The International Organization for Standardization has issued the world's first international standard for karst critical zones, marking a major step toward unified monitoring of these fragile yet vital ecosystems worldwide.

The standard, titled Specification of Monitoring Technology for Karst Critical Zones, was developed under China's leadership with the participation of experts from Austria, Canada, Iran, Russia, Saudi Arabia and Serbia.

"The karst critical zone is a special hydrogeological structure formed by the dissolution of soluble rocks by flowing water, extending from the vegetation canopy to groundwater circulation," said Bai Bing, a research assistant at the Institute of Karst Geology under the Chinese Academy of Geological Sciences and China Geological Survey, who participated in the development of the standard.

"It is an important and unique system widely distributed around the world, covering about 22 million square kilometers, or roughly 15 percent of the Earth's land surface," Bai said.

He highlighted the importance of karst critical zones in supplying water to about one-quarter of the world's population. However, he noted that surface water in karst regions is vulnerable to infiltration losses and contamination, affecting both water quantity and quality.

In addition, karst critical zones face challenges including geological disasters, poor soil fertility and rocky desertification, which the international scientific community believes can only be addressed through a deeper understanding of these systems.

Drawing on the distinctive characteristics of different countries, the standard builds on China's years of research in karst water resource management, ecological restoration, carbon cycle studies, and disaster prevention and mitigation.

For the first time, the standard provides a systematic classification of karst critical zone types based on climate conditions. It also identifies key hydrological, geochemical, and biological processes to improve understanding of the zones' structures, regional differences and environmental evolution trends, supporting efforts to address resource and environmental challenges.

The standard also provides specific guidance on monitoring procedures and carbon sink calculations including detailed instructions on data collection, transmission, storage, processing, quality control and sharing.

"The karst critical zone plays an important role in the global carbon cycle. Establishing a unified monitoring framework can improve the efficiency of data management and services, which is crucial for the accuracy and reliability of environmental assessments and for promoting collaborative efforts in karst critical zone management," said Zhang Cheng, a researcher at the Institute of Karst Geology who led the development work.

Zhang, who is also executive deputy director of the International Research Center on Karst under the United Nations Educational, Scientific and Cultural Organization, said the standard will contribute to China's "dual carbon" goals — peaking carbon dioxide emissions before 2030 and achieving carbon neutrality before 2060 — as well as the United Nations Sustainable Development Goals related to clean water, climate action and life on land.

"The release of this standard represents a major breakthrough in China's deep participation in global geological governance, reflecting strong international recognition of China's scientific research capabilities, technical expertise and industrial influence in the field," he said.

He added that China will continue contributing its expertise to the sustainable management of global karst critical zones.