Donald Trump told the world’s business leaders to stop listening to “prophets of doom” as he used a keynote speech at the World Economic Forum to attack the teenage activist Greta Thunberg over her climate crisis warnings.

The US president hailed America’s growth record and compared campaigners against global heating with those who feared a population explosion in the 1960s and mass starvation in the 1970s.

On an opening day in Switzerland dominated by the climate emergency, Thunberg scoffed at Trump’s claim that his backing for a new initiative to plant 1tn trees showed his concern for the environment.

Quick guide What is Davos 2020? Show Hide Davos is a Swiss ski resort now more famous for hosting the annual four-day conference for the World Economic Forum. For participants it is a festival of networking. Getting an invitation is a sign you have made it – and the elaborate system of badges reveals your place in the Davos hierarchy. The meeting is sponsored by a huge number of international banks and corporations.

For critics, “Davos man” is shorthand for the globe-trotting elite, disconnected from their home countries after spending too much time in the club-class lounge. Others just wonder if it is all a big waste of time. The 2020 meeting is being advertised as focusing on seven themes: Fairer economies, better business, healthy futures, future of work, tech for good, beyond geopolitics and how to save the planet. Young climate activists and school strikers from around the world will be present at the event to put pressure on world leaders over that last theme.

“Our house is still on fire. Your inaction is fuelling the flames by the hour,” Thunberg said. “And we’re asking you to act as if you love your children more than anything else.”

The US president and Thunberg did not meet face to face at the WEF, but Trump left few in doubt about who he was referring to as he defended his record since entering the White House three years ago.

“This is not a time for pessimism,” he said. “This is a time for optimism. To embrace the possibilities of tomorrow, we must reject the perennial prophets of doom and their predictions of the apocalypse. They are the heirs of yesterday’s foolish fortune tellers.

“They want to see us do badly, but we don’t let that happen. They predicted an overpopulation crisis in the 1960s, mass starvation in the 70s, and an end of oil in the 1990s. 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.”

Play Video 3:44 'What will you tell your children?': Greta Thunberg blasts climate inaction at Davos – video

He said he was “a big believer in the environment” in a speech that ensured he was absent from Washington as impeachment hearings took place on Capitol Hill. “The environment to me is very important,” he said.

He made no mention of the climate emergency but backed the plan – launched in Davos – to capture carbon by planting trees on a mass scale in the coming years. “What I want is the cleanest water and the cleanest air,” he said.

Environmentalists were unimpressed by a speech in which Trump boasted that his support for the coal and oil industries meant the US was self-sufficient in energy.

Thunberg said: “Planting trees is good, of course, but it’s nowhere near enough, and it cannot replace real mitigation and re-wilding nature. We don’t need to lower emissions. Emissions need to stop.”

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Thunberg had three demands for her Davos audience:

The halt of all investment in fossil fuel exploration and extraction by companies, banks, institutions and governments.

An immediate end to all fossil fuel subsidies.

An immediate exit from fossil fuel investments.

“We don’t want it done in 2050, 2030, or even 2021, we want it done now,” Thunberg said. “You might think we’re naive, but if you won’t do it, you must explain to your children why you’ve given up on the Paris agreement goals, and knowingly created a climate crisis,” she said.

She then added that the right, the left, and the centre of politics had all failed the sustainability test. “No political ideology or economic structure has managed to tackle the climate and environmental emergency and create a cohesive and sustainable world.”

Jennifer Morgan, Greenpeace’s executive director, said: “The 1tn trees initiative didn’t make up for the lack of a wider attack on the climate emergency, and Trump had failed to appreciate the scale of the crisis.

“To assume you can have a great, profitable America, and happy Americans without understanding the risk to Americans from climate change is astounding. It just demonstrates the level of denial, and the capture of this government by the coal, oil and gas industries.”

Trump said the American dream was back, “bigger, better and stronger” than before, adding that the benefits of growth were going primarily to low-income workers rather than the better off. Trump added that 7m jobs had been created and 12,000 factories opened during his presidency.

Many of the president’s claims were rejected by the Columbia University economics professor Joseph Stiglitz. “Research shows that Trump normally tells five or six lies a day. He far exceeded that today,” he said, noting that growth had been faster under Barack Obama than it was currently under Trump, and that life expectancy had fallen every year of his presidency.

Although the US economy grew far more rapidly in previous decades than it has since he was elected in November 2016, Trump said: “I’m proud to say that the US is in an economic boom, the likes of which the world has never seen before.”

The main hall in Davos, together with an overspill room, were packed to hear the president, although there were some titters as he ran through a litany of boasts.

“I hold up the American model as an example to the world,” Trump said, contrasting his record with that of his predecessor, Obama.

The US was “thriving, flourishing and winning” unprecedentedly, he added, citing trade deals signed last week with China and Mexico-Canada as models for the 21st century.

“I am looking forward to a tremendous new trade deal with the UK,” Trump said, noting that Britain had a “wonderful new prime minister” in Boris Johnson, who was keen on a deal.

The president said the economic boom had happened despite the US Federal Reserve, which “raised rates too fast and cut them too slowly”.