Collaborative Research: Tracking Carbon, Water, and Energy Balance of the Arctic Landscape at Flagship Observatories in Alaska and Siberia

北极的变暖速度比世界其他地区更快，并且有可能加剧全球变暖。这种放大效应来自永久冻土层（冻土）的融化，释放出温室气体，尤其是二氧化碳和甲烷，从而导致进一步变暖、更多的融化，并释放出更多的温室气体。然而，永久冻土融化的速度有多快，会释放多少温室气体，以及逐渐融化与地面冰融化或洪水引起的突然融化相比有多重要，这些都是未知的。这项北极观测网络研究将记录阿拉斯加和俄罗斯北极地区永久冻土融化、温室气体释放以及陆地和淡水系统能量平衡的变化。北极生态系统的永久冻土融化加速，温室气体向大气中释放，这可能不容易逆转。需要进一步观察来确定变化率和对气候的潜在影响，以便最好地告知社会将会发生什么以及如何做好准备。除了增进对环境变化的理解之外，该研究的更广泛影响还包括通过将研究结果纳入学校课堂、支持本科生暑期研究以及对阿拉斯加土著社区和 K-12 学校的推广，对教学、学习和推广做出贡献。阿拉斯加和俄罗斯北极的两个社区将学习绘制形成危险冰的甲烷冒泡热点的地图，这将导致知识的共同生产并提高冬季旅行者的安全。对社会的其他好处包括更好地了解永久冻土融化如何威胁道路和建筑物，以及北极融化如何影响低纬度地区的气候变化。这项研究将扩展阿拉斯加北部四个不同苔原生态系统（自 2007 年以来测量的全年涡流协方差）和俄罗斯切尔斯基两个地点的碳、水和能量平衡的时间序列数据。已经收集的记录显示了近期变化和临界点的证据，凸显了支持长期测量的价值。此外，将在西伯利亚的一个新的热喀斯特湖中监测通过涡度协方差和沸腾测量的二氧化碳和甲烷通量，并将在利用遥感绘制的现有和新的阿拉斯加和西伯利亚湖泊上测量沸腾。将维持并扩大对阿拉斯加伊姆纳瓦伊特溪水文和河流化学及其流域融雪深度的长期监测。为了帮助解释这些核心数据，该项目将继续对植物物候、融雪和复雪日期进行摄像记录、评估植物生物量和净初级生产力的收获，以及对土壤特性和碳氮储量进行分析。永久冻土钻孔将在 Imnavait Creek 的涡流协变塔附近和 Cherskii 的新湖附近安装仪器。所有数据将继续公开提供并通过北极数据中心、NSF-LTER 数据门户和 Ameriflux 存档。该项目收集的数据将被其他研究人员广泛使用，并纳入其他观测网络，如 Ameriflux、Phenocam 网络，以及包括 NASA 项目和卫星活动在内的其他工作。研究成果还将通过科学出版物和演示文稿进行传播。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

The Arctic is warming faster than other parts of the world and it has the potential to amplify global warming. The amplification comes from thawing permafrost (frozen soils) that release greenhouse gases, especially carbon dioxide and methane, that lead to additional warming, more thaw, and more greenhouse gases released. However, how fast the permafrost will thaw, how much greenhouse gas will be released, and how important gradual thaw is versus abrupt thaw caused by melting ground ice or floods, is unknown. This Arctic Observing Network research will document changes in permafrost thaw, greenhouse gas releases, and energy balance in terrestrial and freshwater systems in the Alaskan and Russian Arctic. Arctic ecosystems have seen an acceleration of permafrost thaw and greenhouse gas release to the atmosphere that may not be easily reversed. Further observations are required to determine the rates of change and potential impacts on climate to best inform society on what to expect and how to prepare. In addition to advancing understanding of environmental change, broader impacts of the research include contributions to teaching, learning, and outreach by including findings in school classrooms, support of undergraduate summer research, and outreach to Indigenous communities and K-12 schools in Alaska. Two communities in the Alaskan and Russian Arctic will learn to map methane bubbling hotspots that create dangerous ice, which will result in co-production of knowledge and improved safety for winter travelers. Other benefits to society include improved understanding of how permafrost thaw threatens roads and buildings, and how a thawing Arctic influences climate change at lower latitudes.This research will extend time-series data on carbon, water, and energy balance in four different tundra ecosystems in northern Alaska (year-round eddy covariance measured since 2007), and at two sites in Cherskii, Russia. The records already collected show evidence of recent change and tipping points, highlighting the value of supporting long-term measurements. In addition, carbon dioxide and methane fluxes measured by eddy covariance and ebullition will be monitored in a new thermokarst lake in Siberia, and ebullition will be measured on existing and new Alaskan and Siberian lakes mapped using remote sensing. Long-term monitoring of hydrology and stream chemistry of Imnavait Creek, Alaska, and depth of thaw in its catchment will be maintained and expanded. To help interpret these core data, the project will continue camera records of plant phenology and dates of snowmelt and snow return, harvests to assess plant biomass and net primary productivity, and analysis of soil properties and stocks of carbon and nitrogen. Permafrost boreholes will be instrumented near eddy covariance towers at Imnavait Creek and near the new lake in Cherskii. All data will continue to be made publicly available and archived with the Arctic Data Center, NSF-LTER Data Portal, and Ameriflux. Data collected by this project will be used extensively by other researchers and incorporated into other observing networks such as Ameriflux, the Phenocam Network, and other efforts including NASA projects and satellite campaigns. Research will also be disseminated though scientific publications and presentations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.