called it a "hoax."

Robinson, who is running a foundation focused on seeking justice for people hit hard by climate impacts despite having very little carbon footprint, warned that if the U.S. will pull out of the international agreement, the world and other countries would become more vulnerable to droughts and other climate extremes. She said she was confident other countries would continue their backing for the agreement regardless of any action taken by the U.S.

"I don't think that the process itself will be affected (if) one country, however big and important that country is, decides not to go ahead," she said during the United Nations climate talks in Marrakesh, which is due to end on Friday.

However, Robinson said that a withdrawal from the agreement would make a huge impact to the already difficult challenge of gathering enough international finance to help poorer nations develop their economies without hurting the Earth's climate.

"The moral obligation of the United States as a big emitter, and a historically big emitter that built its whole economy on fossil fuels that are now damaging the world," Robinson said. "It's unconscionable the United States would walk away from it."

The Paris Agreement aims to prevent the devastating effects of climate change by limiting the increase in average world temperatures to between 1.5 and 2.0 degrees Celsius. It was agreed in December 2015 by nearly 200 nations but it was only earlier this month that it officially entered into force after countries representing 55 percent of the world's greenhouse gas emissions committed to join the deal.