By Wang Hairong

At the age of 69， Yao Tandong， a renowned member of the Chinese Academy of Sciences （CAS）， is still busy at work. As the chief scientist of Chinas second Tibetan Plateau Scientific Expedition and Research （STEP）， he also periodically chairs seminars sharing his teams research findings.

Over the past four decades， Yao has devoted himself to studying glaciers and environmental changes. He once served as director of the Institute of Tibetan Plateau Research （ITP） under the CAS， and currently still conducts research for the institute and acts as its honorary director.

The second STEP program， launched in 2017 and scheduled to last five to 10 years， aims to study the glaciers， biodiversity and ecological changes， as well as changes in the climate of the Qinghai-Tibet Plateau. In the past five years， under Yaos leadership， more than 7，000 researchers from universities and research institutions， have conducted extensive research and yielded some remarkable results.

Through the expedition， a team led by Zhai Panmao， a researcher with the Chinese Academy of Meteorological Sciences， found that the rapid warming of the plateau that has occurred since the early 20th century is unprecedented in the previous 2，000 years. They further revealed that， since the mid-1970s， the rate at which it is warming has nearly doubled.

Another recently released outcome is the Global Observation-based System for Monitoring Greenhouse Gas （GONGGA）. Carbon flux is the movement of carbon between oceans， land， the atmosphere and living things， and GONGGA estimates this flux in and out of the land and the ocean. The system also assesses， in real time， the global carbon budget， the maximum amount of humanproduced carbon that can be released into the atmosphere while limiting global warming to a given level. It was recently selected as one of the four advanced inversion systems for the Global Carbon Project （GCP）， a multilateral research partnership， to establish a knowledge base on the carbon cycle.

Yao said China is already at the international forefront in the fields of glacier change and related ecological research. “As our research advances， we will share more new discoveries and progress with the international community，” he told Beijing Review.

Decoding changes

Chinas first STEP program began in the 1970s and continued for about two decades. While that mission mainly described what was there， on the plateau， the latest one seeks to reveal what changes have occurred there， as well as how and why， Yao said.

Since the 1970s， many changes have been observed on the plateau. A notable one is that the lakes there， known for their tranquil beauty， have grown significantly in size and number. A fast expanding lake is Serling Co near Nagqu City in Tibet Autonomous Region. According to Xinhua News Agency， when scientists participating in the second STEP program studied the lake in 2017， they found that in less than 40 years， it had nearly doubled its surface area.

Yao told Beijing Review that in the prior half century， the number of lakes larger than one square km on the QinghaiTibet Plateau had increased from 1，081 to 1，424 and their total area had expanded from 40，000 square km to 50，000 square km.

Global warming is increasing the rate at which the regions glaciers melt， leading to a decrease in solid ice and an increase in liquid water on the plateau， Yao explained.

In the past 50 years， the glacier coverage in the region and its adjacent areas had shrunk by 15 percent， and the area of permafrost there had decreased by 16 percent， Yao said in 2018. He added that over the previous 35 years， the volume of vegetation during the plateaus growing season had significantly increased， and the runoff into rivers originating from the plateau had become larger.

As the origin of about a dozen Asian rivers， the plateau is dubbed the Water Tower of Asia. Yao said a significant outcome of the program is that scientists found that the region currently holds at least 9 trillion cubic meters of water， either as ice or as liquid water.

However， as the glaciers continue to retreat， glacial meltwater will sharply decrease. If the worsening trend continues， rivers mainly fed by meltwater， especially small and medium-sized tributaries， are likely to gradually dry up， Zhu Liping，Deputy Director of the ITP， wrote in an article published in Beijingbased Science and Technology Daily.

Under the second program， Zhu led the research team in studying the regions lakes. He said the size of lakes on the plateau also affects the pattern of droughts and floods in the monsoon region in east China. If the lakes continue to expand at the current rate， the affected areas will need to adjust their plans for dealing with major weather events and other natural disasters， he added.

Keeping up with the times

Glaciers and snowfields are a vital part of the ecology on the QinghaiTibet Plateau and drilling ice cores is an essential part of monitoring their health. Ice cores， with layers like tree rings， contain continuous records of the past. From ice core records， scientists can learn about the concentrations of greenhouse gases and temperatures in the past， learn how they relate to one another and deduce other details about the atmosphere and environment at the time the ice was formed.

However， drilling and transporting ice cores is a challenging job as scientists must climb towering glacier-covered mountains and then carry the collected samples down. Moreover， the operation has to be carried out mostly during the cold nighttime， as ice is more likely to melt during the daytime， Wu Guangjian， a researcher with the ITP， said. During the expedition， Wu and his colleagues obtained ice cores from glaciers in the headwater zones of important rivers， as well as from Mount Qomolangma， the worlds tallest mountain.

The mission to Mount Qomolangma in April and May of 2022 created several firsts in history. For the first time， a meteorological observation station capable of automatically sending back data was built on the worlds highest summit， high-precision radar was used to measure the thickness of ice and snow at the peak， and ice and snow samples were taken there. It was also the first time that a floating airship reached an altitude of 9，050 meters to observe the environment， and helicopter flights were executed to study the concentration of greenhouse gases in the atmosphere. These breakthroughs were listed by members of the CAS and the Chinese Academy of Engineering among the countrys top 10 science and technology achievements in 2022.

To achieve these feats at such a height， mountaineers underwent two years of training in installing and operating the scientific equipment and instruments， Yao said.

During the second expedition， more emphasis has been placed on interdisciplinary research， and advanced equipment and instruments launched to ensure the accuracy of observation and quality of study， according to Yao. Home-grown high-altitude flying robots have played an important role in monitoring glaciers and lakes. Big data， the Internet and supercomputing technologies， plus satellites， have also contributed to improving research efficiency. BR