Scientists say climate change is real, mostly caused by humans, and getting worse. They point to rising temperatures, stronger storms, and melting ice as clear signs.
Groups like the UN have warned that waiting too long to act could cause serious damage to the planet and people.
Trump spoke for several minutes out of his near-hour speech on Tuesday on climate change during his address to the United Nations General Assembly, criticising the European Union for reducing its carbon footprint, which he claimed has taken a toll on its economy, and warning countries that have invested heavily in renewable energy that their economies will suffer.
"It's the greatest con job ever perpetrated on the world, in my opinion," Trump told the General Assembly.
"All of these predictions made by the United Nations and many others, often for bad reasons, were wrong."
He added: "They were made by stupid people that have cost their country's fortunes and given those same countries no chance for success."
Once Trump took office in January, the US submitted its withdrawal for a second time from the Paris Agreement, a 2015 pact agreed by 195 countries to strive to keep global temperatures from rising beyond 1.5 C, leaving it in the company of only Yemen, Iran and Libya.
His administration is carrying out an "energy dominance" agenda that focuses on producing and exporting oil, gas and coal, as well as nuclear, while sidelining renewable energy, which has become cost-competitive.
"We have the most oil of any nation anywhere, oil and gas in the world, and if you add coal, we have the most of any nation in the world," he said.
His remarks come a day before UN Secretary-General Antonio Guterres hosts a climate summit at the UN that will focus on countries' new climate action plans.
Guterres has tried to keep the world focused on continuing a global transition away from fossil fuels towards clean energy.
"Just follow the money," Guterres said in June, adding that $US2 trillion ($A3 trillion) flowed into clean energy last year, $US800 billion ($A1.2 trillion) more than fossil fuels and up almost 70 per cent in a decade.
