Tibetan Plateau

The Tibetan Plateau, also known as the Qinghai–Tibet Plateau, Qingzang Plateau, or as the Himalayan Plateau, is a large, high plateau in Central, South, and East Asia. It is the world's highest and largest plateau. It covers an area of 2,500,000 square kilometres (970,000 sq mi). With an average height above 4,500 metres (14,800 ft), the Tibetan Plateau is often called "the Roof of the World" because it is so tall.

It is surrounded by big mountain ranges that include the world's two highest peaks, Mount Everest and K2. The plateau stretches about 1,000 kilometres (620 mi) from north to south and 2,500 kilometres (1,600 mi) from east to west. It covers parts of Tibet Autonomous Region, Qinghai, Sichuan, Gansu, Xinjiang in Northwestern China, and also areas in Bhutan, India, Pakistan, Nepal, Tajikistan, and Kyrgyzstan.

The Tibetan Plateau is very important for the environment. It contains the headwaters of many important rivers, including the three longest rivers in Asia: the Yellow, Yangtze, and Mekong. It has many glaciers and other features that store fresh water, acting like a "water tower". Because of its large ice fields, it is sometimes called the Third Pole, holding the most fresh water outside the polar regions. Scientists watch closely how climate change affects this important area.

Description

The Tibetan Plateau is surrounded by big mountain ranges. To the south is the inner Himalayan range. The Kunlun Mountains are to the north, and they separate the plateau from the Tarim Basin. The Qilian Mountains are to the northeast, dividing the plateau from the Hexi Corridor and Gobi Desert. To the east and southeast, important rivers flow through parts of Yunnan, Sichuan, and Qinghai. These rivers include the Salween, Mekong, and Yangtze.

The plateau has a dry, grassy landscape with some mountains and lakes. Rainfall is low and often falls as hail. Frost can happen for six months of the year. In the far northwest, the Changtang region is very cold and high, making it one of the least populated places in the world.

Geology and geological history

Main article: Geology of the Himalayas

The Tibetan Plateau's history is linked to the formation of the Himalayas. These mountains are very young, created by the collision of the Indo-Australian Plate and the Eurasian Plate about 70 million years ago. This collision closed the Tethys Ocean and pushed up layers of sedimentary and metamorphic rock, forming tall mountain ranges.

Over millions of years, the Tibetan Plateau rose to its current height. It was once lower and even had tropical lowlands, but by about 14 to 8 million years ago, it had reached nearly its present height. Today, the plateau continues to rise slowly, about 5 mm per year, as the Indo-Australian Plate moves beneath it. Scientists discuss why the plateau has flat terrain, with ideas from ancient uplift to ongoing erosion.

Environment

The Tibetan Plateau has many plants and animals, even though it is very high and dry. You can find grasslands, some shrublands, and even forests in some areas. Animals like the Tibetan wolf, snow leopard, wild yak, and water buffalo live there. There are also many birds, such as cranes and vultures, and special spiders that can jump high up in the mountains.

The World Wide Fund for Nature has identified several different areas, or ecoregions, on the Tibetan Plateau. These include alpine deserts, steppes, shrublands, and meadows. Some of these areas are very dry, while others have more rain. The plateau’s southern edge, close to the Himalayas, has some of the world’s highest forests. Each ecoregion supports plants and animals that can live in this extreme environment.

The ecoregions found on the Tibetan Plateau are:

• The Pamir alpine desert and tundra covers the western end of the Tibetan Plateau where it transitions to the Pamir Mountains
• The North Tibetan Plateau–Kunlun Mountains alpine desert covers the northwestern limits of the Tibetan Plateau along the Kunlun Mountains
• The Karakoram–West Tibetan Plateau alpine steppe covers the westernmost parts of the Tibetan Plateau and Ladakh
• The Northwestern Himalayan alpine shrub and meadows on the edges mountains bordering the extreme west of the Tibetan Plateau
• The Central Tibetan Plateau alpine steppe covers most of the central portions of the Tibetan Plateau and the eastern Changtang
• The Western Himalayan alpine shrub and meadows covers the southwestern plateau in the Garuda Valley region
• The Qaidam Basin semi-desert located in the Qaidam Basin on the northern Tibetan Plateau
• The Qilian Mountains subalpine meadows covering the Qilian Mountains in the northernmost portions of the plateau
• The Qilian Mountains conifer forests covering parts of the mountain ranges in the northeastern Tibetan Plateau
• The Tibetan Plateau alpine shrublands and meadows covering a swath of the central and northeastern Tibetan Plateau
• The Yarlung Tsangpo arid steppe in the Yarlung Tsangpo river Valley, where most of the permanent human population on the Tibetan Plateau lives
• The Eastern Himalayan alpine shrub and meadows cover the southern Tibetan Plateau on the north side of the Himalayas
• The Southeast Tibet shrub and meadows cover the southeastern and eastern parts of the plateau and are generally rainier than the other high-altitude Tibetan Plateau regions
• The Northeastern Himalayan subalpine conifer forests reach up mountain valleys in the southern plateau and contain some of the highest altitude forests in the world
• The Nujiang Lancang Gorge alpine conifer and mixed forests cover the mountain valleys that reach 500 km (310 mi) into the southeastern Tibetan Plateau
• The Hengduan Mountains subalpine conifer forests cover the southeasternmost mountain valleys on the plateau
• The Qionglai–Minshan conifer forests cover the eastern edges of the plateau and are the densest forests to be found anywhere on the Tibetan Plateau

Human history

Main article: History of Tibet

Extinct humans called Denisovans lived on the Tibetan Plateau long ago. Today, many people on the plateau and in the Himalayas live as nomads. These nomads move with their animals instead of farming. They have learned to live on the grassland by raising animals. The plateau was first home to humans thousands of years ago. One famous ancient kingdom was the Tibetan Empire. The northern area, called the Changtang, is too cold and high for many people to live there permanently.

Impact on other regions

Monsoons are big seasonal winds that bring rain to many parts of the world. They happen because land and oceans heat up and cool down at different speeds. Land warms up and cools down faster than the ocean. This makes air over land warmer and rise. This creates a low-pressure area that pulls in moist air from the ocean, which leads to rainfall.

The Tibetan Plateau helps create the strongest monsoons on Earth. In winter, the ocean stays warmer than the land. This causes air over the ocean to rise and creates a breeze that moves from land to ocean. These monsoons are much larger and stronger than the daily sea and land breezes found near coastlines.

Glaciers

The Tibetan Plateau holds the world's third-largest amount of ice. Scientists study the ice from its glaciers to learn about Earth's past. They find very old samples that help us understand ancient weather and climate.

Because temperatures are rising fast here, the glaciers are melting quicker than anywhere else on Earth. This melting can cause flooding and might affect water supplies for big rivers like the Indus and the Ganges. In the last 50 years, many of the plateau’s glaciers have gotten much smaller.