Investigations on methane emission from rice ecosystems using remote sensing modeling and ground observations

Abstract

The atmospheric increase in greenhouse gases especially of anthropogenic sources is serious concern. Agriculture accounts for approximately about 20% of the annual increase in anthropogenic greenhouse gas emission through emission of Carbon dioxide (CO2), Methane (CH4) and Nitrous Oxide (N2O) gases. CH4 is second in importance to CO2 with respect to its contribution as a greenhouse gas with global warming potential of 25. Rice cultivation has been accredited as one of the most important source of anthropogenic CH4 with estimates of annual global emission ranging between 41 and 54 Tg/yr. Despite recent studies on identification of controlling variables, the uncertainty in the global CH4 source strength estimate for rice paddies is still very high among all the established CH4 sources due to large spatial differences. Taking cognizance from the above and realising the importance of CH4 emission from rice crop, an important anthropogenic source of CH4 contributing to global warming, it is imperative that the scientific inventorying techniques for the same has to be developed. With the advent of the development of satellite based remote sensing (RS) techniques and Geographic Information System (GIS) tools, the spatial variability can be better captured to aid in sampling design and extrapolation apart from deriving the methanogenic cover itself. The current research investigates on the technique of deriving seasonal rice maps and rice cultural types paving the way for stratification of rice crop into Intergovernmental Panel on Climate Change (IPCC) compliance rice cultural types and spatial and temporal field sampling strategies with aim of generating reliable CH4 emission inventory from rice crop. The study further uses three to four-point data observations to compute cultural type wise emission coefficients and seasonal integrated flux. The second part of research deals with using point data to arrive at spatial maps of CH4. Considering the growing research interest in biogeochemical simulation models, an attempt