John Kerry, whom former Vice President Joe Biden has selected to serve as his administration’s “climate czar,” proclaimed Tuesday that the Paris climate agreement is insufficient in fighting climate change.

“Mr. president-elect, you’ve put forward a bold transformative climate plan. But you’ve also underscored that no country alone can solve this challenge,” Kerry stated during a press conference hosted by Biden in Delaware.

“You’re right, to rejoin Paris on Day 1,” Kerry then said, before adding, “And you’re right to recognize that Paris alone is not enough.”

The Hill notes:

Biden has proposed a $2 trillion climate plan that would push the U.S. to net-zero emissions by 2050. But Kerry noted on Tuesday that the U.S., which is responsible for about 15 percent of all emissions, will have to help other countries meet similar targets — a move that presents an opportunity to boost jobs and sell U.S. technology.

“Failure is not an option. Succeeding together means tapping into the best of American ingenuity and creativity and diplomacy, from brainpower to alternative energy power,” Kerry continued.

“No one should doubt the determination of this president [and] vice president,” he added. “They shouldn’t doubt the determination of a country that went to the moon, cured supposedly incurable diseases, and beat back global tyranny in World War Two. This kind of crisis demands that kind of leadership again.”

Kerry, who served as Secretary of State under then-President Barack Obama, helped secure the Paris agreement aimed at reducing greenhouse gas emissions in November 2016. President Trump would go onto remove the U.S. from the accord, citing its job-killing rules.