* Modern plant breeding threatens traditional crop varieties and crop wild relatives, but is completely dependent on the genetic diversity that they represent.

## 2.1 The Diversity of Foods Produced and Available Is Insufficient for Healthy Diets

While there is no single solution to the hunger and dietary health challenges afflicting nearly half the global population, low dietary diversity is a common thread. Only around 130 internationally significant food plants – including 20 cereal crops, 7 roots and tubers, 28 fruits, 19 vegetables, 11 pulses, 8 nuts, 16 oils, 15 herbs and spices, 2 sugars and 3 stimulants – make up the bulk of peoples’ diets around the world. In addition, just 15–20 major domesticated land animals are used in food and agriculture (Bélanger and Pilling 2019).

Food diversity is as much about choice as it is about health. There is robust evidence showing that, while we produce enough food to meet the caloric needs of today’s global population, current production systems fail to provide a healthy diet for all because of underproduction of food diversity. Global analyses of regional trends signal a nearly universal underconsumption of fruits, nuts, vegetables, whole grains and seeds; with regional patterns of over- and underconsumption of red and processed meat; and equally variable consumption of legumes (Afshin et al. 2019). High-sodium, low-diversity diets are the leading cause of mortality attributed to diet, accounting for an estimated 11 million premature deaths per year (Willett et al. 2019).

Global production and the availability of foods are fundamentally mismatched with recommended healthy consumption patterns (Willett et al. 2019; Kc et al. 2018). Ensuring healthy diets for all by 2050 requires an important shift in what foods are produced and consumed, including no significant increase in cereal production coupled with significant increases in vegetables, legumes, fruit, fish, nuts and seeds and a large reduction in red meat production and consumption globally (Afshin et al. 2019) – although, in some regions, meat consumption could be increased to counter nutritional deficiencies such as iron-deficient anemia (Golden et al. 2011) (Table 1). Increasing the diversity of animal-sourced proteins, notably, of healthier and often less energy intensive fish, shellfish, and poultry proteins, is consistently underexplored in discussions on shifts towards healthy and sustainable diets (see the UNFSS Blue Foods and Livestock Reports).

## 2.2 Healthy Diets Include a Wide Range of Choices

At least five major food groups, and thus, at minimum, 4–5 species, are required in a healthy diet, with whole grains, fruits, vegetables, oils and protein (plant or animal) being essential (Table 1). The absence of one food group drives critical challenges of
<table><caption>**Table 1** Summary of food groups, recommended healthy daily consumption</caption><thead><tr><th>Food Group</th><th>Recommended Per Capita Daily Consumption (g)</th><th>Estimated Global Production Change (2050)</th><th>Diversity of Species/Varieties</th></tr></thead><tbody><tr><td>Whole grains</td><td>232</td><td>0</td><td>20 major cultivated species with 850,000 varieties; dozens of minor species; many wild species as well</td></tr><tr><td>Tubers or starchy vegetables</td><td>0–100</td><td>+20%</td><td>7 major cultivated species with 25,000 varieties; 12 minor species; various wild species as well</td></tr><tr><td>Vegetables</td><td>200–600</td><td>+75%</td><td>19 major cultivated species; 40 minor species; hundreds of wild species as well</td></tr><tr><td>Seaweeds</td><td>–</td><td>–</td><td>7 commonly cultivated species, unknown diversity, and contribution to health</td></tr><tr><td>Fruits</td><td>100–300</td><td>+50%</td><td>28 major cultivated species; 45 minor species; hundreds of wild species as well</td></tr><tr><td>Dairy foods</td><td>0–500</td><td>+5%</td><td>3 major domesticated species.</td></tr><tr><td>Red meat</td><td>0–28</td><td>-65%</td><td>4 major cultivated species</td></tr><tr><td>Poultry</td><td>0–58</td><td>+2%</td><td>6 major cultivated species</td></tr><tr><td>Eggs</td><td>0–25</td><td>-25%</td><td>1 major cultivated species</td></tr><tr><td>Fish, shell-fish and crustaceans</td><td>0–100</td><td></td><td>&gt;3200 taxa</td></tr><tr><td>Legumes</td><td>0–100</td><td>+75%</td><td>11 major cultivated species with 120,000 varieties; 25 minor species; various wild species as well</td></tr><tr><td>Nuts</td><td>0–75</td><td>+150%</td><td>8 major cultivated species; 6 minor species; various wild species as well</td></tr><tr><td>Unsaturated oils</td><td>20–80</td><td></td><td>16 major cultivated oil crop species; 15 minor species; various wild species as well</td></tr><tr><td>Sugars</td><td>0–30</td><td></td><td>2 major cultivated species; various minor species and wild species as well</td></tr></tbody></table>

Willett et al. (2019) required change in production volume compared to current production to secure low risk diets globally, and approximate diversity of cultivable species.

malnutrition, which are stubbornly persistent in several hotspots requiring emergency assistance or fortification as an intermediate remedy. In both high- and low-income countries, however, increasing dietary diversity, within energetic requirements, would have significant impacts on improved health. Thousands more species, breeds and varieties could support human nutrition. Beyond the 130 odd species that dominate global production and consumption, about 120 other food crops that are less well monitored in production, trade and dietary data have regional significance. Practically nonexistent in food system data are well over 1000 wild plants known to be used, at least occasionally, as human food
(Khoury et al. 2019), and the nutritional value of over 3200 aquatic animal species used as food has been documented, not including growing interest in edible aquatic plants (algae) commonly consumed in Asian diets (Rajapakse and Kim 2011). Seaweeds have largely been unexplored as a more important food source, but present an area of innovation for nutritious food production without land, freshwater, or fertilizer requirements (Bernhardt and O'Connor 2021).

Context will determine whether any single food group is over- or under-consumed. Whole-of-plate approaches that ensure that everyone everywhere has access to a diversity of foods, notably, across food groups, are key to SDGs 2 and 3. While a healthy diet with balanced consumption across food groups is a universal goal, the diversity of foods within food groups offers people the possibility to match foods across the year to environmental contexts, individual tastes and cultural preferences.

## 2.3 The Demand and Supply of Healthy Diets Contributes to Climate and Environmental Outcomes

Diverse production can bring us closer to planetary health goals. A shift towards healthy diets could reduce per capita emissions from food production between 30% and 50%, while also accounting for a 20% reduction in freshwater consumption and a 20% decrease in the land needed to meet consumption demand (Willett et al. 2019; Clark et al. 2019; Tilman and Clark 2014). Globally, this would mean no net increase in agricultural lands, in line with CBD goals of no net loss of nature by 2050, primarily driven by reduced overconsumption of red meat (Tilman and Clark 2014; Clark et al. 2020).

# 3 Agriculture Must Share Space with Biodiversity to Meet Global Environmental Goals

## Take-Home Messages

* Diversification strategies within fields, between fields and across landscapes are often regenerative, synergistic and multipurpose, and can bolster ecosystem functions within resilient agricultural production systems.

* There is no evidence that diversified production systems compromise food security – many agricultural diversification practices provide multiple complementary benefits.

* At least 10–20% of semi-natural habitat per km² is needed to ensure ecosystem functions, notably, pollination, biological pest control and climate regulation, and to prevent soil erosion, nutrient loss and water contamination. Today, 18–33% of agricultural lands are below these respective threshold values for biological integrity.
* Regenerative agricultural practices have the potential to mitigate emissions by 4.3–6.9 Gt CO₂e year⁻¹ globally, and agricultural lands represent 47% of the soil carbon climate mitigation potential.

* Agricultural, field and farm biodiversity can reduce agriculture's dependence on water capture and water quality through soil carbon sequestration, on-farm practices and appropriate crop selection.

* Crop wild relatives provide critically important traits to cultivated crops through breeding. Many crop wild relatives are also collected for direct dietary, medicinal and other cultural uses, and various species represent attractive candidates for development into new crops.

**3.1 Agriculture Depends on Biodiversity**

All agricultural systems depend on biodiversity for crop genetic diversity, pest control, animal-mediated pollination and healthy soils that promote nutrient capture and water delivery for crop growth. Diversified agroecological practices offer numerous opportunities at the field, farm and landscape scales, but are not a panacea. Thoughtful application and integration of novel technologies and practices that complement diversification are required, as well as mitigation of trade-offs such as pest species spilling over from natural or semi-natural habitats (Zhang et al. 2007).

**3.2 Diversification Strategies Are Often Regenerative, Synergistic and Multipurpose**

Agricultural practices that support biodiversity's contribution to soil nutrients, water, pollination and pest reduction, more often than not, are synergistic (Garibaldi et al. 2020; Tamburini et al. 2020; Garbach et al. 2016; Kennedy et al. 2013; Scheper et al. 2015; Landis et al. 2000; Rusch et al. 2017). Taken with genetic diversity, these ecosystem functions represent critical inputs into production systems globally. The aim of agroecology and diversification practices is to secure and make use of ecosystem services both to and from agriculture (DeClerck et al. 2016). Within the AR3T framework, the aim of diversification is to *regenerate* the ecosystem functions and services both from and to agriculture, while *reducing* its negative impacts, notably, habitat loss and pollution of soil and water (DeClerck et al. 2016).

**3.2.1 Diversification Within Fields and Pastures**

Replacing low diversity annual systems with higher diversity annual or perennial systems has numerous beneficial impacts on ecosystem functions, for example, by
reducing soil nutrient loss to aquatic environments, and extending the portion of the year that crops are actively being grown, thus reducing nutrient leaching. Integrating nitrogen-fixing legumes, either as a harvestable or cover crop, is one of the most common forms of diversification (Duchene et al. 2017; Bedoussac et al. 2015; Ghosh et al. 2007). Crop types have variable water needs and can influence demands on available water resources. Management techniques for promoting carbon sequestration and improving drought resilience include organic residue management, mulching and reduced or no-tillage (Amelung et al. 2020). Excessive use of biocides, nutrient inputs and tillage, in turn, favor soil ecosystems with very high carbon loss and little long-term storage potential (Palm et al. 2014). High-diversity cropping systems can also increase natural enemies of pests upwards of 44%, increase pest mortality by 54% and reduce crop damage by 23% (Letourneau et al. 2011; Cook et al. 2007). In-field diversification provides habitat, alternative hosts, pollen and nectar, as well as overwintering or nesting sites essential to diverse communities of pollinators, predators and parasitoids (Landis et al. 2000; Lichtenberg et al. 2017).

### 3.2.2 Diversification Between Fields and Pastures

Natural elements such as grassed waterways, riparian buffers, prairie strips, hedge-rows, live fences and wetlands incorporated around field and pasture margins are highly effective at capturing excess nutrients. To reduce erosion and regulate water, between-field habitat infrastructure can be complemented with engineered features such as terraces, water and sediment control basins, bioreactors and saturated buffers to control nutrient loss. These features also support pollination (Scheper et al. 2015; Nicholson et al. 2020; Kremen et al. 2019; M'Gonigle et al. 2015; Ponisio et al. 2016) and pest regulation (Letourneau et al. 2011; Shelton and Badenes-Perez 2006; Cook et al. 2007; Tschumi et al. 2015) by providing habitat for pollinating and pest-regulating organisms, can serve as barriers to pest movement (Avelino et al. 2012), or can draw pests out of crop fields (Cook et al. 2007; Pickett et al. 2014). A recent synthesis indicated that the planting of annual flower strips on field borders increases pest control by 16% (Albrecht et al. 2020). Between-field habitats can have added value when they comprise multi-use species that provide fodder, fuel or food, and can be designed to reduce wind or evaporative stress in crops while creating corridors for wild biodiversity.

### 3.2.3 Landscape Diversification

Even where the most extensive monocultures are practiced, landscape diversification, combined with habitat structures between fields, can have significant positive impacts on many services provided by agricultural biodiversity, notably, hydrological, pest regulation (Avelino et al. 2012; Chaplin-Kramer et al. 2011; Veres et al.
2013; Holland et al. 2017) and pollination services (Kennedy et al. 2013; Dainese et al. 2019; Garibaldi et al. 2011). In contrast, landscape simplification often leads to increased risk of pest infestation (Rusch et al. 2016). Diverse mosaics in agricultural land that include multiple farms and integrate natural areas are required to capture and potentially convert, store or sequester nutrients lost to the environment. Policies, or markets that either support increases in field or farm sizes, and/or concentrate the production of a single crop in a landscape, may increase efficiency, but drive loss of between-field cropping diversity and increase risks.

### 3.2.4 Agricultural Landscapes Need at Least 10–20% of Diversified Habitats to Retain Ecological Integrity

Proposed targets for nature retention within agricultural landscapes (Willett et al. 2019; Garibaldi et al. 2020) are beginning to be reflected in agricultural policy (Díaz et al. 2020). A conservation target for agricultural ecosystems to retain at least 10–20% of habitat per km² has been proposed to maintain ecological integrity in production landscapes (Willett et al. 2019; Maron et al. 2018; DeClerck et al., DeClerck et al. In Review; Garibaldi et al. 2020). The rationale for this target is that the services provided by biodiversity to agriculture are locally produced. Nitrogen fixation by legumes impacts soil fertility at the plant scale (0–10 cm), and pollination and pest control are provided by habitats at a wider scale (0–300 m), occasionally further for honeybees (3000 m) (Willett et al. 2019; DeClerck et al., DeClerck et al. In Review; Garibaldi et al. 2020; Fremier et al. 2013; Tscharntke et al. 2005; Tscharntke et al. 2007). Similarly, interception of sediment and nutrients lost from agriculture by buffers is most effective within tens of meters (Fremier et al. 2013). While specific impacts are highly contextual and difficult to predict, the evidence is clear: in the absence of proximate habitat (<500 m), ecosystem services to agriculture are not provided. Alarmingly, 18–33% of global agricultural lands are below this 10–20% km² threshold respectively (Fig. 2; DeClerck et al. In Review).

