The China Global Atmosphere Watch Baseline Observatory on Mount Waliguan in Qinghai province. [Photo provided to CHINA DAILY]

For the past 30 years, researchers based at the peak of Mount Waliguan in Northwest China's Qinghai province have worked around the clock to monitor the atmosphere, tracking the changes and makeup of the air to further study the effects climate change is having on the planet.

At 3,800 meters above sea level, the China Global Atmosphere Watch Baseline Observatory, the highest baseline observatory in the hinterland of Eurasia, plays an important role in "taking the temperature of the Earth".

Established in 1994 in Gonghe county of the Hainan Tibetan autonomous prefecture, the observatory has tracked what has become known as the "Waliguan Curve", a curve that shows the increase of carbon dioxide levels in the atmosphere over the past three decades.

As the observatory is so isolated, with little to be found in a 50-kilometer radius around it, monitoring can be carried out on atmosphere that has not been affected by human activities, and so the data that it produces is particularly vital for global climate change research.

As one of 32 similarly isolated and hard-to-reach observatories of the World Meteorological Organization's Global Atmosphere Watch, the team that works there live in relatively harsh conditions.

The average annual temperature at the Waliguan station is below 0 C, dropping to minus 20 C at its lowest, with the average oxygen content in the air equivalent to 67 percent of that at sea level.

Observers Wang Ningzhang (left) and Ren Lei conduct maintenance work at the observatory in May. QU CHEN/XINHUA

"When I first arrived here, it felt like carrying a 30-kilogram load on my back when walking. Even a short distance would leave me breathless. Due to the lack of oxygen, headaches were common, making it difficult to sleep at night," said deputy director of the Waliguan observatory Wang Jianqiong, who's been working at the station for over 20 years.

Wang's colleague, Hu Chengrong, appears on the rooftop of the observatory each day before 8 am to survey the surroundings. He records the cloud cover, visibility and weather phenomena in a logbook. These manual observations are conducted three times a day — morning, noon and evening.

"It's a bit easier now. The older workers at the station said that in the past, all meteorological observation data was recorded manually every 3 hours, 24 hours a day, year-round without breaks," Hu said. "Back then, on really windy days, two people had to tie themselves together to avoid being blown away when walking outside."

To ensure the absolute purity of the atmosphere sample being taken, observers must hold their breath before cleaning and sterilizing the sample container and running it downwind some 10 meters. From there, the container is left to collect its atmosphere sample for the next 15 minutes.

"The procedures for bottle cleaning and sampling are strictly regulated to prevent exhaled gases of the staff from affecting the results," said observer Wang Ningzhang. To avoid the influence of near-surface updrafts on air samples, sampling must be completed before 9 am each day.

To protect the air on the mountain from human interference to the greatest extent possible, the observatory is staffed with two workers in each team, who rotate shifts every seven days. While on the mountain, the workers cannot make fires for cooking and instead eat dry rations and instant noodles.

Those wishing to visit Mount Waliguan may encounter Tibetan volunteers at the foot of the mountain discouraging them from ascending to avoid affecting the monitoring results.

Observers Li Ming (left) and Huang Jianqing check equipment at the station in January last year. [Photo provided to CHINA DAILY]

The meteorological data recorded at Waliguan has never stopped and has never been interrupted. "The observational data from nearly 30 years are a valuable asset to China's meteorological endeavors," Hu said.

In the late 1980s, then director of the National Meteorological Administration and World Meteorological Organization president Zou Jingmeng said that China must establish a high-standard, global atmospheric background observatory inland or on a plateau to enhance global monitoring of greenhouse gases and research on climate change.

In Beijing and Geneva on Sept 15, 1994, representatives from the Chinese government and the World Meteorological Organization, said the Waliguan observatory was to become the world's highest observatory for monitoring ozone and greenhouse gases at that time, filling the void in global atmospheric background monitoring in the Eurasian continent's hinterland.

Gregory R. Carmichael, chair of the Scientific Steering Committee of Global Atmosphere Watch, said during the 30th anniversary of the establishment of the Waliguan observatory: "It faced many challenges in construction and in establishing operations. This site joined observatories at Cape Grim, Cape Point, Mauna Loa, Jungfraujoch and Zugspitze, among others to form the backbone of a high-quality global network of background/baseline stations."

To date, the Waliguan observatory has provided the world with continuous data on globally representative atmospheric elements such as carbon dioxide, methane, nitrous oxide and stable isotopes. Particularly noteworthy is the Waliguan Curve's tracking of carbon dioxide variations, one of its most representative achievements.

"The international contributions of the China Meteorological Association and its partner institutions through the operation of Mount Waliguan are truly exemplary. Mount Waliguan and China are key contributors to Global Atmosphere Watch, not only through their GAW sites, but also through their active participation in GAW scientific advisory boards and expert teams," Carmichael said.

The Waliguan Curve shows a yearly increase in atmospheric carbon dioxide concentration, perfectly aligning with observational data from the Mauna Loa Observatory in Hawaii, and serving as a crucial basis for countries worldwide to formulate international climate agreements.

Observers serving at different times get together at the station in August 2021. [Photo provided to CHINA DAILY]

Chao Qingchen, director of the National Climate Center, said: "This curve provides key data support for studying the laws of climate change, influencing factors and predicting future climate, serving as an important basis for supporting the United Nations Framework Convention on Climate Change and playing a significant guiding role in climate policy formulation, including providing a scientific basis for China's dual carbon strategy.

"Some of the data have become primary materials for China's negotiations on the international stage, greatly enhancing China's influence and discourse power in the field of international climate change," she added.

The Waliguan station continues to conduct round-the-clock, high-density, accurate observations across more than 60 observation metrics in a total of 30 observation projects, generating over 60,000 data points daily. It collaborates with numerous domestic and foreign universities and research institutions to jointly conduct dozens of scientific research and experiments.

Academician Du Xiangwan, former vice-president of the Chinese Academy of Engineering, said: "Monitoring personnel stand guard at this mountaintop year-round, enduring hardships and solitude. Their meticulous meteorological observations have earned China global acclaim for its contributions to atmospheric research. Here, we witness the true essence of scientific workers."