Carbon footprint of Canadian dairy products: Calculations and issues

The Canadian dairy sector is a major industry with about 1 million cows. This industry emits about 20% of the total greenhouse gas (GHG) emissions from the main livestock sectors (beef, dairy, swine, and poultry). In 2006, the Canadian dairy herd produced about 7.7 Mt of raw milk, resulting in about 4.4 Mt of dairy products (notably 64% fluid milk and 12% cheese). An integrated cradle-to-gate model (field to processing plant) has been developed to estimate the carbon footprint (CF) of 11 Canadian dairy products. The on-farm part of the model is the Unified Livestock Industry and Crop Emissions Estimation System (ULICEES). It considers all GHG emissions associated with livestock production but, for this study, it was run for the dairy sector specifically. Off-farm GHG emissions were estimated using the Canadian Food Carbon Footprint calculator, (cafoo)²-milk. It considers GHG emissions from the farm gate to the exit gate of the processing plants. The CF of the raw milk has been found lower in western provinces [0.93 kg of CO₂ equivalents (CO₂e)/L of milk] than in eastern provinces (1.12 kg of CO₂e/L of milk) because of differences in climate conditions and dairy herd management. Most of the CF estimates of dairy products ranged between 1 and 3 kg of CO₂e/kg of product. Three products were, however, significantly higher: cheese (5.3 kg of CO₂e/kg), butter (7.3 kg of CO₂e/kg), and milk powder (10.1 kg of CO₂e/kg). The CF results depend on the milk volume needed, the co-product allocation process (based on milk solids content), and the amount of energy used to manufacture each product. The GHG emissions per kilogram of protein ranged from 13 to 40 kg of CO₂e. Two products had higher values: cream and sour cream, at 83 and 78 kg of CO₂e/kg, respectively. Finally, the highest CF value was for butter, at about 730 kg of CO₂e/kg. This extremely high value is due to the fact that the intensity indicator per kilogram of product is high and that butter is almost exclusively fat. Protein content is often used to compare the CF of products; however, this study demonstrates that the use of a common food component is not suitable as a comparison unit in some cases. Functionality has to be considered too, but it might be insufficient for food product labeling because different reporting units (adapted to a specific food product) will be used, and the resulting confusion could lead consumers to lose confidence in such labeling. Therefore, simple units might not be ideal and a more comprehensive approach will likely have to be developed.     

The carbon footprint of dairy production systems through partial life cycle assessment

Greenhouse gas (GHG) emissions and their potential effect on the environment has become an important national and international issue. Dairy production, along with all other types of animal agriculture, is a recognized source of GHG emissions, but little information exists on the net emissions from dairy farms. Component models for predicting all important sources and sinks of CH₄, N₂O, and CO₂ from primary and secondary sources in dairy production were integrated in a software tool called the Dairy Greenhouse Gas model, or DairyGHG. This tool calculates the carbon footprint of a dairy production system as the net exchange of all GHG in CO₂ equivalent units per unit of energy-corrected milk produced. Primary emission sources include enteric fermentation, manure, cropland used in feed production, and the combustion of fuel in machinery used to produce feed and handle manure. Secondary emissions are those occurring during the production of resources used on the farm, which can include fuel, electricity, machinery, fertilizer, pesticides, plastic, and purchased replacement animals. A long-term C balance is assumed for the production system, which does not account for potential depletion or sequestration of soil carbon. An evaluation of dairy farms of various sizes and production strategies gave carbon footprints of 0.37 to 0.69 kg of CO₂ equivalent units/kg of energy-corrected milk, depending upon milk production level and the feeding and manure handling strategies used. In a comparison with previous studies, DairyGHG predicted C footprints similar to those reported when similar assumptions were made for feeding strategy, milk production, allocation method between milk and animal coproducts, and sources of CO₂ and secondary emissions. DairyGHG provides a relatively simple tool for evaluating management effects on net GHG emissions and the overall carbon footprint of dairy production systems.     