Both the retention of habitat within agriculture and the diversity of cropping systems per unit area have been proposed as indicators to the CBD and to UNFSS¹². The attraction of these targets is that they allow for alignment and the setting of both global and national goals while leaving ample scope for farming communities to identify the most locally appropriate practices contributing to their achievement. Additional research will be needed to define what qualifies as “semi-natural” habitat in different regions. Pastures are considered to be semi-natural habitats in European analyses. Agroforests, plantations and orchards may be more appropriate in agricultural systems located in forest biomes. In contrast, winter flooding of rice fields in California have provided critical overwintering habitat for migratory waterfowl and other biodiversity without compromising yield. Investments in local research on the relationships between semi-natural habitats and ecological integrity are needed.
<figure><img src="image_100.png" /><figcaption>**Fig. 2** Global distribution of biodiversity intactness (light green) and ecological integrity. Regions in red are below proposed thresholds for biodiversity in agriculture. (Data from DeClerck et al. *In Review*. Nearly half the terrestrial landmass is currently classified as “intact.” However, many agricultural lands have lost integrity (red), where remaining habitat quantity is insufficient to ensure biodiversity’s contributions to food production)</figcaption></figure>

# 4 Agriculture Must Spare Space for Biodiversity to Meet Global Environmental Goals

## Take-Home Messages

* Halting the expansion of agriculture into intact ecosystems is necessary to halt the loss of biodiversity and mitigate climate change, and is likely to contribute significantly to stabilizing hydrological cycles.

* Half of the global land surface is currently intact, with strong biases toward desert, boreal and tundra biomes. Halting extinction loss will require the retention of most remaining intact ecosystems across ice-free areas and is compatible with CBD goals of ‘no net loss.’

* Restoring 15% of converted lands in priority areas could avoid 60% of expected extinctions and help provide vital ecosystem services, such as sequestering 30% of the total CO₂ increase in the atmosphere since the Industrial Revolution.

Reducing and reversing the impact of agricultural systems on biodiversity requires a system-wide transformation of agriculture and food production (Tilman et al. 2017; Williams et al. 2020). A sustainable future must therefore be grounded in improving environmental quality and placing strong limits on biodiversity loss. At least 79% of Earth's remaining natural and semi-natural (terrestrial) ecosystems need to be retained simply to meet existing international goals for biodiversity conservation, carbon storage, soil conservation and freshwater regulation (Simmonds et al. 2021).
This equates to keeping half of the planet intact – about the proportion that remains intact today. We can afford to lose very little more: so much land has been converted to agriculture that we are globally either at or nearing land conversion limits (Ceballos et al. 2020). Actions to ensure that intact habitats and their biodiversity can contribute to Earth system processes while also halting the ongoing biodiversity extinction crisis require both *avoiding* further loss of and *restoring* intact nature.

## 4.1 Halting the Loss of Intact Ecosystems

Preventing the loss or conversion of intact areas, and, where necessary, enhancing their condition, requires setting limits on loss. How much intact land is needed to preserve functioning populations of all species is difficult to quantify precisely. Local contexts are important in determining extinction risk and are important spaces for setting conservation priorities. There is no ‘one size fits all’ solution (Maron et al. 2018; Allan et al. 2019). However, there is broad consensus that retaining intact habitat, and connectivity between habitats, is necessary to halt loss.

Biological intactness is not incompatible with human use. Relatively intact and ecologically functioning systems can and do support a multitude of human uses, including productive and extractive uses: many such ecosystems rely upon human intervention, and represent the product of millennia of sustainable traditional management. Extensive grazing in grassland and savannah biomes and the sustainable harvest of natural forests are demonstrable activities that retain intactness while supporting livelihoods. Indigenous areas critically overlap with intact nature, with strong evidence that recognizing Indigenous Peoples’ rights to land, benefit sharing, and institutions is essential to meeting local and global conservation goals (Garnett et al. 2018). Identifying the range of nature-based benefits that each priority avoidance area supports can provide a guide to the human uses that are compatible with its ongoing provision of those benefits, so long as retaining biodiversity intactness is an explicit priority in these areas.

Interventions should therefore aim *not* to exclude human activities entirely from the areas we need to retain, particularly where local people depend on the natural resource base for their livelihoods. Proposed agricultural expansion can be managed to minimize impacts on biodiversity through the involvement of local people in decision-making. Land use policies, decision-making tools and private sector levers can contribute to nature retention (Garnett et al. 2018).

There is a growing call for the retention of at least half of the global land surface as intact (BII > 90) in order to halt extinction loss at 80% of known biodiversity (Willett et al. 2019; Rockström et al. 2020; Maron et al. 2018; Newbold et al. 2016; Dinerstein et al. 2017). Other estimates, using species-based approaches, find that 44% might be sufficient to protect the most important sites for terrestrial biodiversity (64 million km²) (Allan et al. 2019). While the specificity of this boundary is vigorously debated, most ecologists agree that, as the intact area of ecosystems dips below 50%, there is growing risk of population decline and extinction risk.
Retaining at least half of the terrestrial realm, in each of the 782 ecoregions, would thus be necessary to halt extinction loss, and has been signaled as a biodiversity boundary for food systems (Willett et al. 2019). Retaining intact regions in ice-free areas (>67 M km²) and achieving half intactness for all ecoregions would require restoration on 23.9 M km². Observing that currently half of the terrestrial realm is considered intact, the CBD has adopted the boundary measure in its ongoing negotiations for a 'no net loss of nature' target. Ensemble models have demonstrated that no net loss is possible to achieve, but requires aligned actions across biodiversity conservation, food production and food consumption (Leclère et al. 2020).

Many parts of the world are currently in intactness deficit, considering a 50% intactness target. Estimates of how much restoration is needed range between 19 and 24 million km², with the lower value targeting high conservation value areas (Allan et al. 2019; Strassburg et al. 2020), and the higher value targeting half-intact ecoregions, across all ecoregions (DeClerck et al. In Review). In 552 ecoregions globally (69%), less than 10% of the area remains intact and may be too far gone for meaningful restoration of intactness, or may conflict with food and nutrition security. In these locations, integrating biodiversity into production will be a more viable option.

## 4.2 Mitigating Climate Change

While reducing fossil fuel burning and halting land conversion are critical strategies to reduce GHG emissions, biodiversity, through photosynthesis, is the only known process to transfer GHG from the atmosphere to the biosphere. The retention and restoration of natural ecosystems, notably, carbon-dense forest and wetland ecosystems, are key in this regard. It has been proposed that 75% of forest biomes be conserved globally because of their specific contribution to climate mitigation (Steffen et al. 2015). Temperate and tropical forest biomes are currently below this threshold, although temperate forest areas are increasing due to agricultural abandonment, whereas tropical forest areas are decreasing due to agricultural expansion. Boreal forest biomes remain above this threshold for the moment (Dinerstein et al. 2017; Ramankutty et al. 2018). The potential of reforestation to contribute to climate mitigation (i.e., 2.7–17.9 Pg CO₂e y⁻¹) depends on several assumptions (Griscom et al. 2017).

## 4.3 Regulating Hydrological Cycles

Large tracts of intact nature are key to maintaining regional hydrological patterns (Chapman et al. 2020; McAlpine et al. 2009), including flood pulse flow regulation (Bradshaw et al. 2007) and distribution of rainfall patterns that are critical to agriculture. However, the relationship between water fluxes (storage, evapotranspiration,
precipitation and run-off) of extensive intact areas is complex. Intact nature may or
may not produce greater volumes of water than converted lands, as losses to storage
and evapotranspiration can be greater than in simplified systems such as agricultural
ecosystems. However, most evidence does indicate that heavily vegetated ecosystems
(e.g., forests, grasslands) provide better flow regulation – while natural ecosystems
reduce run-off, they may have greater losses to evapotranspiration. Studies suggest
that about 40% of irrigation water currently drawing from surface water bodies is at
the expense of environmental flows (Jägermeyr 2020) and roughly 20% of irrigation
water depletes groundwater bodies (Döll et al. 2012; Wada et al. 2012; Wada et al.
2016), indicating that 50–60% of current global irrigation practice is unsustainable
(Rosa et al. 2019; Rosa et al. 2018).

## 4.4 Restoring Ecosystems

A growing number of research articles now point toward options for restoration, and evaluate contributions to climate, biodiversity, and food security, but there remains an important research gap on local and regional implementation of such strategies, including the trade-offs over multiple spatial and temporal scales, as well as between different social groups (Leclère et al. 2020; Strassburg et al. 2020; Mehrabi et al. 2018). Restoration, in contrast to regeneration, must include improvements in biodiversity intactness (Newbold et al. 2016; Scholes and Biggs 2005) measured by changes in species richness and population abundance. Defined as such, restoration can be interpreted as driving a net reduction in land available for food production, with the exception of wild harvest systems, and potentially extensive grazing systems. Restoring 15% of converted lands in priority areas could avoid 60% of expected extinctions while sequestering 299 Gt CO₂e – 30% of the total CO₂ increase in the atmosphere since the Industrial Revolution (Strassburg et al. 2020).

# 5 Conclusions and Recommendations: Food and Agriculture Must Be the Solution to Food, Environmental and Climate Security

While the evidence on when and how biodiversity contributes to global goals is
highly context specific, we find that agriculture has the potential to reconcile global
goals that have often been considered contradictory: food and nutritional security
versus environmental and climate security. There is strong evidence that realizing
this potential requires placing biodiversity at the heart of agriculture policy, invest-
ment and innovation, with much greater consideration of the role of agriculture as a
provider of benefits to biodiversity, rather than just a driver of biodiversity loss. As
the lifeline of the entire system, people must be anchored in solutions to upend the
system of policies and incentives that are currently stacked against their livelihoods and health.

Understanding that there is a menu of solutions, with related opportunities and trade-offs, will help in progress toward a future that optimizes sustainable agriculture and prioritizes feeding everyone. Biodiversity strategies are among those solutions and can help us move beyond staple crops and commodities when considering policy, investment and research. Three elements, as already detailed in this review, can offer a way to bridge conversations among policymakers engaged in the environment, food, agriculture, finance and social protection sectors, and must be considered in a holistic solution for food and biodiversity: (1) How can we optimize the opportunities and minimize the trade-offs for ensuring diverse diets for all? (2) How can we maintain shared space where agriculture optimizes ecosystem services, and other contributors to regenerative and resilient production systems? And (3) how can we strike the right balance of land sparing, by halting the expansion of agriculture into the intact ecosystems necessary to halt the loss of biodiversity while mitigating climate change and producing enough healthy food?

## 5.1 Policy Implications: The Transformation Challenge

Biodiversity needs to be part of a sustainable agriculture that will feed a projected population of 10 billion with healthy, culturally appropriate and delicious foods by 2050. The first step is for policymakers to adopt a new conceptual framing that recognizes that all parts of food systems need to work together as a whole if they are to deliver diets that are high quality and sustainable. This leads to thinking about ‘food system productivity,’ rather than agricultural productivity (Benton and Bailey 2019), and requires all sectors of government to break out of their own conceptual silos and institutional structures. For a true transformation of the food system, there is a need to create the policy instruments, demand and incentives for food production systems that leverage biodiversity’s capacity to contribute to climate, environmental, food and nutritional security (Willett et al. 2019; Rockström et al. 2009; Steffen et al. 2015).

## 5.2 Correcting Distortions Requires Reinvestment

Our food system has been distorted by a framework of subsidies (including for research focused on staples), market incentives (including investment in commodity-based transport infrastructure and marketing/retail incentives for hyper-processed food), and a lack of regulations to curb the externalization of costs onto environmental and healthcare systems. The heavily subsidized agricultural sectors of many countries in the Global North result in trade distortion, or in inequitable trade relationships among many developed and developing countries, adversely affecting
the economic prospects of farmers in the Global South (OECD, 2016). These have a strong influence on both the foods that are delivered and their price and accessibility, and in encouraging the supply, demand and consumption of foods that may be less conducive to healthy diets and sustainability in food systems.

In considering the relationship between agriculture and biodiversity, several key areas for investment emerge [High Agreement, Robust Evidence]:

* Closing the gap between the current composition of crop production and consumption to supply healthy diets at the local, regional and global scales in line with SDG2 and SDG3.

* Transitioning to managing agricultural systems as ecological systems (agroecosystems).

During the next decade, priority approaches to diversify production systems should target:

* Urgent investments in undervalued crops and cropping systems, notably, underproduced crops that underpin dietary health.

* Greater investment in tools, technologies and enabling environments that amplify and/or complement biodiversity's contribution to agriculture, rather than seeking to replace it.

* Repurposing public funds in agriculture to support farmers producing public goods, including the production of healthy foods, carbon capture, clean water and habitat for biodiversity.

Food security cannot trump other critical goals, notably, nutritional, climate, environmental and livelihood security. Treating these as inevitable trade-offs fails to highlight key areas of synergy. Making the transition to food production systems that achieve synergy with biodiversity will require significant transitions in the policy landscape. Therefore, agriculture must be more strongly:

* Integrated into global environmental policies, both in recognition of its role as a driver of environmental change and to leverage its potential contribution to mitigating climate and biodiversity loss.

* Included in global agreements, recognizing its current impacts on climate, degradation and biodiversity and leveraging its potential contribution to global goals.

* Interwoven into global health policies, as in recent collaborations between the World Health Organization and the Food and Agriculture Organization to define healthy and sustainable diets.

