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Anaerobic digestion of organic solid waste is one of the mechanisms for sustainable development since it permits both the energy-efficient disposal of solid waste and the use of biogas. As a result, this study provides an assessment of the potential energy and emissions saved by using biogas energy generated from the biodegradation of solid waste. For present study two major cities are selected in south India namely Madurai, Tamil Nādu and Hyderabad, Telangana. The LandGEM 3.03 model is used to estimate the concentration of total landfill gases. The landfill in Madurai produced 2.162 × 106 cu. m per year of methane emissions in the year 2013. The production of biogas has increased over time would continue to increase until 2045, when a production rate of 6.32 × 107 cu. m per year was recorded as the largest concentration of biogas ever generated. For the Hyderabad landfill, methane concentrations during the year 2013 was recorded to be 2.5 × 107 cu. m per year and reached a peak in 2046 with a concentration of 3.7 × 108 cu. m per year, was found to have a potential to generate 2.1 × 106 kWh per year. For the Madurai dump site, the energy potential increases gradually and reaches a peak during the year 2047 with a value of 4.54 × 107 kWh per year. Whereas for Hyderabad dump site was found to have an energy equivalent of 2.1 × 108 kWh per year during 2024 and reaches a peak during 2046 with an energy equivalent of 5.1 × 108 kWh per year. [ABSTRACT FROM AUTHOR]

Along with the main objective of politicians, other economic variables are variously affected by the environmental taxes, policies, and limitations like a price on pollution, clean electricity, the cap on emissions, methane emissions, and nature‐based solutions. The objective of the environmental solutions is to decrease pollutant emissions and energy consumption while reducing labor costs and taxes as the incentives for creating new occupations. An overall equilibrium model was considered in the present study as a nonlinear equations system, which was calibrated for the reference year of 2018 utilizing Canada's economy's data table. The effects of utilizing these environmental policies considered by Canada in COP26 are examined. In all scenarios, minimum, maximum, and optimum values for reducing pollutant emissions are calculated under these policies. According to the simulation results, welfare is reduced by the price of pollution policy. Moreover, the actual consumed budget of the household is reduced by 8%. However, such indices will be incremented by 2% in the nature‐based policy. In all scenarios, the gross domestic product is decreased. However, in the methane emission policy, this reduction is 1.05% in the lowest state. In all scenarios, the consumer price index will be incremented by 3.8%–9.8%. It is concluded that the clean electricity policy is an appropriate policy for reducing greenhouse gas emissions and at the same time adhering to international commitments. [ABSTRACT FROM AUTHOR]

The recent rise in atmospheric methane (CH4) concentrations accelerates climate change and offsets mitigation efforts. Although wetlands are the largest natural CH4 source, estimates of global wetland CH4 emissions vary widely among approaches taken by bottom‐up (BU) process‐based biogeochemical models and top‐down (TD) atmospheric inversion methods. Here, we integrate in situ measurements, multi‐model ensembles, and a machine learning upscaling product into the International Land Model Benchmarking system to examine the relationship between wetland CH4 emission estimates and model performance. We find that using better‐performing models identified by observational constraints reduces the spread of wetland CH4 emission estimates by 62% and 39% for BU‐ and TD‐based approaches, respectively. However, global BU and TD CH4 emission estimate discrepancies increased by about 15% (from 31 to 36 TgCH4 year−1) when the top 20% models were used, although we consider this result moderately uncertain given the unevenly distributed global observations. Our analyses demonstrate that model performance ranking is subject to benchmark selection due to large inter‐site variability, highlighting the importance of expanding coverage of benchmark sites to diverse environmental conditions. We encourage future development of wetland CH4 models to move beyond static benchmarking and focus on evaluating site‐specific and ecosystem‐specific variabilities inferred from observations. [ABSTRACT FROM AUTHOR]

Radiocarbon (14C) measurements offer a unique investigative tool to study methane emissions by identifying fossil-fuel methane in air. Fossil-fuel methane is devoid of 14C and, when emitted to the atmosphere, causes a strong decrease in the ratio of radiocarbon to total carbon in methane (Δ14CH4). By observing the changes in Δ14CH4, the fossil fraction of methane emissions can be quantified. Presently, there are very few published Δ14CH4 measurements, mainly because it is challenging to collect and process the large volumes of air needed for radiocarbon measurements. We present a new sampling system that collects enough methane carbon for high precision Δ14CH4 measurements without having to transport large volumes of air. The system catalytically combusts CH4 into CO2 and adsorbs the combustion-derived CO2 onto a molecular sieve trap, after first removing CO2, CO, and H2O. Tests using reference air show a Δ14CH4 measurement repeatability of 5.4‰, similar or better than the precision in the most recent reported measurements. We use the system to produce the first Δ14CH4 measurements in central London and show that day-to-day differences in Δ14CH4 in these samples can be attributed to fossil methane input. The new system could be deployed in a range of settings to investigate CH4 sources.

Highlights Biochar showed promise in adsorbing methane. Biochar could store more methane than gas cylinders up to 75 bar gas pressure. Biochar could contribute to the reduction of methane emissions in oil and gas fields.

To align with climate initiatives, multiple reporting programs are transitioning from generic activity-based emission factors to site-specific measured emissions data to estimate greenhouse gas emissions at oil and gas facilities. This study contemporaneously deployed two top-down (TD) aerial methods across 14 midstream facilities, building upon previous research in the field. The methods produced multiple whole-facility estimates at each facility, resulting in 773 individual paired estimates (same facility, same day), and robust mean estimates for each facility. Mean estimates for each facility, aggregated across all facilities, differed by nearly 2:1 (49% [32% to 69%]). At 6 of 14 facilities, the methods produced mean estimates that differed by more than a factor of two. These data suggest that one or both methods did not produce accurate facility-level estimates at a majority of facilities and in aggregate across all facilities. The overall results are augmented with two case studies where TD estimates at two pre-selected facilities were coupled with comprehensive onsite measurements to understand the factors driving the divergence between TD and bottom-up (BU) emissions estimates. In 3 of 4 paired comparisons between the intensive onsite estimates and one of the TD methods, the intensive onsite surveys did not conclusively diagnose the difference in estimates. In these cases, our work suggests that the TD methods mis-estimate emissions an unknown fraction of the time, for unknown reasons. While two methods were selected for this study, it is unlikely that the issues identified here are confined to these two methods; similar issues may exist for other similar whole-facility methods on midstream and/or other facility types. These findings have important implications for the construction of voluntary and regulatory reporting programs that rely on emission estimates for reporting fees or penalties, or for studies using whole-facility estimates to aggregate TD emissions to basin or regional estimates.

