Mitigation Of Methane Emissions Research Articles

Analysis of Determinants of Envitonmrntal Awareness Among Beef Consumers

Objective: The objective of this study is to analyze the determinants of environmental awareness among beef consumers in Brazil, focusing on the acceptance of the Carbon Neutral Beef label. Theoretical Framework: The literature review covers the growing consumer concern for sustainability and animal welfare. The concept of Carbon Neutral Beef, developed by EMBRAPA, is discussed as a strategy to mitigate methane emissions in livestock production. Previous studies indicate that factors such as education, income, and environmental awareness influence consumers' willingness to pay more for sustainable beef. Method: The research employed a quantitative approach, applying a survey to beef consumers in Brazil. A total of 256 completed questionnaires were analyzed, and the data were processed using Confirmatory Factor Analysis (CFA) and Structural Equation Modeling (SEM). The Tobit econometric model was employed to identify the determinants of consumers' environmental awareness. Results and Discussion: The results show that most consumers prefer beef with sustainability attributes, influenced by income, education, and concern for the environment. The Tobit model indicated that variables such as educational level and household income are significant determinants of environmental awareness. These consumers are willing to pay more for beef that respects the environment and animal welfare. Research Implications: The study provides insights for the beef industry on the importance of adopting sustainable production practices. Originality/Value: The study provides insights for the beef industry on the importance of adopting sustainable production practices.

Influence of the Thickness of Freezing of the Soil Surface and Snow Cover on Methane Emissions during Freezing of Seasonal Permafrost

Methane, a type of greenhouse gas, poses considerable concern for humans. This study uses field experiments and satellite measurements to explore methane emission mechanisms during the freezing of seasonal permafrost and the contributing factors. In the transitional seasons of autumn and winter, as soil begins to freeze, methane emissions surge dramatically in a brief period. During this phase, the emissions peak, enabling the soil to accumulate over 9000 mg/m3 of methane rapidly. Snow cover also plays a crucial role in mitigating methane emissions. The porous nature of a sufficiently thick snow cover aids in temporarily trapping methane through a stratified blocking process, effectively matching the inhibitory capability of unfrozen soil. In comparison to unfrozen soil (54–237 mg/m3), snow cover can suppress methane emissions up to 20 times more, reducing emissions by as much as 3399 mg/m3.

The Effect of Adding Green and Black Tea Waste Extracts on Rumen Fermentation Parameters by In Vitro Techniques

The increase in global temperatures over the past few decades due to greenhouse gas emissions has raised concerns and necessitated further research in climate change mitigation and adaptation. Methane is a prominent greenhouse gas that significantly contributes to climate change, with a substantial amount generated through fermentation processes occurring in the rumen of ruminant animals. The potential of plant secondary metabolites, especially those derived from tannin-rich plants, warrants investigation to modify rumen fermentation and mitigate methane emissions in livestock diets. The objective of this study was to assess the impact of extracts obtained from green and black tea waste on rumen fermentation dynamics and gas (methane) production, utilizing in vitro methods. For this purpose, rumen fluid was collected from two fistulated sheep and subjected to three treatments: (1) a basal diet (control), (2) a basal diet + green tea waste extract (5% of dry matter), (3) a basal diet + black tea waste extract (5% of dry matter). The study assessed the effects of incorporating extracts from green and black tea waste on various parameters, including digestibility, protozoa population, ammonia nitrogen levels, volatile fatty acids, and methane gas production following a 24-h incubation period. Statistical analysis of the data was conducted using SAS software within a completely randomized design framework. The findings indicated that the addition of green and black tea waste extracts significantly decreased methane gas production (p < 0.05), protozoa count (p < 0.05), and ammonia nitrogen concentrations in rumen fluid (p < 0.05) when compared to the control group. The addition of green and black tea waste extracts has significantly altered the concentration of VFAs in rumen fluid (p < 0.05). Specifically, the addition of green tea waste extract has led to a highly significant reduction in acetic acid, (p < 0.01) and the addition of both extracts has resulted in a significant increase in propionic acid (p < 0.05). Consequently, the results suggest that the inclusion of green and black tea waste extracts in livestock diets may effectively mitigate methane emissions in the rumen, thereby reducing feed costs and reducing environmental pollution.

