Quantifying methane emissions in remote tropical settings: a new 3D approach

GSTDTAP

项目编号	NE/S00159X/1
	Quantifying methane emissions in remote tropical settings: a new 3D approach
	Euan George Nisbet
主持机构	Royal Holloway, University of London
项目开始年	2018
	2018-09-01
项目结束日期	2020-08-31
资助机构	UK-NERC
项目类别	Research Grant
项目经费	408603(GBP)
国家	英国
语种	英语
英文摘要	The purpose of this proposal is to develop a viable methodology to quantify methane emissions in remote seasonal tropical wetland settings in Africa, and thus to place constraints on the causes of growth. The NERC/Met Office FAAM aircraft is scheduled to be deployed to Uganda in early 2019: this proposal builds on the opportunity that deployment offers, by adding a detachment to the major seasonal southern tropical wetlands in Zambia's Congo and Zambesi river drainages. Atmospheric methane began rising rapidly in 2007, after a period of stability, and the growth rate then accelerated in 2014 and subsequent years. Concurrently with the rise, the methane burden has shown a marked isotopic shift, becoming more C-13 depleted. We do not know why the methane growth and isotopic shift is happening. Much of the growth since 2007 has been in the tropics, and sub-tropics. One hypothesis for the growth and isotopic shift in the methane burden is that methane emissions from tropical wetlands and cattle are rapidly increasing, as a response to the tropical expansion and increased precipitation that has accompanied meteorological warming. An alternative hypothesis is that a marked decline in OH, the main sink, has lengthened methane's lifetime. Thus determining the flux and isotopic signatures of methane emissions from large representative seasonal African wetlands is a key requirement, enabling models to have better treatment of tropical latitudinal zones, so that the methane puzzle can be understood. African tropical wetlands are dominated by C-13 rich C4 plants such as papyrus, and subsistence cattle also graze C4 plants. In comparison to temperate and cool climate sources, biogenic methane emitted to the air from African wetlands and cattle has a very different isotopic signature, richer in 13C. This isotopic signature of methane from African wetlands overlaps somewhat with some fossil fuel emissions. To use isotopes effectively to differentiate between source types in the global budget (e.g. fossil fuels or wetlands and cattle) it is urgent that much better information is obtained on the regional isotopic signatures of African biogenic emissions. Methane growth since 2007 has been so rapid that methane is already far from its expected pathway under the UN Paris Agreement on Climate Change. There is a large discrepancy between reported national emissions inventories and atmsopheric estimates: in particular there is an urgent need for better tropical inventories if the budget is to be understood. To address these problems, we intend: 1. To conduct a FAAM (Facility for Airborne Atmospheric Measurement) field deployment over Zambian wetlands, as a southern 'add-on' to our planned MOYA deployment to Uganda in January 2019, to measure wet-season greenhouse gas fluxes from the very extensive Zambian wetlands and farming areas around Lakes Bangweulu and Mweru, and in the Kafue and Zambesi basins. Flights would be carried out downwind of major wetland source regions, quantifying emission plumes at the height of the wet season. 2. To help solve the 'are emissions rising or is the OH sink falling?' debate, on-ground campaigns will be used to determine d13C[CH4] and dD[CH4] isotopic signatures, measured in emissions from Zambian C4 wetlands. The lack of measurement of isotopic signatures of tropical emissions is a crucial impediment to successful global inverse modelling (Turner et al., 2017; Rigby et al., 2017). 3. To develop low-cost ways of quantifying emission fluxes and determining isotopic signatures from major sources in remote tropical settings, including wetlands, cattle and biomass burning. In particular, a simple drone (UAV) and balloon bag-sampling methodology will be tested. 4. To improve 'bottom-up' assessment of local emission inventors, working with local colleagues in Zambia and Zimbabwe to construct national methane emission inventories, and thus support the intentions of the Paris Agreement.
来源学科分类	Natural Environment Research
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/87216
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Euan George Nisbet.Quantifying methane emissions in remote tropical settings: a new 3D approach.2018.