Integrating degrowth and efficiency perspectives enables an emission-neutral food system by 2100

Localized nitrogen management strategies can halve fertilizer use in Chinese staple crop production

Nitrogen (N) management is the key to achieving food security and environmental sustainability. Here we analyse N flows using a localized N management model for wheat, maize and rice in 1,690 Chinese counties, with a breakdown of multiple reactive N (Nr) loss pathways. Results show that the total N input for producing these three staple crops in China was 22.2 Tg N in 2015, of which 7.4 Tg N was harvested as grain N and 4.0 Tg N was Nr losses in the forms of NH3 (47%), NOx (10%), N2O (3%), and leaching and runoff (40%). By assuming a production level equivalent to that of the top 10% of counties with the highest N use efficiency and yields surpassing the regional average, we reveal the possibility of achieving national staple crop production targets while improving net ecosystem economic benefit in 2050 through a 49% reduction (10.4 Tg N) in synthetic N fertilizer inputs and a 52% decrease (2.9 Tg N) in Nr losses.

Mixed diets can meet nutrient requirements with lower carbon footprints

Achieving sustainable dietary change is essential for safeguarding human and environmental health. However, dietary recommendations based on broad food groups may not accurately reflect real-world realities because individuals select and consume dishes with multiple food items influenced by diverse context-specific factors. Therefore, here we explored the sustainability trade-offs of dietary choices at the dish level through an optimization modeling approach tested in Japan. We estimated the nutritional quality, price, and carbon footprint of major Japanese dishes and examined 16 dietary scenarios to identify options that meet the nutritional requirements and minimize carbon footprint. Overall, mixed diets contain more combinations of dishes that meet nutritional requirements with lower carbon footprints compared to more restrictive dietary scenarios. We argue that the approach developed here enables a better understanding of dietary trade-offs, complements existing methods, and helps identify sustainable diets by offering nuanced information at the national and sub-national levels.

Beyond the Farm to Fork Strategy: Methodology for designing a European agro-ecological future

The publication of the European Commission's Farm to Fork Strategy has sparked a heated debate between those who advocate the intensification of agriculture in the name of food security and those who recommend its de-intensification for environmental reasons. The design of quantified scenarios is a key approach to objectively evaluate the arguments of the two sides. To this end, we used the accounting methodology GRAFS (Generalized Representation of Agri-Food Systems) to describe the agri-food system of Europe divided into 127 geographical units of similar agricultural area, in terms of nitrogen (N) fluxes across cropland, grassland, livestock, and human consumption. This analysis reveals, in current European agriculture, a high level of territorial specialization, a strong dependence on long distance trade, and environmental N losses amounting to about 14 TgN/yr, i.e. nearly 70 % of the annual N input (including N synthetic fertilizers, symbiotic N fixation, oxidized N deposition and import of food and feed). Based on the analysis of the yield-fertilization relationship of cropping systems at the scale of their full rotation cycle, and on a simplified model of livestock ingestion, excretion and production, we advanced the GRAFS methodology for prospective scenario design. Three scenarios for the European agri-food system were explored for 2050: a business-as-usual (BAU) scenario, a scenario based on the measures considered by the EU Farm to Fork Strategy (F2F), and a fully agro-ecological scenario (AE). The results show that the F2F scenario reduces the dependence of Europe on imports of synthetic fertilizers and feed resources by 40 % as well as the environmental N losses by 30 %, but not to the level of its claimed ambitions as N lost to the environment still amounts to about 10 TgN/yr, i.e. 67 % of N inputs. Of the three scenarios studied, only in the AE scenario, involving the relocation of feed production, the generalization of organic crop rotations with N fixing legume crops, and a shift of agricultural production and food consumption toward less animal-based products, would Europe be able to dispense with N imports, still being able to export some cereals, meat, and milk products to the rest of the world, while halving today's reactive N emissions to the environment.

Is green growth happening? An empirical analysis of achieved versus Paris-compliant CO2-GDP decoupling in high-income countries

BACKGROUND

Scientists have raised concerns about whether high-income countries, with their high per-capita CO2 emissions, can decarbonise fast enough to meet their obligations under the Paris Agreement if they continue to pursue aggregate economic growth. Over the past decade, some countries have reduced their CO2 emissions while increasing their gross domestic product (absolute decoupling). Politicians and media have hailed this as green growth. In this empirical study, we aimed to assess whether these achievements are consistent with the Paris Agreement, and whether Paris-compliant decoupling is within reach.

METHODS

We developed and implemented a novel approach to assess whether decoupling achievements in high-income countries are consistent with the Paris climate and equity goals. We identified 11 high-income countries that achieved absolute decoupling between 2013 and 2019. We assessed the achieved consumption-based CO2 emission reductions and decoupling rates of these countries against Paris-compliant rates, defined here as rates consistent with national fair-shares of the remaining global carbon budgets for a 50% chance of limiting global warming to 1·5°C or 1·7°C (representing the lower [1·5°C] and upper [well below 2°C] bounds of the Paris target).

