President Xi Jinping delivers a speech for the opening day of the World Climate Change Conference 2015 (COP21) at Le Bourget, near Paris, France, November 30, 2015. [Photo/Xinhua]

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.

After the signing ceremony, China will begin the legal process to join the agreement and will ratify it as soon as possible, said Su Wei, director of the Department of Climate Change of the National Development and Reform Commission.

Countries that don't sign the agreement on Friday will still have a year to do so. Countries that sign must then have the agreement ratified by their own legislative procedures.

At least 55 countries, representing at least 55 percent of global greenhouse gas emissions, must ratify the agreement before it can take effect.

The agreement aims to hold the increase in the global average temperature to less than 2 degrees Celsius above pre-industrial levels and to work toward limiting the increase to 1.5 C.

China and the US have announced that they will join the agreement this year. There are indications that more countries will also join this year.