Understanding the drivers and climate sensitivity of open ocean methane emissions to the atmosphere

了解公海甲烷排放到大气中的驱动因素和气候敏感性

• 批准号: 2241744
• 负责人: Thomas Weber
• 金额: $ 29.41万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2241744&HistoricalAwards=false
• 关键词: Understanding; drivers; climate; sensitivity; open

Methane is a potent greenhouse gas with a global warming potential thirty times larger than carbon dioxide. In addition to human emissions methane has many natural sources to the atmosphere, which could be amplified by future climate warming. Methane emissions from the vast open ocean are relatively small but their sensitivity to climate change is highly uncertain. This is because the processes that supply methane to surface ocean waters are not well understood. To improve our understanding of the open ocean methane cycle, this project will use a computer model to interpret a large database of methane concentration measurements. First, the model will be used to determine the dominant biological source of methane within surface waters. Candidates include production during algae growth, production in the guts of small animals, and bacterial decay of organic matter. Each of these processes would produce a different surface methane pattern, allowing the model to distinguish between them. Second, the model will quantify the supply of methane from the seafloor in low oxygen zones of the ocean, and determine whether this methane is consumed by bacteria before escaping to the atmosphere. This is important because low oxygen zones will likely grow as the climate warms. Leakage of methane from these regions could therefore act as a feedback on climate change. The global model developed in this project will simulate the open ocean sources and sinks of methane, including in situ aerobic methanogenesis in surface waters, diffusion from anoxic sediments, oxidation in the water column, and exchange with the atmosphere. Data will be assimilated to optimize model parameters, and ultimately determine the balance of sources and sinks that is most consistent with the observed ocean methane distribution. Aerobic methane production will be formulated as function of phytoplankton growth, zooplankton abundance, and organic matter recycling, to determine which mechanisms best explains the pattern of surface methane supersaturation. The oxygen dependence of sedimentary methane sources and bacterial methane oxidation will be optimized to best match the observed plumes that spread laterally from suboxic waters and upwell towards the surface. The resulting optimized model will then be used to predict future perturbation of the open ocean methane source in response to ecosystem changes and ocean oxygen loss.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.

甲烷是一种有效的温室气体，其全球变暖潜力比二氧化碳大三十倍。除了人类的排放外，甲烷还具有许多自然来源，可以通过未来的气候变暖来扩大。广阔的开海中的甲烷排放相对较小，但它们对气候变化的敏感性高度不确定。这是因为向表面海水提供甲烷的过程尚不清楚。为了提高我们对开放海洋甲烷周期的理解，该项目将使用计算机模型来解释大型甲烷浓度测量数据库。首先，该模型将用于确定地表水中甲烷的主要生物学来源。候选人包括在藻类生长过程中产生的生产，小动物的胆量产生以及有机物的细菌衰减。这些过程中的每一个都会产生不同的表面甲烷图案，从而使模型可以区分它们。其次，该模型将量化海底低氧区域中从海底的供应，并确定该甲烷是否被细菌消耗在大气中。这很重要，因为随着气候温暖，低氧气带很可能会增长。因此，从这些地区泄漏甲烷可以充当气候变化的反馈。该项目中开发的全球模型将模拟甲烷的开海源和水槽，包括地表水中的原位有氧甲烷发生，从缺氧沉积物中扩散，水柱中的氧化以及与大气交换。数据将被吸收以优化模型参数，并最终确定与观察到的海洋甲烷分布最一致的来源和汇的平衡。有氧甲烷的产生将作为浮游植物生长，浮游动物丰度和有机物回收的功能，以确定哪些机制最好地解释了表面甲烷过饱和的模式。沉积甲烷源和细菌氧化的氧依赖性将被优化，以最佳与观察到的羽流相匹配，这些羽流从亚氧化的水面横向传播，向上向上向上朝向表面。然后，将使用最终的优化模型来预测开放海洋甲烷源的未来扰动，以响应生态系统变化和海洋氧损失。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响来通过评估来获得支持的。