Methane Emissions Research Articles

Insights into the Driving Factors of Methane Emission from Double-Season Rice Field Under Different Fertilization Practices in South China

Insights into the Driving Factors of Methane Emission from Double-Season Rice Field Under Different Fertilization Practices in South China

Emissions of methane from coal fields, thermal power plants, and wetlands and their implications for atmospheric methane across the south Asian region

Abstract. Atmospheric methane (CH4) is a potent climate change agent responsible for a fraction of global warming. The present study investigated the spatiotemporal variability of atmospheric-column-averaged CH4 (XCH4) concentrations using data from the Greenhouse gases Observing SATellite (GOSAT) and the TROPOspheric Monitoring Instrument on board the Sentinel-5 Precursor (S5P/TROPOMI) from 2009 to 2022 over the south Asian region. During the study period, the long-term trends in XCH4 increased from 1700 to 1950 ppb, with an annual growth rate of 8.76 ppb yr−1. Among all natural and anthropogenic sources of CH4, the rate of increase in XCH4 was higher over the coal site at about 10.15 ± 0.55 ppb yr−1 (Paschim Bardhaman) followed by Mundra Ultra Mega Power Project at about 9.72 ± 0.41 ppb yr−1. Most of the wetlands exhibit an annual trend of XCH4 of more than 9.50 ppb yr−1, with a minimum rate of 8.72 ± 0.3 ppb yr−1 over Wular Lake. The WetCHARTs-based emissions of CH4 from the wetlands were minimal during the winter and pre-monsoon seasons. Maximum CH4 emissions were reported during the monsoon, with a maximum value of 23.62 ± 3.66 mg m−2 per month over the Sundarbans Wetland. For the 15 Indian agroclimatic zones, significant high emissions of CH4 were observed over the Middle Gangetic Plain, Trans-Gangetic Plain, Upper Gangetic Plain, Eastern Coastal Plains, Lower Gangetic Plain, and East Gangetic Plain. Further, the bottom-up anthropogenic CH4 emissions data are mapped against the XCH4 concentrations, and a high correlation was found in the Indo-Gangetic Plain region, indicating the hotspots of anthropogenic CH4.

Dry Heat, Wet Heat, and Wetland Methane Emissions

Dry Heat, Wet Heat, and Wetland Methane Emissions

Effects of Straw and Green Manure Addition on Crop Yield, Soil Properties and CH4 Emissions: A Meta-Analysis

The incorporation of organic amendments is widely acknowledged for its capacity to enhance soil fertility and boost crop productivity. However, whether the addition of organic amendments can improve soil quality and crop production, simultaneously causing methane emissions in paddy fields, deserves further investigation. In this meta-analysis, the effects of different organic amendments on soil nutrient levels, rice yield and CH4 emissions were evaluated in paddy fields based on 328 observations from 77 field trial studies. Our results revealed that the addition of organic amendments significantly increased soil organic carbon (9.47%), microbial biomass carbon (21.13%), microbial biomass nitrogen (28.91%), urease (25.07%) and β-glucosidase (24.41%). Moreover, straw addition significantly increased the CH4 emissions by 152.68% and rice yield by 7.16%; green manure addition significantly increased CH4 emissions by 71.62% and rice yield by 10.09%, respectively. Although both increased the CH4 emissions, green manure had the ability to improve the availability of N, which could improve rice uptake. The regression results showed that the variation in crop yield, soil nutrients and CH4 emissions are influenced through the types and quality of organic amendments. Overall, this study suggests that organic amendments are beneficial in maintaining soil quality and improving rice yield, whereas it also increased the CH4 emissions. These meta-analysis results may provide some references for optimizing organic amendments incorporated into the soil to sustain soil fertility and crop production while mitigating soil constraints and methane emissions.

Ebullition mediated transport dominates methane emission from open water area of the floating national park in Indo Burma hotspot.

