The formal exiting by the United States from the Paris Agreement has been greeted with dismay internationally on the basis it would dampen efforts to curb global heating.
The US withdrawal on Wednesday fulfils a promise by president Donald Trump to pull the world's second-largest greenhouse gas emitter from the global pact to fight climate change.
But the outcome of the US election will determine for how long. Mr Trump's Democratic rival, Joe Biden, has committed to rejoining the 2015 agreement quickly, if elected.
The US departure, however, means it is the only country of 197 signatories to have withdrawn for a commitment to limit global temperature rise to “well below 2 degrees” above pre-industrial temperatures this century.
"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 Patricia Espinosa, executive secretary of the UN Framework Convention on Climate Change.
The body was “ready to assist the US in any effort in order to rejoin the Paris Agreement”, Ms Espinosa added.
Mr Trump first announced his intention to withdraw in June 2017, arguing it would undermine the US economy. Since then he has claimed repeatedly that climate change is a hoax, and more recently suggested its impact may be quickly reversed.
The administration formally served notice of withdrawal to the UN on November 4th, 2019, which took one year to take effect.
Tougher task
The task of curbing global warming to safe levels would be tougher without the financial and diplomatic might of the US, according to climate diplomats.
“This will be a lost opportunity for a collective global fight against climate change,” said Tanguy Gahouma-Bekale, chairman of the African Group of Negotiators in global climate talks.
"The challenge to close the global ambition gap becomes much, much harder in the short term," said Thom Woodroofe, a former diplomat at the Asia Society Policy Institute.
Japan, Korea and China, however, have committed to greater climate ambition recently, matching the EU's target of carbon neutrality.
Those pledges will help drive the huge low-carbon investments needed to curb climate change, Mr Woodroofe said. If the US were to re-enter the accord, it would give those efforts “a massive shot in the arm”.
A Trump win would be a "huge uphill battle" for US climate action, said Kate Larsen, director at Rhodium Group, an independent research consultancy.
“It would mean that any progress we will see will come from states and cities and companies that are trying to pick up the slack. It will come nowhere close to what is needed, to what we will be able to do with a mobilised federal government,” she added.
Pete Betts, the former lead climate negotiator for the EU and the UK, said global action would continue, albeit at a slower pace without the US.
“The big picture is that Paris will continue, come what may. Although I don’t think anyone will follow Trump, if you’ve got the world’s biggest economy and second-biggest emitter saying it doesn’t want to take action itself – it is a little bit of a dampener on ambition.”
Control of Senate
Should Mr Trump get re-elected, climate advocates "will be going all-in to help states, cities and businesses do more, to get them international recognition and to help them in legal battles against the administration", said Andrew Light, a former US climate negotiator.
We Are Still In, a coalition of non-federal actors committed to climate action, said it could step in where a Trump government would be absent, cutting climate pollution up to 37 per cent below 2005 levels by 2030, he noted.
But Mr Biden's ambitions could be hamstrung if Republicans maintain control of the Senate, which they are on track to do. And even if he takes the White House and Democrats control both the House and the Senate, it's unclear how aggressive US climate policies might be, said Julian Brave NoiseCat, director of Green New Deal Strategy at Data for Progress.
“Climate needs to be seen as part of a political winner for Democrats, rather than a liability,” he said. If the Senate is nearly evenly divided and the key vote ends up being a moderate Democrat from a fossil fuel state, that lawmaker’s constituents will have outsized influence, he said.
Rachel Cleetus, policy director at the Union of Concerned Scientists said: "The decision to exit the Paris Agreement leaves the US globally isolated in its defiance of scientific realities, and causes real harm to people, the planet and the economy. However, the nearly 200 other nations of the world will continue moving full steam ahead toward realising the goals of the agreement." – Additional reporting: Guardian