## 5.3 Developing more Dynamic Investment and Financial Opportunities

There is potential to unlock and unblock investment and facilitate better financial flows to encourage farmers to protect and enhance the environment by rewarding them for the provision of ecosystem services, while mitigating the risks to the
adoption of sustainable practices. Current agricultural investments and practices often overlook the important potential for increasing the ecosystem services that agroecosystems can provide (Wood et al. 2018). The CGIAR Commission on the Sustainable Intensification of Agriculture finds “an uplift in finance could come from reorienting current innovation spending to promote environmental, climate change, inclusivity and nutrition outcomes. A recent study commissioned by CoSAI identified that although around USD 50–70 bn per year is spent on agricultural innovation for the Global South, less than 7% explicitly aims to improve environmental and climate outcomes. And only around half of this also addresses social or nutrition outcomes” (CoSAI. 2021).

Farmers and farming communities can produce public goods (e.g., climate mitigation, soil water-holding capacity, water quality improvement), but promoting these public good functions has been consistently underexplored and under-resourced, even though they are also necessary for creating sustainable and resilient production systems. Recognizing that farmers and farmlands can produce these benefits in addition to quality food presents an opportunity for revitalizing rural communities by repurposing public funds for public goods.

## 5.4 Changing Availability Through Subsidy and Research Reform

Currently, more than US$620 billion is spent globally each year on agricultural subsidies (e.g., commodity support, services) (OECD 2020). Over the past decade, OECD governments have allocated roughly 26% of their subsidy support to cereal grains, and 14% to fruits and vegetables (Freund and Springmann Under review). This value is inverse to the diversity of potential crops within these food categories, inverse to the recommended consumption levels of food groups, and inverse to the projected yield production deficits. While the share of sectoral support to fruit and vegetables was much higher in non-OECD countries, at 37%, the other 63% of subsidy support went to cereals, livestock, oilseeds, sugar, production of fiber (wool) and more (Freund and Springmann Under review).

Even a relatively modest repurposing of subsidies (e.g., 25%) toward promoting production of nutrient-rich perishable foods, and reduced food loss and nutrient waste, would amount to US$150 billion in capital to support the generation of a greater diversity of nutrient-rich foods, while simultaneously lowering the environmental footprint, potentially allowing more nature-positive farming methods.

Only 6% of public sector support to the agricultural sector is dedicated to research (Searchinger et al. 2020). This is a small percentage, but amounts to a big number globally. However, it is typically targeted at productivity improvements in major commodities. A key research need is for a much greater focus on innovation in diverse farming systems, rather than individual crops, for instance, through circular agriculture to prevent waste and leakage while supporting reuse, regenerative, agroecological systems, complex rotations, mixed farming, and so on.
## 5.5 Reimagining International Trade

With almost 20% of the global dietary energy supply derived from imported foodstuffs, trade policy must better integrate its impact by creating greater space for diversification of commodities, supporting the conservation of intact ecosystems, and including trade in environmental goods and services. Trade expansion over recent decades has enabled "higher-income countries to 'off-shore' the adverse impacts of their consumption on ecosystems and biodiversity through trade in commodities, goods and services with lower-income countries" (Dasgupta 2021). International market stability and prices are highly dependent on a few key players (Dasgupta 2021), yet investing well in international trade could bring a range of benefits. It is crucial to find ways to support sustainability via trade (e.g., 'due diligence' requirements for supply chains such as the Global Reporting Initiative (GRI), enhancing traceability through mechanisms such as Trase, or through border tariffs). A key component of the evolution of the food system's focus on large-scale commodity production is the ability to store, transport and process grains with less loss than with fresh produce.

**Acknowledgements** This paper was funded with support from the CGIAR Collaborative Research Program on Water Land and Ecosystems.

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<figure><img src="image_101.png" /></figure>
<figure><img src="image_102.png" /></figure>

Claudia Ringler, Mure Agbonlahor, Kaleab Baye, Jennie Barron, Mohsin Hafeez, Jan Lundqvist, J. V. Meenakshi, Lyla Mehta, Dawit Mekonnen, Franz Rojas-Ortuste, Aliya Tankibayeva, and Stefan Uhlenbrook

# 1 Introduction

Water is essential for all life and is integral to the function and productivity of the Earth's ecosystems, which depend on a complex cycle of continuous movement of water between the Earth and the atmosphere. Water is also fundamental for food systems, and a food systems transformation will be essential to meeting SDG 6 on water and sanitation. As described by the High-Level Panel of Experts on Food

C. Ringler (✉)

International Food Policy Research Institute (IFPRI), Washington, DC, USA

e-mail: c.ringler@cgiar.org

M. Agbonlahor

African Union Commission, Ouagadougou, Burkina Faso

K. Baye

Addis Ababa University, Addis Ababa, Ethiopia

J. Barron

Swedish University of Agricultural Sciences, Uppsala, Sweden

M. Hafeez

International Water Management Institute, Lahore, Pakistan

J. Lundqvist

Stockholm International Water Institute, Stockholm, Sweden

J. V. Meenakshi

University of Delhi, New Delhi, India

L. Mehta

Institute of Development Studies, Falmer, UK

Norwegian University of Life Sciences, Ås, Norway

D. Mekonnen

International Food Policy Research Institute, Addis Ababa, Ethiopia
<figure><img src="image_103.png" /><figcaption>**Fig. 1** The linkages between water and food systems (Source: HLPE 2015)</figcaption></figure>

Security and Nutrition (HLPE) (HLPE 2015) and illustrated in Fig. 1, the key dimensions of water that are of importance for humanity are its availability, access, stability, and quality. These have multiple, close linkages and feedback loops with food systems, which can be defined as the activities involved in the production, processing, distribution, preparation, and consumption of food within wider socio-economic, political, and environmental contexts (HLPE 2017). For example, waste streams from food processing often re-enter water bodies, affecting other components of food systems, such as drinking water supplies (water is itself essential for all bodily functions and processes, and is an important source of nutrients) (UNSCN 2020), as well as water-based and water-related ecosystems.

More than 70% of all freshwater withdrawals are currently used for agriculture, and about 85% of withdrawn resources are consumed in irrigated agricultural production. With these resources, irrigated crop areas generate 40% of global food production on less than one-third of the globally harvested area (Ringler 2017). Another key water-food system linkage is water supply for WASH (water, sanitation

<footnote>F. Rojas-Ortuste
Development Bank of Latin America, Montevideo, Uruguay</footnote>

<footnote>A. Tankibayeva
Al-Farabi Kazakh National University, Almaty, Kazakhstan</footnote>

<footnote>S. Uhlenbrook
International Water Management Institute (IWMI), Battaramulla, Sri Lanka</footnote>
and hygiene), which is important for human health, can support nutrition outcomes, particularly if combined with other interventions (Cumming et al. 2019), and is a basic human right, as is the right to food. Water is also essential for agricultural processing and food preparation.

Climate change and other environmental and societal changes (e.g., land use changes, biodiversity loss, urbanisation, and changing lifestyles and diets) are impacting the dynamics of natural water cycles and water resource availability, with further, subsequent impacts on food systems. More than half of all natural wetland areas have been lost due to human activity since 1900 and forest degradation affects streamflow regulation (Sun et al. 2017). At the same time, the growing frequency and severity of floods and droughts in many regions of the world (IPCC 2021) increase competition over water resources. This calls for changes in water management, including increased water productivity, integrated storage solutions, accelerated land restoration and smarter water distribution to support food systems, as well as a reduction in impacts on domestic, industrial, energy-related, and environmental water uses.

# 2 SDG 2 and SDG 6 Can Only Be Achieved If the Water and Food System Communities Work Together

## 2.1 Water Scarcity and Pollution Are Growing, Affecting Poorer Populations, Particularly Food Producers

Freshwater-related ecosystems include wetlands, rivers, aquifers, and lakes that sustain biodiversity and life (UN Environment 2018). Although they cover less than 1% of the Earth's surface, these habitats host approximately one-third of vertebrate species and 10% of all species (Stayer and Dudgeon 2010), including mammals, birds (IUCN 2019), and fish (Fricke et al. 2020). Water-related ecosystems are also vital for the function of all terrestrial ecosystems, providing regulating, provisioning, and cultural services (Martin-Ortega et al. 2015). Furthermore, hydro-power is an essential energy source, accounting for 85% of global renewable electricity generation in 2015, but has since declined to around 60% (IEA 2016, 2020), and is also key for commerce and industry (Willet et al. 2019). Notably, de-carbonising the energy system can also adversely impact the water system, particularly in the case of increasing hydropower and biofuel production.

Progress on achieving the water and sanitation targets of SDG 6 has been unsatisfactory and uneven. More than 2 billion people live in places with high water stress (FAO SOFA 2020; UN 2018): by 2050, every second person, half of the world's grain production, and close to half of the globe's Gross Domestic Product might well be at risk from water insecurity (Ringler et al. 2016). In 2020, approximately 2.0 billion people lacked access to safely managed drinking water, and 3.6 billion people lacked access to safely managed sanitation services.
One in ten people lacked basic services, including the 122 million people who depend on untreated surface water, mostly in sub-Saharan Africa (UNICEF, WHO 2021). Poor women and girls, who are responsible for more than 70% of all water collection, spend about 200 million hours a day on this task, undermining their health and livelihood opportunities (UNICEF n.d.; Geere and Cortobius 2017).

In terms of agricultural water use, farmers across the world, but particularly in sub-Saharan Africa, continue to rely heavily on rainfall for food production. More than 62 million hectares of crop and pastureland experience high to very high water stress and drought, affecting about 300 million farm households (FAO 2020). With climate change, temperatures and crop evaporation levels are increasing, and there is growing uncertainty about the timing, duration and quantity of rainfall, increasing the risks related to producing food and undermining the livelihood security of the majority of rural people (AUC 2020). Fertiliser use on crop land and livestock excreta are key sources of agricultural water pollution, affecting aquatic life and threatening human health. Projections suggest that nitrogen and phosphorous deposition in water bodies will grow rapidly, particularly in low- and middle-income countries (Xie and Ringler 2017).

With respect to the other SDG 6 targets, such as water use efficiency, water-dependent ecosystems, and integrated water management, progress has been slow and is often not well understood, due to the lack of effective monitoring mechanisms and insufficient data. New, integrated approaches and reinforced efforts to measure and manage water are urgently needed (Sadoff et al. 2020).

While water availability differs dramatically around the globe, differences in access are most often due to politics, public policy, lack of capacity and investment, and flawed water management strategies, as well as exclusions due to geography (i.e., remote rural areas), gender, ethnicity, caste, race, and class. In many cases, water does ‘flow uphill’ to power and money (Mehta et al. 2019). Furthermore, increasing urbanisation and changing diets are affecting the demand and supply of water resources for food systems and aggravating water stress in many parts of the world, particularly in water-scarce areas of low/middle-income countries where coping capacity is often insufficient.

## 2.2 Malnutrition Levels Are on the Rise and Are Closely Linked to Water Scarcity

An estimated 690 million people, or 8.9% of the global population, were undernourished in 2019, prior to the COVID-19 pandemic (Headey et al. 2020). The number has since grown to between 720 and 811 million people (2020 values). Moreover, 149 million children below the age of five were stunted, 45 million were wasted, and another 39 million were overweight (FAO, IFAD, UNICEF, WFP and WHO 2021). Climate change, associated conflict, and a lack of sufficient water for
food production, including irrigation for fruit and vegetable production, are key contributors to unaffordable diets and overall levels of undernutrition. At the same time, overweight continues to dramatically increase around the globe, including in children. Latin America, in particular, suffers from the associated public health burden. Overall, rural areas are currently experiencing the most rapid rate of increase in overweight (NCD Risk Factor Collaboration et al. 2019). Given these trends, neither the 2025 World Health Assembly nutrition targets nor the 2030 SDG nutrition targets will be met. As with inequities in access to water, inequities in access to food and nutrition are highest in rural areas (Perez-Escamilla et al. 2018).

## 2.3 SDG 2 and SDG 6 Targets Are Co-Dependent

Ending hunger and malnutrition requires access to safe drinking water (SDG 6.1), as well as equitable sanitation and hygiene (SDG 6.2). The underlying productivity (SDG 2.3) and sustainability (SDG 2.4) of agricultural systems are also dependent on adequate availability (SDG 6.4 and 6.6) of good quality (SDG 6.3) water. Moreover, water and related ecosystems (e.g., wetlands, river or lakes in SDG 6.6), which are embedded in sustainable landscapes, are important contributors to sustainable agriculture through regulating and providing water for food production (SDG 2.4) (Ringler et al. 2018).

A key contributor to poor nutritional outcomes in subsistence farming households in low-income countries is the seasonality of production, leading to a seasonality in diets, which can affect pregnancy outcomes and child growth (Baye and Hirvonen 2020; Madan et al. 2018). Well-managed irrigation systems can buffer seasonal gaps in diets, contributing to improved food security and nutritional outcomes, for example, through homestead gardening (Baye et al. n.d.; Hirvonen and Headey 2018).

It is equally important to stress the need for changes in food systems in meeting SDG 6 targets: reducing food loss and waste in food value chains (SDG 12.3), lowering pollution from slaughterhouses, food processing, and food preparation, and considering environmental sustainability in food-based dietary guidelines. All of these actions will be essential to meet the SDG 6 targets (UNSCN 2020).

