A projection of permafrost degradation on the Tibetan Plateau during the 21st century

Abstract

[1] The current distribution and future change of permafrost on the Tibetan Plateau were examined using the Community Land Model version 4 (CLM4) with explicit treatment of frozen soil processes. When forced off-line with archived high-resolution data from The Abdus Salam International Centre for Theoretical Physics Regional Climate Model version 3 nested within the Model for Interdisciplinary Research on Climate 3.2 HiRes, the CLM4 produced a near-surface permafrost area of 122.2 Â 10 4 km 2 for the Tibetan Plateau. This area compares reasonably with area estimates of 126.7 Â 10 4 km 2 for the Plateau frozen soil map. In response to the simulated strong Plateau warming (approximately 0.58°C per decade over the Tibetan Plateau for the period from 1980 to 2100 under the A1B greenhouse gas emissions scenario), the near-surface permafrost area is projected to decrease by approximately 39% by the mid-21st century and by approximately 81% by the end of the 21st century. The near-surface permafrost area exhibits a significant decreasing linear trend, with a rate of decrease of 9.9 Â 10 4 km 2 per decade. The simulated deep permafrost area remains longer than the near-surface permafrost for the same period. The active layer thickness of 0.5-1.5 m found in the present-day increases to approximately 1.5-2.0 m by the period of 2030-2050. This increase will continue and reach a level of 2.0-3.5 m by the period of 2080-2100. Surface runoff decreases but subsurface runoff increases, both relative to the difference between precipitation and evapotranspiration. This is related to the fact that the decrease in ground ice content, as caused by permafrost degradation, facilitates the percolation of more water to deeper soil layers, thus resulting in the reallocation of runoff. These results provide useful references for evaluating the level of permafrost degradation in response to climate warming on the Tibetan Plateau.Citation: Guo, D., H. Wang, and D. Li (2012), A projection of permafrost degradation on the Tibetan Plateau during the 21st century,

Longitudinal patterns of periphyton biomass in Qinghai–Tibetan Plateau streams: An indicator of pasture degradation?

“…Especially in the "Three-River Headwaters" region, moderate or seriously degraded pasture area accounted to 12 million hm 2 , accounting for 58% of the available pasture area (Liu et al, 2008). In recent decades, permafrost on QinghaieTibetan Plateau has also degraded seriously (Wu and Zhang, 2010), and will decrease by approximately 81% by the end of the 21st century (Liu et al, 2011;Guo et al, 2012). The main driving forces of these degenerations are climate change, strong human activity (overgrazing) and devastation due to rodents (Ma et al, 1999;Liu et al, 2008;Yan et al, 2011).…”

Diagnostic and model dependent uncertainty of simulated Tibetan permafrost area

“…Many recent modeling studies (e.g. Guo et al (2012), Guo and Wang (2013), Slater and Lawrence (2013) and references therein), have consistently adapted this for land surface and earth system models by defining a model grid cell as permafrost if the simulated ground temperature (of at least one level in the upper soil) remains at or below 0 • C for at least 24 consecutive months. Furthermore, these modelbased studies are limited by the maximum soil depth of the models (Table 1).…”

“…We make use of all five major permafrost diagnostic methods promoted in the literature (Slater and Lawrence, 2013;Guo et al, 2012;Guo and Wang, 2013;Wang et al, 2006;Wang, 2010;Nan et al, 2002Nan et al, , 2012Saito et al, 2013;Ran et al, 2012;Wang et al, 2006;Jin et al, 2007;Xu et al, 2001;Nelson and Outcalt, 1987). Since the model intercomparison relies on LSMs that are all driven at monthly resolution, the methods we use are tailored, as usual, to reflect the forcing data resolution.…”

“…The results were improved by setting appropriate permafrost parameters for soil organic matter contents and soil texture properties (Luo et al, 2008;Xiong et al, 2014). CLM4.0 has also been used to provide future projections of permafrost extent for the whole TP (Guo and Wang, 2013;Guo et al, 2012), and simulates 81 % loss of permafrost area by the end of 21st century under the A1B greenhouse gas emissions scenario. This raises the question of how reliable the estimate is in comparison with results from other models.…”

Permafrost Thaw and Associated Settlement Hazard Onset Timing over the Qinghai-Tibet Engineering Corridor

“…These data are considered to be reliable (Zhao 2004;Ran et al 2012), and they have been widely used to validate simulated permafrost distribution (Guo et al 2012;Guo and Wang 2013).…”