Reduction of greenhouse gas emissions from feed supply chains by utilizing regionally produced protein sources: the case of Austrian dairy production

BACKGROUND: The aim of this study was to analyse the potential greenhouse gas emissions (GHGE) for regionally alternative produced protein‐rich feedstuffs (APRFs) which are utilized for dairy cattle in Austria in comparison to solvent‐extracted soybean meal (SBME). In addition to GHGE from agriculture and related upstream supply chains, the effects of land use change were calculated and were included in the results for GHGE. Furthermore, mixtures of APRFs were evaluated which provided energy and utilizable protein equivalent to SBME. RESULTS: Highest GHGE were estimated for SBME, mainly due to land use change‐related emissions. Medium GHGE were found for distillers' dried grains with solubles, for seed cake and solvent‐extracted meal from rapeseed and for lucerne cobs. Cake and solvent‐extracted meal from sunflower seed as well as faba beans were loaded with lowest GHGE. Substituting SBME by nutritionally equivalent mixtures of APRFs, on average, resulted in a reduction of GHGE of 42% (22–62%). CONCLUSION: Utilization of locally produced APRFs shows clear advantages in terms of GHGE. Balanced mixtures of APRFs may offer specific benefits, as they allow for a combination of desirable nutritional value and reduced GHGE. Copyright © 2011 Society of Chemical Industry     

Potential growth of Listeria monocytogenes in Italian mozzarella cheese as affected by microbiological and chemical-physical environment

In the present study, 33 brands of mozzarella cheese (pasteurized cow milk mozzarella obtained by direct acidification through the addition of food-grade citric acid or obtained by natural acidification through the addition of thermophilic starter cultures, mozzarella for pizza mainly obtained by addition of citric acid, and pasteurized buffalo milk mozzarella obtained by adding microbial rennet) were characterized for the factors potentially influencing the growth of Listeria monocytogenes (microbial populations, moisture, pH, and organic acids). Then, the growth potential of L. monocytogenes in mozzarella was investigated by challenge tests performed at different temperatures. The presence of heterogeneous microflora (lactobacilli, streptococci, Pseudomonas spp., and, for buffalo mozzarella, yeasts) was evidenced. Almost all the product typologies were classified as high-moisture mozzarella cheese because moisture was >52%. Moreover, pH varied from 5.32 to 6.43 depending on the manufacturing methodology applied. Organic acid concentrations too showed great variability depending on the mozzarella production method, with values ranging from less than limit of detection (LOD; 16 mg/kg) to 14,709 mg/kg, less than LOD (216 mg/kg) to 29,195 mg/kg, and less than LOD (47 mg/kg) to 1,725 mg/kg in the water phase of lactic, citric, and acetic acids, respectively. Despite this presence, the concentration of undissociated acids was lower compared with the minimum inhibitory concentrations estimated for L. monocytogenes by other authors. This was confirmed by the results of the challenge tests conducted inoculating the pathogen in mozzarella produced with the addition of citric acid, as the microorganism grew fast at each temperature considered (4, 9, 15, and 20°C). Good hygiene practices should be strictly applied, especially with the aim of avoiding postproduction contamination of mozzarella, as the presence of organic acids and microflora is insufficient to prevent L. monocytogenes growth.     

纺织服装工业碳足迹核算中的若干问题

针对纺织服装工业的生产特点,重点探讨纺织服装产品工业碳足迹核算中亟待解决的核算边界不清、设备实际工作时间难以计量、公用能耗及物料碳足迹数据拆分不易、能源及物料的碳排放系数及计算方法不统一、产品分类质量基准庞杂、生产环境差异影响显著等几类基本问题,认为需从纺织服装工程、机械设备工程、信息工程和生产管理等多学科全面深入地探索碳足迹核算方法,确保核算方法有理可依。     

气候变暖背景下的低碳可持续发展及碳足迹计算

发达国家自工业革命后的100余年中释放了大量温室气体使地球气候变暖,造成海平面上升,极端天气频现,危害人类生命安全.联合国为此多次召开气候大会,其中具有里程碑意义的有2次:(1)1997年气候会议签署《京都议定书》,确定6种温室气体,开启低碳可持续发展道路并建立碳足迹制度;(2)2015年气候会议中大部分国家签署《巴黎...     

