This paper provides an overview of the state of findings from the global modelling literature on the potential avenues for achieving SDG2 and the interrelations between this objective and attainment of other SDGs – particularly those related to environmental sustainability.

1. Modelling SDG2: the inherent challenges to sufficient, nutritious, sustaining, and sustainable food

SDG2 “Zero hunger” encompasses five outcome targets that can be summarized as follows:

2.1: ending hunger and ensure access to safe, nutritious and sufficient food;

2.2: ending all forms of malnutrition;

2.3: doubling agricultural productivity and income of small-scale food producers;

2.4: ensuring sustainable and resilient food production systems; and

2.5: maintaining the genetic diversity of farm assets.

The food security pillars (2.1 & 2.2) highlight the importance of producing enough food (“availability”) but also the role of income and food prices (“access” pillar), which raises the questions of the cost of nutritious and healthy food, independently from the diversification of food sources (“utilization” pillar), which also touches to malnutrition. Targets 2.3, 2.4 and 2.5 extend the scope of SDG2 to the modalities of agricultural production. Target 2.3 puts a strong emphasis on farm income for small-scale farmers, linking to SDG1 (“No poverty”), through an increase of their farm productivity. This target should however be reached without jeopardizing Target 2.4 that emphasizes sustainable production practices, and Target 2.5 that highlights the importance of keeping genetic diversity. The different SDG2 targets therefore contain their own points of tension: how can we produce more, in a manner that is more healthy, more sustainable and more equitable -- all at the same time?

Providing adequate food for all and reducing hunger (Target 2.1)

FAO estimates that the total food calorie demand will increase by 39% between 2015 and 2050 and agricultural output will grow somewhat faster (40-45%), due to the need to produce feedstuffs for growing livestock consumption.

Dietary needs, nutrition transition and the triple burden of malnutrition (Target 2.2)

Beside undernourishment and micronutrient deficiencies, a third important nutritional challenge is overweight and obesity, leading to the notion of the “triple burden of malnutrition”. It has been estimated that halting overconsumption by 2030 would reduce total caloric requirement by 6% and protein requirement by 9% globally.

Producing more but growing more sustainably (Target 2.4)

The impacts of agricultural production increases on natural resources are well known and researchers have warned about the risks of exceeding a number of planetary limits due to agriculture intensification and expansion. The question of the pressure of agricultural production on natural resources extends much beyond land use expansion but also relate to land quality and many other elements (water, climate, nutrient balance, etc.).

The crucial role of agriculture productivity (Target 2.3 & 2.5)

The prospects on future yield increase remains positive. The assessment of yield gaps indicate that large potentials exist to increase actual yields to the level achieved under best practices, but remain subject to local climatic and management constraints. Closing yield gaps globally could increase global crop production by 45%–70%, by optimizing water and nutrient management, and reallocating crops accordingly could reduce cropland area by 50%. One challenge associated with productivity increases is to ensure that, while saving on land resources, it does not bring any other environmental degradation (e.g. land intensification). Improvements in agricultural productivity, in particular total factor productivity (related to all production factors), offers an opportunity to simultaneously lower the pressure on the environment and increase farmer income by decreasing the input requirements. Finally, increasing agricultural productivity is also key in the context of ongoing climate change impacts which are expected to grow over the coming decades and substantially affect crop yields, irrigation capacity, labour productivity, micronutrient availability and ultimately food security.

2. Synergies between SDG2 and other sustainability dimensions

The “Zero Hunger” goal – and its different targets – is very closely connected to some other goals with which it operates in synergy, and, for some, even in full symbiosis. One of these is poverty elimination (SDG1), crucial for food access, and another is good health and well-being (SDG3), and the need for clean drinking water (SDG6). But beyond these, a broader set of socioeconomic SDGs supports the progress of SDG2 and has been identified as key enablers (SDG4, 5, 8, 10, 11, 16, and 17).

Food access and poverty (SDG1)

Many scholars highlighted that, if in the short term, food price increases could be seen as detrimental for the poor, sustained food prices could be in the long term the best way to reduce rural poverty and improve food security for smallholders. Therefore, if food security and poverty can be seen as part of a same battle, reduction of poverty should not only be sought through lower food prices but also through higher income – as highlighted by Target 2.3.