Online monitoring of methane transfer rates unveils nitrogen fixation dynamics in Methylococcus capsulatus.

This study explores methane utilization by the methanotrophic microorganism Methylococcus capsulatus (Bath) for biomass production, presenting a promising approach to mitigate methane emissions and foster the development sustainable biomaterials. Traditional screening methods for gas cultivations involve either serum flasks without online monitoring or costly, low-throughput fermenters. To address these limitations, the Respiration Activity MOnitoring System was augmented with methane sensors for real-time methane transfer rate (MTR) monitoring in shake flasks. Utilizing online monitoring of the MTR in shake flasks results in enhanced throughput and cost-effectiveness for cultivating M. capsulatus. Simultaneous monitoring of transfer rates for oxygen, methane, and carbon dioxide was conducted in up to eight shake flasks, ensuring the success of the cultivation process. Alterations in methane-to-oxygen transfer rate ratios and carbon fixation rates reveal the impact of transfer limitations on microbial growth. Detection of gas transfer limitations, exploration of process parameter influences, and investigations of medium components were enabled by the introduced method. Optimal nitrogen concentrations could be determined to ensure optimal growth. This streamlined approach accelerates the screening process, offering efficient investigations into metabolic effects, limitations, and parameter influences in gas fermentations without the need for elaborate offline sampling, significantly reducing costs and enhanced reproducibility.

Differentiated strategies for synergistic mitigation of ammonia and methane emissions from agricultural cropping systems in China

Ammonia (NH3) and methane (CH4) emissions from agricultural cropping systems in China have substantially impacted environmental quality and climate change, which become the key sector for synergizing pollution control and carbon reduction. However, the experiences of synergistic NH3 and CH4 emission governance at fine scales in this sector are still lacking. Here, we estimated NH3 and CH4 emissions from agricultural cropping systems in China in 2019 and identified regional characteristics of these emissions using advanced spatial analysis techniques. Subsequently, we developed an innovative synergistic mitigation zoning identification method to establish targeted and spatially differentiated reduction measures, addressing a critical gap in mitigation strategies for agricultural cropping systems in China. The results showed that NH3 and CH4 emissions from the three most important crops were 3.04 Tg N yr-1 and 8.13 Tg C yr-1, respectively. NH3 and CH4 emissions exhibited the highest values in Eastern China, but the highest emission densities of NH3 (49.8 kg N ha-1 yr-1) and CH4 (394 kg C ha-1 yr-1) were observed in Northwest and South China, respectively. Further, bivariate local indicators of spatial association (LISA) maps revealed that the middle and lower reaches of the Yangtze River were hotspots for simultaneous high emissions of NH3 and CH4. Finally, based on the identified eight categories of zones, region-specific mitigation measures were proposed, including improved fertilization practices, irrigation methods, and straw management. These targeted, spatially differentiated mitigation strategies provide a reference framework and feasible approach for synergistic pollution control and carbon reduction in China's agricultural sector.

President’s Column: SPE@Energy Transition

_ Editor’s Note: This is a summary of the October episode of the President’s vodcast. We encourage you to watch the episode to see the full conversation. In this vodcast, Houzé discusses his views on SPE and the energy transition. _ Last month, I presented a to-do list with five main topics: energy transition, finances, governance, membership, and quality. This month, I will discuss the first topic, energy transition. 1. SPE’s polarized views on energy transition As I mentioned last month, there are significant geographic contrasts within our industry and SPE regarding how the energy transition is perceived and developed. In some SPE venues and regions, energy transition is the dominant, if not the only subject, and the P in SPE is indeed a major obstacle for support, even from our traditional stakeholders. In other regions, stakeholders acknowledge the energy transition, but the situation is essentially business as usual. Major investments are underway to sustain production at current levels or even increase hydrocarbon production to record levels, with development plans spanning over several decades. Even in these regions, most, if not all, new projects are designed from the outset to have a low carbon footprint, including mitigating methane emissions. Energy transition is somehow factored in. So, there are very different narratives, which are reflected in a polite but real polarization within SPE—geographic and, occasionally, demographic. As an SPE President visiting many sections and stakeholders, the contrast is often striking. But we are engineers operating on the same planet, and there must be a single energy narrative that accounts for the reality of the energy transition in whatever form or definition this takes, locally or globally. To do this, we can try to assess in the most objective way possible how our license to operate may evolve in the short to medium term. I will start with something you may have seen many times: the three main energy transition scenarios presented by the International Energy Agency (IEA). These scenarios predict the climate impact by the end of the century based on current and predicted variables, including consumption, population, economics, and technologies. These are just models, but as the statistician George Box pointed out: “All models are wrong, but some are useful.” These IEA models are definitely useful (Fig. 1).