## 3 Solutions for Improving Food System Outcomes and Water Security

Based on the above assessment, as well as recent water-food system reviews (Ringler et al. 2018; UNSCN 2020; Mehta et al. 2019; Young et al. 2021), the following actions are proposed for uptake by governments, the private sector, and civil society.
**3.1** *Strengthen Efforts to Retain Water-Based Ecosystems and Their Functions*

The ecological processes underlying the movement, storage, and transformation of water are under severe threat from deforestation, erosion, and pollution, with impacts on local, regional, and global water cycles (WWAP 2018). In addition to a direct halt of deforestation and the destruction of water-based ecosystems, nature-based solutions that use or mimic natural processes to enhance water availability (e.g., ground-water recharge), improve water quality (e.g., riparian buffer strips, wetlands), and reduce risks associated with water-related disasters and climate change (e.g., flood-plain restoration, wetlands) should be strengthened (WWAP 2018). Limiting over-consumption of water, particularly in water-stressed regions, will be necessary to stay within sustainable water use limits (Yu et al. 2021).

**3.2** *Improve Agricultural Water Management for Better Diets for All*

Around 3 billion people on this planet cannot afford a healthy diet, particularly dairy, fruits, vegetables, and protein-rich foods (FAO, IFAD, UNICEF, WFP, WHO 2021). Both rainfed and irrigated systems play essential roles in lowering the prices of nutrient-dense foods, growing incomes to be able to afford these foods, and strengthening the diversity of foods available in local markets (Hirvonen et al. 2017).

**3.2.1 Strengthen the Climate Resilience of Rainfed Food Systems**

Rainfed systems produce the bulk of food, fodder, and fibre, and most animal feed is produced under rainfed conditions (Heinke et al. 2020). These systems are under severe and growing stress from climate change, including extreme weather (FAO 2020). This can be addressed, to some extent, through structural measures (e.g., terracing, soil bunds, drainage), investment in breeding, improved agronomic practices, effective incentives (e.g., payments for watershed conservation), and strong institutions for water, soil and land management (e.g., watershed committees) (Jägermeyr et al. 2016; World Bank 2010).

**3.2.2 Strengthen the Nutrient Density of Irrigated Agriculture**

As irrigation accounts for the largest share of freshwater withdrawals by humans (more than 90% in some agrarian economies), the potential for water conservation is also largest in this sector. Irrigation development needs keep environmental limits – which are increasingly affected by climate change – in mind. This includes addressing
groundwater depletion. The potential for increasing water and nutrition productivity in irrigation remains large. It includes crop breeding for transpiration efficiency, salinity tolerance, climate resilience and increased micronutrients, integrated storage solutions – such as joint use of grey and green infrastructure – advanced irrigation technology, and soil moisture monitoring (Rosegrant et al. 2009). There are clear trade-offs between the nutrient density of foods and irrigation water use. Fruit and vegetable yields depend on frequent water applications in many parts of the world (although the water content of the end product also tends to be high) and need precision applications of agrochemicals to maximise water inputs and avoid water pollution (Meenakshi and Webb 2019). Many livestock products are highly water-intensive due to animal feeds, although the majority of the feed comes from rainfed agriculture. Awareness-raising and social learning interventions can help internalise the water externality of water-intensive diets. Improved coordination of water with other agricultural inputs can also enhance yield per drop of water. This requires access to technology packages, as well as to better agricultural information (Lundqvist et al. 2021), which is increasingly supported by ICTs (Asenso-Okyere and Mekonnen 2012). Moreover, subsidies for water-intensive crops, such as rice, milk and sugar, should be revisited and eventually removed. For water-scarce countries, importing virtual water via food and other commodities will remain essential (Allan 1997).

### 3.2.3 Address Water Pollution to Improve Food Production, Food Safety, and Water-Based Ecosystems

Globally, 80% of municipal sewage and industrial wastewater with heavy metals, solvents, toxic sludge, pharmaceuticals, and other waste are directly discharged into water bodies, affecting the safety of food, particularly vegetable production, and also, directly, human health (WWAP 2018). Agriculture also directly pollutes aquatic ecosystems and risks food production with pesticides, organic matter, fertilisers, sediments, pathogens, and saline drainage (UNEP 2016). Key measures to address agricultural and overall water pollution include the breeding of crops with higher crop nutrient use efficiency, better agronomic practices, the expansion of nature-based solutions for pollution management, low-cost pollution monitoring systems, improved incentive structures for pollution abatement, and continued investment and innovation in wastewater treatment, including approaches such as implementing the 3Rs (reduce, reuse, and recycle) of the circular economy across the entire food system (Mateo-Sagasta et al. 2018).

## 3.3 Reduce Water and Food Losses Beyond the Farmgate

Irrigated agriculture is often focused on high-value crops with a higher share of marketed surplus, compared to rainfed agriculture (Nkonya et al. 2011). At the same time, many irrigated crops, such as fruits and vegetables, are time-sensitive,
perishable products that require efficient market linkages to consumption centres. Strengthening market linkages includes investment in physical infrastructure that supports on-farm production (irrigation, energy, transportation, pre- and post-harvest storage), efficient trading and exchange (telecommunications, covered markets), value addition (agro-processing and packaging facilities), and improved transportation and bulk storage (Warner et al. 2008). Investments are also needed in ICTs that facilitate farmers’ access to localised and tailored information about weather, water consumption, diseases, yield, and input and output prices (Elsabber 2020).

## 3.4 Coordinate Water with Nutrition and Health Interventions

### 3.4.1 Strengthen Institutional Coordination and Develop Joint Programmes

Governance and management of water for various uses and functions, as shown in Fig. 1, follow different institutional arrangements. Similarly, professionals engaged in various roles within water-related institutions have different kinds of training and experiences. Few irrigation engineers have a professional background or skills related to WASH, and few WASH professionals have the technical skills needed to design water infrastructure for multiple uses, for example. The notion of integrated water resource management (SDG 6.5) has been promoted as a principle to overcome problems due to sectoral division. Coordination at the lowest appropriate levels is urgently needed between WASH and irrigation for improved food security, nutrition, and health outcomes, as well as to strengthen women’s agency over water decisions. Multiple-use water systems can increase food security and WASH outcomes (van Koppen et al. 2014). An example is the MiAgua programme in Bolivia supported by CAF, the development bank of Latin America, which included rural water supply, climate change adaptation measures such as watershed protection, and micro-irrigation projects for small-scale agriculture. MiAgua benefited 2.25 million people with improved or new access to water and contributed to increasing rural water coverage from 59 percent in 2011 to 69% in 2020. At a larger scale, improved coordination across riparian countries is essential for improving water securities linked to competing uses. A key example is the Aral Sea Basin, where lack of coordination between upstream and downstream countries affect both energy and food security (Bekchanov et al. 2015).

### 3.4.2 Implement Nutrition-Sensitive Agricultural Water Management

Nutrition and health experts need to join forces with water managers at the farm household level, at the community level, and at the government level to strengthen positive transmission pathways between both rainfed and irrigated agriculture and
food and nutrition security. A recent guidance (Bryan et al. 2019) describes eight actions for increasing the nutrition sensitivity of water resource management and irrigation, as well as indicators for monitoring progress.

## 3.5 Increase the Environmental Sustainability of Food Systems

The water footprint of diets varies dramatically between rich and poor countries, but also by socioeconomic group within countries (Lundqvist et al. 2021). More work is urgently needed on the impact of current dietary trends on environmental resources, including water. Food-based dietary guidelines should consider the environmental footprint of proposed diets, whereby government regulations and consumer awareness should be strengthened to reduce the over-consumption of food, and further efforts are needed to reduce post-harvest waste and losses (UNSCN 2020).

## 3.6 Explicitly Address Social Inequities in Water-Nutrition Linkages

Vulnerable groups need to be proactively included in the development of water services, including incorporating their needs and constraints into initial infrastructure design. For rural smallholders who most lack water and food security, irrigation design should consider multiple uses of water, such as drinking, irrigation, and livestock watering, to meet women's and men's needs. While women make up a large part of the agricultural workforce, they often lack recognition and formal rights, and farmers are often considered to be 'male' in many parts of the world. Women's productive roles should be promoted, and they should be trained in irrigation and water management. Their involvement has important implications for water and food security (Meinzen-Dick et al. 2021; Balasubramanya 2019). It is also important to ensure that women and disadvantaged social groups (e.g., lower castes, stigmatised social groups) have equal access to credit, irrigable land, labour, and markets to be able to buy agricultural inputs and sell their produce (Mehta et al. 2019; UNSCN 2020).

## 3.7 Improve Data Quality and Monitoring for Water-Food System Linkages, Drawing on Innovations in ICT

Better data are needed if we are to truly understand the water footprint of diets and devise policies that co-maximise water and food security and nutrition goals. Challenges include poor water and poor food intake data and a lack of indicators
connecting the two, but improvements are emerging (Bryan et al. 2019; HWISE network (https://hwise-rcn.org/); Lundqvist et al. 2021). More and better data will support better water management and food systems and increase transparency in decision-making. This requires sustained investments in the monitoring of a wide range of hydrological and food-related parameters worldwide. Modern Earth observation methods can support larger-scale assessment, but need to be complemented by dedicated field measurements.

**Acknowledgement** The support of the CGIAR Research Initiative 'NEXUS Gains – Realising benefits across on water, energy, food and ecosystems' and conceptual support from the WASAG Working Group on Water and Nutrition are gratefully acknowledged.

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<figure><img src="image_104.png" /></figure>
<figure><img src="image_105.png" /></figure>

Alisher Mirzabaev, Lennart Olsson, Rachel Bezner Kerr, Prajal Pradhan, Marta Guadalupe Rivera Ferre, and Hermann Lotze-Campen

# 1 Introduction

Climate change affects the functioning of all of the components of food systems (IPCC 2019) that embrace the entire range of actors and their interlinked value-adding activities involved in the production, aggregation, processing, distribution, consumption, and recycling of food products that originate from agriculture (including livestock), forestry, fisheries, and food industries, and the broader economic, societal, and natural environments in which they are embedded (von Braun et al. 2021). At the same time, food systems are a major cause of climate change, contributing about a third (21–37%) of the total GHG emissions through agriculture

A. Mirzabaev (✉)

Center for Development Research (ZEF), University of Bonn, Bonn, Germany
e-mail: almir@uni-bonn.de

L. Olsson

Centre for Sustainability Studies (LUCSUS), Lund University, Lund, Sweden

R. B. Kerr

Department of Global Development, Cornell University, Ithaca, NY, USA

P. Pradhan

Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association,
Potsdam, Germany

M. G. R. Ferre

INGENIO (CSIC-Universitat Politècnica de València), Valencia, Spain

H. Lotze-Campen

Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association,
Potsdam, Germany

The Agricultural Model Intercomparison and Improvement Project (AgMIP),
New York, NY, USA

Food System Economics Commission (FSEC), Potsdam, Germany
<figure><img src="image_106.png" /><figcaption>**Fig. 1** Linkages between climate change and food systems</figcaption></figure>

and land use, storage, transport, packaging, processing, retail, and consumption (Mbow et al. 2019) (Fig. 1).

Climate change will affect food systems differentially across world regions. While some areas, such as northern temperate regions, may even experience some beneficial changes in the short term, tropical and sub-tropical regions worldwide are expected to face changes that are detrimental to food systems. Such changes will have effects on food and nutrition security through a complex web of mechanisms (Fig. 1). Critical climate variabilities that affect food and nutrition security include increasing temperatures, changing precipitation patterns and greater frequency or intensity of extreme weather events such as heatwaves, droughts and floods (Mbow et al. 2019). They impact the productivity of crops, livestock and fisheries by modulating water availability and quality, causing heat stress, and altering the pests and disease environment, including through the faster spread of mycotoxins and pathogens. Increased frequency and intensity of floods and droughts can lead to considerable disruptions in food supply chains through harvest failures and infrastructure damage. The exposure of people to heatwaves, droughts and floods can harm their health and lower their productivity, affecting their livelihoods and incomes, especially for those engaged in climate-sensitive sectors or working outdoors. This exposure can strongly affect more vulnerable groups in many lower-income countries, e.g., smallholder farmers, low-income households, women and children. Other factors related to climate change that affect food systems are the rise in atmospheric concentrations of CO₂, and, indirectly, land degradation, and a reduction in pollination services. Changes in CO₂ levels in the atmosphere affect both crop yields and their nutrient content. Climate change will exacerbate land degradation through increased soil erosion, especially in sloping and coastal areas, increased soil salinity in irrigated lands, and climates that are more arid and more prone to desertification in some dryland areas (Olsson et al. 2019; Mirzabaev et al. 2019). The potential reduction or loss of pollination services also leads to lower crop
yields. Conservative estimates, which consider these climate change impacts only partially, show that the number of people at risk of hunger may increase by 183 million by 2050 under high emission and low adaptation scenario [i.e., under Shared Socioeconomic Pathway (SSP) 3], compared to low emission and high adaptation scenarios (SSP1). An additional 150–600 million people are projected to experience various forms of micronutrient deficiency by 2050 in the higher emission scenario (Myers et al. 2017; Zhu et al. 2018; Medek et al. 2017).

The interactions between climate change and food systems have considerable repercussions across all of the dimensions of sustainable development. In fact, in six of the 17 sustainable development goals (SDGs), climate change-food system interactions increasingly play a major role. These relate to the social goals of zero hunger (SDG 2) and gender equality (SDG5), and the four environmental goals of water resources (SDG 6), climate action (SDG 13), life below water (SDG 14), and life on land (SDG 15). Solutions addressing the challenges posed by climate change-food system interactions can serve as a critical entry point for promoting the 2030 Agenda for sustainable development well beyond the timeline of the current SDGs (Pradhan et al. 2017). Since these interactions vary according to the country's income, region, and population groups (i.e., gender, age, and location of its population), solutions prioritising women, youths, and rural people, i.e., "leaving no one behind," can better leverage the achievements of the SDGs (Warchold et al. 2021).

