The United States and China, together responsible for 40 percent of the world’s carbon emissions, have ratified the Paris global climate agreement on Saturday.

U.S. President Barack Obama and Chinese President Xi Jinping submitted their plan to join the agreement to U.N. Secretary-General Ban Ki-moon, who is in China to witness the announcement.

Senior adviser to Obama, Brian Deese, said the joint declaration should push other countries to formally join the agreement.

Deese said India is also poised to join the agreement this year. He said Obama is expected to meet Prime Minister Narendra Modi on the sidelines of a Group of 20 nations meeting in Hangzhou, this weekend.

In Paris last December, nearly 200 countries agreed on a binding global compact to slash greenhouse gases and keep global temperature increases to well below 2 degrees Celsius.

While 180 countries have now signed the agreement, 55 nations, covering at least 55 percent of global emissions, need to formally ratify the treaty to put it into legal effect.

Meawhile, U.N. Secretary General Ban Ki-moon on Saturday said that he will hold a high-level event in New York to which he will invite country leaders to formally ratify the Paris climate change agreement.

Ban was speaking in the Chinese city of Hangzhou, where the United States and China announced their formal ratification of the deal.