Consequences of permafrost degradation for Arctic infrastructure – bridging the model gap between regional and engineering scales
Consequences of permafrost degradation for Arctic infrastructure – bridging the model gap between regional and engineering scales
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DOI：
10.5194/tc-15-2451-2021
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发表时间：
2021-05
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通讯作者：
Thomas Schneider von Deimling;Hanna Lee;T. Ingeman‐Nielsen;S. Westermann;V. Romanovsky;S. Lamoureux;D. Walker;S. Chadburn;E. Trochim;L. Cai;Jan Nitzbon;S. Jacobi;M. Langer
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作者：
Thomas Schneider von Deimling;Hanna Lee;T. Ingeman‐Nielsen;S. Westermann;V. Romanovsky;S. Lamoureux;D. Walker;S. Chadburn;E. Trochim;L. Cai;Jan Nitzbon;S. Jacobi;M. Langer
抽象的。在常年冰冻的富含冰层的土地上建造的基础设施在很大程度上依赖于地下稳定的热条件。气候变暖导致的地面融化加深使这些基础设施面临失败的风险。为了更好地评估未来对北极基础设施造成大规模破坏的风险，迫切需要改进基于模型的方法的战略。我们使用横向耦合的一维热传导模型CryoGrid3模拟了线性基础设施对多年冻土退化的影响。我们提供了一个在连续的永久冻土(阿拉斯加道尔顿公路)上建造的砾石道路的案例研究，并在历史和强烈的未来变暖条件下强制我们的模型(遵循RCP8.5情景)。正如预期的那样，模型中碎石路的存在导致进入地面的净热流比没有基础设施的参考运行更高，因此解冻速度更快。此外，我们的结果表明，道路故障很可能是由于道路旁边地面上的塔利克地层造成的横向不稳定的结果，而不是道路中心下方的活跃层自上而下解冻和加深的直接结果。与之前的研究一致，我们确定积雪增加和积水(两者都是基础设施存在的结果)是土壤温度上升和道路退化的关键因素。使用不同的水平模型分辨率，我们表明可以用较少的横向模型单元来捕捉这些关键因素及其对融化动力学的影响，强调了我们的模型方法用于泛北极风险评估的潜力。我们的结果表明，多年冻土退化一般有两个阶段：首先是缓慢和逐渐融化的阶段，然后是超过临界地面变暖后融化速度的强劲增加。在未受干扰的冻土带和受基础设施影响的永久冻土层之间，这种转变的时间和融化速度加速的幅度有很大的不同。我们的模型结果表明，当前基于模型的方法在其设计中没有明确考虑基础设施，可能会严重低估未来北极基础设施故障的时间。通过使用横向耦合的一维模型来模拟线性基础设施，我们推断的结果与更复杂的2D和3D模型的结果一致，但我们的模型的计算效率允许我们考虑永冻层退化对基础设施的长期气候变化影响。我们的模型模拟强调，在规划和建设多年冻土上的基础设施时，考虑气候变暖是至关重要的，因为从稳定状态到高度不稳定状态的转变很可能发生在此类建筑的使用寿命内(约30年)。气候变化甚至可能在未来十年引发这种转变，为建立在北纬高纬度连续多年冻土上的基础设施而建立，这些冻土今天显示出寒冷和相对稳定的条件。
Abstract. Infrastructure built on perennially frozen ice-rich ground relies heavily on thermally stable subsurface conditions. Climate-warming-induced deepening of ground thaw puts such infrastructure at risk of failure. For better assessing the risk of large-scale future damage to Arctic infrastructure, improved strategies for model-based approaches are urgently needed. We used the laterally coupled 1D heat conduction model CryoGrid3 to simulate permafrost degradation affected by linear infrastructure. We present a case study of a gravel road built on continuous permafrost (Dalton highway, Alaska) and forced our model under historical and strong future warming conditions (following the RCP8.5 scenario). As expected, the presence of a gravel road in the model leads to higher net heat flux entering the ground compared to a reference run without infrastructure and thus a higher rate of thaw. Further, our results suggest that road failure is likely a consequence of lateral destabilisation due to talik formation in the ground beside the road rather than a direct consequence of a top-down thawing and deepening of the active layer below the road centre. In line with previous studies, we identify enhanced snow accumulation and ponding (both a consequence of infrastructure presence) as key factors for increased soil temperatures and road degradation. Using differing horizontal model resolutions we show that it is possible to capture these key factors and their impact on thawing dynamics with a low number of lateral model units, underlining the potential of our model approach for use in pan-Arctic risk assessments. Our results suggest a general two-phase behaviour of permafrost degradation: an initial phase of slow and gradual thaw, followed by a strong increase in thawing rates after the exceedance of a critical ground warming. The timing of this transition and the magnitude of thaw rate acceleration differ strongly between undisturbed tundra and infrastructure-affected permafrost ground. Our model results suggest that current model-based approaches which do not explicitly take into account infrastructure in their designs are likely to strongly underestimate the timing of future Arctic infrastructure failure. By using a laterally coupled 1D model to simulate linear infrastructure, we infer results in line with outcomes from more complex 2D and 3D models, but our model's computational efficiency allows us to account for long-term climate change impacts on infrastructure from permafrost degradation. Our model simulations underline that it is crucial to consider climate warming when planning and constructing infrastructure on permafrost as a transition from a stable to a highly unstable state can well occur within the service lifetime (about 30 years) of such a construction. Such a transition can even be triggered in the coming decade by climate change for infrastructure built on high northern latitude continuous permafrost that displays cold and relatively stable conditions today.