食品生命周期碳排放评价研究

基于生命周期评价（LCA）理论,探讨界定食品生命周期碳排放的核算范围,对食品生命周期从原料生产、加工、消费到废物处理各阶段的碳排放进行清单分析,并提出了食品生命周期碳排量的评价框架和方法。     

生命周期理论视角下的食品碳足迹分析及其应用研究进展——以国外主要肉类食品为例

随着全球肉类食品需求的增加,在此类食品生产各环节涉及能源和物质投入的同时,也伴随着大量温室气体的排放,基于生命周期理论对肉类食品生产的碳足迹进行分析对于碳标签在中国的应用及食品碳排放具有重要的约束意义。发达国家在此方面已经进行了前沿的理论研究和实践探索,而我国仍处于起步阶段。本文旨在衡量三种主要肉类食品即牛肉、猪肉、鸡肉在世界主要出口大国如澳大利亚、巴西、日本等国的温室气体(GHG)排放数据(也称碳足迹),以生命周期理论为基础,利用这些国家的研究方法,计算肉类食品系统链的GHG排放数据、探索生命周期理论在计算碳排放的优点和限制,发掘此种方法应用在碳标签上的前景,使消费者增强产品生产对环境影响的意识,以期实现碳减排目标方面产生实质性的作用,同时探索碳标签在引导食品消费上的应用前景,这也成为我国探寻碳标签制度进一步发展的驱动力。      

Invited review: Contemporary environmental issues: A review of the dairy industry's role in climate change and air quality and the potential of mitigation through improved production efficiency

Environmental concerns involving the dairy industry are shifting from an exclusive focus on water quality to encompass climate change and air quality issues. The dairy industry's climate change air emissions of concern are the greenhouse gases methane and nitrous oxide. With regard to air quality, the dairy industry's major emission contributions are particulate matter, volatile organic compounds, and ammonia. The emissions of these compounds from dairies can be variable because of a number of factors including weather conditions, animal type, management, and nutrition. To evaluate and compare emissions across the diverse operations that comprise the US dairy industry, emissions should be reported per unit of output (e.g., per kg of 3.5% fat-corrected milk). Accurately modeling emissions with models that can predict the complex bio-geochemical processes responsible for emissions is critical to assess current emissions inventories and develop mitigation strategies. Improving the dairy industry's production efficiency (e.g., improvements in management, nutrition, reproduction, and cow comfort) is an effective way to reduce emissions per unit of milk. With accurate process-based models, emissions reductions due to improved production efficiency could be reported per unit of milk and predicted on a farm-to-farm basis.     

Invited review: Environmental impacts of dairy processing and products: a review

The objective of this review is to summarize research efforts and case studies to date of the environmental impacts from dairy processing. The pervasiveness of greenhouse gas emission, water use, consumer waste, and other environmental impacts of dairy are described. An outline of the method of choice, the life cycle assessment, for conducting research and deciding appropriate allocation of the impacts is provided. Specific research examples in dairy processing highlight how the representative final product is associated with environmental impacts to air, water, and land. The primary conclusion from the study was the usefulness of life cycle assessment methodology and the need for further research due to limited studies, variable data, and the magnitude of environmental impact.     

Environmental impacts of remediation of a trichloroethene-contaminated site: life cycle assessment of remediation alternatives

The environmental impacts of remediation of a chloroethene-contaminated site were evaluated using life cycle assessment (LCA). The compared remediation options are (i) in situ bioremediation by enhanced reductive dechlorination (ERD), (ii) in situ thermal desorption (ISTD), and (iii) excavation of the contaminated soil followed by off-site treatment and disposal. The results showed that choosing the ERD option will reduce the life-cycle impacts of remediation remarkably compared to choosing either ISTD or excavation, which are more energy-demanding. In addition to the secondary impacts of remediation, this study includes assessment of local toxic impacts (the primary impact) related to the on-site contaminant leaching to groundwater and subsequent human exposure via drinking water. The primary human toxic impacts were high for ERD due to the formation and leaching of chlorinated degradation products, especially vinyl chloride during remediation. However, the secondary human toxic impacts of ISTD and excavation are likely to be even higher, particularly due to upstream impacts from steel production. The newly launched model, USEtox, was applied for characterization of primary and secondary toxic impacts and combined with a site-dependent fate model of the leaching of chlorinated ethenes from the fractured clay till site.     

