China and the United States announced on Thursday that they will sign the Paris climate agreement on April 22, as the world's two largest greenhouse gas emitters continue to strengthen their cooperation to combat climate change.

The two countries have pledged to take their respective domestic steps in order to join the agreement as early as possible.

The presidential announcement on climate change was released just hours before a bilateral meeting in Washington between President Xi Jinping and US President Barack Obama on the sidelines of the 4th Nuclear Security Summit.

On Jan 22, UN Secretary-General Ban Ki-moon invited all world leaders to a signing ceremony on April 22 for the Paris agreement. The signing event will take place at the UN Headquarters in New York on the first day that the agreement will be open for signing. It coincides with Earth Day.

The China-US statement noted they were working together and with others and that they had played a critical role in crafting the historic, ambitious global climate-change agreement in December.

China and the US called on other parties to the United Nations Framework Convention on Climate Change to do the same in order to bring the Paris Agreement into force as early as possible, according to the statement.

Cooperation on climate change has become a bright spot in China-US relations, a relationship that is often unsettled by differences on cybersecurity and the South China Sea. As Obama has considered his legacy during his remaining 10 months in office, climate change has been at the top of his list.

David Waskow, international climate director at the World Resources Institute, said the China-US joint statement sends a powerful signal.

"This demonstrates continued momentum from Paris and an ongoing commitment by the United States and China to collaborate and drive climate action forward on the global stage," he said.

A total of 196 parties reached consensus over the Paris agreement last December. It is geared toward spurring action and investment for a low-carbon-emitting world. The goal is to keep the rise in global temperature this century well below 2 C from pre-industrial levels.

"This announcement will foster greater support for the Paris Agreement in the final weeks ahead of the signing ceremony in New York and help drive action on the ground to tackle climate change," Waskow said.

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