President Trump’s decision Thursday to withdraw the United States from the Paris climate agreement could make it difficult, if not impossible, for the world to stay on track to reach an internationally agreed-upon goal for limiting dangerous global warming, scientists said.
That goal, which sought to limit warming to “well below” a 2-degree Celsius (3.6-degree Fahrenheit) rise above preindustrial temperatures, was already a stretch before Trump announced the U.S. exit in a speech in the White House Rose Garden.
With the United States, the world’s second-largest emitter of greenhouse-gas emissions after China, walking away from the accord, other countries will presumably have to ramp up their ambitions still further if they want to avoid the prospect of dangerous warming.
“Avoiding a 2-degree warming was already hard when all of the key countries were rowing together,” said Michael Oppenheimer, a climate researcher at Princeton University. “With the U.S. becoming a climate outlaw by withdrawing from Paris, that target becomes nearly impossible.