Ebullition is an important route of methane emission from aquatic ecosystems. Ebullitive CH4 emissions from the wetlands, particularly the mountain wetlands of Eastern Himalayan, are poorly understood. To gain insights into the role of ebullition in CH4 emissions and understand the factors influencing CH4 ebullition, we conducted field measurements of the spatial and temporal variation of ebullition in a freshwater wetland area in floating national park (40 sq. km, 780m amsl, maximum depth < 4.5) in Northeast India. The average ebullitive CH4 flux ranged from 220.24 to 1889.35mgm-2 d-1, while the overall CH4 fluxes varied widely ranging from 345.81 to 2240.56mgm-2 d-1. Methane constituted 90.18% of the gas bubbles produced from the sediment, with CO2 comprising 8.82% of the total sediment gas in the wetland. This suggests that CH4 emission through ebullition plays an important role in transporting biogenic CH4 to the atmosphere. The ebullition rate was markedly higher during summer and lower during winter and exhibited a significant seasonal variation. At a spatial scale, the sites with dense aquatic vegetation growth increase CH4 emission where plants derived autochthonous sediment organic matter, substantiating the supply of carbon substrate for CH4 production. Linear mixed-effect models revealed that water temperature, organic matter, organic carbon and dissolved organic matter are the important factors affecting the ebullitive methane flux. Our results indicate that mountainous wetlands with organic-rich sediments may be potential hotspots for CH4 ebullition. However, the lack of information on these wetlands in the scientific literature emphasizes the need for further research.

Animal Feed as a Lever to Reduce Methane Emissions: a Micro-econometric Approach Applied to French Dairy Farms

Animal Feed as a Lever to Reduce Methane Emissions: a Micro-econometric Approach Applied to French Dairy Farms

Carbon footprint assessment and reduction strategies for aquaculture: A review

AbstractAquaculture generates less greenhouse gas emissions compared to other agriculture practices due to its limited land‐use changes, improved feed conversion rates, and reduced methane emissions from animals' digestive systems. The aquaculture carbon emissions come from various production stages, including feed production, farm operations, processing, transportation, and so forth. This review illustrates the theories, calculation methods, and practical applications of the carbon footprint in fisheries and aquaculture, as well as the challenges and strategies for emission reduction. The factors influencing the carbon footprint of fishing and manufacturing aquaculture are also discussed. Further research should focus on refining carbon footprint assessment techniques, promoting green technologies and sustainable aquaculture practices. Managing aquaculture's carbon footprint though is crucial for mitigating environmental impacts and supporting sustainable development.

Assessing Best Practices in Natural Gas Production and Emerging CO2 Capture Techniques to Minimize the Carbon Footprint of Electricity Generation.

Natural gas (NG) is expected to provide a substantial portion of electricity generation in many jurisdictions for the foreseeable future. Postcombustion carbon capture and storage (CCS) effectively abates direct CO2 emissions; however, indirect NG supply chain emissions in most jurisdictions are incompatible with climate change mitigation goals. This life cycle assessment evaluates specific opportunities to reduce the carbon footprint of combined cycle gas turbine (CCGT) generation with CCS using existing low-emission NG production practices, technologies, and processes combined with emerging CCS techniques to achieve high CO2 capture rates and mitigate startup emissions. We find baseload life cycle greenhouse gas (GHG) emission intensity ranges from 22 to 62 kgCO2e/MWh for 95-98.5% CO2 capture, within the range of published estimates for wind and photovoltaic power and considerably below prior estimates of CCGT with CCS. Low-emission NG production practices reduce other environmental impacts, which are dominated by combustion-related air pollution. We also show how interim solvent storage can effectively mitigate emissions from CCGT start/stop cycles. This work highlights the importance of mitigating both CO2 and methane emissions from NG supply chains and proposes a more nuanced discussion regarding the potential contribution of NG to the future energy supply. A surrogate model is provided to estimate life cycle GHG emissions for CCGT with CCS and user-input parameters.

Effects of Rice Root Development and Rhizosphere Soil on Methane Emission in Paddy Fields.

