France's former prime minister says the world's climate is worsening faster than imagined and he calls the U.S. decision to pull out of the Paris climate accord "dangerous nonsense."

Laurent Fabius told a climate conference Friday that the U.S. withdrawal last year dealt "a very serious blow" to environmental protection.

Fabius was instrumental in negotiations to establish the 2015 Paris accord.

He says it is a "race against time" to stop global warming with carbon dioxide emissions on the rise.

Fabius is reiterating the need for a global environmental pact to prevent nations from backsliding on their environmental protection obligations.