Simulated responses of permafrost distribution to climate change on the Qinghai\u2013Tibet Plateau

Qing Lu,Dongsheng Zhao,Shaohong Wu

doi:10.1038/s41598-017-04140-7

Abstract

Climate warming causes changes in permafrost distribution, which affects the surface energy balance, hydrologic cycle and carbon flux in cold regions. In this study, the Surface Frost Number model was applied to examine permafrost distribution on the Qinghai–Tibet Plateau (QTP) under the four RCPs (RCP2.6, RCP4.5, RCP6.0, and RCP8.5). The Kappa statistic was used to evaluate model results by comparing simulations of baseline permafrost distribution (1981–2010) with the existing frozen soil maps. The comparison shows that the Surface Frost Number model is suitable for simulating the general characteristics of permafrost distribution on the QTP. Simulated results suggest that areas of permafrost degradation would be the smallest in the near-term (2011‒2040) with the rates of 17.17%, 18.07%, 12.95% and 15.66% under RCP2.6, RCP4.5, RCP6.0 and RCP8.5, respectively. The rate of permafrost degradation would be faster in the mid-term (2041‒2070), especially under the RCP8.5 scenario (about 41.42%). Areas of permafrost degradation would be the largest in the long-term (2071‒2099) relative to baseline conditions, with a modelled 64.31% decrease in permafrost distribution using the RCP8.5 scenario. Our results would help the decision‒making for engineering construction program on the QTP, and support local units in their efforts to adapt climate change.

Highlights

Permafrost is defined as ground that remains at or below 0 °C for at least 2 consecutive years[1, 2]
A recent study suggested that global permafrost distribution would obviously retreat northward under RCP4.5, and the permafrost would basically disappear on the Tibetan Plateau[37]
The results indicated that, under a scenario of 0.02 °C/yr air temperature increase, permafrost area on the Qinghai–Tibet Plateau (QTP) would decrease by 8.8% in the 50 years and by 13.4% in the 100 years

Summary

Introduction

Permafrost is defined as ground that remains at or below 0 °C for at least 2 consecutive years[1, 2]. Due to the combined effects of both climate warming and human activity, the QTP is experiencing remarkable permafrost degradation, such as shortened durations of below-freezing temperatures, shrunk permafrost surface areas, deepened the active layer, increased ground temperatures and rose the lower limit of permafrost[14, 16,17,18,19,20]. Permafrost distribution on the QTP has been simulated by different models, including the Altitude Model[30], the Mean Annual Ground Temperature Model[31], the Response Model[32] and the Surface Frost Number model[33]. The results indicated that, under a scenario of 0.02 °C/yr air temperature increase, permafrost area on the QTP would decrease by 8.8% in the 50 years and by 13.4% in the 100 years. While the studies described above all attempted to reveal trends in permafrost distribution, there is uncertainty in the results due to input data and other factors not taken into account in the models

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Conclusion