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On the heels of the massive youth climate strike at the end of last week, teenage activist Greta Thunberg made waves at the United Nations Climate Action Summit with one of the most emotional speeches ever seen at the UN.

This was all while world leaders—including a surprising visit from U.S. President Donald Trump—watched, and announcements of countries’ actual commitments to reducing greenhouse gas emissions, containing global warming, and financing all these efforts were made.

“How dare you?” Thunberg asked world leaders who have been praising youth climate strikers like her but have also relied on them for some measure of diplomatic and political cover to act on climate change within their countries.

Choking back tears, Thunberg said: “I should be in school on the other side of the ocean. You have stolen my dreams and childhood with your empty words…and I am one of the lucky ones.”

The teenager began her journey just a year ago, practically alone, in her home country of Sweden and has gotten permission to take time off from school for it. It was a bold rebuke of heads of state in the room and what she described as emissions reductions targets which are too weak to stop her generation from inheriting a dying planet.

“You are still not mature enough to tell it like it is,” Thunberg said. “You are failing us. Young people are starting to understand your betrayal. The eyes of all future generations are upon you.”

It was met with loud cheers and applause from the audience full of diplomats.

This summit will have no binding document or resolutions, but it did not stop UN Secretary General Antonio Guterres from what appeared to be stronger words than he has said before during his time at the helm. Staff members and NGOs working in the development sector told Fortune he was adamant about this year’s General Assembly: climate action would take priority.

“Nature is angry. We fool ourselves if we think we can fool nature,” he said, adding “this is not a climate talk summit, we’ve had enough talk. This is not a climate negotiation summit because we don’t negotiate with nature. This is a climate action summit.”

He urged countries to go beyond the many millions of dollars in unmet, but ambitious, pledges towards moving economies to clean and renewable energy.

“We are in a deep climate hole and to get out we must first stop digging,” Guterres said. He echoed a sentiment of many older world leaders: you are not going to be around for the planet, but your grandchildren will be. He said he will “not be a silent witness” to dooming that generation.

Among other leaders to take the stage were New Zealand Prime Minister Jacinda Ardern, Indian Prime Minister Narendra Modi, German Chancellor Angela Merkel, and French President Emmanuel Macron. It was after Merkel’s speech, when the official UN camera feed showed a surprising attendee: Trump.

The president was at the UN to attend a summit on religious freedom and was supposed to snub this meeting, but instead he was seen sitting and clapping with the U.S. delegation, which has no official role in the summit.

To wit, Trump is well along in the process of withdrawing the U.S. from the Paris Agreement, the 2015 UN-brokered deal 200 countries signed. The administration has also been steadily relaxing environmental regulations and standards at home.

The White House has not yet responded to a request for comment on the schedule change and if it could be indicative of some sort of announcement.

UN Special Envoy on climate change and former New York City Mayor Michael Bloomberg even seemed to make a tongue-in-cheek comment about it. After thanking leaders from Chile and Finland for leading on financing climate action, he thanked Trump for his attendance and said: “hopefully our discussions here will be useful for you when you formulate climate policy.” It was met with laughter throughout the hall.

Bloomberg’s philanthropic organization has overseen the closing of more than half of American coal plants and noted, in another apparent jab at the Trump administration: “Net zero emissions is an ambitious but achievable goal and non-state actors can lead the way,” like state and local governments, as well as private businesses.

In another surprising announcement, Macron announced that Russia has ratified the Paris Agreement. Until today, Russia was the world’s largest emitter of greenhouse gas emissions to not have ratified the deal. It is the fourth-largest emitter overall behind the U.S., China, and India.

Greta Thunberg Says World Leaders ‘Stole Her Childhood’ at UN Climate Summit

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