## 2 How Climate Change Interacts with Food Systems and Food Security

### 2.1 Food Availability

Considerable evidence has by now emerged indicating that climate change is already negatively affecting crop production in many areas across the world (Kim et al. 2019; FAO 2018). Reductions of 21% in total factor productivity of global agriculture since 1961 have been estimated (Ortiz-Bobea et al. 2021). It has been found that climate change over the last four-five decades has reduced the yields of cereals by about 2–5% on average globally, compared to the situation if there had been no climate change (Iizumi et al. 2018). This range of about 5% lower cereal yields due to climate change was also found in regional studies, for example, for wheat and barley in Europe (Moore and Lobell 2015), for wheat in India (Gupta et al. 2017), and for maize in Africa, Central and Eastern Asia (Ray et al. 2019), and Central and South America (Verón et al. 2015). Higher losses equalling about 5–20% were found for millet and sorghum yields in West Africa (Sultan et al. 2019), and maize yields in Eastern and Southern Europe were estimated to be lower by about 5–25% (Agnolucci and De Lipsis 2020). There is growing literature documenting the negative impacts of climate change on the yields of legumes, vegetables, and fruits in drylands, tropical and sub-tropical areas (Mbow et al. 2019; Scheelbeek et al.
2018). These losses in yields have occurred after the taking of coping and adaptive actions (Mbow et al. 2019).

In temperate climatic zones, such as northern China, parts of Russia, northern Europe, and parts of Canada, observed climatic changes are increasing the agricultural potentials, leading to higher crop production (Moore and Lobell 2015; Ray et al. 2019; Potopová et al. 2017; Meng et al. 2014; Wang and Hijmans 2019; Bisbis et al. 2018). However, in many areas, this increased production is coming at the expense of lower yield stability due to higher weather variability between seasons. Climate change accounts for about half of food production variability globally. Presently, adaptive strategies for increasing crop yields (crop breeding, improved agronomic management, adaptations based on indigenous and local knowledge, etc.) can withstand, at a global average, any impacts of climate change on said yields. However, the acceleration of climate change can overwhelm this trend in the future; and the impacts are already being experienced in many regions. Climate change increased drought-induced food production losses in southern Africa, leading to 26 million people in the region requiring humanitarian assistance in 2015–2016 (Funk et al. 2018). Climate change is also increasing ocean acidification and temperatures, reducing farmed fish and shellfish production, as well as wild fish catches, with some regions experiencing losses of 15%–35% (Mbow et al. 2019).

The impacts of climate change on food production are projected to worsen after the 2050s, particularly under higher emission scenarios (Mbow et al. 2019). In agriculture, the biggest crop yield declines due to climate change are expected to occur in those areas that are already hot and dry, especially in the tropics and sub-tropics, as well as in the global drylands where water scarcity is projected to become more acute (Mirzabaev et al. 2019). More recent modelling shows that previous projections of climate change impacts on future crop yields underestimated the extent of potential yield declines. For example, many crop modelling studies do not consider the effect of short-term extreme weather events. Although extreme weather events have always posed the threat of disruptions in food systems, climate change is increasing the likelihood of simultaneous crop failures in major crop-producing areas in the world (Anderson et al. 2019; Heino et al. 2020). Disruptions in storage and distribution infrastructures and on food provisioning due to extreme event systems will also impact food availability, as well as bringing about a reduction in food exchanges due to lower productivity (Rivera Ferre 2014).

New twenty-first century projections by the Agricultural Model Intercomparison and Improvement Project (AgMIP) (Rosenzweig et al. 2021a), using ensembles of latest-generation crop and climate models, suggest markedly more pessimistic yield responses for maize, soybean, and rice, compared to the original ensemble. End-of-century maize productivity is shifted from +5 to −5% (SSP126) and from +1 to −23% (SSP585), explained by warmer climate projections and a revised crop model ensemble (Jägermeyr et al. 2021). In contrast, wheat shows stronger high-latitude gains, related to higher CO₂ responses. The ‘emergence’ of the climate impact signal—when mean changes leave the historical variability—consistently occurs earlier in the new projections, as early as 2030 in several of the main producing
regions. While future yield estimates remain uncertain, these results suggest that major breadbasket regions may contend with a changing profile of climatic risks within the next few decades (Jägermeyr et al. 2021). While many fruit, vegetable and perennial crops are understudied, higher temperatures are projected to negatively impact their production, with one study estimating a 4% reduction in fruit and vegetable production as the result of climate change (Springmann et al. 2016).

The impacts of climate change on livestock systems and fisheries have been studied much less than those on the major crops. Nonetheless, considerable evidence indicates that increased frequency of heatwaves and droughts under climate change can lower livestock productivity and reproduction through heat stress, reduced availability of forage, increased water scarcity and the spread of livestock diseases (Mbow et al. 2019; Rojas-Downing et al. 2017). Increased levels of CO₂ can favour the growth of pasture grasses, especially during rainier seasons and in more humid locations (Mirzabaev et al. 2019; Herrero et al. 2016). In contrast, in many arid and semi-arid locations, the projected effects are mostly negative (Rojas-Downing et al. 2017; FAO 2015; Boone et al. 2018). Climate change was found to reduce the maximum sustainable yield of several marine fish populations by about 4% (Free et al. 2019). Every 1 °C increase in global warming was projected to decrease mean global animal biomass in the oceans by 5% (Lotze et al. 2019), as well as redistributing fish populations away from sub-tropical and tropical seas towards poleward areas (Oremus et al. 2020). It is clear that the association between climate change and human nutrition goes beyond issues of caloric availability, and a growing challenge by 2050 will be providing nutritious and affordable diets (Springmann et al. 2016).

## 2.2 Food Access

The impacts of climate change on agricultural production, supply chains and labour productivity in climate-sensitive sectors will influence both food prices and incomes, strongly affecting people's ability to purchase food through these price and income changes (Baarsch et al. 2020). Climate change is projected to increase global cereal prices by between 1% to 29%, depending on the Shared Socioeconomic Pathway considered (Mbow et al. 2019). The reductions in the yields of legumes, fruits and vegetables will also lead to higher prices for them. The impacts of these price increases on food access are not straightforward. Net food-selling agricultural producers can benefit from higher food prices (Hertel et al. 2010). Those same higher food prices will primarily hurt the urban poor and net food-buying agricultural producers (Mbow et al. 2019). Increased temperatures and more frequent heatwaves will reduce labour productivity for outdoor work and work in closed areas without air conditioning. Lower labour productivity will result in lower incomes and lower purchasing power.
## 2.3 Food Stability

Climate change will increase the frequency of extreme water events, such as droughts, floods, hurricanes, and sea storms. Resulting inter-annual variability in food production, the destruction of transportation infrastructures, and greater food price instability can ultimately lead to more volatile global and regional food trade, undermining people's ability to access food in a stable way (Mbow et al. 2019). These disruptions could have a particularly negative impact on land-locked countries with less infrastructural access to the global food trade, as well as vulnerable social groups, especially in those locations without functioning or sufficient social protection schemes (FAO 2018).

## 2.4 Food Utilisation and Safety

Climate change is projected to adversely impact childhood undernutrition, stunting, and undernutrition-related childhood mortality and increase the number of disability-adjusted life years lost, with the largest risks being in Africa and Asia (Hasegawa et al. 2018a). Moreover, climate-related changes in food availability and diet quality are estimated to result in 529,000 excess climate-related deaths with about 2 °C warming by 2050 (Springmann et al. 2016). Most of these deaths are projected to occur in South and East Asia. Extreme climate events will even increase risks of undernutrition on a regional scale, via spikes in food prices and reduced income. Exposure to one pathway of food insecurity risk (e.g., lower yields) does not exclude exposure to other pathways (e.g., income reduction). Higher concentrations of atmospheric CO₂ reduces the protein and mineral content of cereals, degrading the quality of food and, subsequently, food utilisation (Mbow et al. 2019). Rising temperatures are improving the conditions for the spread of pathogens and myco-toxins, posing risks to human health and increasing food waste and loss (Battilani 2016). Climate change is projected to increase the area of spread of mycotoxins from tropical and sub-tropical areas to temperate zones (Mbow et al. 2019). Reduction in water quality due to climate change will also negatively affect food utilisation.

## 2.5 Impacts of Food Systems on Climate Systems

GHG emissions from food systems are a major contributor to climate change. Food systems are responsible for about one-quarter of global GHG emissions, or even up to one-third if indirect effects on deforestation are included (21%–37%) (Mbow et al. 2019). Specifically, new estimates by the Food Climate Partnership (Rosenzweig et al. 2021b) show that total GHG emissions from the food system were about 16 CO₂ eq year⁻¹ in 2018, or one-third of the total global anthropogenic
GHG emissions. Three-quarters of these emissions, 13 Gt CO₂ eq year⁻¹, were generated either during on-farm production or in pre- and post-production activities, such as manufacturing, transport, processing, and waste disposal. The remainder was generated through land use change of natural ecosystems to agricultural land. Results further indicate that pre- and post-production emissions were proportionally more important in high-income than in low-income countries, and that, during the period 1990–2018, land use change emissions decreased while pre- and post-production emissions increased (Tubiello et al. 2021).

Even if fossil fuel-related emissions were stopped immediately, continuation of the current food system emissions could make the below 2 °C climate target unachievable (Clark et al. 2020). There are significant opportunities for reducing these emissions (Smith et al. 2019), but at the same time, it is important to bear the food security implications in mind when implementing climate mitigation efforts (Frank et al. 2019; Hasegawa et al. 2018b). Without compensatory policies in place, stringent, abrupt and large-scale application of mitigation options, particularly those that are land-based, can have a negative impact on global hunger and food consumption, with the detrimental impacts being especially acute for vulnerable, low-income regions that already face food security challenges (Hasegawa et al. 2018a). However, many climate solutions can have mitigation and adaptation synergies together with other co-benefits, including for health, livelihood, and biodiversity (Smith et al. 2019; Rosenzweig et al. 2020).

## 3 Solutions for Climate Change Adaptation and Mitigation in Food Systems

Based on the above assessment, as well as the recent IPCC special report on Climate Change and Land (IPCC 2019), the following actions are proposed for uptake by governments, the private sector and civil society. These actions are of two types. Firstly, there are a wide range of both well-tested, ready-to-go solutions, and potential solutions for climate change adaptation and mitigation within food systems (Herrero et al. 2020) (Actions 1 to 7). Many of these already available solutions are well known and are being applied at local scales around the world, even if not at sufficient levels. Hence, the major effort to unleash their potential would involve overcoming various technical and structural barriers for their much wider application. The second type of action (8 and 9) focuses on key promising solutions that can help us meet the longer-term challenges of climate change within the context of food systems in the second half of this century, when most food production practices will face unprecedented challenges.

### 1. Amplify efforts for sustainable land management

Sustainable management of land (SLM), which includes water, supports and maintains ecosystem health, increases agricultural productivity, and contributes to climate
change adaptation and mitigation (Olsson et al. 2019; Mirzabaev et al. 2019). SLM is defined as the use of land resources, including soils, water, animals and plants, to produce goods that meet changing human needs, while simultaneously ensuring the long-term productive potential of these resources and the maintenance of their environmental functions (UN 1992 Rio Earth Summit).

There are many practical examples of SLM. Application of water-efficient irrigation methods such as sprinkler and drip irrigation can help increase resilience to increasing aridity under climate change (Mirzabaev et al. 2019). Adoption of drought-resistant crop cultivars under diversified cropping systems is an essential adaptive strategy in many dryland areas (Mirzabaev et al. 2019). Where suitable, agroforestry is a powerful practice for reducing soil erosion and increasing carbon sequestration, while diversifying livelihoods (Smith et al. 2019). Rangeland management systems based on sustainable grazing and re-vegetation can increase range-land resilience and long-term productivity while supporting a wide range of ecosystem services. Agroforestry practices, shelterbelts and silvio-pasture systems help reduce soil erosion and sequester carbon, while increasing biodiversity that supports pollination and other ecosystem services (Kuyah et al. 2019). SLM also includes agroecological practices, such as use of organic soil amendments, crop diversification, cover crops, intercropping, conservation agriculture practices, etc., that can have positive impacts on ecosystem services, food security and nutrition (Bezner Kerr et al. 2021; Beillouin et al. 2019; Muller et al. 2017; Tamburini et al. 2020; Kremen and Merenlender 2018). Indigenous knowledge and local knowledge hold a great array of practices for SLM (Rivera Ferre et al. 2021). Protection, restoration and climate-friendly management of peatlands are key elements for ambitious emission reduction strategies (Humpenöder et al. 2020).

Although SLM has been proven to provide positive social and economic returns, the adoption is currently insufficient. Important barriers for adoption are access to the resources for changing practices and the time required for the new practices to become productive. Introduction of payments for ecosystem services and subsidies for SLM can help. Enabling policy frameworks that include both incentives and disincentives are needed for promoting the adoption of SLM. Land tenure considerations are a major factor contributing to the adoption of SLM (Olsson et al. 2019), particularly for women. Various forms of collective action are crucial for implementing SLM in both privately and communally managed lands (Pretty 2003), although such efforts need to be strengthened and supported by policy (Isgren 2018). A greater emphasis on understanding gender-specific differences over land use and land management practices can promote SLM practices more effectively. Improved access to markets, including physical (e.g., transportation), economic (e.g., fair prices), and political (e.g., fair competition) support, raises agricultural profitability and motivates investment into climate change adaptation and SLM. Developing, enabling and promoting access to clean energy sources and technologies can contribute to reducing land degradation and mitigating climate change through decreasing the use of fuelwood and crop residues for energy, while significantly improving health for women and children (Sana et al. 2019). Finally, looking at co-benefits between addressing climate change (adaptation and mitigation) and
other urgent problems, like land degradation and biodiversity conservation, much
can be gained by promoting SLM in agriculture.

