LANZHOU, May 18 (Xinhua) -- A new study by Chinese scientists is deepening the comprehension of the asynchronous relationship between climate change and permafrost degradation on the Qinghai-Tibet Plateau, according to the Northwest Institute of Eco-Environment and Resources (NIEER) under the Chinese Academy of Sciences.

This study provides a scientific basis for improving permafrost change prediction, assessing risks of permafrost carbon feedback, and ensuring the safety of engineering facilities on the Qinghai-Tibet Plateau, said the institute.

Conducted by NIEER researchers, the study has been published in the journal npj Climate and Atmospheric Science.

Permafrost stability plays a pivotal role in Earth's climate regulation. Global warming is disrupting the long-term thermal equilibrium of permafrost worldwide, triggering extensive degradation and potentially mobilizing vast soil organic carbon reserves that could amplify global warming through a positive feedback loop, according to Wu Qingbai, a researcher at NIEER and the study's leader.

The Qinghai-Tibet Plateau houses the world's largest high-altitude permafrost region, and changes in the permafrost significantly affect regional ecosystems, hydrological processes, carbon cycling, and the safety of major engineering projects.

Climate warming is driving continuous permafrost degradation. However, permafrost does not respond instantaneously to changes in air temperature. Instead, its thermal behavior is collectively regulated by surface energy exchange, soil water-heat processes, latent heat of phase change, and subsurface heat conduction, exhibiting hysteresis and thermal memory effects, according to Wu.

"We initiated the study to systematically understand the temporal scales, spatial patterns, and influencing factors of the thermal response of permafrost on the Qinghai-Tibet Plateau," Wu added.

The research team integrated long-term in-situ borehole observations from 54 sites over the 2001-2020 period with high-resolution reanalysis climate data to statistically characterize the apparent temporal offsets between air temperature and key permafrost thermal indicators, including active layer thickness, temperature at the permafrost table, and ground temperatures at depths of 10 meters and 15 meters underground.

The study showed that the thermal state of permafrost on the Qinghai-Tibet Plateau exhibits a pronounced multi-year-to-decadal-scale thermal memory effect in response to climate change, with a median apparent temporal offset relative to air temperature changes of approximately 8 to 11 years.

This timescale demonstrates significant spatial variation -- it is shorter in the warm and humid southeastern region of the plateau at about 6 to 8 years, and longer in the cold and arid northwestern region at 12 to 15 years.

The study further indicated that climatic factors explain 31-51 percent of its spatial variance, with air pressure and precipitation serving as dominant statistical contributors, reflecting large-scale climatic background conditions, while topography and soil moisture exert local controls.

This new study unveiled the existence of a decadal thermal memory effect during permafrost degradation on the Qinghai-Tibet Plateau, according to Fu Ziteng, a postdoctoral researcher at NIEER.

"It indicates that even if the rate of near-surface air temperature rise slows down in certain phases, the subsurface permafrost of the Qinghai-Tibet Plateau may continue to warm and degrade due to cumulative heat from earlier periods," Fu said. ■