Vulnerability and resiliency of continuous permafrost in a changing climate: Thresholds of non-recoverable change.

气候变化中连续永久冻土的脆弱性和恢复力：不可恢复变化的阈值。

• 批准号: RGPIN-2017-04030
• 负责人: Pollard, Wayne
• 金额: $ 2.84万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=687466
• 关键词: Vulnerability; resiliency; continuous; permafrost; changing

Despite the well-documented warming trend in Arctic climate and a corresponding increase in permafrost temperatures there remains tremendous uncertainty about the response of continuous permafrost systems to climate change. Several model-based studies suggest widespread terrain instability, melting and disappearance of permafrost, while recent field-based studies indicate that permafrost systems may be more resilient than modelling scenarios imply. Generalizations concerning permafrost response to climate change can result in errors in estimates of carbon flux, landscape change and infrastructure problems. There is an urgent need for empirical observation of heat and moisture fluxes for the active layer and the upper part of permafrost to better constrain modeling activities. ***The primary goal of this research is to assess the vulnerability of key high Arctic permafrost systems to climate change by focusing on thermodynamic processes in the active layer and at the active layer permafrost interface. ******Field sites on Ellesmere and Axel Heiberg Islands will include areas characterized by ice wedge systems, wetlands, and tundra landscapes underlain by ground ice. ******Methods By making detailed measurements of boundary layer climate, surface temperature, temperatures, and mass and energy fluxes through the active layer and at the permafrost table coupled with observations on seasonal snow depth and distribution, vegetation, and local topographic changes for specific geo-ecosystems this research will contribute a better understanding about the dynamic relationship between climate inputs and permafrost response. By looking at permafrost as a complex adaptive system this study will identify various feedback processes that contribute to system resiliency and potential tipping points. It is well understood that once widespread thermokarst begins permafrost systems become highly unstable and the normal self regulating processes often require decades to re-establish a new equilibrium. By coupling measurements of CO2 and CH4 flux to these observations this study not only defines the thresholds of change but potential feedbacks to the climate system. ******Applied research This study will assess the potential impact of changing active layer conditions on contaminated soils. There are many sites throughout the high Arctic of past and present fuel storage in steel drums that are notorious for leaking and fuel transfer processes that lead to spills. This study will assess the extent of residual contamination and potential remobilization of contaminants under scenarios of increased active layer depth and melting ground ice. This research involves the use of a wide range in research tools; in addition to site specific monitoring systems and subsurface mapping tools like GPR and Resistivity this research will use an unmanned aerial vehicle (UAV) to map small scale changes and identify thaw hotspots.

尽管北极气候变暖趋势和永久冻土温度相应上升已有充分记录，但连续永久冻土系统对气候变化的响应仍然存在巨大的不确定性。一些基于模型的研究表明，永久冻土广泛存在地形不稳定、融化和消失，而最近的实地研究表明，永久冻土系统可能比建模情景所暗示的更有弹性。关于永久冻土对气候变化响应的概括可能会导致碳通量、景观变化和基础设施问题的估计错误。迫切需要对活动层和永久冻土上部的热量和水分通量进行实证观测，以更好地约束建模活动。 ***本研究的主要目标是通过关注活动层和活动层永久冻土界面的热力学过程来评估关键高北极永久冻土系统对气候变化的脆弱性。 ******埃尔斯米尔岛和阿克塞尔海伯格岛的野外考察点将包括以冰楔系统、湿地和地面冰下的苔原景观为特征的区域。 ******方法通过对边界层气候、地表温度、温度以及通过活动层和永久冻土层的质量和能量通量进行详细测量，并结合对季节性雪深和分布、植被和当地地形的观测针对特定地理生态系统的变化这项研究将有助于更好地了解气候输入与永久冻土响应之间的动态关系。通过将永久冻土视为一个复杂的适应性系统，这项研究将确定有助于系统弹性和潜在临界点的各种反馈过程。众所周知，一旦广泛的热岩溶开始，永久冻土系统就会变得高度不稳定，正常的自我调节过程通常需要几十年的时间才能重新建立新的平衡。通过将二氧化碳和甲烷通量的测量与这些观测结果结合起来，这项研究不仅定义了变化的阈值，还定义了对气候系统的潜在反馈。 ******应用研究 这项研究将评估活性层条件变化对污染土壤的潜在影响。在过去和现在的北极地区，有许多地点都用钢桶储存燃料，这些地点因泄漏和导致泄漏的燃料传输过程而臭名昭著。这项研究将评估在活动层深度增加和地面冰融化的情况下残留污染的程度和污染物的潜在再活动。这项研究涉及使用广泛的研究工具；除了特定地点的监测系统和地下测绘工具（如探地雷达和电阻率）之外，这项研究还将使用无人机（UAV）来绘制小规模变化并识别解冻热点。