Abstract
Abstract. Air temperature increases thermally degrade permafrost, which has widespread impacts on engineering design, resource development, and environmental protection in cold regions. This study evaluates the potential thermal degradation of permafrost over the Qinghai–Tibet Plateau (QTP) from the 1960s to the 2000s using estimated decadal mean annual air temperatures (MAATs) by integrating remote-sensing-based estimates of mean annual land surface temperatures (MASTs), leaf area index (LAI) and fractional snow cover values, and decadal mean MAAT date from 152 weather stations with a geographically weighted regression (GWR). The results reflect a continuous rise of approximately 0.04 ∘C a−1 in the decadal mean MAAT values over the past half century. A thermal-condition classification matrix is used to convert modelled MAATs to permafrost thermal type. Results show that the climate warming has led to a thermal degradation of permafrost in the past half century. The total area of thermally degraded permafrost is approximately 153.76×104 km2, which corresponds to 88 % of the permafrost area in the 1960s. The thermal condition of 75.2 % of the very cold permafrost, 89.6 % of the cold permafrost, 90.3 % of the cool permafrost, 92.3 % of the warm permafrost, and 32.8 % of the very warm permafrost has been degraded to lower levels of thermal condition. Approximately 49.4 % of the very warm permafrost and 96 % of the likely thawing permafrost has degraded to seasonally frozen ground. The mean elevations of the very cold, cold, cool, warm, very warm, and likely thawing permafrost areas increased by 88, 97, 155, 185, 161, and 250 m, respectively. The degradation mainly occurred from the 1960s to the 1970s and from the 1990s to the 2000s. This degradation may lead to increased risks to infrastructure, reductions in ecosystem resilience, increased flood risks, and positive climate feedback effects. It therefore affects the well-being of millions of people and sustainable development at the Third Pole.
Highlights
Permafrost is defined as earth materials, including ice or organic material, that remain at or below 0 ◦C for at least 2 years (Permafrost Subcommittee, National Research Council of Canada, 1988; Williams and Smith, 1989)
The mean mean annual air temperatures (MAATs) values for the 1960s, 1970s, 1980s, 1990s, and 2000s are −2.38, −1.85, −1.78, −1.32, and −0.58◦C, respectively. These values reflect a continuous rise at a rate of approximately 0.04 ◦C a−1. This value is higher than the global average warming rate, as well as the estimated warming rates for the Qinghai–Tibet Plateau (QTP) reported by Cheng et al (2012) and Ran and Li (2016) that are based on interpolated elevation-based air temperature data or surface air temperature reanalysis data
The physical mechanisms of this phenomenon may be related to the combined effects of the cloud-radiation and snow-albedo feedback (Giorgi et al, 1997; Liu et al, 2009; Pepin et al, 2015). These elevated warming rates may have a substantial impact on the thermal condition of the permafrost
Summary
Permafrost is defined as earth materials, including ice or organic material, that remain at or below 0 ◦C for at least 2 years (Permafrost Subcommittee, National Research Council of Canada, 1988; Williams and Smith, 1989). An increase in air temperatures often thermally degrades permafrost, which has widespread impacts on engineering design, construction, resource development, carbon and water cycles, and ecological protection in cold regions (Collett, 2002; Cheng and Wu, 2007; Tarnocai et al, 2009; Schuur et al, 2009; Schaefer et al, 2011; Hinzman et al, 2013; Mu et al, 2015; Zhu et al, 2016). In terms of middle- and high-elevation permafrost regions, the area of permafrost in the Qinghai–Tibet Plateau (QTP) is the largest in the world. Y. Ran et al.: Thermal degradation of permafrost in the Qinghai–Tibet Plateau
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
