Advances in Climate Change Research (Apr 2023)
Decadal expansion and contraction of permafrost in the Three-River Source Region, Qinghai–Tibet Plateau (1901–2020)
Abstract
Permafrost and its spatiotemporal variation considerably influence the surface and sub-surface hydrological processes, biogeochemical cycles, fauna and flora growth and cold region engineering projects in the Three-River Source Region (TRSR), Qinghai–Tibet Plateau. However, the dynamics of permafrost over a relatively long term duration (e.g. >100 years) in the TRSR is not well quantified. Thus, the spatial and temporal variations of the temperature at the top of the perennially frozen/unfrozen ground (TTOP), active layer thickness (ALT) in permafrost regions and the maximum depth of frost penetration (MDFP) in the seasonally frozen ground of the TRSR during 1901–2020 were simulated using the TTOP model and Stefan equation driven by the widely used reanalysis Climatic Research Unit 4.05 dataset. Results revealed that the permafrost in the TRSR over the past 120 years did not degrade monotonically but experienced considerable fluctuations in area with the decadal oscillations of climate warming and cooling: shrinking from 263.9 × 103 km2 in the 1900s to 233.3 × 103 km2 in the 1930s, expanding from 232.3 × 103 km2 in the 1940s to 260.9 × 103 km2 in the 1970s and shrinking again from 254.1 × 103 km2 in the 1980s to 228.9 × 103 km2 in the 2010s. The regional average TTOP increased from −1.34 ± 2.74 °C in the 1910s to −0.48 ± 2.69 °C in the 2010s, demonstrating the most noticeable change for the extremely stable permafrost (TTOP 3.0 m by 12% from 1901 to 2020. Notably, minor changes were observed for the regional average MDFP, probably due to the increase in the area proportion of MDFP 3.5 m (owing to the transformation of permafrost to seasonally frozen ground) by 7.39% and 4.77%, respectively. These findings can facilitate an in-depth understanding of permafrost dynamics and thus provide a scientific reference for eco-environment protection and sustainable development under climate change in the TRSR.