Satellite‐Based Surveys Reveal Substantial Methane Point‐Source Emissions in Major Oil & Gas Basins of North America During 2022–2023

AbstractUtilizing imaging spectroscopy technology to identify methane super‐emitters plays a vital role in mitigating methane emissions in the Oil & Gas (O&G) sector. While earlier research has uncovered significant point‐source methane emissions from O&G production in the US and Canada, which are key regions with large methane emissions, a comprehensive post‐COVID‐19 survey has been notably absent. Here, we perform a detailed survey of methane super‐emitters across multiple basins of North America (Marcellus Shale, Haynesville/Bossier Shale, Permian Basin and Montney Shale) using the new Chinese Gaofen5‐01A/02 (GF5‐01A/02) satellite measurements during 2022–2023. We detect 139 individual methane plumes emanating from 122 point sources, with flux rates ranging from 519 to 16,071 kg hr−1. These emissions exhibit a highly skewed and heavy‐tailed distribution, constituting approximately 23% of the flux inversion with TROPOMI in the sample region, with a range of 13%–40%. Moreover, we observe a 66.7% reduction in methane emissions in Permian Basin during COVID‐19, followed by fluctuations until spring 2023. By summer 2023, methane emissions rebound to twice their previous magnitude (1.68 ± 0.58 Tg a−1). Using these point‐source surveys, we further quantify a regional methane emission of 2.69 ± 0.86 Tg a−1 in Permian Basin. This estimation closely aligns with top‐down inversions (2.22 ± 0.40 Tg a−1) from TROPOMI. The upscale estimation underscores the effectiveness of high‐resolution remote sensing measurements in improving bottom‐up emissions inventories and refining regional methane emission assessments. Our results highlight the potential climate benefits derived from regular monitoring and specific remediation efforts focused on relatively few strong point‐source emissions.

Assessing methane emissions and multiple benefits of mitigation through coupled crop-livestock system

A potent greenhouse gas, methane, contributes to global warming, primarily from livestock activities such as fermentation and manure management. Recognized as a low-carbon agricultural approach, coupled crop–livestock systems are gaining increasing attention for mitigating methane emissions and environmental impacts. This study focused on Inner Mongolia to estimate its methane reduction potential. We calculated methane emissions using a combination of bottom-up and top-down methods, analyzed livestock distribution, estimated manure production, and assessed the potential of manure to replace chemical fertilizers based on crop nutrient demand. Livestock emissions totaled approximately 769.0 kt. Adopting crop–livestock coupling could reduce emissions by 30.1 kt. Returning manure as fertilizer can cover 57.7% of cropland, saving 57% nitrogen and 20% phosphorus fertilizers, thus reducing costs by $296.3 million. The study has provided a scientific reference for developing methane emission reduction strategies, which can shed light on tackling climate change in the context of agricultural systems.

Tidal control on aerobic methane oxidation and mitigation of methane emissions from coastal mangrove sediments