The dairy industry is facing criticism for its role in exacerbating global GHG emissions, as climate change becomes an increasingly pressing issue. These emissions mostly originate from methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2). An optimal strategy involves the creation of an economical monitoring device to evaluate methane emissions from dairy animals. Livestock production systems encounter difficulties because of escalating food demand and environmental concerns. Enhancing animal productivity via nutrition, feeding management, reproduction, or genetics can result in a decrease in CH4 emissions per unit of meat or milk. This CH4 unit approach allows for a more accurate comparison of emissions across different animal production systems, considering variations in productivity. Expressing methane emissions per unit allows for easier comparison between different sources of emissions. Expressing emissions per unit (e.g., per cow) highlights the relative impact of these sources on the environment. By quantifying emissions on a per unit basis, it becomes easier to identify high-emission sources and target mitigation efforts accordingly. Many environmental policies and regulations focus on reducing emissions per unit of activity or output. By focusing on emissions per unit, policymakers and producers can work together to implement practices that lower emissions without sacrificing productivity. Expressing methane emissions in this way aligns with policy goals aimed at curbing overall greenhouse gas emissions. While it is true that total emissions affect the atmosphere globally, breaking down emissions per unit helps to understand the specific contributions of different activities and sectors to overall greenhouse gas emissions. Tackling cattle health issues can increase productivity, reduce GHG emissions, and improve animal welfare. Addressing livestock health issues can also provide favourable impacts on human health by reducing the prevalence of infectious illnesses in livestock, thereby mitigating the likelihood of zoonotic infections transmitting to humans. The progress in animal health offers the potential for a future in which the likelihood of animal diseases is reduced because of improved immunity, more effective preventative techniques, earlier identification, and innovative treatments. The primary objective of veterinary medicine is to eradicate clinical infectious diseases in small groups of animals. However, as the animal population grows, the emphasis shifts towards proactive treatment to tackle subclinical diseases and enhance production. Proactive treatment encompasses the consistent monitoring and implementation of preventive measures, such as vaccination and adherence to appropriate nutrition. Through the implementation of these measures, the livestock industry may enhance both animal well-being and mitigate the release of methane and nitrous oxide, thereby fostering environmental sustainability. In addition, advocating for sustainable farming methods and providing farmers with education on the significance of mitigating GHG emissions can bolster the industry’s endeavours to tackle climate change and infectious illnesses. This will result in a more robust and environmentally sustainable agriculture industry. This review seeks to conduct a thorough examination of the correlation between the health condition of cattle, the composition of milk produced, and the emissions of methane gas. It aims to identify areas where research is lacking and to provide guidance for future scientific investigations, policy making, and industry practices. The goal is to address the difficulties associated with methane emissions in the cattle industry. The primary global health challenge is to identify the causative relationship between climate change and infectious illnesses. Reducing CH4 and N2O emissions from digestive fermentation and animal manure can be achieved by improving animal well-being and limiting disease and mortality.

Methane is the second most important anthropogenic greenhouse gas, whose emissions need to be mitigated to curb global warming. There is a large uncertainty about its point source, but thanks to a new generation of high-spatial-resolution satellites, this situation is changing drastically, revealing thousands of emission point sources worldwide. In this paper, several hotspot areas are mapped, looking for methane emission point sources with different types of high-resolution satellites. Our results demonstrate the potential of satellite remote sensing to reveal methane emission point sources in different scenarios.

Cattle production in Colombia has an important social and economic role but causes considerable environmental impacts, such as deforestation and greenhouse gas emissions by ruminants, particularly methane. Thus, technological innovations aimed at reducing these impacts must focus on both economic and environmental sustainability. Silvo-pastoral systems (SPS) offer productivity increases while generating environmental benefits and ecosystem services and are therefore at the center of debate around sustainable production alternatives. The objective of this article is to evaluate the economic-environmental performance of two proposed SPS for a cattle fattening system for the Colombian context: (i) Urochloa brizantha cv. Toledo and (ii) Urochloa hybrid cv. Cayman, both in association with Leucaena leucocephala trees for browsing and shade provision. They are compared with the respective base scenarios of only using the grasses in monocultures. The study consists of a financial analysis, which estimates potential profitability increases in beef production in the SPS, and an environmental evaluation, which estimates the monetary values of microclimatic regulation and reduction of methane emissions. The value of methane emission reductions is then integrated into a combined economic-environmental evaluation. Results show that both SPS improve the profitability indicators of the production system and reduce the probability of economic loss. Likewise, the reduction of methane emissions in the SPS is estimated at US$6.12 per cattle, and the economic value of microclimatic regulation at US$2,026 per hectare.

The quantification of gas emissions from waste storage and treatment ponds is an important problem. The objective of this study was to better understand the use of micrometeorological techniques for this purpose. Methane emissions were estimated from a large tailings pond (surface area >11 km2) at an oil sands mine site using datasets collected by different groups over a nine-month period. Emissions were calculated with eddy-covariance (EC) and inverse dispersion modelling (IDM) techniques. Three different IDM calculations were made using methane concentrations measured with either fixed-point sensors (IDM-LGR), a long-path laser (IDM-GL), or an unmanned aerial vehicle (IDM-UAV). Emissions were also estimated from a flux-chamber (FC) survey. Although the temporal overlap between the different datasets was limited, the results indicate substantial differences in emission-rate estimates. During a summer interval the EC, IDM-LGR, and IDM-GL estimates were 19%, 41%, and 56% of the FC-estimated rate, respectively. The overall ordering was EC ≈ IDM-UAV

The goal of this study was to investigate Candida tropicalis as a kind of environmentally friendly dietary additive to manipulate ruminal fermentation patterns, reduce methane emissions and nitrogen excretion, and to screen the appropriate dose for sheep. Twenty-four Dorper × thin-tailed Han crossbred ewes (51.12 kg ± 2.23 kg BW) were selected and randomly divided into four groups which were fed Candida tropicalis at dose of 0 (control), 4 × 108 (low dose), 4 × 109 (medium dose), and 4 × 1010 (high dose) colony-forming units (CFU)/d per head, respectively. The experiment lasted 33 days with 21 days for adaptation and 12 days for nutrient digestibility trial and respiratory gases sampling. The results showed that nutrients intake was not affected by Candida tropicalis supplementation (P > 0.05), whereas apparent digestibility of nutrients significantly increased compared with the control group (P < 0.05). Nitrogen and energy utilization increased with Candida tropicalis supplementation (P < 0.05). Compared with the ewes of the control group, rumen fluid pH and NH3-N concentration were not affected (P > 0.05), whereas total volatile fatty acid concentration and molar proportion of propionate were greater (P < 0.05), and molar proportion of acetate and the ratio of acetate to propionate were less (P < 0.05) when the ewes were fed Candida tropicalis. Daily total CH4 production (L/d) and CH4 emissions yield (L/d of CH4 per kg of dry matter intake, metabolic weight, or digestibility dry matter intake) were decreased at the low dose group (P < 0.05). The abundance of total bacteria, methanogen, and protozoa in rumen fluid was significantly higher at medium dose and high dose of Candida tropicalis supplementation (P < 0.05) compared with low dose and the control group. In summary, Candida tropicalis supplementation has a potential to reduce CH4 emissions and nitrogen excretion, and the optimal dose should be 4 × 108 CFU/d per head. [ABSTRACT FROM AUTHOR]

Natural and anthropogenic sources of methane in the Republic are considered. The main anthropogenic sources are coal mining and oil and gas production areas. Coal mining is concentrated in the central regions of the republic, and oil and gas production is concentrated in the western regions. It is shown that as a result of a noticeable reduction in underground coal mining, methane emissions have significantly decreased. Oil and gas production sites remain fairly stable sources of methane. There is an increase in the share of emissions from the transportation of hydrocarbon fuels; significant dynamics are observed in maritime transportation, as one of the most dynamically growing sources. The purpose of this study was to study the main sources of emissions on the territory of Kazakhstan, to estimate the volume of methane emitted, to assess its dynamics over the past decades and to make some prognostic estimates of this dynamics. The materials of the inventory for a thirty-year period and data from satellites carrying out regular sounding of pollutants in the atmosphere were used. A satellite that successfully measures concentrations of major impurities in the atmosphere, clouds, etc. with the help of a modern lidar, having a horizontal resolution of 333 m. Analyzing satellite data, it was possible to detect other sources of methane besides. The spatial distribution of methane is significantly affected by transboundary transport. [ABSTRACT FROM AUTHOR]

