Aerial photo shows a flock of sheep roaming along the Siling Lake in Naqu City, southwest China`s Tibet Autonomous Region, April 29, 2020. The frozen surface of the plateau lake in Tibet is thawing with temperature rising up. (Xinhua/Tian Jinwen)

Sheep are seen by the Siling Lake in Naqu City, southwest China`s Tibet Autonomous Region, April 29, 2020. The frozen surface of the plateau lake in Tibet is thawing with temperature rising up. (Xinhua/Hou Jie)

Photo taken on April 29, 2020 shows the scenery of Siling Lake in Naqu City, southwest China`s Tibet Autonomous Region. The frozen surface of the plateau lake in Tibet is thawing with temperature rising up. (Xinhua/Hou Jie)

Aerial photo shows a flock of sheep roaming along the Siling Lake in Naqu City, southwest China`s Tibet Autonomous Region, April 29, 2020. The frozen surface of the plateau lake in Tibet is thawing with temperature rising up. (Xinhua/Tian Jinwen)