The extent of permafrost in China during the local Last Glacial Maximum (LLGM)

摘要

Recent investigations into relict periglacial phenomena in northern and western China and on the Qinghai-Tibet Plateau provide information for delineating the extent of permafrost in China during the Late Pleistocene. Polygonal and wedge-shaped structures indicate that, during the local Last Glacial Maximum (LLGM, between ～35 and 10.5 ka BP), the southern limit of latitudinal permafrost in northern China advanced southward at least to ～38-40°N in the east and to ～37-39°N in the west. This represents an advance of about 5-10° of latitude beyond present-day permafrost limits. The lower limits of elevationally controlled permafrost on the Qinghai-Tibet Plateau and its peripheries were about 1000 m lower: this permafrost was largely continuous during the LLGM. This suggests a cooling of between 4 and 10°C, or more. This paper discusses the extent of permafrost during the LLGM and presents maps that have been constructed on the basis of extensive and integrative analysis of all reliable and pertinent data. The results indicate that the extent of LLGM permafrost in China was between ～3.8 and 4.3×10~6 km~2. This is 80 to 100% more than that of ～2.15×10~6 km~2 in the 1970s, and 120 to ～150% more than that of ～1.75×10~6 km2 today.