In Australia, 71% of agricultural greenhouse gas (GHG) emissions are enteric methane (CH4), mostly produced by grazing sheep and cattle. Temperate low CH4 yielding legumes and herbs can mitigate enteric CH4 production, but system-level GHG emissions need to be considered. The aims of the study were to: (1) devise a framework to assess GHG reductions when introducing low CH4 yielding species; (2) assess mechanisms of CH4 reduction in temperate legume and herb species for Australia; (3) use a case study to demonstrate expected changes to system-level GHG emissions with the introduction of low CH4 yielding legumes; and (4) identify knowledge gaps and research priorities. Results demonstrate lowering emissions intensity (kg CO2-equivalent/kg product) is crucial to mitigate GHG emissions, but livestock productivity is also important. Several pasture species have anti-methanogenic properties, but responses often vary considerably. Of the species investigated biserrula (Biserrula pelecinus) has great potential to reduce enteric CH4 emissions, but in a case study its emission intensity was similar to subterranean clover (Trifolium subterraneum) but higher than lucerne (Medicago sativa). We conclude that there are temperate legumes and herbs with anti-methanogenic properties, and/or high productivity that could reduce total CH4 emissions and emissions intensity of ruminant livestock production. There is also great diversity in some plant genotypes that can be exploited, and this will be aided by more detailed understanding of plant secondary compounds associated with CH4 reduction. This review suggests an opportunity to formulate pasture species mixtures to achieve reduced CH4 emissions with greater or equal livestock production. Temperate low methane (CH4) yielding legumes and herbs can reduce enteric methane, but greenhouse gas emissions at a system level need to be considered. This review identified several pasture species with anti-methanogenic properties, with biserrula having the most potential to reduce enteric CH4. However, a case study demonstrated that emission intensity of biserrula was similar to that of subterranean clover but higher than that of lucerne. An opportunity exists to formulate pasture mixtures to reduce CH4 and increase livestock production. [ABSTRACT FROM AUTHOR]

Drainage and agricultural use transform natural peatlands from a net carbon (C) sink to a net C source. Rewetting of peatlands, despite of high methane (CH4) emissions, holds the potential to mitigate climate change by greatly reducing CO2 emissions. However, the time span for this transition is unknown because most studies are limited to a few years. Especially, nonpermanent open water areas often created after rewetting, are highly productive. Here, we present 14 consecutive years of CH4 flux measurements following rewetting of a formerly long‐term drained peatland in the Peene valley. Measurements were made at two rewetted sites (non‐inundated vs. inundated) using manual chambers. During the study period, significant differences in measured CH4 emissions occurred. In general, these differences overlapped with stages of ecosystem transition from a cultivated grassland to a polytrophic lake dominated by emergent helophytes, but could also be additionally explained by other variables. This transition started with a rapid vegetation shift from dying cultivated grasses to open water floating and submerged hydrophytes and significantly increased CH4 emissions. Since 2008, helophytes have gradually spread from the shoreline into the open water area, especially in drier years. This process was periodically delayed by exceptional inundation and eventually resulted in the inundated site being covered by emergent helophytes. While the period between 2009 and 2015 showed exceptionally high CH4 emissions, these decreased significantly after cattail and other emergent helophytes became dominant at the inundated site. Therefore, CH4 emissions declined only after 10 years of transition following rewetting, potentially reaching a new steady state. Overall, this study highlights the importance of an integrative approach to understand the shallow lakes CH4 biogeochemistry, encompassing the entire area with its mosaic of different vegetation forms. This should be ideally done through a study design including proper measurement site allocation as well as long‐term measurements. [ABSTRACT FROM AUTHOR]

• LCA was conducted on landfill biocover and gas collection with energy utilisation. • Biocovers had fewer environmental impacts at landfills with low gas production. • Fugitive CH 4 emissions were the major contributor to climate change. • High biocover oxidation efficiency is crucial for reducing environmental impacts. A life cycle-based environmental assessment was conducted on the mitigation of landfill gas emissions, by implementing biocover and gas collection along with energy utilisation at aging landfills. Based on recent studies about gas generation at Danish landfills, the efficiency of the mitigation technologies involved and the composition of substituted energy production, 15 scenarios were modelled using the EASETECH life cycle assessment model, through which potential environmental impacts in the category "Climate change" were calculated. In all scenarios, biocover and gas collection systems with energy utilisation led to significant environmental improvements compared to the baseline scenario with no emission mitigation action. Scenarios representing biocovers with methane oxidation efficiencies between 70 and 90 % were environmentally superior in terms of climate change impact – in comparison to scenarios with 20–30 years of gas collection and energy utilisation (collection efficiencies between 40 and 80 %). Combining gas collection with energy utilisation and the subsequent installation of a biocover saw major improvements in comparison to where only gas collection and energy utilisation were in effect. Overall, it can be concluded that a biocover under the given assumptions is environmentally more appropriate than gas collection and utilisation at aging landfills, mainly due to methane emissions escaping through the landfill cover during and after the gas collection period playing a crucial role in the latter situation. Maintaining high methane oxidation efficiency for a biocover throughout the lifetime of a landfill is vital for reducing environmental impacts. [ABSTRACT FROM AUTHOR]

To reduce methane (CH 4) emissions of dairy cows by animal breeding, CH 4 measurements have to be recorded on thousands of individual cows. Currently, several techniques are used to phenotype cows for CH 4 , differing in costs and applicability. However, there is uncertainty about the agreement between techniques. To judge the similarity and repeatability between measurements of different recording techniques, the repeatability, heritability, and genetic correlation are useful metrics. Therefore, our objective was to estimate (1) the repeatability and heritability for CH 4 and carbon dioxide production recorded by GreenFeed (GF) and for CH 4 and carbon dioxide concentration measured by cost-effective but less accurate sniffers, and (2) the genetic correlation between CH 4 recorded with these 2 different on farm and high throughput techniques. Data were available from repeated measurements of CH 4 production (grams/day) by GF units and of CH 4 concentration (ppm) by sniffers, recorded on commercial dairy farms in the Netherlands. The final data comprised 24,284 GF daily means from 822 cows, 170,826 sniffer daily means from 1,800 cows, and 1,786 daily means from 75 cows by both GF and sniffer (in the same period). Additionally, CH 4 records were averaged per week. For daily and weekly mean GF CH 4 the heritabilities were 0.19 ± 0.02 and 0.33 ± 0.04, and for daily and weekly mean sniffer CH 4 the heritabilities were similar and were 0.18 ± 0.01 and 0.32 ± 0.02, respectively. Phenotypic correlations between GF CH 4 production and sniffer CH 4 concentration were moderate (0.39 ± 0.03 for daily means and 0.37 ± 0.05 for weekly means). However, genetic correlations were high; 0.71 ± 0.13 for daily means and 0.76 ± 0.15 for weekly means. The high genetic correlation indicates that selection on low CH 4 concentrations (ppm) recorded by the cost-effective sniffer method, will result in reduced CH 4 production (grams/day) as recorded with GF. [ABSTRACT FROM AUTHOR]