Mangrove forests represent important sources of methane, partly thwarting their ecosystem function as an efficient atmospheric carbon dioxide sink. Many studies have focused on the spatial and temporal variability of methane emissions from mangrove ecosystems, yet little is known about the microbial and physical controls on the release of biogenic methane from tidally influenced mangrove sediments. Here, we show that aerobic methane oxidation is a key microbial process that effectively reduces methane emissions from mangrove sediments. We further demonstrate clear links between the tidal cycle and fluctuations in methane fluxes, with contrasting methane emission rates under different tidal amplitudes. Our data suggest that both the microbial methane oxidation activity and pressure-induced advective transport modulated methane fluxes in the mangrove sediments. Methane oxidation activity is limited by the availability of oxygen in the surface sediments, which in turn is controlled by tidal dynamics, further highlighting the interactive physico-biogeochemical controls on biological methane fluxes. Although we found some molecular evidence for anaerobic methanotrophs in the deeper sediments, anaerobic methane oxidation seems to play only a minor role in the mangrove sediments, with potential rates being two orders of magnitude lower than those of aerobic methane oxidation. Our findings confirmed the importance of surface sediments as biological barrier for methane. Specifically, when sediments were exposed to the air, methane consumption increased by ∼227%, and the methane flux was reduced by ∼62%, compared to inundated conditions. Our data demonstrate how tides can orchestrate the daily rhythm of methane consumption and production within mangrove sediments, thus explaining the temporal variability of methane emissions in the tidally influenced coastal mangrove systems.

130 Meta-analysis of the impact of Quebracho and Chestnut tannin extract supplementation on the growth performance in growing and finishing beef cattle

Abstract Integrating tannin extracts (TE) into the diet of growing and finishing beef cattle has shown promise in optimizing protein utilization while potentially mitigating methane emissions. Despite these potential benefits, there is a notable gap in a comprehensive analysis of the influence of TE on growth rate. This study addressed this gap by collecting data on the supplementation of a blend of condensed (from Schinopsis spp.) and hydrolyzable (from Castanea spp.) tannins, which has about 70% total tannins, and its impact on critical metrics, such as average daily gain (ADG, kg/d), dry matter intake (DMI, kg/d), and feed efficiency ratio (FER, g/kg). Our objective was to conduct meta-regression analyses to understand better the nuanced effects of condensed tannin supplementation on the overall performance of beef cattle during the critical stages of growth and finishing. The dataset was constructed by collecting published studies that reported in vivo experimental data on growing and finishing beef cattle supplemented with different levels of TE. It contained 132 observations from 35 publications. The meta-analysis was conducted by linear regression with a mixed-effects model fitted by the restricted maximum likelihood method using the nlme package of R software (ver. 4.3.1). Studies were assumed as random variables, and their interaction with the intercept and slope were included in the regression. The number of animals per treatment was used as a study-specific weight. Studies accounted for 32%, 35%, or 27% of the total variance when regressing ADG, DMI, or FER, respectively, on TE (% DM). After adjusting for random effects, the ADG increased (P < 0.001) with increasing levels of dietary TE (P < 0.001): 1.344 (± 0.0071) + 0.240 (±0.0298) × TE (n = 99, r2 = 0.40). It was observed that as the dietary TE level increased, its impact on the ADG tended to decrease from 0.33 kgּ d-1ּ % TE-1 when fed up to 0.5% TE to 0.24 kgּ d-1ּ % TE-1 when fed up to 1.5% TE, suggesting a possible nonlinear relationship between these two variables. Similarly, DMI decreased slightly (P < 0.001) at 0.61 kg/d/% TE, but with a lower precision (n = 115, r2 = 0.14). Consequently, FER increased (P < 0.001) at 17 kgּ d-1ּ % TE-1 (n = 93, r2 = 0.34). Initial findings suggest that incorporating TE into the diet of growing and finishing cattle, up to a concentration of 0.5% DM, positively influences the growth rate and enhances FER while minimally affecting DMI. Subsequent research endeavors should delve into a more intricate examination of optimal TE inclusion levels and explore additional performance indicators for a comprehensive understanding of its impact.

