Trump sits in at UN climate summit that could be 'slingshot' toward global goals World leaders discussed plans to combat climate change Monday.

Leaders from around the world are set to discuss climate change on Monday at a United Nations summit in what one U.N. official said could be a "slingshot" to catalyze global action toward reducing emissions and limiting global warming.

President Donald Trump was not scheduled to attend but showed up unexpectedly Monday morning.

The climate summit is part of the United Nations General Assembly and was planned to "discuss a leap in collective national ambition," not unlike the Paris Climate Agreement, the 2016 agreement from which Trump vowed to withdraw the U.S. in 2017.

On Friday, young people protested around the world, including in the U.S., to pressure leaders to take significant action toward preventing climate change.

Rachel Kyte, the U.N.'s special representative for sustainable energy for all, said the summit is meant to be a response to that call for action.

"The climate emergency has been declared by people, and especially young people on the streets, the world over, and this is about an appropriate response to that emergency," Kyte said.

Kyte said it will be an "extraordinary week" of discussion among world leaders and private companies about what they can do to drastically reduce emissions, with a possible goal of net-zero emissions by 2050.

"We can use this summit as a slingshot toward further agreements that need to be reached in the climate negotiations, at the end of this year and at the end of 2020," she said.

Trump's critics in the U.S. have said he abdicated the country's role as a global leader on climate change after announcing the U.S. would no longer abide by the Paris Climate Agreement.

Trump and other administration officials have signaled that they don't see climate change as an immediate crisis. Environmental Protection Agency chief Andrew Wheeler said water quality and ocean pollution are bigger global threats.

"My frustration with the current dialogue around environmental issues," Wheeler said in a speech earlier this year, "is that water issues often take a backseat. It's time to change that."

Trump will be in New York at U.N. headquarters during the climate summit attending an unrelated event on religious freedom and religious persecution around the world.

A senior administration official told reporters the president wants to focus on personal diplomacy with some of the leaders attending the religious freedom event but declined to say if they discussed whether Trump should attend the climate summit.

A spokesperson from the State Department said Principal Deputy Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs Marcia Bernicat will represent the United States at the summit, and that the U.S. will "continue to be a leader in assisting our partners to reduce emissions, protect natural resources like forests, increase resilience, and respond to natural disasters."

The U.S. has reduced greenhouse gas emissions significantly from 2005 to 2017, and the spokesperson said the country is a world leader in innovative energy technologies.

Greta Thunberg, the Swedish 16-year-old celebrated for her role in spearheading the global climate strike movement, said Trump's actions on climate change may be seen as a lack of commitment from the U.S. and influence other countries to not set ambitious goals.

"I am from Sweden, a small country. And there, it is the same argument. 'Why should we do anything, just look at the U.S.,' they say. So, just so you know, that is being used against you as well," she told members of Congress last week.

Democratic presidential candidates have promised to recommit to the Paris agreement and re-engage with the U.N. and other world leaders on climate if victorious in 2020.

A coalition of governors, mayors and private companies also have committed to reduce greenhouse gas emissions and expand renewable energy even without the federal government's commitment.