2. Promote open and equitable food trade

The very heterogeneous effects of climate change on food production worldwide and the increase in extreme weather events that disrupt local food production activities highlight the importance of international food trade as a key adaptation option to this volatile environment (Van Meijl et al. 2018; Stevanović et al. 2016). At the same time, strengthening regional and local food systems, through policies and programmes that support sustainable local production, can help build a resilient food system. Such policies can include support for urban and peri-urban production, public procurement, and subsidies that encourage the application of sustainable production approaches.

Adapting to changing climate will require a combination of enhanced regional and local food trade, as well as international food trade, that can act as safety nets in the context of climate crises. To this aim, reducing transaction costs of food trade and maintaining transparent and well-enforced international food trade governance can strengthen food systems’ resilience. This will particularly include avoiding imposing export bans. Food trade and food sovereignty are complementary elements of food security, and should not be regarded as mutually exclusive; rather, transparent and fair norms need to be agreed upon.

Fiscal instruments (e.g., carbon taxes) need to be given high priority in order to reduce fossil fuel use in agriculture. Agricultural subsidies need to be adjusted to encourage the application of sustainable production approaches and make sure that any negative effects that arise from them will be reduced through trade, and they need to take power differences into account, e.g., the impacts of subsidised food exports by high-income countries that make it harder for farmers in low-income countries to use sustainable methods or sell their products. Trade agreement mechanisms that allow low-income countries to have an equal say in trade governance are needed.

3. Include food systems in climate financing at scale

Food systems represent a range of actors and their interlinked value-adding activities that are most impacted by climate change. Food systems are also a major source of GHG emissions. This makes food systems a high priority target for adaptation and mitigation investments. However, investments into climate change adaptation and mitigation in food systems to date have only accounted for a tiny fraction of the total amounts of climate finance. Investments into climate change mitigation in food systems need to be commensurate with the share of GHG emissions coming from those systems, i.e., about a third of all mitigation funding, which is presently dominated by the energy sector and infrastructure. To illustrate, there are considerable opportunities for climate change adaptation and mitigation through investments into land restoration (e.g., reforestation, sustainable land management, re-seeding degraded rangelands) that allow for sequestering carbon in soils, increasing crop and livestock productivity and providing a wide range of other ecosystem services.
Estimates show that every dollar invested in land restoration yields anywhere from 3 to 6 dollars of return, depending on the location across the world (Nkonya et al. 2015). Investments in food value chains for reducing food waste and loss is another area with substantial mitigation and adaptation benefits. A wide range of public and private sources could be harnessed for these investments, such as increasing substantially the annual development aid dedicated to agricultural and rural development, food and nutrition security, increased investments by international and regional development banks in food systems, and more active involvement of the private sector (e.g., green bonds) and philanthropies.

### 4. Strengthen social protection and empowerment of the vulnerable

It is now practically impossible to fully adapt to climate change impacts. Even without climate change, extreme weather events periodically inflict significant disruptions on food systems at the local, regional and even global levels. Climate change will make these disruptions more frequent and more extensive. Therefore, it is essential to strengthen the social protection for vulnerable populations in terms of accessing food during the times of such disruptions. Social protection can involve many forms, such as access to subsidised food banks, cash transfers, insurance products, pension and employment guarantee schemes, weather index insurance, and universal income.

The impacts of climate change on food systems are not suffered equally by all social groups. Age, class, gender, race, ethnicity, and disability, among others, are social factors that make some people more vulnerable than others. Actions to address such inequality and differential impacts imply, on the one hand, strengthening social protection and, on the other hand, empowering marginalised social groups through collective action. Empowering women in societies increases their capacity to improve food security under climate change, making substantial contributions to their own well-being, that of their families and that of their communities. Women's empowerment is crucial to creating effective synergies among adaptation, mitigation, and food security, including targeted agriculture programmes to change socially-constructed gender biases (Kerr et al. 2016). Empowerment through collective action and groups-based approaches in the near-term has the potential to equalise relationships on the local, national and global scales (Ringler et al. 2014).

### 5. Encourage healthy and sustainable diets

Transitioning to more healthy and sustainable diets and minimising food waste could reduce global mortality from 6% to 19% and food-related GHG emissions by 29%–70% by 2050 (Springmann et al. 2016; Willett et al. 2019). According to the WHO, healthy diets are essential to end all forms of malnutrition and protect people from non-communicable diseases, including diabetes, heart disease, stroke and cancer. Currently, food consumption deviates from healthy diets with either too much (e.g., red meat and calories) or too little (e.g., fruits and vegetables) food and nutrition supply (Pradhan and Kropp 2020). Healthy diets have an appropriate calorie intake, according to gender, age and physical activity level. They are mainly composed of a diversity of plant-based foods, including coarse grains, pulses, fruits and vegetables,
nuts, and seeds, with low amounts of animal source foods (Willett et al. 2019). The current diets of many high-income countries comprise a large share of animal source foods that are emission-intensive, with red meat consumption higher than the recommended value. Simultaneously, consumption of fresh fruits and vegetables is below the recommended value in most countries (Bodirsky et al. 2020). Changes towards healthier diets have a mitigation potential of 0.7–8.0 GtCO₂-eq year⁻¹ by 2050, but social, cultural, environmental, and traditional factors need to be considered to achieve this potential at broad scales (Mbow et al. 2019; Rosenzweig et al. 2020). One critical problem is that, currently, healthy diets are unaffordable to broad sections of societies, even in high-income countries. Sustainable and healthy diets based on diversified intake are often linked to diversified production systems, highlighting the linkages between production and consumption (Chepkoech et al. 2020).

To encourage dietary transitions towards healthy and sustainable diets, a full range of policy instruments, from hard to soft measures, is needed (Willett et al. 2019). For example, unhealthy consumption of emission-intensive animal source foods can be disincentivised by applying taxes and charges, whereas adequate consumption of healthy foods such as fruits and vegetables can be incentivised by providing subsidies and raising consumer awareness. Importantly, policies promoting healthy diets need to pay due consideration to the differential roles of animal source foods in different parts of the world and the important role livestock can play in sustainable agriculture. For example, a recent study from Nepal, Bangladesh and Uganda showed a reduction in stunting in young children due to adequate intake of animal source foods (Zaharia et al. 2021).

## 6. Reduce GHG emissions from the food systems

Before promoting particular changes to the food systems, it is important to have an overview of where the most important potentials for reducing GHG emissions are. Agriculture is responsible for about 60% (or even 80%, if the indirect land use change is included) of total GHG emissions from the global food system (Mbow et al. 2019). One important message from a systematic meta-analysis of 38,700 farms and 1,600 food processors is the wide range of emissions – about a 50-fold difference between the best and worst practices (Poore and Nemecek 2018). This means that political and economic measures can achieve major reductions in GHG emissions from existing food systems by more broadly applying current best practices and without waiting for new technologies or behaviour changes.

Reducing GHG emissions requires integrated interventions both at the production and consumption sides. On the production side, all of those practices that increase soil organic matter contribute to both adaptation and mitigation, while also decreasing soil degradation and erosion. Globally, cropland soils have lost an estimated 37 GtC (136 GtCO₂) since the Neolithic revolution (Sanderman et al. 2017); recapturing that lost carbon through SLM would not only contribute to climate change mitigation, it would also increase the ecological resilience of agroecosystems and provide opportunities for income and employment in rural societies. A wide range of practices exist, e.g., conservation agriculture practices, lower GHG
emissions from fertilisers, agroecology-based approaches, agroforestry or the integration of agriculture and livestock systems that have an estimated potential to sequester 3–6.5 GtCO₂-eq/year (Arneth et al. 2021). In rangelands as well, extensive and mixed farming systems, through improved management practices, have the capacity to reduce emissions. Presently, there are between 200 and 500 million pastoralists in the world who act as stewards for 25% of the world’s land (Niamir-Fuller 2016).

Meat and dairy consumption is often considered a major culprit of high GHG emissions from food systems, but the discussion often lacks nuance. It is clear that the overall emissions from consumption of animal protein (mainly meat and dairy products) must be reduced to achieve mitigation targets compatible with the Paris Agreement. However, in some regions of the world, an increased consumption of animal protein would be desirable from a health perspective. It is also clear that livestock plays an important role in sustainable food systems – in particular, extensive livestock can help to reduce the need for mineral fertilisers, and they can produce food from areas unsuitable for growing crops (notably, drylands, cold regions and mountainous regions). Finally, expansion of post-harvest processing, refrigeration, subsidy shifts and behavioural changes are needed to reduce food loss and waste and lower the consumption of animal products in those places where intake is too high. Incentives for emission reductions should also be given to agricultural producers by applying GHG emission taxes in agriculture, or including agriculture in existing emission trading schemes.

## 7. Support urban and peri-urban agriculture

Promoting urban and peri-urban agriculture (PUA) can help increase the resilience of local and regional food systems, create jobs, and, under certain conditions, help reduce GHG emissions from food transportation (Pradhan et al. 2020) and decrease uncertainties that may be associated with disruptions in food systems. PUA includes crop production, livestock rearing, aquaculture, agroforestry, beekeeping, and hor-ticulture within and around urban areas (Clinton et al. 2018). Around 1 billion urban inhabitants (i.e., 30% of the global urban population) can be nourished by producing food through PUA (Kriewald et al. 2019). Simultaneously, PUA can support the regionalisation of food systems, reducing emissions from food transportation (Pradhan et al. 2020). Moreover, PUA is multi-functional and is practised to follow various purposes: it helps to improve food security, generate income, provide employment (Poulsen et al. 2015; Warren et al. 2015), especially for women and youths, and reconnect urban habitants with nature cycles. Subsequently, PUA not only has great potential to reduce poverty and improve nutrition, but also provides a series of ecosystem services such as reduced urban heat island effects (Li et al. 2014) or the fixation of atmospheric nitrogen and carbon when using the appropriate vegetation (Beniston and Lal 2012), thus contributing to climate change mitigation and adaptation. PUA also comprises elements of a circular economy, in which household organic waste can be used as livestock and poultry feed, rather than treated as waste (Ibrahim and Elariane 2018), subsequently reducing environmental pollution and GHG emissions. PUA contributes to increasing the resilience of urban
poor households to food price shocks. Previous research on PUA showed that it was the main and only economic activity of poor urban households in many low-income countries. And even when PUA is not the main economic activity of poor urban households, it made a significant contribution to smoothening seasonal food consumption shocks among the urban poor (Poulsen et al. 2015).

## 8. Invest in research

There have been tremendous advances in better understanding of the interactions between climate change and food systems in recent decades (IPCC 2019; Wheeler and Von Braun 2013). These investments in research and science need to be expanded into the future, not least to ensure viable agricultural systems in the long term when climate change will expose current staple food crops to unprecedented stress. Areas for investment include agroecological approaches to food production, which have so far received far lower investment (HLPE 2019), the breeding of drought-resistant crop cultivars and cultivars with improved nitrogen use to avoid emission of N₂O (Coskun et al. 2017), improved understanding of climate change impacts on both staple and non-staple foods, including impacts on the nutrition values of crops (Soares et al. 2019), particularly vegetables and fruits, and the subsequent implications for healthy diets and the full costs of said diets. Along with these environmental dimensions, increased investment in research on the social and economic impacts of climate change are needed, for example, in such areas as understanding the impacts of climate change and mitigation and adaptation options on vulnerable groups, research on participatory and transdisciplinary approaches to facilitating dialogue between indigenous and scientific knowledge, research on collective action, social innovation and mechanisms to increase food security.

## 9. Support perennial crop development and cultivation

About 87% of the world's harvested area is cultivated with annual crops, mainly grains (cereals, oilseeds, and pulses) that are germinated [?] and re-sown every year/ season (Monfreda et al. 2008). A shift to perennial grain crops would drastically cut GHG emissions from agriculture, and even turn cropping into a carbon sink, while significantly reducing erosion and nutrient leakage. Continued climate change is rendering our existing cultivars increasingly vulnerable to stress, and will ultimately make them unfit for many regions of the world (Altieri et al. 2015). New perennial cultivars have the potential to create cropping systems that are genuinely adapted for the climatic conditions towards the second half of this century. Perennial crops have the potential to drastically reduce the costs of farming by cutting the need for external inputs (seeds, fertilisers, pesticides, machinery, energy, and labour), and hence generate social and economic advantages, particularly or farmers and rural societies (Crews et al. 2018).

Development of new perennial grain crops through *de novo* domestication and wide hybridisation have advanced tremendously in the last decade, thanks to scientific and technological advancements such as genomic selection technology (Crain et al. 2021). The key benefits of perennial crops are that their widespread root systems can help sequester carbon in the soils for extended periods of time, water
and minerals are used more efficiently by perennial plants, and weeds are more effectively managed (Crews et al. 2018; DeHaan et al. 2020). They are also exceptionally drought-resistant and can bring soil erosion and nutrient-leaching to a practical minimum (Crews et al. 2016). There are already commercial cultivars of perennial rice (Zhang et al. 2021) and successful semi-commercial experiments with perennial Kernza, a wheat relative (Lanker et al. 2020). The yields of Kernza are still low compared to conventional wheat, but continued breeding can result in a competitive perennial alternative to wheat in 20–25 years (Bajgain et al. 2020). A range of other crops is in the pipeline for domestication and breeding as perennial crops, such as barley, oilseeds and pulses. Equally important is the development of perennial polycultures, such as the intercropping of perennial grains and legumes, making the system more or less self-sufficient in nitrogen. These results are proof of concept that high yielding perennial cultivars can be developed within the timeframe of a few decades, but research on all aspects of such a “perennial revolution” is urgently needed.