We investigate the relationship between EU Common Agricultural Policy environmental payments, and dairy and beef farm level competitiveness and environmental performance. We use an Irish panel of farm level financial data for the years 2000-2017 and apply stochastic frontier analysis. Our estimates identify a positive relationship between technical efficiency and the Green, Low-Carbon, Agri-Environment Scheme for dairy farms, in contrast with the negative relation identified for previous payments of this kind such as the Rural Environment Protection Scheme for both beef and dairy. We then simulate increases in the first type of environmental payments financed through reductions in decoupled payments. We use alternative scenarios for payment redistribution such as flat allocation, allocation to farms with low stocking rates or proportional reallocation of payments. We find that under the second scenario, marginal environmental gains can potentially be achieved for dairy farms. For beef farms, the proportional allocation performs best regarding environmental gains. We also find that under this scenario, the impacts on income inequality can be smoothed for both farm types. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) production in the future aims to increase productivity every year with high input technology, including irrigated rice. However, the practices of irrigated rice fields have a high methane (CH4) production potential. Soil tillage could affect CH4 emission conditions. Puddling and flooding through soil tillage create reduction conditions that promote CH4 production by methanogenic bacteria. The objective was to determine the effect of soil tillage and N fertilizer management on CH4 emissions from rice fields with heavytextured soil. The field experiment was arranged in a split-plot design in which soil tillage was the main plot and consisted of maximum tillage and no-tillage. Nitrogen fertilizer management was the split plot and consisted of a control without N, prilled urea broadcasting, prilled urea deep placement, ammonium sulfate (AS) broadcasting, AS deep placement, and tablet urea deep placement. No-tillage could reduce CH4 emissions by 15.58% compared with maximum tillage. However, grain yield for no-tillage was lower than for maximum tillage with 2.73 and 3.68 t ha-1, respectively. The AS and tablet urea deep placement emitted lower CH4 and grain yield was higher than with other N management practices. The CH4 emissions for AS and tablet urea deep placement was 96 and 97 kg CH4 ha-1 season-1 and grain yield was 3.79 and 4.25 t ha-1, respectively. The application of fertilizers incorporated into the soil increased rice productivity and mitigated CH4 emissions from rice fields. [ABSTRACT FROM AUTHOR]

The storage of liquid manure (slurry) is a major source of methane (CH 4) and thus contributes significantly to the climate impact of agriculture. The necessity to store slurry in barns and storage tanks at different seasons has led to increasing research in the mitigation of CH 4 emissions from the manure management chain. In this review, a holistic view of CH 4 mitigation strategies targeting slurry pits and storage tanks classified based on the mechanism of interaction (physical, chemical, and biological) with slurry and their CH 4 mitigation efficiency is presented. Also, the combination of chemical additives with other methods is discussed. The key methods include slurry cover, solid–liquid separation, acidification, antimicrobial agents, and aeration. Among various methods, acidification to pH 5.5 acts as a benchmark since it achieves a reduction in CH 4 emission in the range of 95–99% and 65–99% from stored pig slurry and cattle slurry, respectively. Other chemical treatments such as antimicrobial agents and oxidants also reduce CH 4 in a wide range depending on efficiency and dosage. Further, the combination of acidification with physical and chemical treatments yields a cumulative or synergistic effect in reducing the CH 4 emission. This review identifies significant factors that influence the efficiency of the additives, which helps to mitigate CH 4 emissions from slurry storage. Based on mitigation efficiency, acidification is a good choice of technology to reduce CH 4 emissions from slurry storages. This technology would fit well with frequent removal of slurry from the barn to the outside storage in cold regions. • Acidification acts as a benchmark in mitigating methane emissions in stored slurry. • Efficacy of chemical additives to mitigate methane emissions varied with dosage. • Physical methods show reduced mitigation efficiency compared to acidification. • Biological methods result in other gaseous emissions affecting implementation. • Combination of chemical additives increased mitigation efficiency. [ABSTRACT FROM AUTHOR]

Assessments of the efficiency of grazing systems, in terms of productivity and ecological sustainability, are necessary in view of the increased demand for animal protein. In this study, the methane (CH4) emissions (sniffer methodology), dry matter (DM) yield, paddock chemical composition (AOAC and Van Soest methods), nutrient intake (dry matter, DMI; crude protein, CPI; metabolizable energy, MEI), daily milk yield (DMY), body condition score (BCS), and body weight (BW) of cattle, in intensive silvopastoral systems (ISPSs) and monoculture systems (MSs), in the tropics of Mexico were evaluated. In the ISPS, CH4 emissions (18% less) and DMY were lower than in the MS. Cows from MSs tend to disperse across higher values of CH4 emissions per kg of DMI, as well as higher milk production, while cows from the ISPS were dispersed over a higher intake (DMI, CPI, and MEI) and lower CH4 emissions. There were no differences between systems in paddock DM yield, chemical composition, cows' BCS, and BW, regardless of whether it was the dry (April to May) and rainy (September to October) season. Based on the results obtained in this study, ISPSs contribute to the mitigation of methane emissions in cattle; forage and animal production variables in both systems were similar, with a lower use of imported inputs in the ISPS. [ABSTRACT FROM AUTHOR]

Wetlands are the largest natural source of methane (CH4) to the atmosphere. The eddy covariance method provides robust measurements of net ecosystem exchange of CH4, but interpreting its spatiotemporal variations is challenging due to the co‐occurrence of CH4 production, oxidation, and transport dynamics. Here, we estimate these three processes using a data‐model fusion approach across 25 wetlands in temperate, boreal, and Arctic regions. Our data‐constrained model—iPEACE—reasonably reproduced CH4 emissions at 19 of the 25 sites with normalized root mean square error of 0.59, correlation coefficient of 0.82, and normalized standard deviation of 0.87. Among the three processes, CH4 production appeared to be the most important process, followed by oxidation in explaining inter‐site variations in CH4 emissions. Based on a sensitivity analysis, CH4 emissions were generally more sensitive to decreased water table than to increased gross primary productivity or soil temperature. For periods with leaf area index (LAI) of ≥20% of its annual peak, plant‐mediated transport appeared to be the major pathway for CH4 transport. Contributions from ebullition and diffusion were relatively high during low LAI (<20%) periods. The lag time between CH4 production and CH4 emissions tended to be short in fen sites (3 ± 2 days) and long in bog sites (13 ± 10 days). Based on a principal component analysis, we found that parameters for CH4 production, plant‐mediated transport, and diffusion through water explained 77% of the variance in the parameters across the 19 sites, highlighting the importance of these parameters for predicting wetland CH4 emissions across biomes. These processes and associated parameters for CH4 emissions among and within the wetlands provide useful insights for interpreting observed net CH4 fluxes, estimating sensitivities to biophysical variables, and modeling global CH4 fluxes. [ABSTRACT FROM AUTHOR]

