Permafrost Changes in the Northern Limit of Permafrost on the Qinghai-Tibet Plateau in the Last 30 Years
近30年来青藏高原西大滩多年冻土变化

A radar survey on permafrost changes has been conducted in Xidatan, the northern limit of permafrost on the Qinghai-Tibet Plateau (QTP). Comparison with the survey result of 1975 in the same region shows that, in the last 30 years, permafrost degradation has occurred on a relatively large scale in the northern limit of permafrost on the QTP. Permafrost area in the region of interest has been shrunk to 141.0 km 2 from original 160.5 km 2 in 1975, or permafrost reduction rate estimated being about 12%. The lowest altitude with permafrost coverage is 4385 m exposed in this survey, 25 m higher than that of 1975. Climate change during the past 3 decades in the permafrost northern limit mostly contributes to the reduction. However, under the same climate scenario, no significant degradation was found in the scale of 30 years in the continuous permafrost zone, despite distinct ground temperature rising there. The survey result shows a fact to tell how and how much permafrost responses to climate change, and provides a reference to identify interaction models between permafrost and climate system.