Dependence on the socio-economic system impairs the sustainability of pasture-based animal agriculture.

Livestock systems contribution to environmental change is controversial. Pasture-based systems are considered a sustainable alternative due to their adaptation to the use of local natural resources. However, they have limited productivity per product unit and, in Europe, depend on public economic support. Furthermore, they are heterogeneous in farm structure and resources use, which may determine their sustainability. We use emergy accounting to assess the sustainability of mountain pasture-based cattle systems and analyse the variability among farms. Emergy accounting assesses the sustainability performance of complex systems (i.e., farming systems) and their interaction with other systems (i.e., the environment and the socio-economic system) focusing on the origin, quality and quantity of the energy required for the system to function. Results show that pasture-based systems largely use local natural renewable resources but depend largely on the wider socio-economic system given their reliance on public economic support and purchased animal feeds. This economic dependence turns out in most farms largely using non-renewable resources. Increasing self-produced feeds and grazing on natural pastures can reduce the dependence on the socio-economic system and improve farm sustainability.

Investigating the environmental sustainability of a seabass and seabream aquaculture system in Portugal based on life cycle and nexus approaches.

Aquaculture plays an essential role in supplying animal-source food and protein worldwide, in this way contributing to several sustainable development goals. Notwithstanding this, the aquaculture sector's long-term environmental sustainability is a major concern due to overall environmental impacts. To date, and to the best of the authors' knowledge, assessments of aquaculture systems in Portugal from an environmental perspective, and the nexus between resource consumption and nutrition issues, are still lacking. This study bridges this gap by analysing an aquaculture system in Portugal in a comprehensive manner by applying and combining life cycle assessment and resources-protein nexus approaches. The overall results highlight feed as the main factor responsible for the total impact in all impact categories selected, ranging from 74 % to 98 %. Climate change impact results in 2.88 kg CO2-eq per kg of medium-size fish (functional unit). The resources-protein nexus shows that 504.1 MJex is needed to obtain 1 kg of edible protein, with a high dependency on non-renewable resources (59 %), mainly oil by-product fuels used in feed production. After identifying environmental hotspots, potential strategies to be adopted such as resource consumption reduction, eco-certification and ecosystem-based management are suggested, in this way ensuring long-term aquaculture production and environmental sustainability.

Determining the net environmental performance of hydropower: A new methodological approach by combining life cycle and ecosystem services assessment.

In the face of climate-ecological breakdown, it is well known that the world aims at developing renewable energies in order to replace fossil fuels. However, there is a great concern regarding their environmental-ecological issues specially with those ones that have a deep interplay with its immediate environment such the case of hydropower. Despite efforts, the existing environmental-ecological methodologies and approaches are incapable to encompass the wide impacts of hydropower. To bridge this knowledge gap, the goal of this paper is twofold: first, to propose a methodological approach that combines and balances two well-known environmental-ecological assessments: life cycle (LCA) and ecosystem services assessment (ESA). This way, the proposal enables a deeper look into the environmental-ecological performance. Second, to determine the total environmental-ecological accounting and hence the net environmental performance of hydropower. In order to expose the applicability of the proposed methodological approach, case studies of a dam and run-of-river hydropower plant located in Ecuador were examined. Analysis found a net environmental performance (NEP) of -0.98 $/kWh and -0.08 $/kWh, respectively. These results clearly indicate a marked environmental-ecological difference between these two hydropower schemes, awareness of which may be helpful for further decision-making and developing new energy policies in pursuit of sustainable development goals. What is more, this methodological approach may be applied and extended not only to other renewable energy technologies, but also to any other project or activity where the exploitation and use of natural resources are involved.