## 4 Conclusion

This chapter has two central messages. The bad news is that climate change is projected to affect food systems around the world significantly, often in ways that exacerbate existing frailties/weaknesses and inequalities among regions of the world and groups in society. The good news is that many practices, technologies, and wells of knowledge and social capital already exist to address climate change constructively, in terms of both mitigation and adaptation, as well as synergies between them and co-benefits with other important goals such as the conservation of biodiversity and other ecosystem services. Therefore, food systems can and should play a much bigger role in climate policies. In the short term, pro-poor policy changes and support systems can unleash a range of positive changes well beyond food systems without delay. In the long term, there is an urgent need to invest in research to ensure food security and ecosystem integrity for coming generations.

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# Delivering Climate Change Outcomes with Agroecology in Low- and Middle-Income Countries: Evidence and Actions Needed

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Sieglinde Snapp, Yodit Kebede, Eva Wollenberg, Kyle M. Dittmer, Sarah Brickman, Cecelia Egler, and Sadie Shelton

## 1 Introduction

### 1.1 Does Agroecology Lead to Better Climate Change Outcomes?

Food systems need to meet food security, nutrition and environmental goals, especially in a world with growing demand and a changing climate. There is now broad consensus on the need to transform current food systems towards more sustainable models. Agroecology is increasingly seen as a framework for transforming food systems (HLPE 2019). A key question is: how far can agroecology meet the needs for climate change adaptation and mitigation in food systems, especially in low- and middle-income countries (LMICs) and at large scales?

S. Snapp (✉)

Department of Plant, Soil and Microbial Sciences, Center for Global Change and Earth Observations, Michigan State University, East Lansing, MI, USA

e-mail: snapp@msu.edu

Y. Kebede

French National Research Institute for Sustainable Development (IRD), Montpellier, France

E. Wollenberg · C. Egler · S. Shelton

CGIAR Research Program of the CGIAR on Climate Change, Agriculture and Food Security (CCAFS), University of Vermont, Burlington, VT, USA

K. M. Dittmer

The Alliance of Bioversity International and International Center for Tropical Agriculture (CIAT), University of Vermont, Burlington, VT, USA

S. Brickman

University of Vermont, Burlington, VT, USA
**Box 1: Contemporary Approaches to Defining Agroecology**

**Ten elements of agroecology:** Diversity, the co-creation and sharing of knowledge, synergies, efficiency, recycling, resilience, human and social values, culture and food traditions, responsible governance, circular and solidarity economy

**Thirteen principles of agroecology** (HLPE 2019, also summarised here): recycling, input reduction, soil health, animal health, biodiversity, synergy, economic diversification, the co-creation of knowledge, social values and diets, fairness, connectivity, land and natural resource governance, participation.

Gliessman (2018): “Agroecology is the integration of research, education, action and change that brings sustainability to all parts of the food system: ecological, economic, and social.” It is transdisciplinary, participatory, action-oriented and “grounded in ecological thinking where a holistic, systems-level understanding of food system sustainability is required.”

To address this question, we conducted a rapid, evidence-based review to assess the quality and strength of evidence regarding (i) the impact of agroecological approaches on climate change mitigation and adaptation in LMICs, and (ii) the programming approaches and conditions supporting large-scale transitions to agroecology.

Defining agroecology with precision is a challenge. The interpretation of agroecology in development has been divergent and contested, viewed variously as a set of practices, a social movement or the science of sustainable agriculture (Wezel et al. 2009, 2020). Moreover, differentiating agroecology from other forms of alternative agriculture for sustainability can be challenging due to vague or diverse definitions (Newton et al. 2020; Giller et al. 2021; Petersen and Snapp 2015). Box 1 provides examples of approaches to defining agroecology. Box 2 summarises major schemes for sustainable agriculture related to agroecology and climate change. All share the aim to reduce the negative impacts of agriculture, but approaches vary in their reliance on ecological processes, external inputs, whole system design, or emphasis on specific outcomes.

For this analysis, we considered approaches to be more agroecological to the extent that they made use of ecological processes, supported increasing autonomy from external inputs, or enabled whole system change, rather than focusing on changing single practices (Sinclair et al. 2019; Leippert et al. 2020). We focused on the biophysical science and practice aspects of agroecology to assess impacts on climate change adaptation and mitigation, and on drivers and enabling conditions of farmer behaviour for the analysis of scaling.

We identified agroecology practices and systems guided by the United Nations’ Food and Agriculture Organisation (FAO) 10 Elements of Agroecology and Gliessman’s (2016) transitions framework. To distinguish agricultural approaches aligned with agroecology, we considered field, farm and landscape-level approaches
**Box 2: Schemes for Sustainable Agriculture Related to Agroecology and Climate Change (Adapted from Petersen and Snapp 2015)**

* **Regenerative agriculture** seeks “to improve the health of soil or to restore highly degraded soil, which symbiotically enhances the quality of water, vegetation and land-productivity” (Rhodes 2017). The potential to enhance soil carbon has recently made these practices more prominent in climate discussions.

* **Sustainable intensification** is the production of more food on a sustainable basis with minimal use of additional land (Baulcombe et al. 2009). It creates “synergistic opportunities for the co-production of agricultural and natural capital outcomes” (Pretty et al. 2020). Often associated with increased energy or fertiliser inputs and viewed as a means for sparing land, e.g., to avoid the conversion of forests.

* **Ecological intensification** “harness(es) biological understanding to improve agricultural system performance, both in terms of productivity and environmental services” (Petersen and Snapp 2015).

* **Biodynamic farming** involves “organic farming techniques that improve soil health” in ways that “influence biological as well as metaphysical aspects of the farm” (Ponzio et al. 2013). Developed by Rudolf Steiner.

* **Organic agriculture** is a production system that sustains the health of soils, ecosystems, and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than inputs with adverse effects. Organic agriculture combines tradition, innovation, and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved.

* **Climate-smart agriculture** is “agriculture that sustainably increases productivity, enhances resilience (adaptation), reduces/removes GHGs (mitigation) where possible, and enhances achievement of national food security and development goals” (Lipper et al. 2014).

that relied on enhanced ecological processes and services, compared to business-as-usual agricultural development. Examples of the agroecology approaches reviewed included diversifying crop production through cover crops, green manure and hosts for beneficial insects; managing organic nutrient sources; biopesticides; crop-livestock integration; agroforestry and organic farming.

The evidence for the review was based on the published scientific literature and semi-structured interviews with representatives from agricultural development programmes. For the literature review, we identified eighteen synthesis papers relevant to the impacts of agroecology on climate change adaptation and mitigation or to the scaling of agroecology, representing over 10,212 studies. Only four of the eighteen synthesis papers focused on LMICs, and only five others included at least 50% of the studies reviewed on LMICs, indicating the poor representation of LMICs
for available syntheses in English. In addition, we conducted a systematic literature
review of the primary evidence from LMICs for agroecological approaches and
climate change outcomes related to nutrient management (15,674 articles) and pests
and diseases (5,498 articles), resulting in a final selection of 138 papers representing
about 20 agroecological practices. Of these papers, 71% represented data from
Africa, 21% from Asia and 7% from Latin America, the latter suggesting the need
for a similar review of the Spanish-language literature. One percent of the papers
covered multiple regions. Seventy-eight percent of the papers addressed small farms,
9% addressed medium farms and 2% large farms. The full report is available online.

**2 What Does the Evidence Tell Us?**

**2.1 Climate Change Adaptation**

Substantial evidence<fnref n="1" /> exists in favour of climate change adaptation in LMICs that is associated with practices and systems aligned with agroecology, e.g., farm diversification,<fnref n="2" /> agroforestry and organic agriculture (Fig. 1). The agroecological approach with the strongest body of evidence for its impacts on climate change adaptation was farm diversification (strong evidence and high agreement). This included positive impacts of diversification on crop yield, pollination, pest control, nutrient cycling, water regulation and soil fertility. This is consistent with a recent global systematic review of similar practices within smallholder agriculture (Reich et al. 2021).

We found profound evidence concerning the impacts of agroforestry and organic agriculture on adaptation. Agroforestry had a positive impact on biodiversity, water regulation, soil carbon, nitrogen and soil fertility and the buffering of temperature extremes (Beillouin et al. 2019; Niether et al. 2020; Kuyah et al. 2019). Organic agriculture improved regulating (pest, water, nutrient) and supporting services (soils, biodiversity) (Smith et al. 2019).

Very little information was found about how agroecological approaches can
improve resilience to extreme weather, which may be partly due to the challenges

<footnote n="1">¹The number of articles with primary evidence from LMICs for adaptation was 120 out of 138, based on indicators of productivity (100), diversity (58), water and nutrient regulation (41), soil health (52), and pollination services and pest regulation (59). The quality and relevance of the eight synthesis papers found were mostly medium to high.</footnote>

<footnote>Two synthesis papers were found for diversification (covering crop diversification, organic farming, intercropping, accessory crops, and agroforestry) with 98 and 99 high-quality meta-analysis articles, respectively.</footnote>

<footnote n="2">²“Agricultural diversification is the intentional addition of functional biodiversity to cropping [and livestock] systems at multiple spatial and/or temporal scales, and it aims at regenerating biotic interactions underpinning provisioning [regulating and supporting] …ecosystem services. It embraces a variety of practices encompassing the management of crops, noncrop habitats, soil, and landscapes.” Tamburini et al. 2020. *Brackets added by brief authors.*</footnote>
<figure><img src="image_109.png" /><figcaption>**Fig. 1** Evidence base for climate change adaptation and mitigation outcomes</figcaption></figure>

of studying responses to erratic, rare events and the need for modelling and global analytical approaches that were outside the scope of the studies reviewed.

## 2.2 Climate Change Mitigation

Evidence regarding impacts on mitigation is modest,<fnref n="3" /> except for enhanced carbon sequestration in soil and biomass (Fig. 1). The agroecological approach with the strongest body of evidence concerning its impacts on climate change mitigation was tropical agroforestry, which was associated with the sequestration of carbon in biomass and soil (medium evidence, high agreement) (Corbeels et al. 2019; Feliciano et al. 2018). Also, there is a moderate and growing body of evidence in favour of organic agriculture and associated gains in soil carbon, predominantly from temperate regions and high income countries (Gattinger et al. 2012; Smith et al. 2019).

For example, Gattinger et al. (2012) reported that soil carbon stocks were higher by 3.50 ± 1.08 Mg C ha⁻¹, and soil carbon sequestration rates were higher by 0.45 ± 0.21 Mg C for pairwise comparisons of organic compared to non-organic farming, based on datasets from 74 studies. Nitrous oxide mitigation evidence was modest for tropical agriculture overall, and data on methane mitigation was very limited. Evidence from the global North suggests that reliance on organic nutrient sources and organic farming would likely avoid increased nitrous oxide emissions

<footnote n="3">³The number of articles with primary evidence from LMICs was limited: greenhouse gas emissions (6 articles), biomass carbon (4), and soil carbon (12), from a total of 138 articles. The quality and relevance of the six synthesis papers found were low to medium. Two synthesis papers were found for agroforestry, with 66 and 86 articles, respectively.</footnote>
compared to the use of synthetic nitrogen fertiliser (medium evidence, medium agreement).

As the greenhouse gas (GHG) footprint of outcomes depends on where system boundaries are drawn, multi-scalar analysis is needed to capture flows of inputs and GHG impacts beyond the farm scale; for example, emissions associated with nutrient sources (e.g., industrial fertiliser production), land-use change or feed production (Connor 2018). The almost complete lack of data on tropical agriculture GHG emissions in agroecology exacerbates this research gap (Box 3).

**Box 3: Evidence Used for the Assessment**

To assess the evidence concerning the impact of agroecology on climate change outcomes, we compiled information from two sources and triangulated findings. We selected:

1. high-quality, peer-reviewed review papers relevant to agroecology and climate change adaptation and mitigation impacts or the scaling of agroecology; and

2. primary evidence in scientific papers on approaches aligned with agroecology for (a) nutrient management and (b) integrated pest and disease management.

For the primary evidence papers, studies were only selected for analysis if they also indicated an aspect of scaling up agroecology. Scaling was defined broadly, and included adoption, farmer innovation, scaling mechanisms or enabling conditions, learning, market or policy incentives and participatory research methods. For these papers, we documented the presence of indicators as evidence in favour of adaptation and mitigation impacts. This did not include whether impacts were positive or negative relative to a control.

We also conducted semi-structured interviews with twelve organisations involved in agricultural development in LMICs, including several organisations implementing agroecology at large scales. These interviews aimed to explore the conditions and constraints for scaling up agroecology, as experience with agroecology is still novel, and thus this information was not widely available in the scientific literature.

Evidence was evaluated based on its quality and the level of agreement based on Intergovernmental Panel on Climate Change (IPCC) guidance for conducting syntheses (Mastrandrea et al. 2010). The evaluation was qualitative and relative. The strength of evidence was based on the degree of scientific robustness (statistical significance, sample size, use of systematic comparison, pairwise comparison, number of articles), relevance to agroecology, extent of geographic representativeness, relevance to LMICs, and overall quality or credibility of an article. The level of agreement was generally “high” if there were more than 100 articles with strong evidence, “medium” if there were 50–99 articles with strong evidence, or “low” if there were less than 50 articles with strong evidence, or, in the case of interviews, where the majority of the respondents agreed.
## 2.3 Adaptive Capacity

Evidence suggests that agroecology provides more climate change adaptation and mitigation than conventional, higher-input agricultural development in LMICs by emphasising locally relevant solutions, participatory processes and the co-creation of knowledge as core values. Specifically, the co-creation and sharing of knowledge supported farmers’ capacity to adapt practices more successfully to local conditions (strong evidence, medium agreement). In addition, multiple lines of evidence have shown that engaging with local knowledge through participatory and educational approaches effectively adapts technologies to local contexts, and thereby delivers improved climate change adaptation and mitigation.

