Long-term responses of permafrost to the dual impacts of climate warming and engineering disturbance along the Qinghai-Tibet Highway.

The sensitivity of near-surface permafrost to both climate warming and engineering disturbance is widely acknowledged. However, long-term responses of permafrost to the dual impacts of climate warming and engineering disturbances remain poorly understood. Using a 20-year dataset of ground temperature under roadway and natural ground surface, in this study not only we identify the thermal impacts of the Qinghai-Tibet Highway, in addition to those of climate warming, but also quantify the differences between these two impacts. The results show that variation rate of permafrost table under the highway was approximately 3.3 to 11.1 times greater than that under natural ground surface, along with a significant warming rate of permafrost under the highway. Under the dual thermal impacts of climate warming and engineering disturbances, the duration of ground frozen state at a depth of 0.5 m under roadway is 38.5 ± 6.36% shorter than that under natural ground surface. Meanwhile, rising rate of ground temperature at depth of 0.5 m beneath the asphaltic road surface is 51.7 ± 14.46% faster than that beneath the natural ground surface. This work underscores the importance for correctly understanding the response mechanisms and mitigative measures for hazards resulting from the dual impacts of climate warming and engineering disturbances, particularly by altering the heat absorption effect of asphalt pavement and by utilizing the roadbed cooling approaches. • Dual thermal impacts accelerate warming and thawing of the permafrost under highway. • Permafrost under highway thaws 3.3–11.1 times faster than that under natural ground. • 0.5 m in depth under natural ground remains frozen ~38.5% longer than under highway. [ABSTRACT FROM AUTHOR]