Paddy fields are important anthropogenic emission sources of methane (CH4). However, it is not clear how rice root development and rhizosphere soil properties affect CH4 emissions. Therefore, we selected rice varieties with similar growth periods but different root traits in the local area. We measured CH4 emission fluxes, cumulative CH4 emissions, root dry weight, root length, and the dissolved organic carbon (DOC), microbial biomass carbon (MBC), redox potential (Eh), ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3--N) contents in rhizosphere soil. Methanogens and methanotrophs are crucial factors influencing CH4 emissions; thus, their abundance and community composition were also assessed. The result showed that CH4 fluxes of each rice variety reached the peak at tillering stage and jointing-booting stage. The CH4 emissions in tillering stage were the largest in each growth period. CH4 emissions had negative correlations with root length, root dry weight, Eh NO3--N, methanotroph abundance, and the pmoA/mcrA ratio, and positive correlations with NH4+-N, MBC, DOC, and methanogen abundance. Path analysis confirmed methanogens and methanotrophs as direct influences on CH4 emissions. Root development and rhizosphere soil properties affect CH4 emissions indirectly through these microbes. This study suggests that choosing rice varieties with good root systems and managing the rhizosphere soil can effectively reduce CH4 emissions.

Climate change mitigation and adaptation for rice-based farming systems in the Red River Delta, Vietnam

BackgroundRice is a major contributor to anthropogenic greenhouse gas (GHG) emissions, primarily methane, and at the same time will be negatively impacted by regional climate changes. Identifying rice management interventions to reduce methane emissions while improving productivity is, therefore, critical for climate change mitigation, adaptation, and food security. However, it can be challenging to conduct multivariate assessments of rice interventions in the field owing to the intensiveness of data collection and/or the challenges in testing long-term changes in meteorological and climate conditions. Process-based modeling, evaluated against site-based data, provides an entry point for evaluating the impacts of climate change on rice systems and assessing the impacts, co-benefits, and trade-offs of interventions under historical and future climate conditions.MethodsWe leverage existing site-based management data to model combined rice yields, methane emissions, and water productivity using a suite of process-based coupled crop-soil model experiments for 83 growing sites across the Red River Delta, Vietnam. We test three rice management interventions with our coupled crop-soil model, characterized by Alternate Wetting and Drying (AWD) water management and other principles representing the System of Rice Intensification (SRI). Our simulations are forced with historical as well as future climate conditions, represented by five Earth System Models for a high-emission climate scenario centered on the year 2050. We evaluate the efficacy of these interventions for combined climate change mitigation and adaptation under historical and future climate change.ResultsTwo SRI interventions significantly increased yields (one by over 50%) under historical climate conditions while also reducing (or not increasing) methane emissions. These interventions also increase yields under future climate conditions relative to baseline management practices, although climate change decreases absolute yields across all management practices. Generally, where yield improved, so did crop water-use efficiency. However, impacts on methane emissions were mixed across the sites under future climate conditions. Two of the interventions resulted in increased methane emissions, depending on the baseline management point of comparison. Nevertheless, one intervention reduced (or did not significantly increase) methane under both historical and future climate conditions and relative to all baseline management systems, although there was considerable variation across five selected climate models.ConclusionsSRI management principles combined with high-yielding varieties, implemented for site-specific conditions, can serve climate change adaptation and mitigation goals, although the magnitude of future climate changes, particularly warming, may reduce the efficacy of these interventions with respect to methane reductions. Future work should better bracket important sensitivities of coupled crop-soil models and disentangle which management and climate factors drive the responses shown. Furthermore, future analyses that integrate these findings into socio-economic assessment can better inform if and how SRI/AWD can potentially benefit farmer livelihoods now and in the future, which will be critical to the adoption and scaling of these management principles.