Metagenomic insights into the mechanistic differences of plant polyphenols and nitrocompounds in reducing methane emissions using the rumen simulation technique

Methane (CH4) emissions from ruminants contribute significantly to greenhouse gas levels and also result in considerable feed energy losses. Plant polyphenols and nitrocompounds are two typical types of methane inhibitors. The study investigates the mechanistic differences between 2-nitroethanol (NE) and proanthocyanidins (PAC) in reducing methane emissions from ruminant livestock using the rumen simulation technique (RUSITEC) combined with metagenomic analyses.The experiment was performed as a complete randomized block design with 3 runs. Run was used as a blocking factor. The treatments included a control (CON) with no additive, NE at 0.5 g/kg dry matter (DM), and PAC at 20 g/kg DM, all incubated in vitro for 24 h (h) with eight replicates per treatment. The results showed that NE significantly reduced CH4 production by 94.9 % (P < 0.01) and total volatile fatty acid (TVFA) concentration by 11.1 % (P < 0.05) compared to the control. NE also decreased the acetate-to-propionate ratio (A/P) from 1.93 to 1.60 (P < 0.01), indicating a shift towards more efficient fermentation. In contrast, PAC reduced methane production by 11.7 % (P < 0.05) and decreased the A/P (P < 0.05) while maintaining microbial diversity and fermentation stability, with no significant impact on TVFA concentration (P > 0.05). Metagenomic analysis revealed that NE markedly suppressed the abundance of key genera involved in carbohydrate metabolism, including Prevotella and Bacteroides, leading to reduced acetate and butyrate pathways. NE also selectively inhibited methanogenic archaea, particularly Methanobrevibacter spp., which are integral to the hydrogenotrophic pathway (P < 0.01). On the other hand, PAC showed selective inhibition of Methanosphaera spp., targeting the methylotrophic pathway (P < 0.01). These findings provide valuable insights into the distinct microbial and metabolic pathways modulated by NE and PAC, offering potential strategies for developing effective dietary interventions to mitigate methane emissions in ruminant livestock.

Integrating genome-and transcriptome-wide association studies to uncover the host-microbiome interactions in bovine rumen methanogenesis.

The ruminal microbiota generates biogenic methane in ruminants. However, the role of host genetics in modifying ruminal microbiota-mediated methane emissions remains mysterious, which has severely hindered the emission control of this notorious greenhouse gas. Here, we uncover the host genetic basis of rumen microorganisms by genome-and transcriptome-wide association studies with matched genome, rumen transcriptome, and microbiome data from a cohort of 574 Holstein cattle. Heritability estimation revealed that approximately 70% of microbial taxa had significant heritability, but only 43 genetic variants with significant association with 22 microbial taxa were identified through a genome-wide association study (GWAS). In contrast, the transcriptome-wide association study (TWAS) of rumen microbiota detected 28,260 significant gene-microbe associations, involving 210 taxa and 4652 unique genes. On average, host genetic factors explained approximately 28% of the microbial abundance variance, while rumen gene expression explained 43%. In addition, we highlighted that TWAS exhibits a strong advantage in detecting gene expression and phenotypic trait associations in direct effector organs. For methanogenic archaea, only one significant signal was detected by GWAS, whereas the TWAS obtained 1703 significant associated host genes. By combining multiple correlation analyses based on these host TWAS genes, rumen microbiota, and volatile fatty acids, we observed that substrate hydrogen metabolism is an essential factor linking host-microbe interactions in methanogenesis. Overall, these findings provide valuable guidelines for mitigating methane emissions through genetic regulation and microbial management strategies in ruminants.

Deep learning for detecting and characterizing oil and gas well pads in satellite imagery

Methane emissions from the oil and gas sector are a large contributor to climate change. Robust emission quantification and source attribution are needed for mitigating methane emissions, requiring a transparent, comprehensive, and accurate geospatial database of oil and gas infrastructure. Realizing such a database is hindered by data gaps nationally and globally. To fill these gaps, we present a deep learning approach on freely available, high-resolution satellite imagery for automatically mapping well pads and storage tanks. We validate the results in the Permian and Denver-Julesburg basins, two high-producing basins in the United States. Our approach achieves high performance on expert-curated datasets of well pads (Precision = 0.955, Recall = 0.904) and storage tanks (Precision = 0.962, Recall = 0.968). When deployed across the entire basins, the approach captures a majority of well pads in existing datasets (79.5%) and detects a substantial number (>70,000) of well pads not present in those datasets. Furthermore, we detect storage tanks (>169,000) on well pads, which were not mapped in existing datasets. We identify remaining challenges with the approach, which, when solved, should enable a globally scalable and public framework for mapping well pads, storage tanks, and other oil and gas infrastructure.

