Methane emission estimate from South Asia: AMASA project (original) (raw)
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Remote Sensing Based Methane Emission Inventory Vis-A-Vis Rice Cultural Types Of South Asia
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2014
Rice cultivation has been recognized as one of the major anthropogenic source for methane (CH4) emissions which is a microbial mediated anaerobic activity, mainly favoured by the flooded conditions in the rice fields. Information available on CH4 emission is limited, especially in a spatial domain, mainly because of the complexity involved in generating such data. The current approach demonstrates the use of secondary data sources available on the methane emission scaling factors, coupled with the information derived on rice cultural types and crop calendar. Methane emission from each type of rice field was firstly calculated by multiplying the emission factor by the corresponding cultivation area and length of cropping period. The values were then extrapolated over each country with respect to the rice area and crop duration for under each cultural type. The rice cultural type wise methane emission value for South Asia was derived by summation of individual emission values for the respective cultural type within each country. The total methane emission derived for South Asia region is (4.7817 Tg/yr). The mean methane emission estimates derived for each country are viz. India (3.3860 Tg/yr), Bangladesh (0.9136 Tg/yr), Pakistan (0.2675 Tg/yr), Sri Lanka (0.1073 Tg/yr) and Nepal (0.1074 Tg/yr). The derived methane emission estimates could be used to study the regional variations within the country and also to adopt the mitigation strategies to combat the high methane emission values within specific cultural type by means of altering the farming practise or water regime.
Hydrobiology
Methane is produced by various natural processes that directly or indirectly contribute to the entire Earth’s methane budget. If the Earth’s overall methane budget becomes imbalanced, CH4 has an impact on climate change. Wetlands, rice fields, animals, factories, and fossil fuels are major sources of methane emissions. Among all the resources, wetlands and rice fields are more prominent factors in methane emission, dependent on the water table, temperature, and vegetation. Our study employed the GIS remote sensing technique to analyze methane emissions from 2003 to 2021 in the northern part of India, East Uttar Pradesh and Bihar, and the northeast region of India that is Assam. We also predicted the water table, temperature, and vegetation as raw materials for methane creation. Water table, temperature, and vegetation are essential for wetland ecosystem life, particularly for methanogenic organisms; however, the water table and temperature are critical for rice plant growth and deve...
Remote Sensing of Environment, 2013
We have analyzed the column-averaged CH 4 concentration (xCH 4) using scanning imaging absorption spectrometer for atmospheric chartography (SCIAMACHY) and compared the data with the bottom-up emission inventory data sets and other satellite-derived indices such as the land-surface water coverage (LSWC) and the normalized difference vegetation index (NDVI). The geographical distribution of high CH 4 values corresponds to strong emissions from regions where rice is cultivated, as indicated in the inventory maps. The Pearson's correlation coefficients (r) between xCH 4 and the rice emission inventory data are observed to be greater than~0.6 over typical rice fields, with outstanding r-values of~0.8 in the Ganges Basin, Myanmar, and Thailand. This suggests that the emission of CH 4 from rice cultivation mainly controls the seasonality of the CH 4 concentration over such regions. The correlation between xCH 4 and LSWC and NDVI is also as large as 0.6. In Southeast Asia, the r-values of xCH 4 with bottom-up inventory data that includes all categories are not as high as those with the emission, as estimated from the rice category only. This is indicative of the relative importance of rice emissions among all other emission categories in Southeast Asia.
Atmospheric observations show accurate reporting and little growth in India's methane emissions
Nature communications, 2017
Changes in tropical wetland, ruminant or rice emissions are thought to have played a role in recent variations in atmospheric methane (CH4) concentrations. India has the world's largest ruminant population and produces ~ 20% of the world's rice. Therefore, changes in these sources could have significant implications for global warming. Here, we infer India's CH4 emissions for the period 2010-2015 using a combination of satellite, surface and aircraft data. We apply a high-resolution atmospheric transport model to simulate data from these platforms to infer fluxes at sub-national scales and to quantify changes in rice emissions. We find that average emissions over this period are 22.0 (19.6-24.3) Tg yr-1, which is consistent with the emissions reported by India to the United Framework Convention on Climate Change. Annual emissions have not changed significantly (0.2 ± 0.7 Tg yr-1) between 2010 and 2015, suggesting that major CH4 sources did not change appreciably. These f...
