China has announced it is aiming to become carbon neutral before 2060, in what could prove to be a major step forward for the climate fight.
The world's biggest polluter also said it would scale up its efforts under the global Paris Agreement on climate change, with an aim to have its carbon dioxide emissions peak before 2030.
In a statement to United National General Assembly, the Chinese President Xi Jinping said the Covid-19 crisis reminded the world that "humankind should launch a green revolution and move faster to create a green way of development and life, preserve the environment and make Mother Earth a better place for all."
He called for a green recovery of the world economy in the post-Covid era.
Commenting on the announcement, Richard Black, director of the Energy and Climate Intelligence Unit (ECIU) said: "This is the first time that China, the world's biggest greenhouse gas emitter, has pledged to end its net contribution to climate change so although details are scarce at the moment, this looks like a very significant step forward.
"China isn't just the world's biggest emitter but the biggest energy financier and biggest market, so its decisions play a major role in shaping how the rest of the world progresses with its transition away from the fossil fuels that cause climate change," he said.
And he added it was a boost for the European Union, which had urged Mr Xi to take such a step as part of a joint push on lowering emissions and showed international moves to curb climate change "remain alive" despite the efforts of US President Donald Trump and Brazil's Jair Bolsonaro.
Scientists have warned that global carbon dioxide emissions need to nearly halve in the next decade and fall to zero overall by 2050 in order to prevent global temperatures rising more than 1.5C above pre-industrial levels.
The carbon neutrality pledge would see China emit no more carbon dioxide, the most significant greenhouse gas, than it was able to capture and store through measures such as planting trees, and would require major action to cut pollution from electricity generation, industry, heating and transport.