Health and sustainability co-benefits from dietary changes (SDG3)

The relation between SDG2 and SDG3 on good health and well-being is also strongly synergistic, as nutrition is a key element of good health. Adequate diet does not only limit the risk of malnutrition, but also prevents the prevalence of a number of non-communicable diseases. The EAT-Lancet Commission has proposed a sustainable and healthy diet prescription integrating a large number of dietary risks, with ambitious nutritional and planetary synergies. Adopting such a diet would allow reduce mortality by 19–23.6% by 2050. However, providing such diet to all would require bridging the yield gaps by 75%, requiring substantial resource management improvements in order to be sustainably attainable. One other important limitation to the adoption of these healthy diets is the question of affordability. Therefore, improving access to healthy diets cannot be dissociated from the progress on poverty elimination (SDG1).

One additional synergy between SDG2 and SDG3, comes from environmental health through a more sustainable agriculture (Target 2.4). Agricultural activities indeed substantially contribute to global pollution through various channels.

A last area of synergy between SDG2 and SDG3 attracted more attention since the COVID-19 crisis: the risk of zoonosis epidemic associated to expansion of human settlements and agriculture into wilderness areas, directly referred to in Target 3.3.

Education, gender equality, decent work and other socioeconomic enablers (SDG4, 5, 8, 10, 11, 16, 17)

Education (SDG4) is a first important development driver influencing consumption patterns and healthy diet choice. Target 4.7 highlights education to sustainable lifestyle, which goes one step further into supporting sustainable food systems.

Gender equality (SDG5) is another key goal for food security as female workers are a substantial share of the agricultural workforce – 40-50% in developing countries. SDG5 can therefore support income and productivity increases (Target 2.3) for small-scale women farmer by enhancing their access to land and natural resources (Target 5.a) and empowering them to safeguard the nutritional status in the households.

Decent work and economic growth (SDG8) and reduction of inequality (SDG10) can also support better nutrition by going beyond SDG1 and bringing economic resources (Target 8.1 and10.1) to households for accessing healthy food.

Peace, justice and strong institutions (SDG16) have a key role to play for food security as conflict remains one of the most severe drivers of severe undernourishment and food crises.

Partnership for the goals (SDG17) emphasizes the role of Development Assistance, for rural economic development in developing countries, and the need to address the most serious food crises through humanitarian aid.

3. Trade-offs between SDG2 and environmental goals

Growing more food for SDG2 will pose some serious challenges for natural resources, and the final impacts will depend on future food demand and our capacity to create a more resource-efficient and sustainable agriculture globally.

Six planet boundaries are directly relevant to agriculture (climate change, biodiversity, nitrogen, phosphorus, freshwater use, land use change), and three of these boundaries have already been exceeded: nitrogen cycle, biodiversity loss and climate change.

Contribution to climate change and trade-offs with nature-based solutions (SDG13)

One of the most widely studied adverse environmental impacts of the food system is its contribution to climate change. The food system (including agriculture, food supply chain and waste management) is considered to represent today 34% of total anthropogenic GHG emissions.

Reducing emissions from the food systems is only one of the climate change mitigation channels. In addition, land may also be used as a resource to store carbon and help decarbonize the economy by producing cleaner sources of energy and substituting fossil fuels.

Water resource competition and environmental flow requirements (SDG6)

Overconsumption of water resources is another critical challenge faced by agriculture. Irrigation represents today 70% of global water withdrawals. Globally, ~30% of total water withdrawals are considered non-sustainable today. This situation will likely worsen with the impact of climate change and the development of new hotspots of water scarcity. Therefore, improving water use efficiency appears crucial to boost water’s foot print per crop calorie, and animal protein.

Nitrogen and phosphorus pollution (SDG6)

Nitrogen (N) and phosphorus (P) cycles represent two planetary boundaries estimated as critically exceeded.

Terrestrial biodiversity impacts and conservation needs (SDG15)

The global food system is among the main causes behind the sixth massive species extinction on Earth. Land use change and overexploitation of resources, closely associated with the food sector, are estimated to be the largest drivers of biodiversity losses, followed by climate change impacts and water pollution, both of which are also partly driven by the food system.

Land degradation (SDG15)

Land degradation is an additional growing threat specially identified through Target 15.3 aiming for degradation neutrality. According to UNCCD (2017), 20% of cropland and 19% of grassland showed a persistent decline in productivity over the period 1998-2013, which directly impacts agricultural production in these areas. In rural areas, soil degradation and food insecurity are intimately related, due to the importance of soil for crop fertility and nutrient provisioning. Increased aridity, affecting 40% of arable land, is a major factor in arable land degradation when coupled with unsustainable land management, followed by soil erosion with 20%, which depletes nutrient stocks, in particular phosphorus.