Spatial and Temporal Changes in Methane emission in INDIA during (2003-2015)
Authorea (Authorea), 2023
One of the most potent greenhouse gases is methane, which is the most basic hydrocarbon in the paraffin series. With a GWP of roughly 28, this is the second most significant greenhouse gas. Since there is a lot of it in the Indian subcontinent, it is important to monitor and research this gas. This study analyses satellite readings that were taken all over the world between 2003 and 2015 and are retrieved for the Indian region. This study made use of the satellite-based SCIAMACHY and TANSO-FTS equipment. Additionally, the work examines how a change in concentration levels depends on a region's location and climate by estimating the rate of change of methane levels through time and obtaining information on the change in concentration. According to this study, it is rising quickly over the Indo-Gangetic Plain, the Northeast, and certain coastal areas. The majority of the sources are man-made, such as fossil fuels and the energy industry, as well as natural sources like wetlands. Both instruments indicate that methane content is rapidly rising in the area, depending on a number of variables and seasonal fluctuations. Methane emissions must be decreased otherwise it will be the main cause of the greenhouse effect.
Global Biogeochemical Cycles, 1991
We present high-resolution global data bases on the geographic and seasonal distribution of rice cultivation and associated methane emission. The data bases were developed by integrating extensive and eclectic information on the cultivation of rice in all 103 rice-producing countries of the world. The geographic distribution of rice-growing locations was developed by combining a 1 ø resolution land-use data base identifying rice-farming regimes, a 1 ø resolution data base of countries of the world, and country statistics on areas of annual rice harvest available from the U. N. Food and Agriculture Organization. The seasonal distribution of cultivated rice areas was derived via the integration of the data base on rice-growing locations with information on cultivation activities and rice cropping practices for each rice-producing country of the world; this information included seasonal rice-cropping calendars for individual countries and statistics or estimates of the seasonal distribution of annual harvest areas in each crop cycle. Since the causes of the variability in methane fluxes from flooded rice fields have yet to be quantified, we did not attempt a new estimate of the role of rice cultivation in the global emission of methane. We evaluate, instead, the temporal and spatial distribution of emissions from a hypothetical annual source of 100 Tg methane. In 1984, 1475 x 109m 2 of rice was harvested in 103 countries. Although rice cultivation extends from about 50øN to Copyright 1991 by the American Geophysical Union. Paper number 90GB02311. 0886-6236/91/90GB-02311510.00 50øS, 48% of the harvest area is confined to a narrow subtropical zone from 30øN to 20øN, while another 35% is harvested in the 10 ø zones directly to the north and south. Globally, about 60% of the harvested rice area is managed under a triple rice crop system,-15% is double cropped, and 25% is harvested from fields planted for rice once a year. In China and India, which together account for 52% of the world's harvest area, rice is harvested predominantly under a triplecrop system. These patterns suggest that much of the potential for multiple rice cropping is currently exploited. In this analysis, methane emission is proportional to the area and duration of each harvest so that the seasonal, zonal and country patterns of annual methane emission mimic the distribution of rice-harvest areas. Although rice is grown throughout the year, the close coupling of rice cultivation with climate results in the concentration of about 55% of the annual methane emission into four months from July through October and almost half the total emission in latitudes between 30øN and 20øN. Even in tropical and subtropical Asia, where over 90% of the rice area is harvested, myriad biotic and abiotic factors such as phenology, temperature, and water status naturally affect rates of methane production and emission. Recent measurements suggest that the type of fertilizers applied and the timing and mode of the application may also be important factors. At the present time, these local