The Scientific Case Against Net Zero: Falsifying the Greenhouse Gas Hypothesis

The UK Net Zero by 2050 Policy was undemocratically adopted by the UK government in 2019. Yet the science of so-called &amp;lsquo;greenhouse gases&amp;rsquo; is well known and there is no reason to reduce emissions of carbon dioxide (CO2), methane (CH4), or nitrous oxide (N2O) because absorption of radiation is logarithmic. Adding to or removing these naturally occurring gases from the atmosphere will make little difference to the temperature or the climate. Water vapor (H2O) is claimed to be a much stronger &amp;lsquo;greenhouse gas&amp;rsquo; than CO2, CH4 or N2O but cannot be regulated because it occurs naturally in vast quantities. This work explores the established science and recent developments in scientific knowledge around Net Zero with a view to making a rational recommendation for policy makers. There is little scientific evidence to support the case for Net Zero and that greenhouse gases are unlikely to contribute to a &amp;lsquo;climate emergency&amp;rsquo; at current or any likely future higher concentrations. There is a case against the adoption of Net Zero given the enormous costs associated with implementing the policy, and the fact it is unlikely to achieve reductions in average near surface global air temperature, regardless of whether Net Zero is fully implemented and adopted worldwide. Therefore, Net Zero does not pass the cost-benefit test. The recommended policy is to abandon Net Zero and do nothing about so-called &amp;lsquo;greenhouse gases&amp;rsquo;.

The Path to Net-Zero in Dairy Production: Are Pronounced Decreases in Enteric Methane Achievable?

Achieving net-zero greenhouse gas (GHG) emissions in dairy production will require >50% reduction in enteric methane (CH4) emissions together with elimination of emissions from feed production, additional carbon sequestration, reduction in manure emissions, anaerobic digestion of manure, and decreased reliance on fossil fuel energy. Over past decades, improved production efficiency has reduced GHG intensity of milk production (i.e., emissions per unit of milk) in the United States, but this trend will continue only if cows are bred for increased efficiency. Genetic selection of low-CH4-producing animals, diet reformulation, use of feed additives, and vaccination show tremendous potential for enteric CH4 mitigation; however, few mitigation strategies are currently available, and added cost without increased revenue is a major barrier to implementation. Complete elimination of CH4 emissions from dairying is likely not possible without negatively affecting milk production; thus, offsets and removals of other GHGs will be needed to achieve net-zero milk production.

Assessment of the influence of inhibitors on carbon dioxide and methane emissions from soils irrigated with alternative water resources

Assessment of the influence of inhibitors on carbon dioxide and methane emissions from soils irrigated with alternative water resources

Correction: Olaguer et al. Landfill Emissions of Methane Inferred from Unmanned Aerial Vehicle and Mobile Ground Measurements. Atmosphere 2022, 13, 983

There was an error in the original publication [...]

In Vitro Plant Regeneration of Sulla coronaria from Floral Explants as a Biotechnological Tool for Plant Breeding

Sulla coronaria L. Medik., a biennial forage legume typical of the Mediterranean basin, plays a significant role in foraging systems due to its high nutritional value, ability to increase ruminant live weight, and potential to reduce methane emissions. However, its allogamous nature complicates genetic improvement and the development of new varieties with desired traits. Given these challenges, this study aims to develop, for the first time, a successful protocol for the in vitro meristematic shoot regeneration of S. coronaria. The experiment utilizes four different flower explants (anther with filament, ovary, petals, and whole immature flower) collected from twenty distinct S. coronaria biotypes with three plant growth regulator (PGR) combinations and under both light and dark conditions. In terms of the regeneration response, the key factors appear to be the combinations of PGRs and the type of explant used. The interactions between all the factors do not seem to be significant.

Technical and environmental inefficiency measurement in agriculture using a flexible by‐production stochastic frontier model

AbstractIn light of the urgent need for farms to mitigate greenhouse gas emissions while maintaining economic viability, this paper analyses technical and environmental inefficiencies and their determinants based on a flexible multi‐equation by‐production stochastic frontier model, which accounts for the stochastic dependence between good and bad outputs via a copula function. An empirical application to Dutch dairy farms illustrates the distortions in the inefficiency scores and in the estimates of their determinants that occur when the dependence between good and bad outputs is ignored. The empirical results indicate a strong positive dependence between the good output (milk) and the bad output (methane emissions), which is particularly pronounced in the upper tail of the distribution. Notably, farms exhibit high efficiency in maximising their good output and minimising their bad output. Subsidies are negatively related to good output inefficiency but positively related to bad output inefficiency, while stock density exhibits a negative association with inefficiencies in both outputs. Disregarding output dependence leads to distortions in inefficiency estimates, particularly affecting the estimates for their determinants.

