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The Global Methane Budget

全球甲烷预算

基本信息

批准号：
NE/N016122/1
负责人：
John Adrian Pyle
金额：
$ 34.53万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FN016122%2F1
关键词：
Global Methane Budget

项目摘要

Atmospheric methane has been increasing in concentration sharply since 2007, for reasons that are not fully understood, with ever-increasing uncertainty in how it should be treated in future climate projects. Overall, the increase since 2007 is comparable to the largest growth events in the Holocene. The largest rises in concentration have been seen in the tropics and southern hemisphere, with the sharpest year-on-year increase thus far occurring in 2014. Strong growth continues in 2015. Carbon isotopic evidence suggests that the increase is due to sources that are predominantly biogenic, with changes in anthropogenic sources (for example natural gas leakage, fracking and so on) playing a more minor role. This, taken with the tropical locus on growth, suggests that the increase has primarily been driven by meteorological change. However, the global methane budget is not well described. "Bottom-up" estimates, made by aggregating inventories of emissions (e.g. from gas leaks, fires, landfills, cows, wetlands, etc) balanced with known loss processes, are significantly different from '"top-down" budgets assessed by direct measurement of the atmosphere. Why this discrepancy occurs is not known.The project has four components, each with a number of work packages.1. Better Observations are needed, to support regional and global atmospheric modelling to derive estimates of emissions. The project will support a UK observation network for methane and its isotopes. Continuous stations will be at Kjolnes (Norway), Weybourne, Jersey, NERC ship RRS JC Ross, Cape Verde, Ascension, Falklands, Halley Bay, Hong Kong, with partner stations in Canada, Spitsbergen, Bolivia, S. Africa, India, Rwanda and Malaysia. Flask or bag sampling (methane, 13C and D/H isotopes) will be at these stations and at a number of continental stations in S. America, Africa and S, SE and E Asia, with offline measurement in the UK. A D/H measurement facility will be set up. The UK FAAM aircraft will carry out flights across the Atlantic tropics, from Azores to Cape Verde to Ascension. 2. Process Studies will address the largest information gaps in the global budget. Tropical emission fluxes and isotopic signatures are not well constrained. Tropical campaigns will be in wetlands in Amazonia, Africa, India and SE Asia, and C4 savanna biomass burn regions. Poorly understood anthropogenic sources will be studied in Kuwait and S, SE and E Asia. Characteristic isotopic signatures of regional emissions will be determined by inexpensive Keeling plot studies, to support global and regional modelling. Land surface modelling and satellite studies will study emissions and responses to change in temperature and precipitation. Major sink processes will be investigated in the tropical atmosphere, with vertically and latitudinal resolved OH and Cl budget studies by the FAAM aircraft, and quantification of tropical methanotrophy.3. Modelling will be used to derive regional and global fluxes, apportioned by source type and geography using integrated in situ and remote sensing observing systems. We will carry out regional trajectory studies using models like NAME to assess regional emissions. Global modelling using 3D models like UKCA will test synthetic estimates of the methane mole fraction and isotopic record. Global inverse modelling for mole fraction, 13C and D/H will be used to estimate fluxes by geographic source and source type, including a comprehensive assessment of the uncertainties that remain once all available observations have been used.4. Integrative studies will use the results from the project to test top-down and bottom-up emission estimates, and evaluate the responses of the global methane budget as it responds to climate change. The project will invest in a state of the art UK greenhouse gas monitoring network as a legacy after the project has ended.

自2007年以来，大气甲烷浓度急剧增加，原因尚不完全清楚，未来气候项目中应如何处理甲烷的不确定性越来越大。总体而言，自2007年以来的增长与全新世最大的增长事件相当。热带和南半球的浓度上升幅度最大，2014年出现了迄今为止最大的同比增长。2015年继续保持强劲增长。碳同位素证据表明，这种增加主要是由于生物来源，人为来源的变化（例如天然气泄漏，水力压裂等）发挥了更小的作用。这与热带增长轨迹一起表明，增长主要是由气象变化驱动的。然而，全球甲烷预算没有得到很好的描述。“自下而上”的估算是通过将排放清单（例如来自气体泄漏、火灾、垃圾填埋场、奶牛、湿地等）与已知损失过程相平衡而得出的，与通过直接测量大气层而评估的“自上而下”的预算有很大不同。这个项目有四个组成部分，每个组成部分都有一些工作包。1.需要更好的观测，以支持区域和全球大气建模，从而得出排放量估计数。该项目将支持英国的甲烷及其同位素观测网络。连续观测站将设在挪威的Kjolnes、泽西岛的Weybourne、NERC船舶RRS JC Ross、佛得角、阿森松岛Ascension、福克兰群岛、哈雷湾、香港，并在加拿大的Spitsbergen、玻利维亚、南太平洋的S.非洲、印度、卢旺达和马来西亚。将在这些台站和南太平洋的一些大陆台站进行烧瓶或袋取样（甲烷、13 C和D/H同位素）。美洲、非洲和南亚、东南亚和东亚，在英国进行离线测量。将建立D/H测量设施。英国FAAM飞机将执行横跨大西洋热带地区的航班，从亚速尔群岛到佛得角再到Ascension。2.过程研究将解决全球预算中最大的信息差距。热带排放通量和同位素特征没有得到很好的约束。热带运动将在亚马逊、非洲、印度和东南亚的湿地以及C4稀树草原生物质燃烧地区开展。将在科威特以及南亚、东南亚和东亚研究人们对人为来源了解不多的情况。将通过廉价的基林地块研究确定区域排放的同位素特征，以支持全球和区域建模。陆地表面建模和卫星研究将研究排放以及对温度和降水变化的反应。将调查热带大气中的主要汇过程，由FAAM飞机进行垂直和纬度分辨的OH和Cl收支研究，并量化热带甲烷营养。将利用综合的现场和遥感观测系统，通过建模得出按源类型和地理分布的区域和全球通量。我们将使用NAME等模型进行区域轨迹研究，以评估区域排放。使用UKCA等3D模型的全球建模将测试甲烷摩尔分数和同位素记录的综合估计。将使用摩尔分数、13 C和D/H的全球逆模型来估计按地理来源和来源类型划分的通量，包括全面评估一旦使用了所有现有观测数据后仍然存在的不确定性。综合研究将利用该项目的结果来测试自上而下和自下而上的排放估计，并评估全球甲烷预算对气候变化的反应。该项目将投资于最先进的英国温室气体监测网络，作为项目结束后的遗产。