The effect of feed demand on greenhouse gas emissions and farm profitability for organic and conventional dairy farms

The reduction of product-related greenhouse gas (GHG) emissions in milk production appears to be necessary. The reduction of emissions on an individual farm might be highly accepted by farm owners if it were accompanied by an increase in profitability. Using life cycle assessments to determine the product carbon footprints (PCF) and farm-level evaluations to record profitability, we explored opportunities for optimization based on analysis of 81 organic and conventional pasture-based dairy farms in southern Germany. The objective of the present study was to detect common determining factors for low PCF and high management incomes (MI) to achieve GHG reductions at the lowest possible operational cost. In our sample, organic farms, which performed economically better than conventional farms, produced PCF that were significantly higher than those produced by conventional farms [1.61 ± 0.29 vs. 1.45 ± 0.28 kg of CO₂ equivalents (CO₂eq) per kg of milk; means ± SD)]. A multiple linear regression analysis of the sample demonstrated that low feed demand per kilogram of milk, high grassland yield, and low forage area requirements per cow are the main factors that decrease PCF. These factors are also useful for improving a farm's profitability in principle. For organic farms, a reduction of feed demand of 100 g/kg of milk resulted in a PCF reduction of 105 g of CO₂eq/kg of milk and an increase in MI of approximately 2.1 euro cents (c)/kg of milk. For conventional farms, a decrease of feed demand of 100 g/kg of milk corresponded to a reduction in PCF of 117 g of CO₂eq/kg of milk and an increase in MI of approximately 3.1 c/kg of milk. Accordingly, farmers could achieve higher profits while reducing GHG emissions. Improved education and training of farmers and consultants regarding GHG mitigation and farm profitability appear to be the best methods of improving efficiency under traditional and organic farming practices.     

Potential for improving the carbon footprint of butter and blend products

To reduce the environmental impact of a product efficiently, it is crucial to consider the entire value chain of the product; that is, to apply life cycle thinking, to avoid suboptimization and identify the areas where the largest potential improvements can be made. This study analyzed the carbon footprint (CF) of butter and dairy blend products, with the focus on fat content and size and type of packaging (including product waste at the consumer level). The products analyzed were butter with 80% fat in 250-g wrap, 250-g tub, and 10-g mini tub, and blends with 80% and 60% fat in 250-g tubs. Life cycle assessment was used to account for all greenhouse gas emissions from cow to consumer. A critical aspect when calculating the CF is how emissions are allocated between different products. Here, allocation of raw milk between products was based on a weighted fat and protein content (1:1.7), based on the price paid for raw milk to dairy farmers. The CF (expressed as carbon dioxide equivalents, CO₂e) for 1 kg of butter or blend (assuming no product waste at consumer) ranged from 5.2 kg (blend with 60% fat content) to 9.3 kg of CO₂e (butter in 250-g tub). When including product waste at the consumer level, the CF ranged from 5.5 kg of CO₂e (blend with 60% fat content) to 14.7 kg of CO₂e (butter in mini tub). Fat content and the proportion of vegetable oil in products had the greatest effect on CF of the products, with lower fat content and a higher proportion of vegetable oil resulting in lower CF. Hence, if the same functionality as butter could be retained while shifting to lower fat and higher proportions of vegetable oil, the CF of the product would be decreased. Size and type of packaging were less important, but it is crucial to have the correct size and type of packaging to avoid product losses at the consumer. The greatest share of greenhouse gas emissions associated with butter production occurred at the farm level; thus, minimizing product losses in the whole value chain—from cow to consumer—is essential for efficient production.     

