The land of putting contrasts in morphology — the rugged Tibetan Plateau has all the time challenged explorers, as do its huge flat expanses. Heinrich Harrer, an Austrian mountaineer who escaped from an internment camp in Dehradun in 1943 with among the inmates, journeyed on foot by way of the difficult mountainous terrain to Lhasa, the capital of Tibet. In a passage in his ebook Seven Years in Tibet, he expressed his awe at this land of topographic extremes: “The subsequent day, we reached the highest of the move and have been astonished to search out that there was no descent and that we had merely come to a excessive plateau. The view over the endless plain was discouraging. One gave the impression to be going through infinity, and the massive areas will surely take months to cross. So far as we might see, there was no signal of life, and an ice-cold wind blew over the snow.”

With a imply elevation of over 4,500 metres and an intensive space of roughly 25,00,000 sq. kilometres, the Tibetan Plateau covers an space that surpasses some nations in dimension.

Geographically, the Tibetan Plateau lies north of the Himalayas and the Indian subcontinent, and south of the Tarim Basin and Mongolia. As the very best plateau on Earth, it additionally options among the area’s deep, glacier-fed lakes. Its glaciers feed main Asian rivers, originating on the Tibetan Plateau, together with the Indus, Sutlej, Brahmaputra, Mekong, Salween, and Irrawaddy, which play a vital function in supplying freshwater to a big portion of the world’s inhabitants. The Plateau, subsequently, has acquired many symbolic titles such because the “Roof of the World,” “Water Tower,” and “Third Pole.” The Plateau has a hypoxic setting of low oxygen, excessive radiation and low temperature. The distinctive genetic variations assist individuals there to outlive in an oxygen-deficient setting.

The rise of the Tibetan Plateau

Tectonic forces have lengthy formed the crumpled, uplifted mountain ridges of the Tibetan Plateau, making it a longstanding focus of geological and climatic analysis. Peter Molnar, an American geophysicist and a pioneer of Tibetan tectonics, describes it as certainly one of Earth’s extraordinary irregularities and a topographic anomaly.

We’ve got now acquired a lot geological and geophysical information to realize deep insights into its evolution. The ultimate rise of the Tibetan Plateau was partly pushed by the collision of the Indian and Eurasian plates 40 to 60 million years in the past. Over geological time, India should have slid as a lot as 1,000 kilometres below southern Asia, thickening the crust below the Plateau. However Tibet is just not a monolithic block shaped throughout a single India-Asia collision occasion. The uplift of the Plateau was heterogeneous in house and in time. Research point out that it’s an assemblage of historic terranes sutured to the Eurasian plate, starting within the early Mesozoic Period (250 million years in the past), previous the India-Asia collision.

The early Paleogene interval (55 ± 10 million years in the past) is probably going probably the most possible time for the beginning of the India–Lhasa terrane collision, which was the ultimate occasion that formed the Tibetan Plateau and marked the start of the Himalayan mountains’ uplift and Tibet’s additional elevation. The interplay between the India and the Asia plates precipitated Tibet’s crust to thicken additional because of the underthrusting of the Indian plate, leading to Tibet being buoyantly uplifted. The immense peak and weight of the Tibetan Plateau created gravitational instability, inflicting it to unfold outward and downward, like a thick pancake collapsing below its weight.

The decrease crust of a plateau can turn out to be weak and cell due to elements comparable to excessive temperatures and the presence of fluids, permitting it to move outward and contribute to the collapse.A couple of million years in the past, the Tibetan plateau started its ‘gravitational collapse’. The crustal extension in Tibet is mirrored within the earthquake mechanisms. These occurring within the central a part of the Plateau, together with the current one on January 7, 2025, with a magnitude of seven.1, show regular faulting mechanisms. A standard fault is a sort of displacement the place the block of rock above the slip aircraft strikes downward relative to the block beneath, and such faulting happens the place the crust is stretched or prolonged.

Gravitational stresses additionally drive Tibet’s eastward extrusion, which is exemplified by earthquakes characterised by horizontal fault actions alongside main strike-slip faults on the japanese a part of the Plateau. The eastward extrusion of Tibet coincided with an acceleration in Himalayan uplift and a slowdown of India’s northward movement round 26 million years in the past. The slowing down of plate motion is attributed to the compressional resistance from Tibet.