The area studied covers unmined Pennsylvanian Ćwiklice and Dankowice coal deposits located in the southern part of the Upper Silesian Coal Basin, Poland. The geological structure of the area clearly affects the current distribution of methane. The content of methane is lower in coal seams lying within porous and permeable sandstones (Łaziska sandstones), whereas it is higher in seams that occur in sequences (Mudstone Series) where impermeable shales and mudstones occur. Due to the previous attempts to extract methane from boreholes, this area, characterized by a dense network of exploratory and prospecting drillings, is worth analyzing with regard to the conditions of methane occurrence in terms of extraction possibilities. Using contour maps, cross-sections and profiles, the variability of methane content and resources, as well as the moisture and ash content of coal seams, were analyzed. Methane content isolines are parallel to the boundary between the Cracow Sandstone Series and the Mudstone Series and to main faults. Coal moisture contents clearly reduce methane contents. A high methane content >8 m3/t coaldaf is typical for coal seams in which moisture contents do not exceed 5%. High- and medium-volatile bituminous coal in the area is characterized by low methane saturation, though saturation increases with depth. Coal permeability is variable (from 0.2 to more than 100 mD), but, below a depth of 1200 m, a clear trend of decreasing permeability with depth is evident. From the point of view of coalbed methane (CBM) recovery, relatively low coal permeabilities and methane saturation levels could make CBM output problematic in the studied area. Methane production will be more probable as a result of demethanation of the Dankowice 1 deposit, where coal mining is planned. This will result in the emission of methane into the atmosphere from ventilation shafts and methane drainage stations. Therefore, effective use of the gas captured by the methane drainage station is highly desirable for environmental and economic reasons. [ABSTRACT FROM AUTHOR]

Methane (CH 4) emissions generated from waste management facilities represent a serious global warming concern. The objective of this study was to monitor a fully instrumented biocover capable of abating fugitive CH 4 emissions from a closed landfill located at Kudjape, Saaremaa Island, Estonia. This investigation documented the alteration in the emission of CH 4 , carbon dioxide, and temperature fluctuation for a monitoring period of 10 years after the implementation of biocover. The fine fraction reclaimed from landfill mining along with natural mineral soil and sewage sludge compost in a proportion of 3:1:1 was used as a biocover substrate. CH 4 emissions were monitored at the surface and from three locations at a regular depth of 25 cm up to 2 m inside the biocover layer. The measurements recorded from three gas monitoring wells present different scenarios of a typical landfill due to the heterogenous nature of waste and non-homogeneous distribution of landfill gas load to the methane-oxidation layer, namely, a) desired situation where a permanent reduction in CH 4 concentration took place over time; b) hot-spot with an extremely high concentration of CH 4 albeit consistent decrease over the years; c) a location with minimal initial concentration of CH 4. Multivariate analysis showed that the CH 4 concentration dynamics and parameters reflecting the CH 4 oxidation process activity were different in biocover across the landfill. Based on data analysis results, the CH 4 oxidation process stabilizes in biocover in 5–6 years after establishing the cover. [ABSTRACT FROM AUTHOR]

We previously introduced the parametric variance Kalman filter (PvKF) assimilation as a cost-efficient system to estimate the dynamics of methane analysis concentrations. As an extension of our development, this study demonstrates the linking of PvKF to a 4D-Var inversion aiming to improve on methane emissions estimation in comparison with the traditional 4D-Var. Using the proposed assimilation–inversion framework, we revisit fundamental assumptions of the perfect and already optimal model state that is typically made in the 4D-Var inversion algorithm. In addition, the new system objectively accounts for error correlations and the evolution of analysis error variances, which are non-trivial or computationally prohibitive to maintain otherwise. We perform observing system simulation experiments (OSSEs) aiming to isolate and explore various effects of the assimilation analysis on the source inversion. The effect of the initial field of analysis, forecast of analysis error covariance, and model error is examined through modified 4D-Var cost functions, while different types of perturbations of the prior emissions are considered. Our results show that using PvKF optimal analysis instead of the model forecast to initialize the inversion improves posterior emissions estimate (~35% reduction in the normalized mean bias, NMB) across the domain. The propagation of analysis error variance using the PvKF formulation also tends to retain the effect of background correlation structures within the observation space and, thus, results in a more reliable estimate of the posterior emissions in most cases (~50% reduction in the normalized mean error, NME). Our sectoral analysis of four main emission categories indicates how the additional information of assimilation analysis enhances the constraints of each emissions sector. Lastly, we found that adding the PvKF optimal analysis field to the cost function benefits the 4D-Var inversion by reducing its computational time (~65%), while including only the error covariance in the cost function has a negligible impact on the inversion time (10–20% reduction). [ABSTRACT FROM AUTHOR]

To contribute to the reduction of methane emissions, using low-cost biochar as adsorbents for capturing and storing methane in oil and gas fields is investigated. This work presents results of methane adsorption on four biochars made from forestry wastes in comparison with the results of three commercial activated carbons. Although the adsorption capacity of the biochars is lower by over 50% than that of the activated carbons, thelow-cost and potential environmental benefits provide the incentive to the investigation. Moreover, it is shown that biochar can store more methane than vessels of compressed gas up to the pressure of 75 bar, suggesting the possibility of avoiding high-pressure gas compression and heavy vessels for cost savings in oil and gas fields. The thermodynamic and kinetic behaviors of the adsorption are studied and implications for the targeted application are discussed. Highlights: Biochar showed promise in adsorbing methane. Biochar could store more methane than gas cylinders up to 75 bar gas pressure. Biochar could contribute to the reduction of methane emissions in oil and gas fields. [ABSTRACT FROM AUTHOR]

Simple Summary: Herbs and spices have been used because they show antimicrobial properties. In this regard, garlic might modify rumen fermentation and potentially reduce methane. However, the effect of garlic inclusion on in vitro fermentation and methane production has been variable. The objective of this experiment was to evaluate the effect of different inclusion levels and processing methods of garlic on in vitro fermentation and methane production using a corn silage-based substrate. The initial condition of the garlic (intact or smashed), drying process (freeze-dried, oven-dried, or autoclaved), and garlic proportion in the diet (0, 2.5, and 5%) were evaluated in vitro. Thus, three different incubations were conducted, and in vitro fermentation and methane emissions were evaluated after 24 h of incubation. Neither the initial condition nor the drying process of garlic modified the fermentation and methane production. However, increasing garlic inclusions increased in vitro digestibility and the concentration of volatile fatty acids and ammonia and modified the proportion of acetate and propionate, suggesting greater in vitro fermentation. Methane was not affected when garlic was increased. Further work should be conducted in vivo to confirm the fermentation improvement when garlic is included in a corn silage-based diet. Garlic (Allium sativum) contains secondary compounds that are known to modify rumen fermentation parameters and decrease methane (CH4) emissions. The objective was to evaluate the effects of increasing the inclusion levels and processing methods of garlic on in vitro fermentation and CH4 production. Treatments were arranged in a randomized complete block design with a 2 × 3 × 2 + 1 factorial arrangement, where the main factors were the initial condition of garlic (intact or smashed), drying process (freeze-dried, oven-dried, or autoclaved), and garlic proportion in the diet (2.5 and 5%) and one control (without garlic supplementation). Incubations were conducted using corn silage and cotton-gin trash (80:20, respectively) as basal substrates on three different days. Final pH, the concentration of volatile fatty acids (VFA) and ammonia nitrogen (NH3-N), in vitro organic matter digestibility (IVOMD), total gas production, and CH4 concentration were determined after 24 h. Initial garlic condition or drying processing neither modify (p > 0.05) the in vitro fermentation nor the CH4 production. However, increasing garlic inclusion linearly increased (p < 0.05) IVOMD, the concentration of the total VFA, and the proportion of propionate. Also, the concentration of NH3-N and the proportion of acetate increased quadratically (p < 0.05) with greater garlic inclusions. Finally, garlic inclusion did not affect (p > 0.05) gas and CH4 production. In conclusion, increasing garlic levels, but not the processing methods, improved in vitro fermentation but did not modify CH4 emissions under in vitro conditions. [ABSTRACT FROM AUTHOR]

