WASHINGTON • The United States formally exited the Paris Agreement yesterday, fulfilling an old promise by President Donald Trump to withdraw the world's second-largest greenhouse gas emitter from the global pact to fight climate change.
But the outcome of the tight US presidential race will determine for how long. Mr Trump's Democratic rival Joe Biden has promised to rejoin the agreement if elected.
"The US withdrawal will leave a gap in our regime, and the global efforts to achieve the goals and ambitions of the Paris Agreement," said Ms Patricia Espinosa, executive secretary of the United Nations Framework Convention on Climate Change (UNFCCC).
The US still remains a party to the UNFCCC.
Ms Espinosa said the body will be "ready to assist the US in any effort in order to rejoin the Paris Agreement".
Mr Trump announced his intention to withdraw the US from the pact in June 2017, arguing it would undermine the US economy.
His administration formally served notice of the withdrawal on Nov 4 last year, which took one year to take effect.
The departure makes the US the only country of 197 signatories to have withdrawn from the agreement, hashed out in 2015.
Current and former climate diplomats said the task of curbing global warming to safe levels would be tougher without the US' financial and diplomatic might.
"This will be a lost opportunity for a collective global fight against climate change," said Mr Tanguy Gahouma-Bekale, chair of the African Group of Negotiators in global climate talks.
A US exit would also create a "significant shortfall" in global climate finances, Mr Gahouma-Bekale said, pointing to an Obama-era pledge to contribute US$3 billion (S$4.1 billion) to a fund to help vulnerable countries tackle climate change, of which only US$1 billion was delivered.
Mr Thom Woodroofe, a former diplomat in UN climate talks and now a senior adviser at the Asia Society Policy Institute, said: "The challenge to close the global ambition gap becomes much, much harder in the short term."
However, other major emitters have doubled down on climate action, even without guarantees that the US will follow suit.
China, Japan and South Korea have all pledged in recent weeks to become carbon neutral - a commitment already made by the European Union.
Those pledges will help drive the huge low-carbon investments needed to curb climate change. If the US were to re-enter the Paris accord, it would give those efforts "a massive shot in the arm", said Mr Woodroofe.
European and US investors, with a collective US$30 trillion in assets, yesterday urged the US to quickly rejoin the Paris deal and warned that the country risked falling behind in the global race to build a low-carbon economy.
Scientists say the world must cut emissions sharply this decade to avoid the most catastrophic effects of global warming.
Under the Paris deal, former US president Barack Obama's administration had pledged to cut US emissions by 26 per cent to 28 per cent by 2025, from 2005 levels.
Mr Biden, who was Mr Obama's vice-president, is broadly expected to ramp up those goals if elected. He has promised to achieve net-zero emissions by 2050, under a sweeping US$2 trillion plan to transform the economy.
The Rhodium Group said that this year, the US will be around 21 per cent below 2005 levels. It added that under a second Trump administration, it expects US emissions would increase by more than 30 per cent through 2035 from last year's levels.
REUTERS, AGENCE FRANCE-PRESSE