Permafrost, a key component of Arctic ecosystems, is currently affected by climate warming and anticipated to undergo further significant changes in this century. The most pronounced changes are expected to occur in the transition zone between the discontinuous and continuous types of permafrost. We apply a transient temperature dynamic model to investigate the spatiotemporal evolution of permafrost conditions on the Seward Peninsula, Alaska—a region currently characterized by continuous permafrost in its northern part and discontinuous permafrost in the south. We calibrate model parameters using a variational data assimilation technique exploiting historical ground temperature measurements collected across the study area. The model is then evaluated with a separate control set of the ground temperature data. Calibrated model parameters are distributed across the domain according to ecosystem types. The forcing applied to our model consists of historic monthly temperature and precipitation data and climate projections based on the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Simulated near‐surface permafrost extent for the 2000–2010 decade agrees well with existing permafrost maps and previous Alaska‐wide modeling studies. Future projections suggest a significant increase (3.0°C under RCP 4.5 and 4.4°C under RCP 8.5 at the 2 m depth) in mean decadal ground temperature on average for the peninsula for the 2090–2100 decade when compared to the period of 2000–2010. Widespread degradation of the near‐surface permafrost is projected to reduce its extent at the end of the 21st century to only 43% of the peninsula's area under RCP 4.5 and 8% under RCP 8.5.

中文翻译：

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对阿拉斯加苏厄德半岛目前和将来的多年冻土分布进行建模

永久冻土是北极生态系统的重要组成部分，目前受到气候变暖的影响，并有望在本世纪发生进一步的重大变化。预计最显着的变化将发生在不连续类型和连续类型的多年冻土之间的过渡带中。我们应用瞬态温度动态模型来研究阿拉斯加苏厄德半岛的多年冻土条件的时空演变，该地区目前以北部为连续多年冻土而南部为不连续多年冻土为特征。我们使用变异数据同化技术校准模型参数，该技术利用了整个研究区域收集的历史地面温度测量值。然后使用单独的地面温度数据控制集评估模型。校准的模型参数根据生态系统类型分布在整个域中。应用到我们模型中的强迫包括历史性的每月温度和降水数据以及基于“代表浓度路径”（RCP）4.5和8.5情景的气候预测。2000-2010年十年间模拟的近地表多年冻土范围与现有的多年冻土图和以前的阿拉斯加全模型研究非常吻合。未来的预测表明，与2000–2000年相比，半岛2090–2100十年的平均十年平均地温将显着增加（在RCP 4.5下为3.0°C，在2m深度下为RCP 8.5，4.4°C）。 2010。预计到21世纪末，近地表多年冻土的广泛退化将使其范围减少到RCP 4下半岛面积的43％。