agricultural, economic and cultural factors are impossible to document over large areas and therefore introduce unquantifiable measures of uncertainty into estimates of the global emission of methane from the cultivation of rice. In this study, we focus on the global and seasonal distribution of rice cultivation. The monthly distribution of rice cultivation areas are presented at 1 ø resolution for the globe. Because the causes of the variability in methane fluxes from flooded rice fields have yet to be quantified, an attempt to arrive at a global annual emission may be unrealistic at this time. We present, instead, a sensitivity analysis that emphasizes patterns in the temporal and spatial distribution of emissions based on an annual hypothetical source of 100 Tg (1012 g) methane. This paper is the third in a series on the distributions of the major methane sources. The first two papers are on methane emission from natural wetlands [Matthews and Fung, 1987] and from domestic animals [Lerner et al., 1988]. As in the earlier papers, an attempt is made to document, with all available information, the spatial and temporal distributions of the sources. These distributions can then be used in two-and three-dimensional atmospheric transport models to test hypotheses about the global budget of methane (I. Fung et al., Threedimensional model synthesis of the global methane cycle, submitted to Journal of Geophysical Research, 1990, hereinafter referred to as Fung et al., 1990).
Measurements of methane emissions from rice fields in China
Journal of Geophysical Research, 1998
Rice fields have always been regarded as one of the largest anthropogenic sources of atmospheric methane. Here we report the results of a 7-year study of methane emissions from rice fields in the Sichuan Province of China. In this region, there is one crop of rice per year, the fields are continuously flooded from transplanting to harvest, and there is heavy use of organic fertilizers. Emissions over the entire growing season were measured from each of up to 24 plots. Environmental variables were measured and relevant supporting data on the agricultural practices were recorded. The fields were studied under prevailing agricultural practices of the local farmers. The results represent emissions under standard agricultural practices and the year to year variability of climate, fertilizers, available irrigation water, and cultivars. Based on some 5000 flux measurements, the average emission rates between 1988 and 1994 were 30 mg/m2/h for a growing season of between 100 and 120 days. This emission rate is comparable to other published data from similar rice fields but somewhat on the high side of the range. There were no systematic trends of emissions during the 7 years of our experiment, but there was substantial year to year variability. The data have been subjected to exhaustive analyses for validity, accuracy, and reliability. From this, a high-quality, spatially averaged data set has been constructed representing average emissions from the rice fields for each day when measurements were taken. We describe here the main observational results and document the spatial and temporal variability observed on timescales ranging from a day to several years and on spatial scales ranging from 0.5 m2to 16m 2. 1. Introduction Methane is a potent greenhouse gas in Earth's environment. Some years ago we showed that its atmospheric concentrations were rapidly increasing [Rasmussen and Khalil, 1981 ]. Even the earliest studies suggested that the increase of methane over the last century and in recent times may be caused in part by the increase of rice agriculture. The hectares of rice harvested have doubled during the last century, and the rice fields are a substantial source in every budget of methane [Khalil and Rasmussen, 1990]. In the mid-1980s, we proposed to systematically study the emission of methane from rice fields. Work started on this project in 1985 [Riches et al., 1992]. The first systematic measurements were taken in 1988. This was a relatively early effort to measure the emissions of methane from rice fields and the factors that control the emission rates [Khalil et al., 1990]. As the experiment unfolded, the complexities of the processes in the rice fields became apparent, requiring new experiments to validate and interpret the early data. This work has been completed, and we are reporting the results here.