Hydrogen-rich water 400ppb as a potential strategy for improving ruminant nutrition and mitigating methane emissions

The objective of this study was to evaluate the effects of different concentrations of hydrogen-rich water (HRW) on in vitro rumen fermentation characteristics and the dynamics of bacterial communities. The experiment included four treatment groups: a control (CON) and hydrogen-rich water (HRW) at 200, 400, and 800 ppb. Each group was analyzed at 12-hour (h) and 48-hour (h) time points with five replicates, totaling 40 samples. The experimental results highlighted the HRW800ppb group as the top production in terms of gas production and CH4 content. In contrast, the HRW200ppb group exhibited significantly lower methane levels at both 12 h and 48 h (P < 0.05). Regarding rumen fermentation, the HRW400ppb group significantly increased the levels of ammonia nitrogen (NH3-N) and microbial crude protein (MCP) at 12 h fermentation, but reduced the dry matter degradation rate (P < 0.05). After 48 h, the HRW400ppb group had highest MCP content (P < 0.05), but no significant differences in NH3-N and dry matter degradation rate compared with the CON group (P > 0.05). Although HRW did not significantly benefit the synthesis of total volatile fatty acids (TVFA) and individual VFA, the HRW800ppb group significantly increased the ratio of acetate to propionate (P < 0.05). Based on CH4 emissions and MCP synthesis, we selected the HRW400ppb group for subsequent bacterial community analysis. Bacterial community analysis showed that at 12 h, compared with the CON group, the Bacterial community analysis revealed that the HRW400ppb group had significant increases in the Simpson index, Firmicutes, Streptococcus, Schwartzia, Prevotellaceae_YAB2003_group, and Oribacterium, and decreases in Prevotella, Ruminobacter, Succinivibrio, unclassified_Succinivibrionaceae, and Prevotellaceae_UCG-003 (P < 0.05). At 48 h, the Prevotellaceae_YAB2003_group and Oribacterium abundances continued to rise significantly, while Rikenellaceae_RC9_gut_group and Succiniclasticum abundances fell in the HRW400ppb group (P < 0.05). Correlation analysis indicated a negative link between CH4 and Streptococcus, and a positive correlation between the abundance of Rikenellaceae_RC9_gut_group and CH4. Collectively, these results indicate that HRW can modulate rumen fermentation and microbial community structure to reduce methane emissions without significantly affecting VFA synthesis, highlighting its potential as drinking water for enhancing ruminant nutrition and mitigating the environmental impact of livestock farming.

Ruminant livestock and climate change: critical discourse moments in mainstream and farming sector news media

AbstractThere is ongoing contestation around greenhouse gas emissions from ruminant livestock and how society should respond. Media discourses play a key role in agenda setting for the general public and policymakers, and may contribute to polarisation. This paper examines how UK news media portrayed ruminant livestock’s impact on climate change between 2016 and 2021. The analysis addresses a gap in the literature by comparing discourses in national and farming sector newspapers using a qualitative approach. Four national and two farming sector news outlets were searched for articles published between 2016 and 2021. A corpus of 996 relevant articles was assembled, from which 154 were selected for in-depth examination using Critical Discourse Analysis. Four ‘Critical Discourse Moments’ (CDMs), each signifying a discursive shift in the debate, were identified over the 6-year studied period: 1) Low salience, diverging discourses, 2) We must eat far less meat, 3) Fighting the anti-meat agenda, and 4) Policy (in)action at COP26. There was a large increase in the number of published articles from January 2019 onward, partly associated with publication of the EAT/Lancet Commission report. CDM 2 (We must eat far less meat) occurred mainly in the national media, while CDM 3 (Fighting the anti-meat agenda) occurred mainly in the farming media. Our findings reveal both opinion polarisation and intergroup polarisation between national and farming sector media, and low engagement with food system power imbalances. Addressing polarisation will be important to enhance capacity for collective decision-making regarding methane emissions from ruminant livestock.

