In our globalised food system, farmers meet domestic and transboundary food needs. As a result, the contribution of farmers to domestic food production is a poor proxy for their role in national... Show moreIn our globalised food system, farmers meet domestic and transboundary food needs. As a result, the contribution of farmers to domestic food production is a poor proxy for their role in national food security. This study offers the first global assessment of how small-, medium-, and large-scale farmers contribute to global food security. We find that the role of small-scale farmers in national and global food security has been significantly underestimated due to the localised focus of previous studies, particularly in high-income nations. Future research must account for the differentiated roles, impacts, and vulnerabilities of farmers within a global context. Show less
The increase in food demand and limited opportunities to expand agricultural land pose a threat to local and global food security. Producing food in urban areas such as green roofs can help satisfy... Show moreThe increase in food demand and limited opportunities to expand agricultural land pose a threat to local and global food security. Producing food in urban areas such as green roofs can help satisfy urban food demand and thus alleviate pressure on agricultural land. However, a modeling framework that simulates crop growth and production potential on green roofs at a city scale is missing. Here, we adapt the Aquacrop model to explore the growth potential of various types of crops on green roofs and apply it to suitable roof areas in the city of Amsterdam. Our modeling framework includes irrigation methods for water use on green roofs that are optimized according to various climate-driven scenarios of water availability. We find that cabbage has the maximum achievable crop yields ranging from 30.8 to 75.9 t ha-1 yr-1, while pea has the minimum achievable crop yields ranging from 1.7 to 6.4 t ha-1 yr-1. The potential suitable green roof area (i.e., roofs with a certain slope and bearing capacity) for Amsterdam is roughly 400 ha for crop production. This represents 16 % of the total rooftop areas of Amsterdam and can produce up to a total of 28 kt of crops on an annual basis. Our modeling framework can be easily applied to other cities to identify the crop growth potential of green roofs. Our results can help policymakers and urban planners find optimal planting strategies and contribute to shorter food supply chains. Show less
Inefficient global nutrient (i.e., phosphorus (P) and nitrogen (N)) management leads to an increase in nutrient delivery to freshwater and coastal ecosystems and induces eutrophication in these... Show moreInefficient global nutrient (i.e., phosphorus (P) and nitrogen (N)) management leads to an increase in nutrient delivery to freshwater and coastal ecosystems and induces eutrophication in these aquatic environments. This process threatens the various species inhabiting these ecosystems. In this study, we developed regionalized characterization factors (CFs) for freshwater eutrophication at 0.5 × 0.5-degree resolution, considering different fates for direct emissions to freshwater, diffuse emissions, and increased erosion due to agricultural land use. The CFs were provided for global and regional species loss of freshwater fish. CFs for global species loss were quantified by integrating global extinction probabilities. Results showed that the CFs for P and N impacts on freshwater fish are higher in densely populated regions that encompass either large lakes or the headwaters of large rivers. Focusing on nutrient-limited areas increases country-level CFs in 51.9 % of the countries for P and 49.5 % of the countries for N compared to not considering nutrient limitation. This study highlights the relevance of considering freshwater eutrophication impacts via both P and N emissions and identifying the limiting nutrient when performing life cycle impact assessments. Show less
Large-scale offshore wind energy developments represent a major player in the energy transition but are likely to have (negative or positive) impacts on marine biodiversity. Wind turbine... Show moreLarge-scale offshore wind energy developments represent a major player in the energy transition but are likely to have (negative or positive) impacts on marine biodiversity. Wind turbine foundations and sour protection often replace soft sediment with hard substrates, creating artificial reefs for sessile dwellers. Offshore wind farm (OWF) furthermore leads to a decrease in (and even a cessation of) bottom trawling, as this activity is prohibited in many OWFs. The long-term cumulative impacts of these changes on marine biodiversity remain largely unknown. This study integrates such impacts into characterization factors for life cycle assessment based on the North Sea and illustrates its application. Our results suggest that there are no net adverse impacts during OWF operation on benthic communities inhabiting the original sand bottom within OWFs. Artificial reefs could lead to a doubling of species richness and a two-order-of-magnitude increase of species abundance. Seabed occupation will also incur in minor biodiversity losses in the soft sediment. Our results were not conclusive concerning the trawling avoidance benefits. The developed characterization factors quantifying biodiversity-related impacts from OWF operation provide a stepping stone toward a better representation of biodiversity in life cycle assessment. Show less
Kortleve, A.J.; Mogollón, J.M.; Heimovaara, T.J.; Gebert, J. 2022
