Estimation of permafrost on the Tibetan Plateau under current and future climate conditions using the CMIP5 data

Abstract

Permafrost has significant impacts on climate change through its strong interaction with the climate system. In order to better understand the permafrost variation and the role it plays in climate change, model outputs from Phase 5 of the Coupled Model Intercomparison Project (CMIP5) are used in the present study to diagnose the near‐surface permafrost on the Tibetan Plateau (TP), assess the abilities of the models to simulate present‐day (1986–2005) permafrost and project future permafrost change on the TP under four different representative concentration pathways (RCPs). The results indicate that estimations of present‐day permafrost using the surface frost index (SFI) and the Kudryavtsev method (KUD) show a spatial distribution similar to that of the frozen soil map on the TP. However, the permafrost area calculated via the KUD is larger than that calculated via the SFI. The SFI produces a present‐day permafrost area of 127.2 × 104 km2. The results also indicate that the permafrost on the TP will undergo regional degradation, mainly at the eastern, southern and northeastern edges, during the 21st century. Furthermore, most of the sustainable permafrost will probably exist only in the northwestern TP by 2099. The SFI also indicates that the permafrost area will shrink by 13.3 × 104 km2 (9.7%) and 14.6 × 104 km2 (10.5%) under the RCP4.5 and RCP8.5 scenarios, respectively, in the next 20 years and by 36.7 × 104 km2 (26.6%) and 45.7 × 104 km2 (32.7%), respectively, in the next 50 years. The results are helpful for us to better understand the permafrost response to climate change over the TP, further investigate the physical mechanism of the freeze–thaw process and improve the model parameterization scheme.

Simulation of the Present and Future Projection of Permafrost on the Qinghai‐Tibet Plateau with Statistical and Machine Learning Models

“…The result is basically consistent with the projected change by Chang et al. (2018, Figure 8). Permafrost is in non‐equilibrium under the influence of climate change, and there may be no permafrost that is driven by the current climate.…”

“…The graph is derived from Chang et al. (2018). Shaded areas show the standard deviations across the CMIP5 models, the black lines show the equivalent present‐day area, and the gray dotted line represent the degraded area in 2070 (red dot) under different Representative Concentration Pathway scenarios (RCPs).…”

“…A growing number of studies have reported the present status and predicted degradation of permafrost under various global warming scenarios (Guo & Wang, 2017; Pang et al, 2010, 2012; W. Wang et al., 2018; Xu, Wu, et al., 2017; Zhang and Wu, 2012a). The degradation of permafrost may trigger the release of organic carbon into the atmosphere (Chang et al., 2018; Cheng & Wu, 2007; Ran et al., 2018; Y. Wang et al., 2018; Wu, Xu et al., 2017). It is also a potential threat to engineering construction and maintenance.…”

“…Projections of the changes in permafrost area on the QTP under RCP2.6, RCP4.5, RCP6.0, and RCP8.5 via 7(a) surface frost index (SFI) and 7(b) Kudryavtsev method (KUD). The graph is derived fromChang et al (2018). Shaded areas show the standard deviations across the CMIP5 models, the black lines show the equivalent presentday area, and the gray dotted line represent the degraded area in 2070 (red dot) under different Representative Concentration Pathway scenarios (RCPs).…”

Numerical modeling of the responses of soil temperature and soil moisture to climate change over the Tibetan Plateau, 1961–2010

“…For the permafrost, however, the active layer thickness (ALT) has decreased with the average value of 2.30 m (Qin et al ., 2017). The reduction of permafrost in the TP is predicted to be accelerated in the 2,100 s (Guo and Wang, 2016) and the permafrost will only exist in the northwest TP (Chang et al ., 2018). These efforts have significantly advanced the model performance and deepened our understanding of freeze/thaw process occurred in surface of the TP.…”