(CN) – U.S. President Donald Trump flew to the mountains of Switzerland on Tuesday and delivered a keynote speech to the world’s business and political leaders who are gathered at the World Economic Forum at Davos to discuss solutions to save the world from climate catastrophe.

What did Trump do? He said nothing about global warming, called climate activists “prophets of doom” and touted a future where “virtually unlimited energy reserves” from fossil fuels and other polluting energy sources will keep factories humming while government cuts regulations and taxes.

During this speech full of descriptions about American greatness and his own, Trump offered one environmental solution: He said the United States is joining an initiative being launched this year at Davos to plant 1 trillion trees.

Up to this point, the audience had been silent, frosty. Now, applause, polite and hesitant at first, broke out.

But the applause was over as quickly as it started, and the room fell back into stony silence as Trump moved on and said “the perennial prophets of doom” must be rejected.

He launched into a part of his speech that was clearly a not-so-veiled reference to teenage Swedish climate change activist Greta Thunberg, whose presence at Davos rivaled that of Trump on Tuesday.

A year ago, Thunberg made headlines when she blasted the elites at Davos for not doing nearly enough to stop climate change and warned that “our house is on fire.” When she made a similar speech to the United Nations and then appeared on the cover of Time magazine as its person of the year, Trump mocked her on Twitter and said she needed to “chill” and work on her “anger management.” He and other conservatives have ridiculed her dire warnings about the future.

Trump is known as being skeptical about the science about global warming and he has appointed climate deniers to his administration. His withdrawal from the 2015 Paris Agreement on climate change shocked world leaders and has seriously damaged efforts to rein in greenhouse gas emissions.

At Davos, he against cast doubt on those who say the world is in the middle of a climate emergency – without specifically mentioning activists.

“These alarmists always demand the same thing: absolute power to dominate, transform and control every aspect of our lives. We will never let radical socialists destroy our economy, wreck our country or eradicate our liberty,” he said. “America will always be the proud, strong and unyielding bastion of freedom.”

Shortly after Trump spoke, Thunberg delivered her remarks – and they were strikingly different and drew a lot more applause.

“One year ago I came to Davos and told you our house is on fire,” the 17-year-old activist said.

“I said I wanted you to panic,” she said. “I’ve been warned that telling people to panic about the climate crisis is a very dangerous thing to do.”

She faulted world leaders for not doing more in the past year to break away from fossil fuels and reverse the trend of ever-increasing emissions. She accused governments and businesses of empty promises and “cheating and fiddling around with numbers” to show that they are reducing emissions.

She then indirectly hit back at the tree-planting initiative touted by Trump and the World Economic Forum.

“Planting trees is good of course but it is nowhere near enough to what is needed and it cannot replace real mitigation and rewilding nature,” she said.

“Let’s be clear: We don’t need a low-carbon economy, we don’t need to lower emissions. Our emissions have to stop if we are to have a chance to stay below the 1.5 degree target,” she said.

Scientists say it is urgent that the planet’s temperature not surge beyond an increase of 1.5 degrees Celsius to avoid catastrophic consequences.

Thunberg criticized the U.S. for withdrawing from the Paris Agreement but also blasted other countries for not living up to commitments they made to reduce greenhouse gases.

“Any plan or policy of yours that doesn’t include radical emission cuts at the source starting today is completely insufficient for meeting the 1.5 or well below 2 degree commitments of the Paris Agreement,” she said.

She then said the climate crisis was beyond party politics and poses an existential threat.

“No political ideology or economic structure has been able to tackle the climate and environmental emergency and create a cohesive and sustainable world,” she said. “Because that world, in case you haven’t noticed, is currently on fire.”

She added: “You say, ‘Children shouldn’t worry.’ You say: ‘Just leave this to us, we will fix this; we promise we won’t let you down; don’t be so pessimistic.’ And then, nothing, silence. Or something worse than silence: Empty words and promises which give the impression that sufficient action is being taken.”

She urged governments, banks, financial institutions and companies to immediately halt all investment in fossil fuel exploration and extraction, stop providing subsidies to fossil fuel projects and completely divest from fossil fuels.

“We don’t want these things done by 2050, or 2030, or even 2021, we want this done now,” she said. “It may seem like we are asking for a lot and you will of course say we are naive. But this is just the very minimal of effort that is needed to start the rapid sustainable transition.”

Thunberg ended her speech by accusing her audience of elites of not doing enough.

“Our house is still on fire,” she said. “Your inaction is fueling the flames by the hour. And we are telling you to act as if you loved your children above all else.”