The European Union (EU) has set a 37.5% GHG reduction target in 2030 for the mobility sector, relative to 1990 levels. This requires increasing the share of zero-emission passenger vehicles, mainly... Show moreThe European Union (EU) has set a 37.5% GHG reduction target in 2030 for the mobility sector, relative to 1990 levels. This requires increasing the share of zero-emission passenger vehicles, mainly in the form of electric vehicles (EVs). This study calculates future GHG emissions related to passenger vehicle manufacturing and use based on stated policy goals of EU Member States for EV promotion. Under these policies, by 2040 the stock of EVs would be about 73 times larger than those of 2020, contributing to a cumulative in-use emission reduction of 2.0 gigatons CO2- eq. Nevertheless, this stated EV adoption will not be sufficiently fast to reach the EU's GHG reduction targets, and some of the GHG environmental burdens may be shifted to the EV battery manufacturing countries. To achieve the 2030 reduction targets, the EU as a whole needs to accelerate the phase-out of internal combustion engine vehicles and transit to e-mobility at the pace of the most ambitious Member States, such that EVs can comprise at least 55% of the EU passenger vehicle fleet in 2030. An accelerated decarbonization of the electricity system will become the most critical prerequisite for minimizing GHG emissions from both EV manufacturing and in-use stages. Show less
The rapid acceleration of anthropogenic phosphorus (P) loadings to watersheds has fuelled massive freshwater and coastal eutrophication and completely changed the global P cycle. Within watersheds,... Show moreThe rapid acceleration of anthropogenic phosphorus (P) loadings to watersheds has fuelled massive freshwater and coastal eutrophication and completely changed the global P cycle. Within watersheds, emitted P is transported downstream towards estuaries. Reservoirs can retain a significant proportion of this P. In the long term, this accumulated P can however be re-mobilized, a process lacking in current global P budgets. Here, we include P cycling in a coupled integrated assessment-hydrology-biogeochemistry framework with 0.5 by 0.5-degree spatial resolution and an annual time resolution, and apply it to the Mississippi River basin (MRB). We show that, while reservoirs have aided in the net retention of P, they serve as dissolved inorganic P (DIP) sources due to the transformation of legacy P in sediments. The increasing DIP sourcing in the MRB has been offsetting P retention in streams, especially towards the end of the twentieth century. Due to its bioavailability, DIP is the most likely form to trigger eutrophication. Although P inputs into the MRB have decreased since the 1970s, legacy effects are delaying positive outcomes of remediation measures. Show less
Navarre, N.H.; Mogollón, J.M.; Tukker, A.; Barbarossa, V. 2022
Plastic food packaging is a cost-effective tool to minimize food waste. However, plastic food packaging rapidly generates waste and if mismanaged can leak to the environment adversely affecting... Show morePlastic food packaging is a cost-effective tool to minimize food waste. However, plastic food packaging rapidly generates waste and if mismanaged can leak to the environment adversely affecting ecosystems. We quantified the plastic waste leaked to the marine environment due to food consumption in the Netherlands. Combining food consumption patterns, food waste estimates, and plastic packaging data, we estimated the plastic packaging intensity of the Dutch diet. We then mapped the fate of the plastic food packaging waste generated using Dutch plastic waste management patterns. We estimate that a total of 296 kt/yr of plastic food packaging is required in the Netherlands. We model that 6.5 kt/yr is leaked to the marine environment, with 75% of this leakage resulting from the exportation of plastic waste to nations in Asia, 3% from all other nations, and 22% due to littering. We conclude that despite being a high-income nation with a post-consumer plastic packaging waste network reporting a 78% recycle rate, Dutch plastic food packaging waste is leaked to the marine environment at a globally average rate, raising questions about plastic recycle rate metrics and Dutch/EU plastic waste export policies. Show less
Offshore wind energy (OWE) is a cornerstone of future clean energy development. Yet, research into global OWE material demand has generally been limited to few materials and/or low technological... Show moreOffshore wind energy (OWE) is a cornerstone of future clean energy development. Yet, research into global OWE material demand has generally been limited to few materials and/or low technological resolution. In this study, we assess the primary raw material demand and secondary material supply of global OWE. It includes a wide assortment of materials, including bulk materials, rare earth elements, key metals, and other materials for manufacturing offshore wind turbines and foundations. Our OWE development scenarios consider important drivers such as growing wind turbine size, introducing new technologies, moving further to deep waters, and wind turbine lifetime extension. We show that the exploitation of OWE will require large quantities of raw materials from 2020 to 2040: 129-235 million tonnes (Mt) of steel, 8.2-14.6 Mt of iron, 3.8-25.9 Mt of concrete, 0.5-1.0 Mt of copper and 0.3-0.5 Mt of aluminium. Substantial amounts of rare earth elements will be required towards 2040, with up to 16, 13, 31 and 20 fold expansions in the current Neodymium (Nd), Dysprosium (Dy), Praseodymium (Pr) and Terbium (Tb) demand, respectively. Closed-loop recycling of end-of-life wind turbines could supply a maximum 3% and 12% of total material demand for OWE from 2020 to 2030, and 2030 to 2040, respectively. Moreover, a potential lifetime extension of wind turbines from 20 to 25 years would help to reduce material requirements by 7-10%. This study provides a basis for better understanding future OWE material requirements and, therefore, for optimizing future OWE developments in the ongoing energy transition. Show less
