Tibetan Plateau

The Tibetan Plateau, also known as the Qinghai–Tibet Plateau, Qingzang Plateau, or as the Himalayan Plateau, is a vast elevated plateau located at the intersection of Central, South, and East Asia. It is the world's highest and largest plateau above sea level, covering an area of 2,500,000 square kilometres (970,000 sq mi). With an average elevation exceeding 4,500 metres (14,800 ft), the Tibetan Plateau is often called "the Roof of the World" because of its towering height.

Surrounded by impressive mountain ranges that include the world's two highest summits, Mount Everest and K2, the plateau stretches approximately 1,000 kilometres (620 mi) north to south and 2,500 kilometres (1,600 mi) east to west. It covers parts of Tibet Autonomous Region, Qinghai, Sichuan, Gansu, Xinjiang in Northwestern China, as well as areas in Bhutan, India, Pakistan, Nepal, Tajikistan, and Kyrgyzstan.

The Tibetan Plateau plays a vital role in the environment, as it contains the headwaters of many important rivers, including the three longest rivers in Asia: the Yellow, Yangtze, and Mekong. Its tens of thousands of glaciers and other features act like a "water tower", storing fresh water and helping maintain river flow. Because of its huge ice fields, it is sometimes called the Third Pole, holding the largest reserve of fresh water outside the polar regions. Scientists are closely watching how climate change affects this important area.

Description

The Tibetan Plateau is surrounded by huge mountain ranges. To the south, it is bordered by the inner Himalayan range, while the Kunlun Mountains lie to the north, separating it from the Tarim Basin. The Qilian Mountains lie to the northeast, dividing the plateau from the Hexi Corridor and Gobi Desert. To the east and southeast are important rivers like the Salween, Mekong, and Yangtze, flowing through parts of Yunnan, Sichuan, and Qinghai.

The plateau features a dry, grassy landscape with scattered mountains and lakes. Rainfall is low, mostly falling as hail, and frost can occur for six months of the year. In the far northwest, the Changtang region is extremely cold and high, making it one of the least populated areas 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 among the youngest on Earth, 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 towering mountain ranges.

Over millions of years, the Tibetan Plateau rose to its current high elevation. 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. Geologists debate why the plateau has relatively flat terrain, with theories ranging from ancient uplift to ongoing erosion.

Environment

The Tibetan Plateau is home to many different kinds of plants and animals, even though it is very high and dry. You can find grasslands, some shrublands, and even forests in certain 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 even special spiders that can jump high up in the mountains.

The World Wide Fund for Nature has identified several distinct areas, or ecoregions, on the Tibetan Plateau. These include alpine deserts, steppes, shrublands, and meadows. Some of these areas are very dry, while others are rainier. The plateau’s southern edge, close to the Himalayas, has some of the world’s highest forests. Each ecoregion supports unique plants and animals suited to life 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, from around 200,000 to 40,000 years ago. Today, many people on the plateau and in the Himalayas live as nomads, moving with their animals instead of farming. These nomads make up about 40% of the Tibetan people. They have learned to live on the grassland by raising animals, since crops cannot grow well there. The plateau was first home to humans between 30,000 and 40,000 years ago. One famous ancient kingdom was the Tibetan Empire, which existed from the 7th to the 9th century AD. The northern area, called the Changtang, is too cold and high for many people to live there permanently.

Impact on other regions

Monsoons are large 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, causing air over land to become warmer and rise. This creates a low-pressure area that pulls in moist air from the ocean, leading to rainfall.

The Tibetan Plateau plays a major role in creating the strongest monsoons on Earth. In winter, the ocean stays warmer than the land, causing air over the ocean to rise and creating 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 has the world's third-largest store of ice. Scientists have studied ice from its glaciers to learn about the distant past, finding very old samples that help us understand ancient conditions.

Because temperatures are rising quickly here, the glaciers are melting faster than anywhere else on Earth. This melting can cause flooding and may eventually affect water supplies for major rivers like the Indus and the Ganges. Over the last 50 years, many of the plateau’s glaciers have shrunk significantly.