Methane emissions from wetland rice areas of Asia
Chemosphere, 1993
reviewed eleven global methane budgets published between 1978 through 1988. They found that methane emissions from rice paddies ranged from 18 to 280 Tg year -1 which correspond to between 10 and 70% of the total anthropogenic methane emissions. For this paper, we have reviewed and replicated three published techniques to estimate methane emissions from rice paddies. We present the results obtained and we propose to include soil characteristics to revise these estimates. Since 90% of rice production occurs in Asia, we have only focused our study on rice in Asia. The first technique we replicated, uses the Food and Agriculture Organization (FAO)'s country statistics and crop calendars to determine the land area under rice cultivation each month. Assuming a constant emission rate, Asian rice fields emit about 82 Tg methane year 1. The second technique we replicated, assumes that methane emissions represent a constant fraction of the net primary production and uses empirical relationships between net primary production and temperature and precipitation records. Asian rice fields then only produce 57 Tg methane year -1. The third technique we replicated, relates methane emissions to rice grain production. It involves the calculation of total organic matter added to rice paddy soils and assumes that a constant fraction is emitted as methane. This leads to an estimate of methane emissions from Asian rice fields of about 63 Tg year -t. We propose to use a classification of rice soils to categorize rice growing locations from potentially methane producing to non-methane producing areas. Using this distinction with any of the three methods we discussed, Asian rice fields emissions are reduced by about 25%.
Modeling methane emission from rice paddies with various agricultural practices
Journal of Geophysical Research, 2004
1] Several models have been developed over the past decade to estimate CH 4 emission from rice paddies. However, few models have been validated against field measurements with various parameters of soil, climate and agricultural practice. Thus reliability of the model's performance remains questionable particularly when extrapolating the model from site microscale to regional scale. In this paper, modification to the original model focuses on the effect of water regime on CH 4 production/emission and the CH 4 transport via bubbles. The modified model, named as CH4MOD, was then validated against a total of 94 field observations. These observations covered main rice cultivation regions from northern (Beijing, 40°30 0 N, 116°25 0 E) to southern China (Guangzhou, 23°08 0 N, 113°20 0 E), and from eastern (Hangzhou, 30°19 0 N, 120°12 0 E) to southwestern (Tuzu, 29°40 0 N, 103°50 0 E) China. Both single rice and double rice cultivations are distributed in these regions with different irrigation patterns and various types of organic matter incorporation. The observed seasonal amount of CH 4 emission ranged from 3.1 to 761.7 kg C ha À1 with an average of 199.4 ± 187.3 kg C ha À1 . In consonance with the observations, model simulations resulted in an average value of 224.6 ± 187.0 kg C ha À1 , ranging from 13.9 to 824.3 kg C ha À1 . Comparison between the computed and the observed seasonal CH 4 emission yielded a correlation coefficient r 2 of 0.84 with a slope of 0.92 and an intercept of 41.1 (n = 94, p < 0.001). It was concluded that the CH4MOD can reasonably simulate CH 4 emissions from irrigated rice fields with a minimal number of inputs and parameters.
Soil Biology and Biochemistry, 1998
SummaryÐMethane¯ux was measured from four tropical, Indian ecosystems: dryland, irrigated rice, seasonally dry forest and savanna. Flux from the irrigated rice paddies was in the range 2.14± 8.23 mg CH 4 m À2 h À1 during the crop period. In contrast, the dryland rice soil consumed 0.12± 0.90 mg CH 4 m À2 h À1 . Application of wheat straw + fertilizer stimulated CH 4 production in irrigated rice soil while it reduced CH 4 consumption in dryland rice plots. CH 4¯u x measurements from nutrientpoor, well-drained dry deciduous forest and savanna soils indicated heavy methane consumption. Maximum CH 4 consumption was observed during the winter season (0.46±0.95 mg CH 4 m À2 h À1 ) at all the sites and was lowest during the rainy season (0.17±0.32 mg CH 4 m À2 h À1 ). The results suggest that dryland rice soils and natural ecosystems are potential sinks of CH 4 . Conservative extrapolation of the results indicates that to compensate for CH 4 production from 1 ha of irrigated rice about 2.4 ha of natural ecosystems are needed. Thus there is a need of further evaluation of the role of tropical dryland rice soils and naturally dry ecosystems in the global methane budget. #