Life cycle assessment of pasture-based dairy production systems: Current and future performance

To overcome the environmental challenges faced by the global agricultural sector while also ensuring economic viability, dairy farmers must improve the efficiency of their systems. To improve system efficiency, the performance of an average production system must be determined, as it establishes a benchmark from which the efficacy of proposed management practices and mitigation strategies can be assessed. Identified management practices and mitigation strategies can then be compiled to create ambitious but realistic targets for the sector to strive toward. Therefore the objective of this study was to calculate the environmental performance of an average spring-calving pasture-based dairy system and an ambitious target dairy system. Life cycle assessment (LCA) of 2 pasture-based dairy systems were conducted: (1) current average spring-calving pasture-based dairy system (current), and (2) a spring-calving pasture-based dairy system that has achieved key performance targets set by the most efficient dairy systems (target). An existing dairy LCA model was updated with country-specific emission factors, life cycle inventory data, and recommended methodologies. The environmental impact categories assessed were global warming potential, nonrenewable energy depletion, acidification potential, and eutrophication potential (marine and freshwater). Two functional units were used: per kilogram of fat- and protein-corrected milk (FPCM), and per hectare. To assess the effects of the model updates, the current dairy system was simulated twice, once with the previous version of the dairy LCA model, and second with the updated LCA model. The addition of country-specific emission factors, updated inventory data, and implementation of recommended methods has resulted in global warming potential and nonrenewable energy depletion being reduced by 10.4% and 10.9%, respectively. The updates had negligible effects on acidification and eutrophication potential. The inclusion of assumptions around carbon sequestration in grassland further reduced global warming potential by 16.4%. Moving from the current dairy system to the target dairy system was reported to reduce the environmental impact per kilogram of FPCM across all impact categories investigated. When expressed per hectare, transitioning toward the target dairy system reduced acidification, freshwater eutrophication, and nonrenewable energy depletion by 2.0%, 8.8%, and 13.8%, respectively. In contrast, transitioning toward the target dairy system increased global warming per hectare and, to a lesser degree, marine eutrophication potential per hectare. The increase in global warming and marine eutrophication potential per hectare was attributed to the increase in stocking rate and subsequently milk production per hectare (9,950 vs. 14,100 kg of FPCM/ha). This study demonstrates that the adoption of management practices that improve system efficiency will reduce the environmental impact per kilogram of FPCM and can contribute to the future sustainability of pasture-based dairy systems. However, improved system efficiency can be offset by the associated increase in productivity, highlighting the importance of reporting multiple environmental impact categories and functional units to prevent pollution swapping. New research and mitigation strategies will be required to improve the environmental sustainability of dairy systems beyond the target system in the future.     

Environmental life cycle assessment of permeable reactive barriers: effects of construction methods, reactive materials and groundwater constituents

The effects of the construction methods, materials of reactive media and groundwater constituents on the environmental impacts of a permeable reactive barrier (PRB) were evaluated using life cycle assessment (LCA). The PRB is assumed to be installed at a simulated site contaminated by either Cr(VI) alone or Cr(VI) and As(V). Results show that the trench-based construction method can reduce the environmental impacts of the remediation remarkably compared to the caisson-based method due to less construction material consumption by the funnel. Compared to using the zerovalent iron (Fe(0)) and quartz sand mixture, the use of the Fe(0) and iron oxide-coated sand (IOCS) mixture can reduce the environmental impacts. In the presence of natural organic matter (NOM) in groundwater, the environmental impacts generated by the reactive media were significantly increased because of the higher usage of Fe(0). The environmental impacts are lower by using the Fe(0) and IOCS mixture in the groundwater with NOM, compared with using the Fe(0) and quartz sand mixture. Since IOCS can enhance the removal efficiency of Cr(VI) and As(V), the usage of the Fe(0) can be reduced, which in turn reduces the impacts induced by the reactive media.     