The expansion of Tibet and the evolution of monsoons

The Tibetan Plateau is formed by each the mid-latitude westerlies (which deliver winter snow and dry circumstances) and the Asian monsoon (which delivers summer season rainfall). The interactions amongst topography, local weather, and biodiversity within the Tibetan area are intricate, and the event of the Asian monsoon is linked to the altering topography of Tibet and the Himalayas. Research combining palaeoaltimetry with local weather modelling have proven that south and central Tibet in the course of the Paleogene — a geologic interval from the tip of the Cretaceous Interval, 66 million years in the past, to the beginning of the Neogene Interval, 23 million years in the past — have been characterised by two east-west mountain ranges — the Gangdese Ranges in southern Tibet which run parallel to the Himalayas to the south, and the Qiangtang Ranges located within the north.

These mountain ranges within the north and south are separated by a broad lowland. Ongoing compression from the south reworked this topography in the course of the Eocene by narrowing the valley. Over time, compression from the northward motion of India continued to scale back the valley as uplift turned lively round 23 million years in the past, and the central plateau reached its present peak of 4,800 metres within the Neogene. By the mid-Miocene (about 15 million years in the past), the Larger Himalayas had surpassed the peak of the Gangdese Ranges in Tibet.

Research recommend that when the Larger Himalayas reached a important elevation, they turned the dominant issue shaping the South Asian monsoon by performing as a barrier, forcing moisture-laden winds from the Indian Ocean to rise, cool, and condense, leading to heavy rainfall over the Indian subcontinent. Nonetheless, mannequin experiments point out that the Indian summer season monsoon is extra delicate to the presence of the Himalayas and the Iranian Plateau than to the Tibetan Plateau. In distinction, the East Asian monsoon is extra influenced by the Tibetan Plateau. Though fashions are important for local weather predictions, they’ve inherent biases that restrict their skill to precisely simulate regional local weather patterns.

The excessive topography of the Tibetan area, together with the Himalayas, serves as a barrier to airflow, affecting regional local weather. By cooling in winter and heating in summer season, the Tibetan Plateau acts as a ‘thermal driver’ or a ‘warmth pump’, shaping the path and depth of monsoon winds. A deeper understanding of the roles of the Himalayas and Tibet in controlling the Asian monsoon may be achieved by learning their long-term incremental topographic improvement and their affect on monsoon evolution.

---

The creator is an adjunct professor on the Nationwide Institute of Superior Research, Bengaluru, and the director of the Consortium for Sustainable Growth, Connecticut, U.S.A.

---

Quotation:

• Boos WR and Kuaang Z., 2010. Dominant management of the South Asian monsoon by orographic insulation versus plateau heating. Nature, 463 (7278): 218-222.
• Molnar, P., and Chen, P. (1983). Focal depths and fault aircraft options of earthquakes below the Tibetan Plateau. Journal of Geophysical Analysis: Stable Earth, 88(B2), 1180-1196. https://doi.org/10.1029/JB088iB02p01180.
• Molnar, P. 1989. The Geologic Evolution of the Tibetan Plateau Creator(s): Supply: American Scientist, July-August 1989, Vol. 77, No. 4 (July-August 1989), pp. 350-360
• Molnar, P., England, P., and Martinod, J. (1993). Uplift of the Tibetan Plateau, and the Indian Monsoon. Critiques of Geophysics, 31, 357–396.
• https://blogs.studying.ac.uk/weather-and-climate-at-reading/2017/without-the-tibetan-plateau-what-would-happen-to-the-asian-summer-monsoons/
• Spicer, R.A., Tao Su, Paul J. Valdes, Alexander Farnsworth, Fei-Xiang Wu, Gongle Shi, Teresa E. V. Spicer and Zhekun Zhou. 2021. The topographic evolution of the Tibetan Area as revealed by palaeontology. Palaeobiodiversity and Palaeoenvironments (2021) 101:213–243 https://doi.org/10.1007/s12549-020-00452-1

---

 

Banner picture: Nyenchen Tanglha peak in central Tibet. Picture by McKay Savage by way of Wikimedia Commons (CC BY 2.0).