China and the United States, the world's top greenhouse gas emitters, on Friday (Apr 22) signed the Paris climate deal at a UN ceremony attended by a record 171 countries, boosting hopes of quick action on combating global warming, reports Channel NewsAsia.
French president François Hollande was the first leader to put his signature to the accord, and was quickly followed by leaders from island-states hardest hit by climate change.
US Secretary of State John Kerry came to the podium cradling one of his granddaughters in his arms and triggered warm applause from delegates as he signed the historic deal.
It was the largest ever one-day signing of an international agreement, marking a first step toward binding countries to the promises they made to cut greenhouse gas emissions.
"This is a moment in history," UN Secretary-General Ban Ki-moon said after announcing that 171 countries were set to sign the accord. "Today you are signing a new covenant with the future," he said.
Held on Earth Day, the ceremony comes four months after the hard-won deal was clinched in Paris after years of tough bargaining.
"Some may say it's only a small step. We need to make it a huge one," said the prime minister of the Polynesian island of Tuvalu, Enele Sosene Sopoaga.
Together the signatories account for 93 per cent of global greenhouse gas, according to calculations by World Resource Institute.
Hollande called on governments to quickly ratify the Paris deal and singled out the European Union, saying the 28-nation bloc should "lead by example" and give final approval before the end of the year.
The Paris agreement will come into force as soon as 55 countries responsible for 55 per cent of the world's greenhouse gases have ratified it.