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Atmospheric methane (CH4) is a potent greenhouse gas, and its mole fraction has more than doubled since the preindustrial era. Fossil fuel extraction and use are among the largest anthropogenic sources of CH4 emissions, but the precise magnitude of these contributions is a subject of debate. Carbon-14 in CH4 (14CH4) can be used to distinguish between fossil (14C-free) CH4 emissions and contemporaneous biogenic sources; however, poorly constrained direct 14CH4 emissions from nuclear reactors have complicated this approach since the middle of the 20th century. Moreover, the partitioning of total fossil CH4 emissions (presently 172 to 195 teragrams CH4 per year) between anthropogenic and natural geological sources (such as seeps and mud volcanoes) is under debate; emission inventories suggest that the latter account for about 40 to 60 teragrams CH4 per year. Geological emissions were less than 15.4 teragrams CH4 per year at the end of the Pleistocene, about 11,600 years ago, but that period is an imperfect analogue for present-day emissions owing to the large terrestrial ice sheet cover, lower sea level and extensive permafrost. Here we use preindustrial-era ice core 14CH4 measurements to show that natural geological CH4 emissions to the atmosphere were about 1.6 teragrams CH4 per year, with a maximum of 5.4 teragrams CH4 per year (95 per cent confidence limit)—an order of magnitude lower than the currently used estimates. This result indicates that anthropogenic fossil CH4 emissions are underestimated by about 38 to 58 teragrams CH4 per year, or about 25 to 40 per cent of recent estimates. Our record highlights the human impact on the atmosphere and climate, provides a firm target for inventories of the global CH4 budget, and will help to inform strategies for targeted emission reductions.

The implementation of industrial-scale facilities for microalgae cultivation is limited due to the high operation costs. One of the main problems in obtaining an efficient and long-lasting microalgae culture system is biofouling. The particular issue when developing antibiofouling surfaces for microalgae cultures is that the material must be transparent. The main purpose of this work was to evaluate the antibiofouling efficiency of a non-toxic polydimethylsiloxane-based coating prepared with polyethylene glycol-based copolymer on different photobioreactors at the pilot-plant scale. The antifouling properties result from the development of a fouling-release coating utilizing hydrogel technology. Nannochloropsis gaditana and Chlorella sorokiniana were cultured outdoors for 3 months over the summer, when biofouling formation is at its highest due to environmental conditions, to test the coating's antibiofouling efficiency. Although biofouling was not completely prevented in either photobioreactor, the coating significantly reduced cell adhesion compared to the polydimethylsiloxane control (70% less adhesion). Therefore, this coating was shown to be a good alternative for constructing efficient closed-photobioreactors at the pilot-plant scale, at least for cultures lasting 3 months.

