What do you think about the Qinghai-Tibet Plateau changing from "cold and high" to "wet and warm"?

In May 2023, my country's Mount Everest expedition team climbed to the top of the earth again to carry out scientific investigation and research. As the "Roof of the World", "Third Pole of the Earth" and "Water Tower of Asia", this plateau has a profound impact on climate change in China, Asia and even the world, but various studies have shown that our Qinghai-Tibet Plateau is changing from "high and cold" to "warm and humid".

01

The “cold” “Asian water tower”

The Qinghai-Tibet Plateau has a resounding title, called the "Roof of the World", because it is the highest plateau in the world, but the Qinghai-Tibet Plateau is not born tall .

About 100 million years ago (when dinosaurs dominated the Earth), the plate carrying the Indian continent began to separate from the Antarctic plate and moved northward toward the Asian continent; between 55 and 45 million years ago, the Indian plate collided with the Asian continent and lasted for thousands of years, which gave the Himalayas and the Qinghai-Tibet Plateau the opportunity to "grow taller."

To this day, the Indian Plate is still squeezing the Eurasian Plate, causing the Himalayas on the plate boundary to continue to rise (about a few centimeters per year), becoming the highest mountain range on Earth today. This has changed the landform pattern of Asia and shaped the current monsoon climate pattern in South Asia and Southeast Asia .

What you may not have expected is that the Qinghai-Tibet Plateau is still a real "young man" - it is one of the "youngest" plateaus in the world, always active at the forefront of crustal movement, and the edge of the Qinghai-Tibet Plateau is still rising.

On December 8, 2020, my country and Nepal jointly announced that the latest measured altitude of Mount Everest is 8,848.86 meters, which is the most accurate Everest altitude measurement result in history.

On May 27, 2020, 13 members of the Mount Everest expedition team successfully reached the summit of Mount Everest and took a photo with the national flag. Image source: Science and Technology Daily

In addition to being the roof of the world, the Qinghai-Tibet Plateau is also widely known by another title, which is the "Water Tower of Asia".

You may wonder how this place, which is so high and so cold, can be called the "Water Tower of Asia"? Yes, the seemingly mysterious and "cold" plateau is the real "water town" of Asia.

In fact, the Qinghai-Tibet Plateau has become a water town because of its unique natural conditions.

The first is that during the uplift of the plateau, the plates constantly squeezed and collided with each other, forming many fault zones. Due to the unevenness of the mountains, this created the basic conditions for the formation of lakes .

The second is that the Qinghai-Tibet Plateau is the region with the largest ice and snow reserves except the North and South Poles. Solid water bodies such as glaciers (an area of ​​about 100,000 square kilometers), snow (annual snow area of ​​about 300,000 square kilometers), and permafrost (an area of ​​about 1.3 million square kilometers) are widely distributed here.

Thanks to the melting of ice and snow and precipitation, this place has the largest number of lakes in my country, accounting for half of the total area of ​​lakes in my country.

The results of the second comprehensive scientific survey of the Qinghai-Tibet Plateau in 2021 show that there are 1,400 lakes with an area larger than 1 square kilometer, with a total area of ​​about 50,000 square kilometers. The amount of fresh water evaporated each year alone reaches 51.7 billion tons, equivalent to the amount of water in 3,570 West Lakes in Hangzhou.

There are not only numerous lakes on the plateau, but each has its own charm.

Among the numerous lakes on the plateau, there is not only the largest lake in my country - Qinghai Lake; the lake with the largest water volume - Nam Co; the second largest saltwater lake - Selin Co; but also Chaka Salt Lake, Yamdrok Lake and so on. These azure blue "eyes" have attracted tourists from all over the world.

From top to bottom, they are Qinghai Lake, Namtso Lake, and Yamdrok Lake. Copyright image. Reprinting and using may cause copyright disputes

Of course, the Qinghai-Tibet Plateau is by no means a mere decoration. Due to its high terrain, water continuously flows out of the plateau under the influence of topography and gravity, giving birth to our mother rivers - the Yangtze River and the Yellow River, as well as other major rivers in Asia, providing a reliable water source for nearly 2 billion people.

It not only shapes the topography of Asia, but also has a profound impact on the climate of Asia and the world. Without its nourishment, the brilliant human civilization in the major river basins of East Asia, South Asia and Central Asia would not have been born, so it is known as the "Asian Water Tower".

