Tibetan Plateau

Long ago, the land of India moved north and pushed into Asia.

The push lifted up the Himalayas and the high land behind them.

The US Geological Survey (USGS) explains that India drifted north and rammed into Asia about 40 to 50 million years ago. Since then, the Himalayas and the Tibetan Plateau to their north have risen very quickly, in geological terms.

India still presses on Asia today, and the plateau in turn presses on the land to its north.

The USGS describes India's northern margin colliding with the Eurasian Plate about 40 to 50 million years ago, after which the Himalayas and the Tibetan Plateau rose very rapidly. Sandstone fossils from Tibet record a mild, wet environment about 105 million years ago, before the region's uplift and a northward shift of nearly 2,000 km; India's movement still puts enormous pressure on Asia, and Tibet in turn presses on the land to its north.

UNESCO describes ongoing geological formation in Hoh Xil, including a large planation surface: a broad, flattened land surface of the plateau.

Under much of the grass, the ground stays frozen all year.

In the mountains, glaciers are melting, and some lakes are getting bigger.

Permafrost is ground that stays frozen for years. A 2017 study mapped permafrost under about 40 percent of the plateau, not counting its glaciers and lakes.

NASA says glaciologists call the region the 'Third Pole' because its high landscapes hold the largest reserve of fresh water outside the polar regions, much of it in glaciers. As temperatures rise, NASA reports, many of its lakes are growing larger and deeper.

Zou and colleagues (2017) mapped permafrost over about 1.06 million km² (40%) of the plateau, seasonally frozen ground over 56% and unfrozen ground over 1%, excluding glaciers and lakes; they note the plateau holds the largest permafrost areas of the world's mid- and low-latitude regions.

NASA's Earth Observatory compared Landsat images from October 1987 and October 2021 of lakes west of the Tanggula Mountains: Chibzhang Co and Dorsoidong Co grew as glaciers thinned, merged in the mid-2000s, and grew in area by 23% between 1976 and 2017, about half of it apparently from glacial melt. Another study found 235 more lakes and 18% more lake area across the plateau in 2014 than in 1977.

Wild yaks, wild asses and antelopes live on the high grasslands.

Tiny cushion plants bloom in summer.

In Hoh Xil, in the plateau's northeast, UNESCO says Tibetan antelope, wild yaks, Tibetan wild asses, Tibetan gazelles, wolves and brown bears are all often seen. All the plant-eating mammals there are found only on the plateau.

Each early summer, tens of thousands of female Tibetan antelopes travel hundreds of kilometers to the lake basins of Hoh Xil to give birth.

UNESCO's Hoh Xil listing (2017) notes that more than a third of the higher plants and all the herbivorous mammals are plateau endemics, and 60% of the mammal species as a whole. Alpine grassland, dominated by the grass Stipa purpurea, makes up 45% of the vegetation, with alpine meadows and talus. The site has 74 vertebrate species: 19 mammals, 48 birds, six fish and one reptile.

It supports almost 40% of the world's Tibetan antelope and up to 50% of its wild yaks. In early summer, tens of thousands of female antelopes migrate hundreds of kilometers to calve in its lake basins, and the property protects the complete migration route from Sanjiangyuan.

The plateau is very high, so the air has less oxygen. People can get headaches.

It is very cold, too. Stay close to your grown-up.

Because the plateau is so high, visitors can get altitude sickness. The US Centers for Disease Control and Prevention (CDC) says children are as likely to get it as adults, that its main sign is a headache, and that going down at least 300 meters helps.

It is also very cold: UNESCO says Hoh Xil's average temperatures stay below freezing all year.

The CDC's Yellow Book notes that any unacclimatized traveler sleeping at 2,450 m or higher is at risk of altitude illness, that children are as susceptible as adults, that headache is the cardinal symptom of acute mountain sickness, and that it improves rapidly with a descent of 300 m or more.

UNESCO describes Hoh Xil's frigid plateau climate, with sub-zero average temperatures all year and lows occasionally reaching -45 °C.