The battle against global warming has received a transformational boost after China, the world's biggest producer of carbon dioxide, proposed to set a cap on its greenhouse gas emissions for the first time.
Under the proposal China, which is responsible for a quarter of the world's carbon emissions, would put a ceiling on greenhouse gas emissions from 2016, in a bid to curb what most scientists agree is the main cause of climate change.
It marks a dramatic change in China's approach to climate change that experts say will make countries around the world more likely to agree to stringent cuts to their carbon emissions in a co-ordinated effort to tackle global warming.
China has no cap up until now due to the principle of common but differentiated responsibilities - that those historically responsible for the problem need to act first to clean it up. Despite agreeing to this principle in the UNFCCC, the US has used China's uncapped emissions to justify inaction and frustrate global climate change talks for a decade. Now the ball is firmly in their court. I wonder what excuse they'll use now?
(My guess: start whinging about India. Because the US's position was never about fairness and was always about undermining international agreements)