The international community has made a good start in tackling climate change, says Prof Dr Niklas Höhne of the New Climate Institute.
But he told BBC World News more still needed to be done and China was still cautious with its commitments.
He said: “The developed countries need to go first and I think they have done that now. So the US has put on an ambitious target. The EU has done so. Canada and Japan have followed yesterday. That’s good.
“And China is a bit cautious. [The] positive about China is that they have really said they want to go to zero greenhouse gas emissions by 2060, which was a very, very good announcement and has had a big impact.”