It's nearly 30 degrees Celsius and the sun is shining brightly on rows of guests in the White House Rose Garden, as a military band plays music.

US President Donald Trump makes his way to a lectern and says the words that many have feared were coming: "The United States will withdraw from the Paris climate accord."

The audience in front of Trump applauds enthusiastically as the world's biggest economy bids farewell to the 2015 international agreement dealing with greenhouse gas mitigation and adaptation.

"As president I can put no other consideration before the wellbeing of American citizens," Trump says, as he backs up his "America First" campaign approach.

With the move, millions of jobs will be saved, billions of dollars of contributions to UN Green Climate Fund will be avoided, Trump adds.

The Trump administration has been at loggerheads on the issue of the US staying on in the climate agreement for some time.

While Secretary of State Rex Tillerson, backed up by scientists and overseas foreign ministers, has been quietly arguing for the US to stay in the agreement, White House Chief Strategist Stephen Bannon and his right-wing allies in Washington have been pulling in the other direction.

In the end, the president's step on Thursday was not much of a surprise, following leaks from the White House over the past days and weeks, and his strong focus on helping domestic business throughout his election campaign.

But the economic benefits for the US, by withdrawing from the agreement, are not really all that clear. From overseas, there have already been signals that some American companies could be denied access to certain markets, if they attempt to do business exploiting advantages that they have because the US will not abide by agreement.

Many analysts also believe a re-focusing on ageing industries like coal and oil will, at the very most, only create jobs in the short term in the US, before the economy hits a dead end.

Furthermore, many American businesses don't back Trump's latest move. In December 2015, 100 major companies signed a full-page advertisement in the Wall Street Journal calling for the US economy to shift to a low-carbon future and showing their support for the Paris climate change conference.

Among the signatories were some of the country's biggest companies, including Coca-Cola, Unilever and Microsoft.

Across the world, the reaction to Trump's announcement has varied between disappointment, outrage and stoic defiance.

"Today is a sad day for the global community, as a key partner turns its back on the fight against climate change," a statement from EU Climate Action and Energy Commissioner Miguel Arias Canete said, before adding that the agreement would nevertheless "endure."

"We are on the right side of history," he concluded.

Earlier, a number of Nordic countries had sent an unsuccessful, last-minute letter to Trump to convince him to keep the US in the accord.

China and Russia

The Paris agreement, which has been signed by 195 countries worldwide and ratified by 147 - the US adopted it in September 2016 - is now facing challenging times. Whether the deal really is doomed, hangs partly on the reaction of China and Russia.

Chinese Prime Minister Li Keqiang has already confirmed in Berlin that his country will abide by the agreement in the future. In Moscow, the press secretary for the Russian president confirmed that the country would also support it, but added that it would be difficult to implement the deal if major companies didn't take part in the agreement, news agency Interfax reported.

For the US president, for the moment at least, those foreign views are likely to be insignificant, however.

As support on Thursday, Trump invited an illustrious cast of climate change deniers to the Rose Garden, including five members of the Heritage Foundation, a conservative think tank critical of the science behind climate change.

Shortly after Trump's announcement of the withdrawal, the group had scolded the agreement online as an "open door for egregious regulation, cronyism, and government spending."

"It's the exact opposite of the 'Make America Great Again' agenda President Trump promised to pursue. Au revoir to the Paris agreement indeed," a statement from the group's energy and environment expert Nick Loris, said.

- dpa