The enteric methane emission conundrum: U.S. beef cattle producer adoption of climate-focused technology

Cattle are ruminant livestock that emit enteric methane (CH4) as part of their natural digestive process. The U.S. beef cattle industry is receiving pressure to reduce greenhouse gas emissions, including methane. The U.S. Roundtable for Sustainable Beef has set a target for the U.S. feedlot sector to reduce emissions by 10 % per pound of beef by 2030. Feed additive 3-Nitrooxypropanol (3-NOP) has been developed to help mitigate methane emissions. While not yet approved for use in U.S. beef production, adoption of 3-NOP in U.S. feedlots upon approval remains unknown as no widespread economic incentive currently exists in the marketplace to spur adoption. The objectives of this study are: (1) to determine potential 3-NOP adoption by U.S. feedlot cattle producers given various marketplace incentives and (2) to explore how differing approaches to reducing emissions from beef production to achieve sector targets impact social welfare. Our study uses data from a U.S. feedlot producer survey to estimate willingness-to-adopt (WTA) measures. Regression results are used to map potential adoption of 3-NOP given various market and policy scenarios. The survey sample is then split into small producers (<2000 head sold in last 12 months) and large producers (2000+ head sold in last 12 months) to determine differences in WTA based on operation size. We find that producers prefer incentives in the form of processor premiums over government subsidies. The incentive level needed to spur adoption increases as the implementation cost of 3-NOP increases and decreases if net profit estimations are included in the messaging. On average, small producers require a higher incentive to adopt 3-NOP than large producers. Improving the emissions reduction efficacy of 3-NOP reduces the level of incentive needed to achieve aggregate emissions targets. The least expensive avenue to achieve emissions reduction targets results in greater outlays to large producers as compared to small producers. The marginal cost to society of feeding 3-NOP to an additional steer or heifer in the feedlot increases with each animal. As such, it may be that improving the efficacy of 3-NOP through increased investment in research and development is less costly than spurring more producers to adopt the additive in their feed rations. Ultimately, producers, processors, beef consumers, voting residents, taxpayers, and policymakers all have influence in shaping how the beef industry tackles the emissions reduction conundrum.

Inhibiting methanogenesis by targeting thermodynamics and enzymatic reactions in mixed cultures of rumen microbes in vitro.

Mitigation of enteric methane (CH4) emissions from ruminant livestock represents an opportunity to improve the sustainability, productivity, and profitability of beef and dairy production. Ruminal methanogenesis can be mitigated via two primary strategies: (1) alternative electron acceptors and (2) enzymatic inhibition of methanogenic pathways. The former utilizes the thermodynamic favorability of certain reactions such as nitrate/nitrite reduction to ammonia (NH3) while the latter targets specific enzymes using structural analogs of CH4 and methanogenic cofactors such as bromochloromethane (BCM). In this study, we investigated the effects of four additives and their combinations on CH4 production by rumen microbes in batch culture. Sodium nitrate (NaNO3), sodium sulfate (Na2SO4), and 3-nitro-1-propionate (3NPA) were included as thermodynamic inhibitors, whereas BCM was included as a enzymatic inhibitor. Individual additives were evaluated at three levels of inclusion in experiments 1 and 2. Highest level of each additive was used to determine the combined effect of NaNO3 + Na2SO4 (NS), NS + 3NPA (NSP), and NSP + BCM (NSPB) in experiments 3 and 4. Experimental diets were high, medium, and low forage diets (HF, MF, and LF, respectively) and consisted of alfalfa hay and a concentrate mix formulated to obtain the following forage to concentrate ratios: 70:30, 50:50, and 30:70, respectively. Diets with additives were placed in fermentation culture bottles and incubated in a water bath (39°C) for 6, 12, or 24h. Microbial DNA was extracted for 16S rRNA and ITS gene amplicon sequencing. In experiments 1 and 2, CH4 concentrations in control cultures decreased in the order of LF, MF, and HF diets, whereas in experiments 3 and 4, CH4 was highest in MF diet followed by HF and LF diets. Culture pH and NH3 in the control decreased in the order of HF, MF, to LF as expected. NaNO3 decreased (p < 0.001) CH4 and butyrate and increased acetate and propionate (p < 0.03 and 0.003, respectively). Cultures receiving NaNO3 had an enrichment of microorganisms capable of nitrate and nitrite reduction. 3NPA also decreased CH4 at 6h with no further decrease at 24 h (p < 0.001). BCM significantly inhibited methanogenesis regardless of inclusion levels as well as in the presence of the thermodynamic inhibitors (p < 0.001) while enriching succinate producers and assimilators as well as propionate producers (p adj < 0.05). However, individual inclusion of BCM decreased total short chain fatty acid (SCFA) concentrations (p < 0.002). Inhibition of methanogenesis with BCM individually and in combination with the other additives increased gaseous H2 concentrations (p < 0.001 individually and 0.028 in combination) while decreasing acetate to propionate ratio (p < 0.001). Only the cultures treated with BCM in combination with other additives significantly (padj < 0.05) decreased the abundance of Methanobrevibacter expressed as log fold change. Overall, the combination of thermodynamic and enzymatic inhibitors presented a promising effect on ruminal fermentation in-vitro, inhibiting methanogenesis while optimizing the other fermentation parameters such as pH, NH3, and SCFAs. Here, we provide a proof of concept that the combination of an electron acceptor and a methane analog may be exploited to improve microbial efficiency via methanogenesis inhibition.

