Photo taken on April 15, 2020 shows the scenery of the Puma Yumco Lake and a snow mountain in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Purbu Zhaxi)

Photo taken on April 15, 2020 shows the scenery of the Puma Yumco Lake in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Jigme Dorje)

Aerial photo taken on April 16, 2020 shows the scenery of the Puma Yumco Lake in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Jigme Dorje)

Aerial photo taken on April 16, 2020 shows the scenery of the Puma Yumco Lake in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Purbu Zhaxi)

Aerial photo taken on April 15, 2020 shows the scenery of the Puma Yumco Lake in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Purbu Zhaxi)

Aerial photo taken on April 15, 2020 shows the scenery of the Puma Yumco Lake in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Purbu Zhaxi)

Aerial photo taken on April 15, 2020 shows the scenery of the Puma Yumco Lake in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Jigme Dorje)

Aerial photo taken on April 15, 2020 shows the scenery of the Puma Yumco Lake in Nagarze County of Shannan City, southwest China`s Tibet Autonomous Region. The frozen lake at an altitude of over 5,000 meters has started to thaw as the temperature rises in spring. (Xinhua/Purbu Zhaxi)