All members of the G20 reaffirmed their commitment to the Paris climate deal on Saturday, excluding the United States.
The 19 signatories have agreed on the "irreversibility" of the treaty on climate, signed in Paris in 2015, and have committed to its "complete implementation".
The commitment was achieved with difficulty as the members faced opposition from the only G20 member not to sig: the United States.
"We must do a lot more on climate," French President Emmanuel Macron said. "Scientists remind us of our duty every day. Young people remind us of our duty, too. We have signed the declaration with 19 members, except the US. We will continue to progress on the essential topic of climate."
Macron added: "I did the maximum in 2017 to convince Trump to ratify the Paris agreement. I can only regret the American position."
Outgoing British Prime Minister Theresa May, speaking at her final G20 news conference, urged other countries to join the UK in enshrining into law the goal to reach net-zero carbon emissions by 2050.