02

"High and cold" turns into "warm and humid"

Water towers like the "Asian Water Tower" are distributed all over the world, and they play a vital role in the global water cycle. Among them, the Qinghai-Tibet Plateau looks the most magnificent. Among the 78 water tower units in the world (the intersection between the main river basins and the mountainous terrain based on altitude and surface roughness), the Qinghai-Tibet Plateau covers 16 and has the most important position. But at the same time, it is also the most vulnerable.

Over the past 50 years, the Qinghai-Tibet Plateau has been one of the regions with the strongest global warming. From 1961 to 2020, the annual average temperature here has risen by 0.35 degrees Celsius per decade, more than twice the global warming rate (0.16 degrees Celsius per decade) during the same period. Rapid warming has led to increased precipitation and accelerated melting of glaciers and permafrost, making the plateau warmer and wetter, and the area of ​​lakes has also expanded significantly.

The water area of ​​Selin Co has increased significantly. Image source: Xinhua News Agency Satellite News Laboratory

Data from the National Climate Center show that annual precipitation on the Qinghai-Tibet Plateau showed an increasing trend from 1981 to 2020, with an average increase of 14 mm every decade; the water area of ​​lakes on the Qinghai-Tibet Plateau showed a continuous increase from 2000 to 2020, reaching 70,304.5 square kilometers in 2020, and more than 80% of the lakes were expanding, with the expansion of lakes in the central and northern parts being more obvious .

The latest research by the Institute of Atmospheric Physics of the Chinese Academy of Sciences also pointed out that the lake water storage of 18 large lakes (lakes larger than 300 square kilometers) in the inland area of ​​the Qinghai-Tibet Plateau increased at a rate of about 26.92 mm/year from 2002 to 2018. Due to the difference in regional change rates, the area of ​​Selin Co Lake exceeded Nam Co Lake in 2014, becoming China's second largest saltwater lake.

It is particularly noteworthy that this warm and humid trend has been consistent over the past two thousand years.

And this is just the tip of the iceberg of the impact of global warming on the Qinghai-Tibet Plateau.

03

What can save you?

My glaciers and frozen soil

While becoming "watery", the area of ​​glaciers and permafrost on the Qinghai-Tibet Plateau is shrinking .

The second comprehensive scientific expedition to the Qinghai-Tibet Plateau found that over the past 50 years, the area of ​​glaciers in the Qinghai-Tibet Plateau and its adjacent areas has retreated by 15%, and the area of ​​permafrost on the plateau has decreased by 16%. Of the 82 glaciers actually observed on the Qinghai-Tibet Plateau (mainly in China), 55 glaciers are in retreat, with the largest ice loss and area shrinkage in southeastern Tibet. Glaciers at the end of lakes retreat and thin faster than those at the end of land . In 2020, 1,019 glaciers terminated as lakes, with a total area of ​​3,337±10 square kilometers, accounting for 7% of the total glacier area.

04

Why should we care about permafrost and glaciers?

Frozen soil is often described as the earth's "natural refrigerator". It affects the water and heat exchange between the earth and the atmosphere, surface hydrological processes, cold-region ecosystems, and the stability of cold-region engineering buildings. The Qinghai-Tibet Plateau has the largest permafrost area in the world's mid- and low-latitude regions. From 1961 to 2020, the area of ​​permafrost has decreased by 16%, affecting infrastructure construction (such as railway and highway safety).

Glaciers are important freshwater reserves. Due to the melting of glaciers, the land water reserves on the Qinghai-Tibet Plateau decreased by about 10 billion cubic meters per year from 2002 to 2017. If this continues, it will bring about a water crisis for downstream residents.

Changes in glacier coverage in different years. Image source: green peace

Glacier meltwater also transports a large amount of biologically active elements (such as iron, silicon, phosphorus, and organic carbon) and harmful elements (such as mercury and arsenic) to the downstream every year, affecting the primary productivity of downstream terrestrial or aquatic ecosystems, ultimately affecting the global material cycle and feeding back to the climate system.