Continuous reduction in the levelized cost of energy is driving the rapid development of offshore wind energy (OWE). It is thus important to evaluate, from an environmental perspective, the... Show moreContinuous reduction in the levelized cost of energy is driving the rapid development of offshore wind energy (OWE). It is thus important to evaluate, from an environmental perspective, the implications of expanding OWE capacity on a global scale. Nevertheless, this assessment must take into account various scenarios for the growth of different OWE technologies in the near future. To evaluate the environmental impacts of future OWE development, this paper conducts a prospective life cycle assessment (LCA) including parameterized supply chains with high technology resolution. Results show that OWE-related environmental impacts, including climate change, marine ecotoxicity, marine eutrophication, and metal depletion, are reduced by similar to 20% per MWh from 2020 to 2040 due to various developments including size expansion, lifetime extension, and technology innovation. At the global scale, 2.6-3.6 Gt CO2 equiv of greenhouse gas emissions are emitted cumulatively due to OWE deployment from 2020 to 2040. The manufacturing of primary raw materials, such as steel and fibers, is the dominant contributor to impacts. Overall, 6-9% of the cumulative OWE-related environmental impacts could be reduced by end-of-life (EoL) recycling and the substitution of raw materials. Show less
Yamamoto, T.; Merciai, S.; Mogollón, J.M.; Tukker, A. 2022
Metal resources are unevenly distributed throughout the globe but are crucial for the global economy. Many economies are highly dependent and vulnerable to material supply from other parts of the... Show moreMetal resources are unevenly distributed throughout the globe but are crucial for the global economy. Many economies are highly dependent and vulnerable to material supply from other parts of the world. This situation can be alleviated by recycling, as regions devoided of important reserves exploit their own urban mine. In this study, we explored an increased domestic recycling scenario utilizing a stock-flow perspective combined with a hybrid input-output database (EXIOBASE). We applied a mass rebalancing procedure on the production and trade flows of ores and metals. We calculated the supply risk with the GeoPolRisk method for single and two -stage supply chains. Results show that recycling reduce the risk associated with trade for most of countries and materials for the metal supply chain, where recycling effectively takes place. In contrast, such risk decrease is not found in the ore supply chain nor in the combined ore and metal supply chain. Show less
Food products require significant amounts of energy and water throughout their lifecycle, yet humanity wastes 1.3e9 tons of food on a yearly basis. A large part of this waste occurs during the... Show moreFood products require significant amounts of energy and water throughout their lifecycle, yet humanity wastes 1.3e9 tons of food on a yearly basis. A large part of this waste occurs during the consumption (post-retail) phase of the food system as avoidable food waste, the discarded edible (parts of) food products. In this study, we explore the effects of avoidable food waste on the Food-Energy-Water nexus. We show that the 344 million tonnes of global avoidable food waste is responsible for squandering 4e18 J of energy and 82e9 m3 of water. While there are important regional differences in terms of avoidable food waste due to varying diets and waste incidences, these energy and water losses are rivaling the electricity and the blue water use of populous nations, and adding to needless pressures on the environment. Show less
Rueda, O.; Mogollón, J.M.; Tukker, A.; Scherer, L. 2021
Our carbon-intensive economy has led to an average temperature rise of 1 °C since pre-industrial times. As a consequence, the world has seen increasing droughts, significant shrinking of the polar... Show moreOur carbon-intensive economy has led to an average temperature rise of 1 °C since pre-industrial times. As a consequence, the world has seen increasing droughts, significant shrinking of the polar ice caps, and steady sea-level rise. To stall these issues’ worsening further, we must limit global warming to 1.5 °C. In addition to the economy’s decarbonization, this endeavour requires the use of negative-emissions technologies (NETs) that remove the main greenhouse gas, carbon dioxide, from the atmosphere. While techno-economic feasibility alone has driven the definition of negative-emissions solutions, NETs’ diverse, far-reaching implications demand a more holistic assessment. Here, we present a comprehensive framework, integrating NETs’ critical performance aspects of feasibility, effectiveness, and side impacts, to define the optimal technology mix within realistic outlooks. The resulting technology portfolios provide a useful new benchmark to compare carbon avoidance and removal measures and deliberately choose the best path to solve the climate emergency. Show less