Fisheries and marine life conservation (SDG14)

Overfishing is putting important pressure on marine fish population and reduces catches in low-income food deficit countries by around 15%. Assessments converge on the fact that marine protected areas could bring win-win solutions to both biodiversity and fisheries by reconstituting fish stocks in overfished areas, and benefitting yields of adjacent fish zones.

Competition for land with urbanization and infrastructure needs (SDG9 & 11)

Urban areas are expected to triple during the period 2000-2030, and could take between 1.8 and 2.4% of global cropland, mostly in Asia and Africa, and 3–4% of crop production due to the higher productivity of that land. This area lost to agriculture could be three times higher than those figures if peri-urban and village systems expansion were also considered.

4. Towards sustainable pathways: transforming the food system for the Agenda 2030

With all the impacts and challenges highlighted above, there is a consensus that the global food system needs deep changes in the 21stcentury to support achievement of the Agenda 2030. Large-scale transformations will be required, both on the supply and demand sides.

Investment, research, and innovation for sustainable agriculture (Target 2.a)

Public spending on agricultural R&D has tripled in developing countries between 1981 and 2011 and now equals those of developed countries. However, budgets remain very uneven depending on the region. Furthermore, the effectiveness of R&D investments in generating real productivity gains varies widely across regions and is often significantly lower in poorer regions such as Sub-Saharan Africa.

Increasing public investments could ensure important productivity gains in the future, but need to be sustained over time as their effects typically materialize on time frames of 11 to 30 years. Innovations should in addition be examined under the broader perspective of their impacts across the full SDG spectrum, to ensure food benefits do no induce some other adverse environmental or socioeconomic trade-offs.

International trade and food markets (Target 2.b and 2.c)

The role of market integration is also well acknowledged in SDG2 through Targets 2.b and 2.c. Trade integration can support food security by lowering agricultural product prices and providing easier access to food products. This is even more important in the context of increased production variability under the threat of climate change extreme events. However, international trade could increase environmental pressure if production is relocated to less sustainable areas. To limit the environmental impacts of trade liberalization, consistent environmental standards are needed across regions or border-tax adjustments would have to be added in trade agreements to correct for the different emission-intensities and displaced externalities between trading countries.

Shifting diets

Other impactful measures can also be taken on the demand side to support the transformation of the food systems. Changing our consumption patterns has been recognized for its potential to leverage considerable benefits on SDG outcomes, both by relieving pressure on natural resources and fostering the health co-benefits.

Quantification of the impact of dietary shifts has been achieved in many studies to date. These scenarios are often assuming replacing animal proteins by vegetal ones, but a shift from meat towards aquaculture would also bring substantial land sparing effects.

The most influential recent publication on the topic from the EAT-Lancet Commission assesses that shifting to a healthier and more sustainable (flexitarian) diet would reduce global emissions by 4.8 Gt CO2e, but do not find any saving in cropland and water consumption due to the extra needs for some specific crops. However a pescatarian, vegetarian or vegan diet would bring higher benefits including up to 500 Mha land savings.

In addition to shifts to other traditional products, an increasing interest also relates to the potential of “future foods” – composed of products not widely consumed until now, such as insects, algae, cultured meat – to bring new sustainable and healthy options. Imitation meat based on vegetal proteins appears the most promising of the options studied and constitute particularly cost-competitive alternatives.

Reducing food waste and losses

Also aligned with SDG12 objectives, reducing inefficiencies along the food supply chain as well as in households and restaurants represent an additional lever for sustainable transformation, explicitly identified in Target 12.3 with the objective of halving food waste per capita and reducing food losses by 2030.

The common assumption has been over the past decade that one third of food lost or wasted. More recent refinements allowed to estimate the extent of global food losses at 14%, whereas consumer waste would range from 2–17% for cereals to14–33% for meat and animal products.

Transformative pathways for the world’s food systems

Not many transformations are win-wins across all dimensions. Reducing food losses is one of them when harvest losses are included and avoidable at low cost for the producer. Some options can be combined, e.g. sustainable and healthy diets could be designed to deliver positive outcomes across all dimensions.

Studies of food system transformation highlight the need for combining a large number of options on both the supply and demand sides in order to achieve sustainable pathways.