An ice avalanche occurred in Dongpugou, Jiala Village, Nyingchi, Tibet in 2018. Image source: Gezhi Lundao Forum

At the same time, glacier melting has further exacerbated the glacial disaster chain of ice-rock avalanches-debris flows, glacial lake outbursts-floods/mudslides, etc. In addition, the rising water level and expansion of the lake surface are not only prone to outbursts, but will also change the water system in the northern source area of ​​the Yangtze River, seriously threatening the lives and property safety of local residents.

In the past 10 years, there have been five new glacial lake outburst disasters in the Himalayas. Among them, the flood and glacial debris flow disaster on July 15, 2013 caused varying degrees of damage to 14 administrative villages downstream, with economic losses reaching 200 million yuan.

In 2018, an ice avalanche blocked the Sedongpu Valley near Gala Village in the lower reaches of the Yarlung Zangbo River, causing the water level in the lower reaches of the Yarlung Zangbo River to rise by more than ten meters, posing a great threat to residents and transportation routes along the coast.

Composition of key water cycle elements of lakes on the Qinghai-Tibet Plateau. Image source: Reference [13]

05

What will happen if this continues?

It is foreseeable that if the glacier and permafrost conditions on the plateau continue to deteriorate, the impact will not only make climbing Mount Everest increasingly difficult.

The World Meteorological Organization has set a goal that by the middle of the 21st century, global temperatures will not rise more than 2 degrees Celsius above pre-industrial levels, and calls it “moderate warming.” In this case, the temperature rise on the Qinghai-Tibet Plateau will reach 4 degrees Celsius.

What is more serious is that it may be difficult to achieve the goal of keeping global warming below 2 degrees Celsius.

In 2022, the World Meteorological Organization stated that there is a 50% chance that the global average temperature will exceed 1.5 degrees Celsius in the next five years, and this probability will increase over time.

Studies have shown that even if global warming can be controlled below 2 degrees Celsius, by the middle of the 21st century, the net loss of water reserves in the Qinghai-Tibet Plateau may reach 230 billion cubic meters, which is roughly the total storage capacity of six Three Gorges Dams .

Another study also pointed out that under the medium emission scenario (greenhouse gas emissions are at a medium level), the trend of future water storage increase in lakes in the inland area of ​​the Qinghai-Tibet Plateau will also slow down. By the middle of the 21st century, the growth rate of lake water reserves will drop to about 40% of the past 20 years.

Of the 16 major cities in the world most likely to face water shortages in the future, 12 are located around the Qinghai-Tibet Plateau and its mid- and lower reaches. The sharp decline in water supply capacity and the serious imbalance of water resources may even bring other problems.

Against the backdrop of global warming, the greening of plateau vegetation and the retreat of the cryosphere will lead to a continuous decrease in the plateau surface albedo, and this trend is expected to continue to intensify in the future.

As the 1.5-degree Celsius critical point approaches, it is hard to imagine what impact a continuously warming Earth will have on the Qinghai-Tibet Plateau...

06

What's next?

It depends on each of us

On June 20, 2023, an assessment report released by the International Centre for Integrated Mountain Development (ICIMOD) pointed out that if greenhouse gas emissions are not significantly reduced, 80% of the total volume of glaciers in the Hindu Kush Himalaya (HKH) region will disappear by the end of this century - this is even far beyond the worst-case scenario forecast by the Intergovernmental Panel on Climate Change (IPCC).

Not only the Qinghai-Tibet Plateau, but also the global glacier mass loss has been accelerating over the past 20 years. From 2000 to 2019, the average annual cumulative loss of glacier mass was 267 billion tons. The impact of glacier melting is far more than just rising sea levels. The ecological imbalance of the Qinghai-Tibet Plateau under global warming is just a microcosm of the "big hand" of human activities.

On April 20, 2023, UN Secretary-General Guterres warned that if countries continue to maintain their current policies, global temperatures will rise by 2.8 degrees Celsius by the end of the 21st century, which will be a "death sentence for the world."

If that day is destined to come, how should we adapt to this increasingly extreme world? Perhaps, the button to end the death penalty is in the hands of each of us.

References:

[1] Robert A Spicer, Tao Su, Paul J Valdes, Alexander Farnsworth, Fei-Xiang Wu, Gongle Shi, Teresa EV Spicer, Zhekun Zhou, Why 'the uplift of the Tibetan Plateau' is a myth, National Science Review, Volume 8, Issue 1, January 2021, nwaa091.

