“This is a very important step for China and the US – two big countries and also two big emitters – to join the agreement,” said Dr Yang Fuqiang, senior adviser on energy, the environment and climate change at the US-based Natural Resources Defense Council.
“It will encourage other G20 members to join the agreement,”
The G20 nations are responsible for about 80 per cent of global carbon emissions.
Nearly 200 countries agreed in Paris in December on a binding global agreement to cut greenhouse gas emissions and keep global temperature increases to “well below” 2 degrees Celsius in the long term.
However, in recent months there has been concern that the historic deal was not receiving the full support of the global community.
Li Shuo, Greenpeace East Asia’s senior climate policy adviser, said the G20 could help add new momentum to the deal.
“These back-to-back meetings must see Paris move from agreement to action,” he said.
Greenpeace is calling on Theresa May, the Prime Minister, to ratify the Paris climate deal and has organised a petition that has gathered more than 100,000 signatures.
China’s ratification takes the agreement “much closer to the critical threshold for adoption”, Dr Doug Parr, chief scientist for Greenpeace, said.
“Now it’s the UK’s turn to help push it over the finishing line,” he added.
China is responsible for just over 20 per cent of global emissions while the United States covers another 17.9 per cent. Russia accounts for 7.5 per cent, with India pushing out 4.1 per cent.
To fulfil its commitments, China will have to cut carbon emissions per unit of GDP by 60 to 65 per cent by 2030 from 2005 levels, state media said.
China will also seek to increase non-fossil fuel sources in primary energy consumption to about 20 per cent