La production animale est une source essentielle de revenus et d'émissions de gaz à effet de serre (GES) agricoles en Colombie, au Brésil, en Argentine, au Costa Rica, en Uruguay, au Mexique et au Pérou. Plusieurs options de gestion et technologiques, avec un potentiel d'atténuation du méthane entérique, ont été évaluées et leur mise à l'échelle devrait contribuer à la réalisation des objectifs de réduction des émissions de GES. Pourtant, l'adoption généralisée d'options d'atténuation prometteuses reste limitée, ce qui soulève des questions quant à savoir si les objectifs de réduction des émissions envisagés sont réalisables. À l'aide de données générées localement, nous explorons les potentiels d'atténuation des technologies et des pratiques de gestion actuellement proposées pour atténuer les émissions de méthane entérique, pour les systèmes de production bovine dans les pays d'Amérique latine les plus émetteurs. Nous discutons ensuite des obstacles à l'adoption d'innovations qui réduisent considérablement les émissions de méthane entérique d'origine bovine et des changements majeurs dans les politiques et les pratiques qui sont nécessaires pour relever les ambitions nationales dans les pays à forte émission. En utilisant la science la plus récente et la pensée actuelle, nous fournissons notre point de vue sur une approche inclusive et ré-imaginons comment les secteurs universitaire, de la recherche, des affaires et des politiques publiques peuvent soutenir et encourager les changements nécessaires pour élever le niveau d'ambition et atteindre les objectifs de développement durable en envisageant des actions allant de la ferme à l'échelle nationale. La producción ganadera es una fuente fundamental de ingresos y emisiones de gases de efecto invernadero (GEI) agrícolas en Colombia, Brasil, Argentina, Costa Rica, Uruguay, México y Perú. Se han evaluado varias opciones de gestión y tecnológicas, con potencial de mitigación de metano entérico, y se prevé que su escalado contribuya al logro de los objetivos de reducción de emisiones de GEI. Sin embargo, la adopción generalizada de opciones de mitigación prometedoras sigue siendo limitada, lo que plantea dudas sobre si los objetivos de reducción de emisiones previstos son alcanzables. Utilizando datos generados localmente, exploramos los potenciales de mitigación de las tecnologías y prácticas de manejo actualmente propuestas para mitigar las emisiones de metano entérico, para los sistemas de producción ganadera en los países de mayor emisión de América Latina. Luego discutimos las barreras para adoptar innovaciones que reduzcan significativamente las emisiones de metano entérico en el ganado y los cambios importantes en las políticas y prácticas que se necesitan para aumentar las ambiciones nacionales en los países con altas emisiones. Utilizando la ciencia más reciente y el pensamiento actual, brindamos nuestra perspectiva sobre un enfoque inclusivo y reimaginamos cómo los sectores académico, de investigación, empresarial y de políticas públicas pueden apoyar e incentivar los cambios necesarios para elevar el nivel de ambición y alcanzar los objetivos de desarrollo sostenible considerando acciones desde la granja hasta la escala nacional. Livestock production is a pivotal source of income and agricultural greenhouse gas (GHG) emissions in Colombia, Brazil, Argentina, Costa Rica, Uruguay, Mexico and Peru. Several management and technological options, with enteric methane mitigation potential, have been evaluated and their scaling is anticipated to contribute towards achieving GHG emission reduction targets. Yet, widespread adoption of promising mitigation options remains limited, raising questions as to whether envisaged emission reduction targets are achievable. Using locally generated data, we explore the mitigation potentials of technologies and management practices currently proposed to mitigate enteric methane emissions, for cattle production systems in the higher emitting countries of Latin America. We then discuss barriers for adopting innovations that significantly reduce cattle-based enteric methane emissions and the major shifts in policy and practice that are needed to raise national ambitions in the high emitting countries. Using the latest science and current thinking, we provide our perspective on an inclusive approach and re-imagine how the academic, research, business and public policy sectors can support and incentivize the changes needed to raise the level of ambition and achieve sustainable development goals considering actions all the way from the farm to the national scale. الإنتاج الحيواني هو مصدر محوري للدخل وانبعاثات غازات الدفيئة الزراعية في كولومبيا والبرازيل والأرجنتين وكوستاريكا وأوروغواي والمكسيك وبيرو. تم تقييم العديد من خيارات الإدارة والخيارات التكنولوجية، مع إمكانية تخفيف الميثان المعوي، ومن المتوقع أن يساهم قياسها في تحقيق أهداف خفض انبعاثات غازات الدفيئة. ومع ذلك، لا يزال الاعتماد الواسع النطاق لخيارات التخفيف الواعدة محدودًا، مما يثير تساؤلات حول ما إذا كانت أهداف خفض الانبعاثات المتوخاة قابلة للتحقيق. باستخدام البيانات التي تم إنشاؤها محليًا، نستكشف إمكانات التخفيف من التقنيات وممارسات الإدارة المقترحة حاليًا للتخفيف من انبعاثات الميثان المعوية، لأنظمة إنتاج الماشية في البلدان ذات الانبعاثات الأعلى في أمريكا اللاتينية. ثم نناقش العوائق التي تحول دون اعتماد الابتكارات التي تقلل بشكل كبير من انبعاثات الميثان المعوي القائم على الماشية والتحولات الرئيسية في السياسات والممارسات اللازمة لرفع الطموحات الوطنية في البلدان ذات الانبعاثات العالية. باستخدام أحدث العلوم والتفكير الحالي، نقدم وجهة نظرنا حول نهج شامل ونعيد تصور كيف يمكن للقطاعات الأكاديمية والبحثية وقطاع الأعمال والسياسة العامة دعم وتحفيز التغييرات اللازمة لرفع مستوى الطموح وتحقيق أهداف التنمية المستدامة مع الأخذ في الاعتبار الإجراءات على طول الطريق من المزرعة إلى النطاق الوطني.