[2] Wang, X., Ge, Q., Geng, X. et al. Unintended consequences of combating desertification in China. Nat Commun 14, 1139 (2023).

[3] Tang, S., Vlug, A., Piao, S. et al. Regional and tele-connected impacts of the Tibetan Plateau surface darkening. Nat Commun 14, 32 (2023).

[4] Li Xiangying, Wang Ninglian, Ding Yongjian, Jon R. Hawkings, Jacob C. Yde, Robert Raiswell, Liu Jintao, Zhang Shiqiang, Kang Shichang, Wang Rongjun, Liu Qiao, Liu Shiyin, Roland Bol, You Xiaoni & Li Guoyu. (2022). Globally elevated chemical weathering rates beneath glaciers. Nature Communications, 13: 407.

[5] Zhu Liping, Peng Ping, Zhang Guoqing, Qiao Baojin, Liu Chong, Yang Ruimin, Wang Junbo. The role of Qinghai-Tibet Plateau lakes in the surface water cycle under global change. Journal of Lake Science, 2020, 32(3): 597-608.

[6] Immerzeel, WW, Lutz, AF, Andrade, M. et al. Importance and vulnerability of the world's water towers. Nature (2019).

[7] Yao, T., Bolch, T., Chen, D. et al. The imbalance of the Asian water tower. Nat Rev Earth Environ 3, 618–632 (2022).

[8] Binbin Wang et al. Quantifying the evaporation amounts of 75 high-elevation large dimictic lakes on the Tibetan Plateau. Sci. Adv.6, eaay8558(2020).

[9] Miaogen Shen*, Shiping Wang*, Nan Jiang, Jianping Sun, Ruyin Cao, Xiaofang Ling, Bo Fang, Lei Zhang, Lihao Zhang, Xiyan Xu, Wangwang Lv, Baolin Li, Qingling Sun, Fandong Meng, Yuhao Jiang, Tsechoe Dorji, Yongshuo Fu, Amy Iler, Yann Vitasse, Heidi Steltzer, Zhenming Ji, Wenwu Zhao, Shilong Piao, Bojie Fu*. Plant phenology changes and drivers on the Qinghai-Tibetan Plateau. Nature Reviews Earth & Environment. 2022.

[10] Zhang, Yulan, Gao, Tanguang, Kang, Shichang, Shangguan, Donghui, Luo, Xi. Albedo reduction as an important driver for glacier melting in Tibetan Plateau and its surrounding areas. EARTH-SCIENCE REVIEWS[J]. 2021, 220.

[11] Nie, Y., Pritchard, HD, Liu, Q. et al. Glacial change and hydrological implications in the Himalaya and Karakoram. Nat Rev Earth Environ 2, 91–106 (2021).

[12] Li, X., Long, D., Scanlon, BR et al. Climate change threatens terrestrial water storage over the Tibetan Plateau. Nat. Clim. Chang. 12, 801–807 (2022).

[13] Zhang, G., T. Yao, H. Xie, K. Yang, L. Zhu, CK Shum, T. Bolch, S. Yi, S. Allen, L. Jiang, W. Chen, and C. Ke (2020), Response of Tibetan Plateau lakes to climate change: Trends, patterns, and mechanisms, Earth-Science Reviews, 103269,

[14] A Scientific Assessment of the Third Pole Environment UNEP. 2022

[15] Binghao Jia, Longhuan Wang, Zhenghui Xie, 2023: Increasing lake water storage on the Inner Tibetan Plateau under climate change. Science Bulletin, 68(5), 489-493.

[16] Zhang, G., Yao, T., Chen, W., Zheng, G., Shum, CK, Yang, K., Piao, S., Sheng, Y., Yi, S., Li, J., O'Reilly, CM, Qi, S., Shen, SSP, Zhang, H., & Jia, Y. (2019). Regional differences of lake evolution across China during 1960s–2015 and its natural and anthropogenic causes. Remote Sensing of Environment, 221, 386-404.

[17] Chen Fahu et al.: Research on the environmental impacts and response strategies of the Qinghai-Tibet Plateau under global change

Produced by: Science Popularization China

Author: Half Lazy (Institute of Atmospheric Physics, Chinese Academy of Sciences)

Producer: China Science Expo

Editor-in-charge: Cui Yinghao

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