Collaborative Research: Permafrost Carbon Network: Synthesizing flux observations for benchmarking model projections of permafrost carbon exchange

永久冻土是常年冻结两年或两年以上的土地。永久冻土中含有数千年来积累的植物、微生物和动物残留物中的碳。目前的估计表明，永久冻土目前的碳含量是大气的两倍，随着气候变暖，永久冻土退化，二氧化碳和甲烷气体被释放出来。这些冻结碳的一小部分释放可能会对全球碳循环产生重大影响，这可能会大大增加未来全球气候变暖的速度，加速海平面上升、极端天气、干旱和对农业的影响，其速度超过目前模型预测的速度。大多数气候模型还没有完全包括导致北方地区向大气中排放额外二氧化碳和甲烷的反馈回路，因此对社会的风险程度是不确定的。该提案支持永久冻土碳网络，该网络旨在将生物碳循环研究与专注于永久冻土热状态的物理科学中发达的网络联系起来。永久冻土碳网络通过将广泛的研究成果综合成一个关于永久冻土碳在推动未来气候变化中的作用的更连贯的极地观点，产生了新的知识。该提案支持永久冻土碳网络的活动，以便：1)扩大社区参与的网络机会，并使新的科学综合思想通过工作组的活动产生；2)综合来自美国和国际站点的永久冻土层碳通量数据，以产生统一的生态系统-大气碳交换时间序列，可以随着新数据的获得而更新；3)利用新的和过去的数据综合和实验结果，对最近完成的多年冻土碳网络模型比对试验进行基准测试。这种研究和网络活动的结合，使科学家和决策者能够根据地球系统模式的预测，每年更新北极向大气排放的变化情况，同时也有助于确定气候模式的优先次序和实施改进。新的研究活动和扩大的网络建立在过去的永久冻土碳网络势头的基础上，作为增加、提炼和交流我们对这一偏远地区变化及其对社会的重要影响的理解的基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Permafrost is ground that is frozen all year round for two or more years. Permafrost contains carbon from the remnants of plants, microbes, and animals that have accumulated over thousands of years. Present estimates suggest that permafrost currently holds twice as much carbon as the atmosphere, which are released as carbon dioxide and methane gas as the permafrost degrades in response to climate warming. Release of just a fraction of this frozen carbon could have significant impacts on the global carbon cycle that may dramatically increase the rate of future global climate warming and accelerate sea-level rise, extreme weather, droughts, and impacts on agriculture at rates beyond those currently projected by models. Most climate models do not yet fully include the feedback loops that cause northern regions to emit additional carbon dioxide and methane to the atmosphere, so the level of risk to society is uncertain. This proposal supports the Permafrost Carbon Network, formed to link biological carbon cycle research with well-developed networks in the physical sciences focused on the thermal state of permafrost. The Permafrost Carbon Network produces new knowledge by synthesizing a wide range of research results into a more coherent circumpolar view of the role of permafrost carbon in driving future climate change.This proposal supports the activities of the Permafrost Carbon Network to: 1) expand networking opportunities that engage the community and enable new science synthesis ideas to arise through the activities of working groups, 2) synthesize permafrost zone carbon flux data from US and international sites to produce a unified time series of ecosystem-atmosphere carbon exchange that can be updated as new data become available, and 3) benchmark the recently completed Permafrost Carbon Network model inter-comparison experiment using new and past data synthesis and experimental results. This combination of research and networking activities gives scientists and decision makers an annually updated view of changing Arctic carbon emissions to the atmosphere in relation to Earth System Model forecasts, while also helping to prioritize and implement improvements to climate models. The new research activities and expanded networking build upon past Permafrost Carbon Network momentum as a foundation to increase, distill, and communicate our understanding of change in this remote region with its important consequences for society.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.