As President Xi Jinping's special envoy prepares to sign the Paris Agreement on climate change on Friday in New York City, international environmental groups are praising China for significantly increasing the chances that the agreement can take effect before the 2020 deadline.

China will sign the historic climate agreement with the United States - the two countries account for 38 percent of the world's greenhouse gas emissions - and about 160 other nations.

The signing of the agreement, which was reached in December, will take place at United Nations headquarters on Friday, which is also International Mother Earth Day. The president's special envoy, Vice-Premier Zhang Gaoli, is also scheduled to meet with UN Secretary-General Ban Ki-moon and some state leaders about further cooperation.