Permafrost degradation on the Qinghai–Tibet Plateau (QTP) has significant impacts on climate, hydrology, and engineering and environmental systems. To understand the temporal and spatial characteristics of permafrost on the QTP, we quantified the variation in active layer thickness (ALT), permafrost thermal state, and future permafrost change under different scenarios using observational data, reanalysis data, and the numerical permafrost model. Generally, ALT ranged from 0.5 to 6.0 m with an average of 2.39 m, and mean annual ground temperature (at a depth of zero annual amplitude for ground temperature) mainly ranged between 0 and −3°C with an average of −0.85°C. The soil temperatures in different layers based on the ERA5‐Land data revealed even stronger increasing trends, for example, 0.245, 0.245, 0.244, and 0.238°C/decade at depths of 0–7, 7–28, 28–100, and 100–289 cm from 1980 to 2021, compared to those during the period from 1960 to 2021, which were 0.153, 0.156, 0.155, and 0.149°C/decade, respectively. The average warming trends in annual mean soil temperature were 0.153 and 0.243°C/decade from 1960 to 2021 and 1980 to 2021, respectively. The average rate of thickening of the ALT among the 10 active layer observation sites was 2.84 cm/year. There was a significant warming trend in ground temperature above ~15 m with warming of 0.063 to 0.120, 0.026 to 0.182, 0.101 to 0.314, and 0.189 to 0.303°C/decade at the QTB01, QTB06, QTB08, and XDTGT sites, respectively, and yearly minimum ground temperatures exhibited stronger warming trends than maximum ground temperatures. In addition, the simulation revealed significant increases in ground temperature at the Xidatan (XDT) and Tanggula (TGL) sites under both historical and future Representative Concentration Pathway (RCP) scenarios, but the increases in ground temperature were significantly greater at TGL than XDT. These findings provide important information for understanding the variability in permafrost degradation processes and improving simulations of permafrost change under climate change on the QTP.

中文翻译：

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青藏高原多年冻土热状态时空特征及变化

青藏高原多年冻土退化对气候、水文、工程和环境系统产生重大影响。为了了解青藏高原多年冻土的时空特征，我们利用观测数据、再分析数据和数值多年冻土模型量化了不同情景下活动层厚度（ALT）、多年冻土热状态和未来多年冻土变化的变化。总体而言，ALT范围为0.5～6.0 m，平均为2.39 m，年平均地温（地温年变幅为零的深度）主要范围为0～-3℃，平均为-0.85℃。 。基于 ERA5-Land 数据的不同层土壤温度显示出更强烈的上升趋势，例如，在 0-7、7-28、28-100 和1980 年至 2021 年，温度升高了 100-289 厘米，而 1960 年至 2021 年期间，温度分别为 0.153、0.156、0.155 和 0.149°C/十年。1960-2021年和1980-2021年年平均土壤温度平均变暖趋势分别为0.153和0.243℃/10年。10个活性层观察部位的ALT平均增厚率为2.84厘米/年。～15 m以上地温有显着增温趋势，QTB01、QTB06、QTB08和XDTGT站点分别增温0.063～0.120、0.026～0.182、0.101～0.314和0.189～0.303℃/10年。年最低地温比最高地温表现出更强的变暖趋势。此外，模拟结果显示，在历史和未来代表性浓度路径（RCP）情景下，西大滩（XDT）和唐古拉（TGL）场地的地温均显着升高，但TGL的地温升高幅度明显大于XDT。这些发现为了解青藏高原多年冻土退化过程的变异性和改进气候变化条件下多年冻土变化的模拟提供了重要信息。