"The U.S. election result is a blow in the fight against the climate crisis," Laurence Tubiana, a lead negotiator of the 2015 Paris Climate Agreement, posted on X.
"The window to limit warming to 1.5 degrees Celsius is closing — these next 4 years are critical," she added.
Tubiana was referring to the 1.5-degree-Celsius (2.7-degree-Fahrenheit) warming threshold that countries said they hoped to stay below at the 2015 U.N. climate summit (COP21), by means of individual emissions-reduction commitments.
During his former presidency, Trump withdrew the U.S. from the Paris Agreement, but President Biden then signed an executive order to resume participation.
Tubiana praised the country for its subsequent turnaround — for assuming what became a lead role "at the forefront of the green industrial revolution."
She credited Biden administration advancements like the Inflation Reduction Act for driving California's emissions cuts and Texas's renewable energy expansions.
Trump already vowed months ago that he would again remove the U.S. from the Paris accord if he won the presidency, sources told Politico at the time.
"Abandoning the transition to a cleaner, fairer, and more affordable economy would be a dereliction of responsibility," Tubiana stated.
Urging other nations to "not despair," she expressed hope that "no other country will follow if the U.S. withdraws from the Paris Agreement."
Christiana Figueres, who served as U.N. climate chief during the Paris summit, offered similar remarks on X, describing the election results as "a major blow to global climate action.”
“But it cannot and will not halt the changes underway to decarbonize the economy and meet the goals of the Paris Agreement,” Figueres stated.
Next week, the U.N. Framework Convention on Climate Change will convene the COP29 summit in Azerbaijan, where countries aim to set new climate finance targets that could help meet those Paris goals in an ever-warming world.
But experts fear that the event may not bring significant progress since the leaders of many major economies — including President Biden and European Commission President Ursula von der Leyen — will not be attending, Reuters reported.
However, U.N. climate chief Simon Stiell on Wednesday stressed that preparations for COP29 "continue apace," according to the Financial Times.
Without a unanimous global effort to curb emissions and strengthen supply chains, no country will be able to "survive unchecked global heating, and no household will be spared its severe inflationary impacts,” Stiell added.