UNITED NATIONS — Leader after leader told the United Nations on Monday that they will do more to prevent a warming world from reaching even more dangerous levels. But as they made their pledges at the Climate Action Summit, they conceded it was not enough.

Sixty-six countries have promised to have more ambitious climate goals and 30 swore to be carbon neutral by midcentury, said Chilean President Sebastian Pinera Echenique, who is hosting the next climate negotiations later this year.

Heads of nations such as Finland and Germany promised to ban coal within a decade. Several also mentioned goals of climate neutrality — when a country is not adding more heat-trapping carbon to the air than is being removed by plants and perhaps technology — by 2050.

US President Donald Trump dropped by, listened to German Chancellor Angela Merkel make detailed pledges, including going coal-free and left without saying anything.

The United States did not ask to have someone speak at the summit, UN officials said. And Secretary-General Antonio Guterres had told countries they couldn’t be on the agenda without making bold new proposals.

Even though there was no speech by Trump, who has denied climate change, called it a Chinese hoax and repealed US carbon-reduction policies, he was talked about.

In a none-too-subtle jibe at Trump’s plans to withdraw the United States from the 2015 Paris climate agreement, Chinese Foreign Minister Wang Yi said countries “must honor our commitments and follow through on the Paris Agreement.”

“The withdrawal of certain parties will not shake the collective goal of the world community,” Wang said to applause.

Former New York City Mayor Michael Bloomberg, the UN’s special climate envoy, thanked Trump for stopping by, adding that it might prove useful “when you formulate climate policy,” drawing a bit of laughter and applause on the floor of the General Assembly.

Before world leaders made their promises in three-minute speeches, 16-year-old climate activist Greta Thunberg gave an emotional appeal in which she chided the leaders with the repeated phrase, “How dare you.”

“This is all wrong. I shouldn’t be up here,” said Thunberg, who began a lone protest outside the Swedish parliament more than a year ago that culminated in Friday’s global climate strikes. “I should be back in school on the other side of the ocean. Yet you have come to us young people for hope. How dare you. You have stolen my dreams and my childhood with your empty words.”

She told the UN that even the strictest emission cuts being talked about only gives the world a 50% chance of limiting future warming to another 0.72 degrees Fahrenheit from now, which is a global goal. Those odds are not good enough, she said.

“We will not let you get away with this,” Thunberg said. “Right now is where we draw the line.”

Hilda Heine, president of the Marshall Islands, said she represents “the most climate-vulnerable people on Earth.” Her tiny country has increased its emission cut proposals in a way that would limit warming to that tight goal of 2.7 degrees Fahrenheit since pre-industrial times.

“We are now calling on others to join us,” Heine said.

Guterres opened the summit Monday by saying: “Earth is issuing a chilling cry: Stop.”

“Time is running out,” Guterres said. “But it is not too late.”

He told the more than 60 world leaders scheduled to speak that it’s not a time to negotiate but to act to make the world carbon neutral by 2050.

While presidents and premiers talked about what they hoped to do inside their own borders, French President Emmanuel Macron reminded them that they need to include climate change in their trade and finance policies so they don’t import goods that increase carbon pollution, nor fund polluting plants in other countries.

Macron begged other nations to increase their pledges to the Green Climate Fund, which helps poorer nations with climate issues. France, the United Kingdom, Germany, Norway, Denmark and Sweden have recently doubled their pledges.

“We are now at $7 billion,” Macron said. “The target is $10 billion to make up for the United States withdrawal,” and he then suggested America should reconsider adding money, to the applause of other leaders.

More than 130 banks adopted policies that are more responsible and green, said Jamaican Prime Minister Andrew Holmes.

The day before summit, 87 companies announced stepped-up plans to cut greenhouse emissions and be greener, with several CEOs, including energy company chiefs, joining presidents and prime ministers at the microphone.

A decade ago, oil, coal and gas was “at the core of our business model,” said Henrik Poulsen, CEO for Danish energy company Orsted. But the company has gone wind-heavy and reduced heat-trapping carbon dioxide emissions by 83% since 2006. The company will quit coal in 2022 and be carbon neutral by 2025, he added.

“Action, action, action,” Macron urged. “We cannot leave our young people to spend all of their Fridays protesting.”