Editing microbes to mitigate enteric methane emissions in livestock.

Livestock production significantly contributes to greenhouse gas (GHG) emissions particularly methane (CH4) emissions thereby influencing climate change. To address this issue further, it is crucial to establish strategies that simultaneously increase ruminant productivity while minimizing GHG emissions, particularly from cattle, sheep, and goats. Recent advancements have revealed the potential for modulating the rumen microbial ecosystem through genetic selection to reduce methane (CH4) production, and by microbial genome editing including CRISPR/Cas9, TALENs (Transcription Activator-Like Effector Nucleases), ZFNs (Zinc Finger Nucleases), RNA interference (RNAi), Pime editing, Base editing and double-stranded break-free (DSB-free). These technologies enable precise genetic modifications, offering opportunities to enhance traits that reduce environmental impact and optimize metabolic pathways. Additionally, various nutrition-related measures have shown promise in mitigating methane emissions to varying extents. This review aims to present a future-oriented viewpoint on reducing methane emissions from ruminants by leveraging CRISPR/Cas9 technology to engineer the microbial consortia within the rumen. The ultimate objective is to develop sustainable livestock production methods that effectively decrease methane emissions, while maintaining animal health and productivity.

Exploring modes of microbial interactions with implications for methane cycling.

Methanotrophs are the sole biological sink of methane. Volatile organic compounds (VOCs) produced by heterotrophic bacteria have been demonstrated to be a potential modulating factor of methane consumption. Here, we identify and disentangle the impact of the volatolome of heterotrophic bacteria on the methanotroph activity and proteome, using Methylomonas as model organism. Our study unambiguously shows how methanotrophy can be influenced by other organisms without direct physical contact. This influence is mediated by VOCs (e.g. dimethyl-polysulphides) or/and CO2 emitted during respiration, which can inhibit growth and methane uptake of the methanotroph, while other VOCs had a stimulating effect on methanotroph activity. Depending on whether the methanotroph was exposed to the volatolome of the heterotroph or to CO2, proteomics revealed differential protein expression patterns with the soluble methane monooxygenase being the most affected enzyme. The interaction between methanotrophs and heterotrophs can have strong positive or negative effects on methane consumption, depending on the species interacting with the methanotroph. We identified potential VOCs involved in the inhibition while positive effects may be triggered by CO2 released by heterotrophic respiration. Our experimental proof of methanotroph-heterotroph interactions clearly calls for detailed research into strategies on how to mitigate methane emissions.

Mitigation of ammonia and methane emissions with manure amendments during storage of cattle slurry.