FINDINGS

The emission reductions that high-income countries achieved through absolute decoupling fall far short of Paris-compliant rates. At the achieved rates, these countries would on average take more than 220 years to reduce their emissions by 95%, emitting 27 times their remaining 1·5°C fair-shares in the process. To meet their 1·5°C fair-shares alongside continued economic growth, decoupling rates would on average need to increase by a factor of ten by 2025.

INTERPRETATION

The decoupling rates achieved in high-income countries are inadequate for meeting the climate and equity commitments of the Paris Agreement and cannot legitimately be considered green. If green is to be consistent with the Paris Agreement, then high-income countries have not achieved green growth, and are very unlikely to be able to achieve it in the future. To achieve Paris-compliant emission reductions, high-income countries will need to pursue post-growth demand-reduction strategies, reorienting the economy towards sufficiency, equity, and human wellbeing, while also accelerating technological change and efficiency improvements.

FUNDING

None.

Building climate resilience, social sustainability and equity in global fisheries

Although the Paris Agreement establishes targets to limit global warming-including carbon market mechanisms-little research has been done on developing operational tools to achieve them. To cover this gap, we use CO2 permit markets towards a market-based solutions (MBS) scheme to implement blue carbon climate targets for global fisheries. The scheme creates a scarcity value for the right to not sequester blue carbon, generating an asset of carbon sequestration allowances based on historical landings, which are considered initial allowances. We use the scheme to identify fishing activities that could be reduced because they are biologically negative, economically inefficient, and socially unequitable. We compute the annual willingness to sequester carbon considering the CO2e trading price for 2022 and the social cost of carbon dioxide (SC-CO2), for years 2025, 2030 and 2050. The application of the MBS scheme will result in 0.122 Gt CO2e sequestered or US$66 billion of potential benefits per year when considering 2050 SC-CO2. The latter also implies that if CO2e trading prices reach the 2050 social cost of carbon, around 75% of the landings worldwide would be more valuable as carbon than as foodstuff in the market. Our findings provide the global economy and policymakers with an alternative for the fisheries sector, which grapples with the complexity to find alternatives to reallocate invested capital. They also provide a potential solution to make climate resilience, social sustainability and equity of global fisheries real, scientific and practical for a wide range of social-ecological and political contexts.

An Equality-Based Approach to Analysing the Global Food System's Fair Share, Overshoot, and Responsibility for Exceeding the Climate Change Planetary Boundary

The climate catastrophe is being caused by human effects on earth system processes that are surpassing several planetary boundaries. This crisis is driven significantly by the global food system. It has been increasing over recent years, yet food systems are essential in upholding food and nutrition security. This study proposed a novel method for enumerating national contributions to the cessation of the climate crisis by approximating nations’ aggregate greenhouse gas (GHG) emissions from food systems, within the equitable and sustainable planetary boundaries of climate change. This study included 221 nations, which were grouped as per their human development index (HDI) categories, income groups, and continental locations. During 1990−2018, the annual fair share, overshoot of emissions, and collective historical responsibility in the world of each country were assessed. There was a 22.52% increase in overshooting of GHG emissions from the global food system, starting in 1990. A group of 15 countries, including Brazil, China, Indonesia, and the U.S.A., were responsible for >67% of global overshoot. The primary liability is borne by countries with upper-, middle-, and high-income economies, and high to very-high HDI groups, as well as Asia and South America. Countries such as India, China, the Democratic Republic of the Congo, and others have steadily increased their share of responsibility over the last 28 years. More than 76% of countries in the world, mostly from Africa, Europe, and Asia, proved to be absolute overshooters. After contextualising the study’s findings, the global food system’s decarbonization and its limits were discussed; some recommendations for prospective research were also offered. It appears that academics, governments, and policymakers should start concentrating more on reshaping and redesigning the global food system to be climate-friendly (i.e., a carbon-neutral food system), whilst being able to fairly allocate food and nutrition security to achieve long-term Sustainable Development Goal 2 (SDG 2).

Insights into Circular Horticulture: Knowledge Diffusion, Resource Circulation, One Health Approach, and Greenhouse Technologies

The integration of the circular economy in agriculture has promoted sustainable innovation in food production systems such as horticulture. The present paper illustrates how horticulture is transitioning to the circular economy. This research field's performance approaches and trends were assessed through a bibliometric and text-mining analysis of the literature. Our findings revealed that circular horticulture is a recent research field that is constantly growing. Its approach has been neither systemic nor integrative but fragmented. Bioeconomy, urban agriculture, recycled nutrients, biochar, fertigation, and desalination have been positioned as research hotspots. Vegetables and fruits are the most studied crops. Resource circulation has focused primarily on biowaste recovery to provide benefits such as biofertilizers and linear-substrate substitutes, and on water reuse for the establishment of hydroponic systems. The One Health approach is scarcely explored and, therefore, weakly articulated, wherein the absence of assessment methodologies encompassing the health of ecosystems, animals, and people is a notable limitation. Science-policy interfaces between One Health and food systems need to be improved. Lastly, greenhouse technologies are aligned with bioenergy, sustainable materials, and sensing technologies. Challenges and directions for future research have been raised to promote the redesign of horticultural production systems, integrating long-term circularity.