Peatlands play a crucial role in mediating the emissions of methane through active biogeochemical cycling of accumulated carbon driven by methane-metabolizing microorganisms; meanwhile, they serve as vital archives of atmospheric heavy metal deposition. Despite many edaphic factors confirmed as determinants to modulate the structure of methanotrophic and methanogenic communities, recognition of interactions among them is limited. In this study, peat soils were collected from Dajiuhu peatland to assess the presence of heavy metals, and methanotrophs and methanogens were investigated via high-throughput sequencing for functional genes mcrA and pmoA. Further analyses of the correlations between methane-related functional groups were conducted. The results demonstrated that both methane-metabolizing microorganisms and heavy metals have prominent vertical heterogeneity upward and downward along the depth of 20 cm. Pb, Cd, and Hg strongly correlated with methanotrophs and methanogens across all seasons and depths, serving as forceful factors in structural variations of methanogenic and methanotrophic communities. Particularly, Pb, Cd, and Hg were identified as excessive elements in Dajiuhu peatland. Furthermore, seasonal variations of networks among methane-related functional groups and environmental factors significantly affected the changes of methane fluxes across different seasons. Concretely, the complicated interactions were detrimental to methane emissions in the Dajiuhu peatland, leading to the minimum methane emissions in winter. Our study identified the key heavy metals affecting the composition of methane-metabolizing microorganisms and linkages between seasonal variations of methane emissions and interaction among heavy metals and methane-metabolizing microorganisms, which provided much new reference and theoretical basis for integrated management of natural peatlands. [ABSTRACT FROM AUTHOR]

With the growth of industries and population, the need for energy consumption has increased, which has inevitably increased greenhouse gas emissions. Further use of fossil fuel for energy consumption exacerbates the situation making it one of the major issues for climate change. China, India, the USA, and Russia are the world's leading countries in energy consumption and emissions and are responsible for climate change. These countries account for 54% of carbon dioxide (CO2) emissions in the global environment. This paper investigates the energy consumption of China, India, the USA, and Russia and its trend in greenhouse gas emissions. Using four available datasets from 1980 to 2018 for China, India, USA, and 1992 to 2018 for Russia, we employed three advanced machine learning algorithms (support vector machine, artificial neural network, and long-short term memory) and verified its predicted capability with actual greenhouse gas emissions. The obtained results were evaluated with three statistical metrics (route mean square, mean absolute percentage error, and mean bias error). The predicted results with three machine learning algorithms were very close to actual greenhouse gas emissions. Besides, we forecasted the trend of greenhouse gas emissions in these countries from 2019 to 2023. The forecasted results with the long-short term memory model confirm an increase in CO2, methane, and Nitrous oxide (N2O) emissions in the case of China and India; in contrast, the results indicate a slowdown of CO2, methane, and N2O emissions in the USA and Russia. [ABSTRACT FROM AUTHOR]

Ambitious methane (CH4) emissions mitigation represents one of the most effective opportunities to slow the rate of global warming over the next decades. The oil and gas (O&G) sector is a significant source of methane emissions, with technically feasible and cost-effective emission mitigation options. Romania, a key O&G producer within the EU, with one of the highest reported annual CH4 emissions from the energy sector (Greenhouse Gas Inventory Data - Comparison by Category, 2022), can play an important role towards the EU's emission reduction targets. In this study, we quantify CH4 emissions from onshore oil production sites in Romania at source and facility level using a combination of ground-based measurement techniques. Measured emissions were characterised by heavily skewed distributions, with 10 % of the sites accounting for more than 70 % of total emissions. Integrating the results from all site-level quantifications with different approaches, we derive a central estimate of 5.4 kg h-1 site-1 of CH4 (3.6 - 8.4, 95 % confidence interval) for oil production sites. This estimate represents one of the highest when compared to measurement-based estimates of similar facilities from other production regions. Based on our results, we estimate a total of 120 ktons CH4 yr-1 (range: 79 - 180 ktons yr-1) from oil wells in our studied areas in Romania. This is approximately 2.5 times higher than the total reported emissions from the Romanian oil production sector for 2020. Based on the source level characterization, up to three quarters of the detected emissions from oil production sites are related to operational venting. Our results suggest that O&G production infrastructure in Romania holds a massive mitigation potential, specifically by implementing measures to capture the gas and minimize operational venting and leaks. [ABSTRACT FROM AUTHOR]

Simple Summary: Milk fatty acid composition has gained the interest of both manufacturers and consumers during recent years. The present paper aimed to perform an analysis of fatty acid composition in cow's milk in relation to the type of ration, parity, lactation phase and season. Milk fatty acid profile varies significantly through the studied effects. According to different studies, fatty acid profile is associated with animal health, organoleptic properties of milk or even methane production, which highlights the importance of studying factors that affect its variation. Milk fatty acid composition has gained the interest of both manufacturers and consumers during recent years. The present paper aimed to perform an analysis of C14:0, C16:0, C18:0, C18:1, saturated (SFA), monounsaturated (MUFA), polyunsaturated (PUFA) and short chain fatty acid (SCFA) concentration in cow's milk in relation to the type of ration, parity, lactation phase and season. Cows' milk from animals being fed total mixed rations, including corn silage, had higher C14:0, C16:0 and SFA concentrations than those being fed pasture-based rations but lower concentrations of C18:0 and PUFA. Comparing to 1st parity cows, 2nd and 3rd parity animals had higher SFA and SCFA concentrations in milk. With respect to spring, C14:0, C16:0 and SFA concentrations increased in summer, autumn and winter while MUFA, PUFA and SCFA concentrations decreased. Considering the lactation phase, C14:0, C16:0 and SFA concentrations decreased in fresh cows with ketosis comparing to healthy fresh cows and increased in peak, mid and late lactation. C18:0, C18:1 and MUFA follow the opposite trend. The milk fatty acid profile varies significantly through the studied effects. The fact that the fatty acid profile is associated with animal health, organoleptic properties of milk or even methane production highlights the importance of studying factors that affect its variation. [ABSTRACT FROM AUTHOR]

Climate change has become a significant concern for developing countries given the risk that it poses to energy and food independence, and to general productivity. Despite having an energy system with low carbon intensity when compared to other Latin American countries, Colombia is already facing climate change impacts and requires urgent efforts to mitigate them. As a developing country, the challenge is bigger as policies for economic growth should be in line with the global commitment of reducing greenhouse gas emissions. With the aim of contributing to the design of climate policies by using data driven methodologies and scientific evidence, this study assesses the impact of economic development on the environment by examining the validity of the environmental Kuznets curve hypothesis for Colombia. Statistically validated and stable autoregressive distributed lag models are estimated for three different environmental indicators: carbon dioxide emissions, methane emissions, and the ecological footprint. Moreover, the effects of other variables such as urbanization, foreign direct investment, the value added by the agricultural and industrial sectors, and energy use are analyzed with dynamic simulations. To the best of our knowledge, there are no reports of EKC estimation using these variables in statistically validated models for Colombia; thus, this paper adds to the scientific evidence of the EKC hypothesis in developing countries. Empirical evidence supports a long-run equilibrium relationship among investigated variables and the existence of an inverted U-shaped EKC relationship between gross domestic product (GDP) and methane emissions, and GDP and the ecological footprint. The results of this paper show that shifting to renewable energy sources and leveraging the use of cleaner technologies in agricultural and industrial sectors are key factors for economic growth without harming the environment, which has important scientific value because of its evidence-based approach for public policy making in developing countries, particularly Colombia. [ABSTRACT FROM AUTHOR]

