Observed on June 5th every year, World Environment Day is the largest global environmental event led by the U.N. Environment Program. This year's theme, "Only One Earth," is the same as that of the 1972 Stockholm Conference, the first conference to bring environmental issues into the global spotlight. 50 years on, where are we now in dealing with climate change? What has China done to tackle the climate crisis? How should countries better cooperate to protect and restore our planet?