Blue and Green: China and the US have both pledged to lead action against climate change, with the former promising for the first time to set targets for greenhouse gas emission cuts. Chinese vice premier Zhang Gaoli said yesterday that by 2020, China hopes to reduce its carbon emissions per unit of GDP by 45% from 2005 levels. Meanwhile, US president Barack Obama admitted that the two countries have a responsibility to lead, but added that all countries must follow. The two largest national carbon emitters...