Biotechnology can greatly improve the efficiency of forest tree breeding for the production of biomass, energy, and materials. However, EU regulations impede the market introduction of genetically modified (GM) trees so their socioeconomic and environmental benefits are not realized. European policy makers should concentrate on a science-based regulatory process.

Reducing methane (CH4) emission from paddy rice production is an important target for many Asian countries in order to comply with their climate policy commitments. National greenhouse gas (GHG) inventory approaches like the Tier-2 approach of the Intergovernmental Panel on Climate Change (IPCC) are useful to assess country-scale emissions from the agricultural sector. In paddy rice, alternate wetting and drying (AWD) is a promising and well-studied water management technique which, as shown in experimental studies, can effectively reduce CH4 emissions. However, so far little is known about GHG emission rates under AWD when the technique is fully controlled by farmers. This study assesses CH4 and nitrous oxide (N2O) fluxes under continuous flooded (CF) and AWD treatments for seven subsequent seasons on farmers’ fields in a pumped irrigation system in Central Luzon, Philippines. Under AWD management, CH4 emissions were substantially reduced (73% in dry season (DS), 21% in wet season (WS)). In all treatments, CH4 is the major contributor to the total GHG emission and is, thus, identified as the driving force to the global warming potential (GWP). The contribution of N2O emissions to the GWP was higher in CF than in AWD, however, these only offset 15% of the decrease in CH4 emission and, therefore, did not jeopardize the strong reduction in the GWP. The study proves the feasibility of AWD under farmers’ management as well as the intended mitigation effect. Resulting from this study, it is recommended to incentivize dissemination strategies in order to improve the effectiveness of mitigation initiatives. A comparison of single CH4 emissions to calculated emissions with the IPCC Tier-2 inventory approach identified that, although averaged values showed a sufficient degree of accuracy, fluctuations for single measurement points have high variation which limit the use of the method for field-level assessments.

Significance Bioethanol produced from waste biomass from crops has the potential to provide a sustainable alternative to petroleum-based transportation fuel that does not compete with human food supply. The main obstacle to this approach is the resistance of this biomass to digestion. Thus, expensive energetic pretreatment and high enzyme inputs are needed to increase digestion. In this study, we screened a population of randomly mutated plants for digestibility with the aim of identifying novel factors that impact on this trait. We found a number of mutants with high digestibility and no impairments in growth or fitness. These mutants show a range of alterations in cell-wall composition, and we have mapped and characterized the mutant with the highest increase in digestibility.

Biomass derived from marine microalgae and macroalgae is globally recognized as a source of valuable chemical constituents with applications in the agri-horticultural sector (including animal feeds and health and plant stimulants), as human food and food ingredients as well as in the nutraceutical, cosmeceutical, and pharmaceutical industries. Algal biomass supply of sufficient quality and quantity however remains a concern with increasing environmental pressures conflicting with the growing demand. Recent attempts in supplying consistent, safe and environmentally acceptable biomass through cultivation of (macro- and micro-) algal biomass have concentrated on characterizing natural variability in bioactives, and optimizing cultivated materials through strain selection and hybridization, as well as breeding and, more recently, genetic improvements of biomass. Biotechnological tools including metabolomics, transcriptomics, and genomics have recently been extended to algae but, in comparison to microbial or plant biomass, still remain underdeveloped. Current progress in algal biotechnology is driven by an increased demand for new sources of biomass due to several global challenges, new discoveries and technologies available as well as an increased global awareness of the many applications of algae. Algal diversity and complexity provides significant potential provided that shortages in suitable and safe biomass can be met, and consumer demands are matched by commercial investment in product development.