Kerry said the U.S.'could've been helping to meet the challenge.'
U.S. climate envoy John Kerry on Thursday lamented "wasted years" under the Trump administration to slow climate change and urged faster work to curb fossil fuel emissions.
Kerry spoke remotely to an Italian business conference in his first international climate address under President Joe Biden.
Biden, in his first hours in office Wednesday, signed an executive order returning the United States to the Paris climate accord. It reversed the withdrawal by Donald Trump, who ridiculed the science of human-caused climate change.
Biden's administration is getting back into the battle to cut climate-damaging coal, gas, and oil emissions with "humility, because we know that the federal government of the United States, until yesterday, walked away from the table for four wasted years when we could've been helping to meet the challenge," Kerry told the European forum in his prepared remarks.
Biden's order starts a roughly 30-day process of getting the United States back into the nearly 200-country U.N. climate treaty. Countries in the accord commit to setting goals to cut climate-damaging fossil fuel emissions and to monitor and report their emissions.
Biden has put Kerry, secretary of state under President Barack Obama, in charge of climate and national security issues.
Kerry's words marked a 180-degree turn from the Trump administration on climate change. Trump withdrew from accords with U.S. allies and questioned scientific consensus that oil, gas, and coal pollutants are to blame for the warming climate and are contributing to worsening natural disasters.
Biden on Wednesday signed other orders undoing dozens of Trump actions that had targeted earlier efforts to curb emissions from industry and transport and that had promoted new oil and gas drilling and production.
Kerry said Biden had "with a few strokes of his pen began to restore domestic environmental leadership."
Preventing the worst of global warming would require $1 trillion in annual investment globally through 2030, Kerry told Thursday's gathering — moving five times faster than currently to phase out dirty-burning coal, 22 times faster to electric vehicles, and six times faster to ramp up solar, wind, and other renewable power.