This study aimed at assessing the efficacy of manure amendments in abating ammonia (NH3) and methane (CH4) emissions during storage. Two experiments were carried out. Experiment 1 was conducted using 20 L of slurry for 98 days. Treatments were: aluminium sulphate (alum), lactogypsum, zeolite, actiglene, ammonium thiosulphate, biochar, dairy processing waste, Digest-IT and control (without amendment). Experiment 2 was conducted using 660 L of slurry in underground storage tanks for 77 days. Treatments were: sulphuric acid, gypsum, biochar and control (without amendment). NH3 measurements for experiment 1 and experiment 2 were conducted using the photoacoustic gas monitor and dynamic chamber techniques, respectively. CH4 was measured using the static chamber technique in both experiments. The effect of amendments on slurry composition was determined at the end of the experiments. Experiment 1 showed a significant reduction in NH3 emissions in the alum (82%), lactogypsum (46%) and zeolite (32%) treatments relative to the control (100.3% total ammoniacal nitrogen (TAN)). CH4 was reduced significantly in the alum (87%), ammonium thiosulphate (64%) and lactogypsum (67%) relative to the control (291.9 g m-2). Experiment 2 showed a significant reduction (32%) in NH3 emissions in the sulphuric acid relative to the control (4.4% TAN). CH4 was reduced significantly in the sulphuric acid (46%), gypsum (39%) and biochar (15%) treatments relative to the control (291.9 g m-2). In general, amendments altered slurry composition such as dry matter, volatile solids, carbon and nitrogen contents at the end of storage. Lactogypsum, alum and sulphuric acid were effective in abating both NH3 and CH4 emissions and can contribute to improving air quality.

Mitigation potential of methane emissions in China's livestock sector can reach one-third by 2030 at low cost.

The mitigation of methane (CH4) emissions from livestock production is crucial to China's carbon neutrality. Here we established a high-spatiotemporal-resolution dataset of the country's livestock CH4 emissions from 1990 to 2020 using four large-scale national livestock greenhouse gas inventory surveys. We estimate CH4 emissions to be 14.1 ± 2.0 Mt in 2020 and to increase by 13% until 2030 despite CH4 intensity per kg animal protein having decreased by 55% in the past 30 years. Approximately half of the emissions come from 13% of all Chinese counties. The technical CH4 mitigation potential is projected to be 36 ± 8% (4.4-6.9 Mt CH4) in 2030, and reducing food loss and waste could mitigate an additional 1.6 Mt of CH4. Overall, most CH4 mitigation could be achieved by increasing animal productivity and coverage of lagoon storage at carbon prices below US$100 tCO2e-1, being more cost-effective than livestock nitrous oxide mitigation in China.

Fantastic wetlands and why to monitor them: Demonstrating the social and financial benefit potential of methane abatement through salt marsh restoration.

Salt marsh restoration has the potential to reduce greenhouse gas emissions thereby providing an opportunity for blue carbon crediting, but implementation has been limited to date because of insufficient data and validation. In this paper, we demonstrate the potential scale of methane emissions that could be avoided if salinity-reducing impairments are mitigated by applying findings from six salt marsh restoration sites in Massachusetts combined with a previously demonstrated application of the salt marsh salinity-methane relationship. We used calculations of these avoided emissions to estimate the social benefit of salt marsh restoration by calculating avoided costs. Of the six sites selected, restorations at two sites were successful in improving salinity which we used as a methane proxy. Our approach and findings demonstrate the potential benefits in developing consistent accounting methodologies to better track, prioritize, and implement wetlands restoration strategies to mitigate methane emissions and contribute toward state-level emissions reduction targets across some of the 475 Massachusetts salt marches with an existing tidal restriction. We found the potential for $12 -$26M in added social benefit from 176 tons of avoided methane across 932 hectares of degraded salt marsh in Massachusetts. A significant limitation in estimating benefits, however, is the lack of coordinated, widespread monitoring strategies to infer methane and other GhGs at scale. While not insurmountable, these challenges will need to be addressed for GhG emissions reduction and/or sequestration through salt marsh restoration to be accepted as an effective strategy. We conclude that while carbon crediting may offer benefits to marsh restoration and state greenhouse gas emissions reduction targets, there remain significant limitations because of a lack of project monitoring and data validation. In the worst case, this could result in the offsetting of actual greenhouse gas emissions with credits that are supported by indirect and less-than-rigorous monitoring data.