Mr Trump, a climate denier, praised Mr Sunak on his social media site, Truth Social, on Saturday.
“I always knew Sunak was smart, that he wasn’t going to destroy and bankrupt his nation for fake climate alarmists that don’t have a clue,” Mr Trump wrote.
“Congratulations to Prime Minister Sunak for recognizing this SCAM before it was too late!” he added.
On Wednesday, Mr Suank announced he would be delaying the UK’s 2030 ban on gas and diesel cars until 2035. He also rejected a series of environmental proposals including one that would require landlords to make properties more energy efficient.
The decision was widely criticized by leading figures in the climate movement and sparked a revolt in Sunak’s Conservative party.
In the wake of the announcement Mr Sunak’s approval rating dropped to the lowest it’s ever been.
New polling from survey firm, Survation, found that most UK voters support climate legislation. This year, the world has hit record-breaking land and ocean temperatures, and is experiencing increasingly extreme disasters.
During his time in the White House, Mr Trump rolled back more than 100 pieces of climate legislation, increased oil and gas leases and withdrew the US from the global Paris Agreement. Many of these decisions have since been restored under the Biden administration.
Mr Trump also claimed that the US should echo Mr Sunak’s decision and reverse the nation’s climate goals, claiming they are too expensive and not a priority.
“In the meantime, the US keeps rolling merrily along, spending Trillions of Dollars trying to do that which is not doable,” Mr Trump said. He went on to blame China, India, Russia and “Parts Unknown” for causing air pollution that affects people in the US.
The US is the world’s second-largest polluter after China. In 2023 alone, the US has suffered $23 billion worth of damages in climate disasters.
The Biden administration secured the largest climate change investment in American history with the Inflation Reduction Act, allocating $369 billion for climate and energy. In 2021, Mr Biden announced a goal of cutting US greenhouse gas pollution in half by 2030.