President Donald Trump used his UN comeback address Tuesday to champion fossil fuels and deride green technologies on the eve of a climate summit called by Secretary-General Antonio Guterres to galvanize countries into issuing updated emission-reduction plans.

The blistering, nearly hour-long speech railed against everything from immigration to what he cast as the UN's failure to help secure peace in Gaza and Ukraine.

But some of his sharpest barbs were reserved for climate change -- seemingly tailored to a political base that sees climate science as another front in America's culture wars, ahead of a major climate announcement expected Wednesday from the United States' chief geopolitical rival China.

"Climate change -- it's the greatest con job ever perpetrated on the world, in my opinion," said Trump, who received hundreds of millions of dollars in campaign donations from Big Oil during the 2024 election.

The "carbon footprint is a hoax made up by people with evil intentions, and they're heading down a path of total destruction."

Carbon footprint refers to the total amount of greenhouse gas emissions caused by a person, group or product, measured in units of carbon dioxide (CO2) or carbon dioxide equivalents.

The term was in fact popularized in the mid-2000s by an advertising firm working for oil supermajor BP, in what critics say was an effort to shift blame for emissions onto individuals rather than corporations.

"We're getting rid of the falsely named renewables, by the way, they're a joke, they don't work, they're too expensive," he said at another point, about his administration's war on solar and wind, bolstered by a new law that ends clean energy tax credits.

The government has particularly targeted wind, attempting to block projects nearing completion and raising new barriers to permits.

Trump called the technology "so pathetic, so bad," and boasted that he had instead "unleashed" massive efforts to drill for new oil, gas and coal reserves.

During his first term, President Trump abandoned the Paris climate accord.

In his second term, Washington has not simply abandoned climate action but has gone on the offensive for oil and gas interests -- threatening to punish countries that participate in the International Maritime Organization's carbon-pricing system for shipping and embedding the sale of US liquefied natural gas (LNG) in trade deals.

China, by contrast, offers a competing pitch, exporting green technologies including solar panels, batteries and electric vehicles to the world.

"President Trump and his administration continue to spew lies and disinformation about climate science and the overwhelming benefits of clean energy, a grave disservice to the American people," Rachel Cleetus of the Union of Concerned Scientists told AFP.

"Climate change is here, it's costly, and people need real solutions, not propaganda designed to boost the profits of fossil fuel polluters."