The energy sector is in the spotlight today for its contribution to global warming and its dependence on global geopolitics. Even though many countries have reduced their use of coal, the COVID-19 crisis, the drop in temperatures in Central Asia, and the war between Russia and Ukraine have shown that coal continues to play an important role in this sector today. As long as we continue to depend energetically on coal, it is necessary to create the basis for the successful extraction and industrial use of coal mine methane (CMM), for example, as an unconventional energy resource. Early degassing technology is a technique that allows for the extraction of the methane contained within the coal seams. The application of this technology would reduce emissions, improve mine safety, and even increase their profitability. However, this technology has been understudied and is still not implemented on a large scale today. Moreover, mines with this technology generally burn the extracted methane in flares, losing a potential unconventional fuel. This study, therefore, presents different scenarios of the use of coalbed methane (CBM), with the aim of generating an impact on pollutant emissions from coal mines. To this end, a model has been designed to evaluate the economic efficiency of degasification. In addition, an emissions analysis was carried out. The results showed that the use of this technology has a negative impact on the economy of mines, which can be completely reversed with the use of CBM as fuel. Furthermore, it is observed that degasification, in addition to reducing the number of accidents in coal mining, reduces emissions by 30–40%. [ABSTRACT FROM AUTHOR]

Methane (CH4) is the second-largest greenhouse gas emitted by human activity and natural sources after carbon dioxide (CO2). Its relatively short lifetime in the atmosphere (about 12 years) means that we can mitigate the human impacts of climate change in a relatively short period of time by reducing CH4 emissions. The creation of CH4 emissions management policies can be based on the distribution maps of surface CH4 concentration that are in large-scale and at high-resolution. The estimate of CH4 emissions with broad coverage are provided by currently extensively used satellite data supplemented with data from model simulations. However, it is at low spatial resolution. In this paper, through the combination of atmospheric CH4 observations from the TROPOMI sensor and wind data from the ECMWF global reanalysis, a straightforward divergence method is proposed to estimate the surface CH4 emissions in China from March 2019 to September 2022 at a resolution of 7 km × 7 km. This method was compared with the average annual CH4 emissions of Emissions Database for Global Atmospheric Research (EDGARv7.0), and the Root Mean Square Error (RMSE) is 2.53 kg/km2/h and within error envelop (EE) is 72.93%, which represents the proportion of reliable values under certain uncertain conditions. We estimated that the average annual CH4 emissions in China from 2019 to 2022 is 81 Tg, with the lowest emissions in 2021 (75 Tg) due to the impact of COVID-19. In 2021, the largest anthropogenic emissions in China are from agriculture, energy activities and livestock, accounting for 28% (20.8 Tg), 25% (18.9 Tg) and 19% (13.9 Tg) of total emissions, respectively, while wetlands, as the largest natural source, produce 14% (10.5 Tg) of CH4 emissions. [ABSTRACT FROM AUTHOR]

Simple Summary: Developing alternative antibiotics is crucial for sustainable animal production worldwide. Bacteriocin has been considered a potential alternative to antibiotics due to its lack of drug resistance, lack of residues, and environmental friendliness. In this study, we investigated the effects of inoculating two bacteriocin-producing strains, Lactiplantibacillus plantarum ATCC14917 and LP1-4, at ensiling on the in vitro ruminal fermentation characteristics and methane emissions of alfalfa silage with two different dry matter contents (355 g/kg fresh weight, moderate dry-matter content; 428 g/kg fresh weight, high dry-matter content). The results showed that inoculating with ATCC14917 and LP1-4 at ensiling reduced in vitro rumen methane production and enhanced the dry matter digestibility of ensiled alfalfa. Therefore, bacteriocin-producing L. plantarum ATCC14917 and LP1-4 inoculants can potentially mitigate ruminal methane emissions but without an adverse effect on the rumen fermentation of the inoculated alfalfa silage. The objective of this study was to investigate the effects of inoculating two bacteriocin-producing strains, Lactiplantibacillus plantarum ATCC14917 and LP1-4, at ensiling on the in vitro ruminal fermentation characteristics and methane production of alfalfa silage with two dry matter (DM)contents. Before ensiling, fresh alfalfa was wilted to a moderate DM content (355 g/kg) and a high DM content (428 g/kg). The wilted alfalfa was treated with (1) distilled water (control), (2) commercial strain L. plantarum MTD/1 (MTD/1), (3) bacteriocin-producing L. plantarum ATCC14917 (ATCC14917), and (4) a bacteriocin-like substance producing L. plantarum LP1-4 (LP1-4) at 1 × 105 colony forming units (CFU)/g fresh weight. After 90 d of ensiling, the silages were used for in vitro rumen fermentation. Inoculation with the two bacteriocin-producing strains at ensiling remarkably reduced (p < 0.05) in vitro ruminal CH4 production and enhanced DM digestibility compared with the control group regardless of DM content. For silages with high DM content, inoculation with the bacteriocin-producing strains even increased (p < 0.05) in vitro ruminal total volatile fatty acid production. Therefore, the bacteriocin-producing inoculants have a great potential to mitigate ruminal methane emission but without an adverse effect on rumen fermentation of the inoculated alfalfa silage. [ABSTRACT FROM AUTHOR]

Rice paddies are one of the main sources of anthropogenic terrestrial CH4. In recent decades, the substitution of single-cropping rice (SCR) for double-crop rice (DCR) has become more common in southern China. However, the concomitant impacts on CH4 emissions have not been quantified. We incorporated high-resolution rice cropping system maps into the CH4MOD model to calculate changes in CH4 emissions in southern China due to DCR conversion to SCR over the period 1990 to 2015. We find that a total planting area of 253.64 ×104 ha was converted from DCR to SCR. This conversion resulted in a 451.94 Gg reduction in CH4 emissions, accounting for 8.4% of CH4 emissions from paddies in China in 2015. The largest reduction was in the Middle–Lower Yangtze plain with high labor pressures. As urbanization continues, we project that the total CH4 emissions have the potential to decrease by between 17.1% and 9.2% under DCR conversion to SCR in southern China in the extreme and most likely scenarios, respectively. As farmers voluntarily move to SCR in response to labor scarcity, making full use of the land-use change trend of DCR to SCR may be an opportunity to reduce agricultural methane emissions, which is important for achieving Sustainable Development Goals (SDGs) and should be given more attention. [ABSTRACT FROM AUTHOR]

We present results from a field study monitoring methane and volatile organic compound emissions near an unconventional oil well development in Northern Colorado from September 2019 to May 2020 using a mid-infrared dual-comb spectrometer. This instrument allowed quantification of methane, ethane, and propane in a single measurement with high time resolution and integrated path sampling. Using ethane and propane as tracer gases for methane from oil and gas activity, we observed emissions during the drilling, hydraulic fracturing, millout, and flowback phases of well development. Large emissions were seen in drilling and millout phases and emissions decreased to background levels during the flowback phase. Ethane/methane and propane/methane ratios varied widely throughout the observations.