Use of CLEANED to Assess the Productive, Environmental, and Economic Impact of Dairy Farms in the Peruvian Amazon.

Dairy farms in developing countries are key to fighting hunger and poverty. However, their environmental and economic impact in the tropical region of Peru has been scarcely studied. The CLEANED tool, developed by the Alliance of Bioversity International and the International Center for Tropical Agriculture, allows us to assess the productive situation and the environmental and economic impact of different dairy systems. The objective of the study was to use the CLEANED tool to evaluate the production, environmental, and economic impacts of extensive and semi-intensive dairy systems in the tropical region of Peru. Data from twelve dairy farms (six extensive and six semi-intensive systems), in two seasons (rainy and dry) were recorded using semi-structured surveys. The required area (ha/year), production (L milk/ha/year), environmental impact (water use in m3/product), and methane (CH4) and nitrous oxide (N2O) emissions in kg CO2eq/kg fat- and protein-corrected milk (FPCM) were estimated, and the economic analysis was performed for each livestock system. Results showed that the required area was of 28.9 and 32.6 ha, milk yield was 382 and 1254 L/ha/year, water use was 0.59 and 0.29 m3/kg FPCM, CH4 emissions were 1.7 and 1.0 kg CO2eq/kg FPCM, and N2O emissions were 0.22 and 0.17 kg CO2eq/kg FPCM, for the extensive and semi-intensive systems, respectively. The study revealed significant positive differences in semi-intensive livestock systems, including increased productivity, the reduced intensity of CH4 and N2O emissions, and greater profitability.

Development of National Emission Factor for Rice Production System in Malaysia: A Step Toward Achieving Sustainable Development Goals

Objective: Currently, methane (CH4) emissions from rice cultivation in Malaysia are calculated using the regional’s methane emission factor (EF) of 1.60 kg CH₄ ha⁻¹ day⁻¹, as Malaysia has not yet developed a national emission factor. The objective of this study is to generate a country-specific EF of CH4 emission from rice cultivation in Malaysian rice fields. The EF generated would then be used in future emission estimates and the country’s greenhouse gas (GHG) inventory reports to the United Nations Framework Convention on Climate Change (UNFCCC). Theoretical Framework: The establishment of a national GHG emission factor for rice cultivation in Malaysia is critical for accurate GHG inventory reporting and effective climate change mitigation. This study utilizes the Intergovernmental Panel on Climate Change (IPCC) guidelines to derive a country-specific emission factor, enhancing Malaysia’s compliance with international climate obligations and promoting sustainable agricultural practices. Method: A new national EF was developed from eleven rice planting seasons in rice granary areas (IADA Pulau Pinang, IADA Barat Laut Selangor, MADA and KADA) and non-granary area (Sik, Kedah). The EF was calculated from methane emissions from the new data sets, published journals and unpublished data from MARDI. For the new data set, methane gas (CH4) was measured using a static chamber method (Minamikawa et al., 2015). Sampling of GHG from the gas chamber is carried out in the field every 2 weeks and gas was analysed by a GC System Agilent 7890A gas chromatography. The daily methane flux and methane emission follow the methods by Habib et al. (2007), Fauzi et al. (2023) and the Guidelines for National Greenhouse Gas Inventories for Cropland (IPCC, 2006a). Results and Discussion: The national EF calculated from CH4 gas emissions over eleven rice planting seasons in Malaysia between 2012-2024 was 1.80 kg CH4 ha-1 day-1, which is higher than the current regional EF used (1.60 kg CH4 ha-1 day-1). However, the value is within the range of the default value of 1.30 kg CH4 ha-1 day-1 by the Intergovernmental Panel on Climate Change (IPCC) 2006 and 2.00 kg CH4 ha-1 day-1 (IPCC, 1996). Research Implications: The use of this new EF resulted in 12.49% increase in the national GHG inventory from the rice cultivation sub-sector as compared to using the current regional EF. This initiative is part of a comprehensive plan to enhance and strengthen GHG inventory reporting for Malaysia's agriculture sector, aiming to meet IPCC requirements and progress to Tier 2 status.