NNA: LTREB: The Arctic Carbon and Climate (ACCLIMATE) Observatory: Tundra Ecosystem Carbon Balance and Old Carbon Loss as a Consequence of Permafrost Degradation

地球大气的未来轨迹取决于陆地和海洋对不断变化的环境的反应，特别是在北极等高纬度地区大量持续释放碳的潜力。理解地球系统将如何应对的一个关键问题是，是否存在转折点-全球碳循环意外-将使海平面上升、极端天气、干旱和对农业的影响等环境变化的影响发生得比目前模型预测的更快。永久冻土碳是数千年来在常年冰冻的北极土壤中积累的植物、微生物和动物的残留物，目前的碳含量是大气的两倍，可能是这样一个临界点。将这些冻结的碳中的一小部分以二氧化碳和甲烷的形式释放到大气中，将大大加快未来全球环境变化的速度。从永久冻土区释放到大气中的碳每增加一吨，就会给社会带来额外的成本，并提出了一项挑战，即需要持续的长期观测来量化速率和揭示机制，以便预测变化。该项目将建立北极碳和气候(气候)永久冻土碳观测站，该观测站将利用实地观测来测量由于区域变暖而正在经历快速和不可逆转变化的冻土生态系统中的碳通量和生态系统碳库。该项目还将包括对一名博士后研究人员和几名本科生的培训，以及由高中生和教师参与的外联活动。北极碳与气候(适应气候)永久冻土碳观测站使用现场观测来测量由于区域变暖而正在经历快速和不可逆转变化的冻土生态系统中的碳通量、碳同位素比率和生态系统碳库。阿拉斯加州内陆的八里湖研究分水岭的永久冻土温度从1990年代初永久冻土开始退化之前就开始了几十年的监测。本世纪初，多年冻土退化对植物、微生物和生态系统碳平衡的影响开始被记录在案。整个研究计划将回答三个重点问题：1)气候变暖和永久冻土退化是否会导致碳从生态系统向大气净释放，以及在几年到几十年的时间里，碳释放的幅度是如何变化的？2)这种碳释放的多大比例来自构成土壤碳库主体的旧碳，这种比例是否会随着融化的进展而增加？3)地表水文学的变化如何与融化相互作用，以控制旧碳的损失和二氧化碳和甲烷的分配？将组织碳测量以及该观测站收集的其他关键生态系统变量，作为区域和地球系统模型的基准，并通过持续的综合和模型间比较活动与这一进程相结合。这些技术活动将与知识转移活动相结合，将成果与更广泛的科学界以及更广泛的公众联系起来。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The future trajectory of Earth's atmosphere depends on the response of land and ocean to a changing environment, especially the potential for substantial sustained carbon release in high latitude regions like the Arctic. A key question in understanding how the Earth system will respond is whether there are tipping points - global carbon cycle surprises - that will make the effects of environmental change such as sea-level rise, extreme weather, droughts, and impacts on agriculture occur faster than currently projected by models. Permafrost carbon, the remnants of plants, microbes, and animals accumulated in perennially frozen Arctic soil over thousands of years, currently holds twice as much carbon as the atmosphere, and could be such a tipping point. Release of just a fraction of this frozen carbon as carbon dioxide and methane into the atmosphere would significantly increase the rate of future global environmental change. Each additional ton of carbon released from the permafrost region to the atmosphere incurs additional costs to society and presents the challenge of requiring sustained long-term observations to quantify rates and unravel mechanisms in order to forecast change. This project will establish the Arctic Carbon and Climate (ACCLIMATE) permafrost carbon observatory, which will use field observations to measure carbon fluxes, and ecosystem carbon pools in a tundra ecosystem that is undergoing rapid and irreversible change due to regional warming. The project will also include training of a postdoctoral researcher and several undergraduate students, and outreach activities involving high school students and teachers.The Arctic Carbon and Climate (ACCLIMATE) permafrost carbon observatory uses field observations to measure carbon fluxes, carbon isotope ratios, and ecosystem carbon pools in a tundra ecosystem that is undergoing rapid and irreversible change due to regional warming. Permafrost temperature at the Eight Mile Lake research watershed in Interior Alaska has been monitored for several decades starting before permafrost degradation began in the early 1990s. The impact of permafrost degradation on plants, microbes, and ecosystem carbon balance began to be documented in the early 2000s. The overall research plan will answer three focal questions: 1) Does warming and permafrost degradation cause a net release of carbon from the ecosystem to the atmosphere, and how does the magnitude change over years to decades? 2) What proportion of this carbon release is derived from old carbon that comprises the bulk of the soil carbon pool, and will this increase as thaw progresses? 3) How does change in surface hydrology interact with thawing to control old carbon losses and the partitioning of carbon dioxide and methane? Carbon measurements, along with other key ecosystem variables collected by this observatory, will be organized for benchmarking regional and Earth System models, and coupled to that process through ongoing synthesis and model inter-comparison activities. These technical activities will be integrated with knowledge-transfer activities that link results to the broader scientific community, as well as to the broader public.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.