Greenhouse gas emissions are related to non-renewable sources. For this reason, the methodological guide for the estimation of methane and carbon dioxide emissions in flooded lands was published in 2006 by the Intergovernmental Panel on Climate Change. Since 2016, several studies have been carried out in temperate and tropical zones reservoirs. Costa Rica is a Central American country known for its large hydroelectric resources and its highly renewable electricity generation matrix. This work represents the first study for 11 of 24 hydroelectric plants managed by the Costa Rican Electricity Institute. Methane emissions, energy density and emission factors for electricity generation are determined. Furthermore, a static mathematical model is used to determine these factors with little input data. It is estimated that the greatest contribution to methane emissions corresponds to the Arenal reservoir, which has the largest surface area and the lowest energy density.

Methane (CH _4 ) emissions from human activities are a major cause of global warming, necessitating effective mitigation strategies. In particular, the palm oil industry generates palm oil mill (POM) effluent, which continuously emits methane into the atmosphere. Satellites are becoming a powerful tool to detect and quantify methane emissions, but there is no evidence of their ability to monitor those from POM ponds. In this work, we have tested the potential of methane-capable satellite instruments to detect and quantify emissions from these ponds. We have focused on the satellite missions with the highest sensitivity to methane emissions, namely the GHGSat commercial constellation and the PRISMA, EnMAP, and EMIT imaging spectroscopy missions. We have also tested the AVIRIS-NG airborne imaging spectrometer. We report three methane plumes from POMs in Indonesia with GHGSat and two in Colombia with AVIRIS-NG. In the cases of EnMAP, PRISMA and EMIT, we observed substantial methane concentration enhancements over several ponds in Indonesia, Malaysia, and Colombia. It remains unclear whether they are due to retrieval artifacts caused by the particular albedo of the ponds, although the low spatial correlation between those enhancements and the ponds suggests that at least a fraction of the enhancements is caused by real emissions. By leveraging advanced imaging techniques and satellite data, this research contributes to progressing strategies to address new methane emissions sources with high mitigation potential, providing a first step toward the satellite-based monitoring of methane emissions from POMs.

Research on methane (CH _4 ) emissions from the oil and gas (O&G) industry informs policies, regulations, and international initiatives that target reductions. However, there has been little integration and synthesis of the literature to document the state of knowledge, identify gaps, and determine key insights that can guide research priorities and mitigation. To address this, we performed a scoping review of 237 English-language peer-reviewed articles on CH _4 emissions from onshore O&G sources, charting data on five research themes: publication trends, geography, measurement levels and methods, emissions sources, and emissions rates. Almost all articles (98%) were published between 2012 and 2022 with an increasing publication rate, indicating a nascent and evolving understanding of the science. Most articles (72%) focused on CH _4 emissions from the U.S. O&G industry and were written by U.S.-based authors (69%), while other major O&G-producing countries like Saudi Arabia, Russia, and China were under-represented. Upstream was the most frequently studied supply chain segment, where U.S.-focused articles accounted for 75% of the research. Nearly half the articles (43%) included in the review reported site-level measurements, limiting the identification of equipment- and component-level emissions sources and root cause. Articles that measured or identified equipment-level sources (18%) noted high emissions from tanks, unlit flares, and compressors. The most common stand-off measurement platforms were vehicles and aircraft, while the use of satellites increased in articles published since 2019. Reported emissions profiles were consistently heavy-tailed and indicate method-based and geographic differences in magnitude and skew. All articles (n = 26) that compared inventory- to measurement-based estimates of emissions found large discrepancies in that inventories under-estimated the latter by a factor of 1.2–10 times. We recommend future research focus on: (i) field-based emissions studies for under-represented regions and source categories, (ii) identifying root causes and linking measurements to mitigation, and (iii) multi-level measurement integration.

Considering the significant role of global methane emissions in the Earth’s radiative budget, global or regionally persistent increasing trends in its emission are of great concern. Understanding the regional contributions of various emissions sectors to the growth rate thus has policy relevance. We used a high-resolution global methane inverse model to independently optimize sectoral emissions using GOSAT and ground-based observations for 2009–2020. Annual emission trends were calculated for top-emitting countries, and the sectoral contributions to the total anthropogenic trend were studied. Global total posterior emissions show a growth rate of 2.6 Tg yr ^−2 ( p < 0.05), with significant contributions from waste (1.1 Tg yr ^−2 ) and agriculture (0.9 Tg yr ^−2 ). Country-level aggregated sectoral emissions showed statistically significant ( p < 0.1) trends in total posterior emissions for China (0.56 Tg yr ^−2 ), India (0.22 Tg yr ^−2 ), United States (0.65 Tg yr ^−2 ), Pakistan (0.22 Tg yr ^−2 ) and Indonesia (0.28 Tg yr ^−2 ) among the top methane emitters. Emission sectors contributing to the above country-level emission trend are, China (waste 0.35; oil and gas 0.07 Tg yr ^−2 ), India (agriculture 0.09; waste 0.11 Tg yr ^−2 ), United States (oil and gas 1.0; agriculture 0.07; coal −0.15 Tg yr ^−2 ), Brazil (waste 0.09; agriculture 0.08 Tg yr ^−2 ), Russia (waste 0.04; biomass burning 0.15; coal 0.11; oil and gas −0.42 Tg yr ^−2 ), Indonesia (coal 0.28 Tg yr ^−2 ), Canada (oil and gas 0.08 Tg yr ^−2 ), Pakistan (agriculture 0.15; waste 0.03 Tg yr ^−2 ) and Mexico (waste 0.04 Tg yr ^−2 ). Additionally, our analysis showed that methane emissions from wetlands in Russia (0.24 Tg yr ^−2 ) and central African countries such as Congo (0.09 Tg yr ^−2 ), etc. have a positive trend with a considerably large increase after 2017, whereas Bolivia (−0.09 Tg yr ^−2 ) have a declining trend. Our results reveal some key emission sectors to be targeted on a national level for designing methane emission mitigation efforts.

The study presents the first results from the multi-platform observational campaign carried out at the Mukhrino peatland in June 2022. The focus of the study is the quantification of spatial contrasts of the surface heat budget terms and methane emissions across the peatland, which arise due to the presence of microlandscape heterogeneities. It is found that surface temperature contrasts across the peatland exceeded 10 °C for clear-sky conditions both during day and night. Diurnal variation of surface temperature was strongest over ridges and drier hollows and was smallest over the waterlogged hollows and shallow lakes. This resulted in strong spatial variations of sensible heat flux (H) and Bowen ratio, while the latent heat varied much less. During the clear-sky days, H over ryam exceeded the one over the waterlogged hollow by more than a factor of two. The Bowen ratio amounted to about unity over ryam, which is similar to values over forests. Methane emissions estimated using the static-chamber method also strongly varied between various microlandscapes, being largest at a hollow within a ridge-hollow complex and smallest at a ridge. A strong nocturnal increase in methane mixing ratio was observed and was used in the framework of the atmospheric boundary layer budget method to estimate nocturnal methane emissions, which were found to be in the same order of magnitude as daytime emissions. Finally, the directions for further research are outlined, including the verification of flux-aggregation techniques, parameterizations of surface roughness and turbulent exchange, and land-surface model evaluation and development.