The leaders of US and China on Thursday both vowed to put their name to the Paris Agreement at a signing ceremony later this month and formally join the pact later this year.

Chinese President Xi Jinping and US President Barack Obama made the pledge in a joint statement as they met in Washington on the sidelines of global nuclear security talks.

It marks a reaffirmation of intent from the world’s two biggest emitters since the global climate pact was struck in December, and reinforces the US’ commitment after its domestic climate strategy was dealt a blow in Feb. when the country’s Supreme Court halted enforcement of its Clean Power Plan – the cornerstone of its emissions reduction strategy.

The two leaders “encourage other parties to the UNFCCC to do the same, with a view to bringing the Paris Agreement into force as early as possible,” the statement said.

The Paris Agreement requires at least 55 parties that collectively accounting for at least 55% of total global GHG emissions to ratify or accept it in order for the pact to enter into force.

The process had been expected to take several years but may now be reached much sooner as the US and China collectively account for around 40% of global emissions.

It could also curtail the ability of a new US president to back out of the pact after Obama leaves office at year’s end.

The UN hopes to get more than 100 signatures from countries when it opens the agreement for approval at a ceremony in New York on Apr. 22, though it is unclear how many world leaders will attend.

“This sends a strong signal from the two biggest emitters in the world and will help continue the positive Paris momentum,” said Li Shuo, climate policy expert for environmental campaigners Greenpeace East Asia.

He was encouraged that the statement included a pledge to work together in other global fora this year, including regulating aviation emissions at ICAO and the Montreal Protocol’s efforts to phase out HFC gases, which he said could could not be unlocked without their close cooperation.

“We look forward to see this bilateral relationship contributing to the advancement of these processes in the same way it helped to achieve the successful outcome of the Paris Agreement,” he added.

By Ben Garside – ben@carbon-pulse.com