Photo taken on June 28, 2014 shows part of the Purog Kangri glacier within the Changtang National Nature Reserve in Shuanghu County of southwest China's Tibet Autonomous Region. The Purog Kangri glacier, with an ice cover area of 422 square kilometers, is the third largest glacier in the world. It is situated at altitudes between 5,350 and 6,400 meters. Research shows that global warming is exerting its negative influence on the Purog Kangri glacier, which has recessed by about 50 meters in the past three decades. [Photo/Xinhua]