Harnessing anaerobic digestion for combined cooling,heat, and power on dairy farms: An environmental life cycle and techno-economic assessment of added cooling pathways

Anaerobic digestion coupled with combined heat and power production on dairy farms is environmentally advantageous; however, high capital and operating costs have limited its adoption, especially in the United States, where renewable electricity and heat production are under-incentivized. Biogas is also at a disadvantage because it has to compete with very low natural gas prices. The objective of this study was to evaluate the feasibility of integrating absorption refrigeration technology for combined cooling, heat, and power (CCHP) on the farm to help bridge this economic hurdle. A combined environmental life cycle and techno-economic assessment was used to compare 2 cooling pathways with and without co-digestion. We considered using CCHP to (1) displace electricity-driven refrigeration processes (e.g., milk chilling/refrigeration, biogas inlet cooling) or (2) mitigate heat stress in dairy cattle via conductive cow cooling. All cooling scenarios reduced environmental emissions compared with combined heat and power only, with an appreciable reduction in land use impacts when employing conductive cow cooling. However, none of the cooling scenarios achieved economically viability. When using cooling power to displace electricity-driven refrigeration processes, economic viability was constrained by low electricity prices and a lack of incentives in the United States. When used for conductive cow cooling, economic viability was constrained by (1) low waste heat-to-cooling conversion efficiency; (2) limited conductive cow cooling effectiveness (i.e., heat-stress mitigation); and (3) low heat stress frequency and limited severity. However, we predict that with minor improvements in conductive cow cooling effectiveness and in hotter climates, CCHP for conductive cow cooling would be economically viable even in current US energy markets.     

Dairy system,parity, and lactation stage affect enteric methane production,yield, and intensity per kilogram of milk and cheese predicted from gas chromatography fatty acids

Ruminants (and milk production) contribute to global climate change through enteric methane emissions (EME), and any attempt to reduce them is complicated by the fact that they are difficult and expensive to measure directly. In the case of dairy cows, a promising indirect method of estimating EME is to use the milk fatty acid profile as a proxy, as a relationship exists between microbial activity in the rumen and the molecules available for milk synthesis in the mammary gland. In the present study, we analyzed the detailed fatty acid profiles (through gas chromatography) of a large number of milk samples from 1,158 Brown Swiss cows reared on 85 farms with the aim of testing in the field 2 equations for estimating EME taken from a published meta-analysis. The average estimated methane yield (CH₄ emission per kg of dry matter intake, 21.34 ± 1.60 g/kg) and methane intensity (per kg of corrected milk, 14.17 ± 1.78 g/kg), and the derived methane production (CH₄ emissions per day per cow, 357 ± 109 g/d) were similar to those previously published. Using data from model cheese makings from individual cows, we also calculated estimated methane intensity per kilogram of fresh cheese (99.7 ± 16.4 g/kg) and cheese solids (207.5 ± 30.9 g/kg). Dairy system affected all EME estimates. Traditional dairy farms, and modern farms including corn silage in the TMR exhibited greater estimated methane intensities. We found very wide variability in estimated EME traits among different farms within dairy system (0.33 to 0.61 of total variance), suggesting the need to modify the farms' feeding regimens and management practices to mitigate emissions. Among the individual factors, parity order affected all estimated EME traits excepted methane yield, with an increase from first lactation to the following ones. Lactation stage exhibited more favorable estimated EME traits during early lactation, concomitant with the availability of nutrients from body tissue mobilization for mammary synthesis of milk. Our results showed a coherence between the EME traits estimated from the analysis of milk fatty acids and the expectations according to current knowledge. Further research is needed to validate the results obtained in this study in other breeds and populations, to assess the magnitude of the genetic variation and the potential of these phenotypes to be exploited in breeding programs with the aim to mitigate emissions.     

More ‘crop per drop’: constraints and opportunities for precision irrigation in European agriculture

Dwindling water supplies, increasing drought frequency and uncertainties associated with a changing climate mean Europe's irrigated agriculture sector needs to improve water efficiency and produce more 'crop per drop'. This paper summarizes the drivers for change, and the constraints and opportunities for improving agricultural water management through uptake of precision irrigation technologies. A multi‐disciplinary and integrated approach involving irrigation engineers, soil scientists, agronomists and plant physiologists will be needed if the potential for precision irrigation within the field crop sector is to be realized. © 2013 Society of Chemical Industry