Most interview respondents agreed that system approaches that prioritised local adaptation provided substantial benefits for climate change outcomes, often more than single practices. One respondent explained that “farmers are inherently system-based, and adjusting to their reality has made the work effective and created more opportunities.”

## 2.4 Yields

Evidence concerning trade-offs between yields and climate change adaptation and mitigation exists, but was not systematically reported. There were win-win outcomes for yields and climate change mitigation associated with crop diversity and organic nutrient management. There was some evidence for modest trade-offs between yields and climate outcomes for organic farming and agroforestry. Diversification was associated with increased or maintained yields (although variable) compared to conventional agriculture (high evidence, high agreement). Conversely, variable and sometimes modestly lower yields were reported for organic agriculture (Skinner et al. 2014). Agroforestry systems had variable impacts on yield depending on the main crop, agroecological zone and soil type. For example, cocoa agroforestry produced lower cocoa yields, but higher overall yields from other crops in the system and improved climate change mitigation and adaptation (Niether et al. 2020). A review of agroforestry in sub-Saharan Africa found that agroforestry significantly increased yields and soil carbon (Kuyah et al. 2019).

## 2.5 Agroecological Transitions for Large-Scale Impacts

Evidence in the scientific literature relevant to scaling and enabling conditions of agroecology was poor, with only four relevant systematic reviews identified. The scientific robustness of the evidence was also mixed. Most reviews did not address agroecology at scale explicitly or compare the scaling conditions of agroecology and
conventional agriculture. The literature review of primary evidence in favour of agroecology approaches to nutrient and pest management reported many of the same interventions and enabling conditions as those observed for scaling conventional agriculture interventions. These included the need for farmer capacity-building, use of markets, the necessity of involving government, the lack of cooperation between government offices of agriculture and offices of the environment, and poor implementation of policies (low evidence, medium agreement).

Based on interviews with field programmes, common components of these programmes' efforts to bring agroecology to scale included the co-creation and exchange of knowledge with farmers, community-based, participatory methods, localised solutions and social organising. According to the literature, scaling agroecology systems, as opposed to practices, made more use of participatory and farmer-to-farmer processes and policy. Scaling also relied on market and policy measures that privileged local production. Agroecology's inherent complexity and knowledge intensity sometimes incurred higher costs and more time than conventional agriculture, but this also enabled effectiveness and sustained benefits over multiple years.

Modest evidence was also found regarding disadvantages and challenges that impede agroecological transitions. Of the eighteen synthesis papers addressing agroecology and climate change impacts, only one explicitly addressed scaling (Cacho et al. 2018). Our review of the primary literature on nutrient and pest management yielded only 58 out of 138 articles on scaling-out processes, enabling conditions or barriers.

Critiques of agroecology have raised the issue of how to transition and reach large numbers of people. Compared to high-input sustainable intensification, agroecology can require more land to enable the use of ecosystem-based inputs and nutrient cycles (Connor 2018; Schreinemachers et al. 2011). The co-design of options with farmers can be slower and more costly for facilitating organisations, compared to top-down technical solutions, but farmers are also more likely to benefit. The attention to local knowledge around adaptation is, in this regard, both a strength and a challenge. Supporting local knowledge also requires a change in mindset of local and international actors involved in agricultural research and development and additional investment. Using conventional economic analysis, agroecological approaches can be more expensive, and some require more labour inputs compared to high-input agriculture optimised for yields; however, long-term and ecosystem benefits can be higher. The yield trade-offs associated with some agroecology approaches are a disadvantage and may pose a substantial challenge to adoption, particularly for farmers with limited resources in LMICs. Because of these constraints, the private sector has lacked incentives to facilitate agroecological practices.

## 2.6 Gaps

There is a need for research, especially in LMICs, that compares agroecology against alternatives, including current practices and expected trajectories in particular
localities. More research is also needed for long-term studies on farms and at
landscape scales in LMICs. A large data gap was found regarding agricultural
GHG emissions and mitigation, with almost no evidence from LMICs. There were
also evidence gaps regarding agroecology approaches involving livestock integra-
tion, landscape-scale redesign and multi-scalar analysis.

Critiques of agroecology question the extent to which scaling agroecology may restrict farmers’ options and become a poverty trap through a lack of access to growth opportunities (Mugwanya 2019). Similarly, to what extent does agroecology empower and enable farmer organisation? There is generally a lack of data or scenarios showing the impacts of agroecological transitions on economic development. A better understanding of the political economy of development, including who wins and who loses, and evaluation of the short-term and long-term social and ecological benefits and trade-offs of agroecology compared with other agricultural development approaches could help inform development investment. The Transformative Partnership Platform on agroecological approaches aims to contribute to this area by evaluating the socioeconomic viability of agroecological practices across Africa.

## 2.7 Donor Investment

Recent reviews of funding for agroecology found that most investments at least partly support agroecological principles (Biovision and IPES-Food 2020; CIDSE 2020). However, these analyses do not examine investments related to climate change adaptation or mitigation. The majority of agricultural investment (63%) is targeted at reinforcing or making minor adjustments to existing systems (sustainable intensification, separate funding mechanisms for agriculture and environment, performance measured mostly via yields) (Biovision and IPES-Food 2020), despite calls for food system transformation (Steiner et al. 2020). Funding for agroecology remains a small proportion of major global agricultural development investment.

To improve investment in agroecology for the sake of climate change, long-term funding modalities, the setting of targets for outcomes that include environmental services and climate change outcomes – in addition to nutritional and livelihood and social outcomes – and a search for systemic change to building farmer capacities and incentives are needed (Biovision and IPES-Food 2020). Rather than treating climate change adaptation and mitigation as co-benefits, which risks limiting progress to incremental change, there is a need to actively manage for climate change benefits. Key programme elements to increase support for agroecology and climate change outcomes include (Fig. 2):

* Processes for the co-design of practices by farmers, with research to generate relevance, fit the local context, and enable ongoing adaptation to climate risks, rather than pre-determined technical packages.
<figure><img src="image_110.png" /><figcaption>**Fig. 2** Programme elements for scaling up agroecology and climate change objectives</figcaption></figure>

* Designing system approaches, including agroforestry, organic farming, diversification, integrated pest and soil management, and landscape management designed for flexibility so as to be contextually specific and effective for climate change mitigation and adaptation.

* Strengthening extension-farmer networks and farmer-based organisations to support finance, training, farmer-to-farmer knowledge exchange, local education, monitoring and decision-making.

* Market, institutional and policy arrangements that promote these approaches and overcome the tendency for environmental and climate change objectives to be treated as separate from agricultural development, and that address trade-offs between environment or social outcomes and productivity or profitability to support more rapid and large-scale impacts, including nationally determined contributions (NDCs) to the Paris Agreement.

* Providing institutional support for monitoring environmental services, in order to assess performance that considers more than productivity or profitability, using climate change mitigation and adaptation indicators. This is needed to inform policy across multiple dimensions and support annual reporting to the UN Framework Convention on Climate Change (UNFCCC).

## 2.8 What Actions Need to Be Taken?

Tackling climate change will require broad cooperation and diverse approaches. Implementing agroecology across organisations with different political visions for development will require transcending the many labels around sustainable
agriculture and climate change (e.g., climate-smart agriculture, regenerative agriculture), including agroecology. Labels like agroecology can still be expedient for communication; the point is to spend less time debating what agroecology is.

We thus **recommend an outcome-based approach to guide donor investment and national policy, using an assessment of the performance of agricultural development that integrates agroecological principles and climate change adaptation and mitigation indicators.** This is to avoid contestation around what is encompassed by a specific label for an agricultural alternative and instead assess performance in terms of environmental services and climate change response. Attention to outcomes relevant to the Sustainable Development Goals (SDGs) such as climate change resilience, environmental health, gender equity and social inclusion, soil health, biodiversity conservation, healthy diets and resource efficiency can provide common points of reference (Leippert et al. 2020).

A number of frameworks can be used to systematise the monitoring of agroecology performance (Wezel et al. 2020; Kapgen and Roudart 2020), including FAO's Tools for Agroecological Performance Evaluation (TAPE) (Barrios et al. 2020). The USAID-supported Sustainable Intensification Assessment Framework provides systematic approaches to outcome-based assessment and trade-off analysis (Grabowski et al. 2018).

Based on the strength of the evidence, a **second important action is to direct agricultural development investments towards agricultural diversification, local adaptation and pathways to scaling both.** Programme implementation experts indicated that promoting agricultural diversity can be a scalable intervention, and that it is often prioritised in programmes supporting agroecology. However, trends in agricultural development overall lean in the opposite direction, with widespread simplification of farms and cropping systems. Local adaptation can be promoted by supporting farmer innovation, co-learning and the adaptation of innovations to local contexts. Top-down technology packages are often promoted, rather than menus of farmer-co-designed options. Thus, diversification and local adaptation may require special attention at the policy and program levels.

In many countries, local and national agroecology platforms already exist, but can be strengthened to successfully use agroecology for climate change adaptation and mitigation in addition to the improvement of local livelihoods. Knowledge systems of agricultural producers need to be affirmed through networks of farmers and other stakeholders within the food systems to support the co-design of climate-friendly practices. To support farmer investment in diversified farms, women and men farmers' access and control over land and other elements of agroecosystems will be key enabling conditions (FAO 2012).

The limited information concerning agroecological approaches' response to extreme weather events and GHG emissions is a matter of great concern. **A third action is to develop national strategies and action to enhance resilience to extreme weather events and climate change mitigation outcomes.** This should build on the knowledge of countries with considerable experience of repeated extreme weather – such as the Philippines, Thailand, Haiti, and Honduras – to support strategies that will embed planning for extreme weather events in national
policies. There is an urgent need to build the capacity of policymakers, scientists and institutions from the global South to work on these issues.

**A fourth action is public investment in research to improve analysis of agroecology relative to other agriculture development approaches at multiple spatial and time scales so as** to better evaluate alternative approaches to sustainable agriculture. Assessment is required for food security, environment and other dimensions of sustainable development, as well as the cost-effectiveness of different options in different contexts, including geographic regions. Assessment of cost-effectiveness should consider how to value environmental and social benefits and how assessment based on current policy contexts (e.g., subsidies) and short-time horizons might bias comparisons. Research includes comparative (alternatives versus conventional) and holistic (social, financial, environmental and agronomic) assessments. Reviews of French and Spanish-language literature would also enrich the foundation of evidence further, particularly for Latin America and West Africa.

**Acknowledgements** We would like to thank Ajay Vir Jakhar, Alan Tollervey, Alesha Miller, Anna De Palma, Barbara Gemmil- Herren, Batamaka Somé, Boru Douthwaite, Bruce Campbell, Christian Huyge, Christian Witt, Christophe Larose, Daniel France van Gilst, Dhanush Dinesh, Diana Salvemini, Emily Weeks, Fabio Leippert, Giles Henley, Guy Faure, Howard Standen, James Birch, Jean-Francois Soussana, Jerry Glover, Joanna Francis, Julian Gonzalez, Mercedes Bustamante, Michael Farrelly, Michael Okoti, Nick Remple, Noel Gurwick, Rachel Lambert, Rikin Gandhi, Stephanie Heiland, Tom Tomich, Ueli Mauderli, Vijay Kumar, Wijnand Van Ijssel, Ken Giller, Confidence Duku, Annemarie Groot, and Joachim von Braun. This work was funded by the New Venture Fund and the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), which is carried out with support from the CGIAR Trust Fund and through bilateral funding agreements. For details, please visit https://ccafs.cgiar.org/donors. The views expressed in this document cannot be taken to reflect the official opinions of these organisations.

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# Crop Diversity, Its Conservation and Use for Better Food Systems

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Stefan Schmitz, Rodrigo Barrios, Hannes Dempewolf, Luigi Guarino, Charlotte Lusty, and Janet Muir

## 1 The Loss of Agrobiodiversity and Its Risks

Climate change, biodiversity loss and the food system crisis are among the major challenges of the twenty-first century, and they are closely interrelated. Climate change is threatening the survival of species and affecting crop yields, for example, and the destruction, degradation and fragmentation of ecosystems is accelerating climate change, driving biodiversity loss and affecting food security.

Biodiversity loss includes the depletion of ecosystem diversity, of species diversity and of genetic diversity within species. One of the strongest drivers of biodiversity loss is agriculture, for example, the conversion of forests and peatlands into arable land. However, there is also a loss of biodiversity within agriculture, for example:

* Loss of species diversity on agricultural land, both the number of crop and livestock species themselves and those of associated biota (e.g., weeds, soil microorganisms, pollinators) due to the use of fertilizers, herbicides and pesticides.

* Loss of genetic diversity within crop and livestock species, or genetic erosion, as the result of modern agricultural practices.

Agriculture is thus both the culprit and the victim.<fnref n="1" />

This loss of crop diversity poses a considerable risk to global food security. This is because the genetic diversity of cultivated plant species, and their wild relatives, is the raw material of crop improvement. It has been thousands of years since the

S. Schmitz (✉) · R. Barrios · H. Dempewolf · L. Guarino · C. Lusty · J. Muir
The Global Crop Diversity Trust, Bonn, Germany
e-mail: stefan.schmitz@croptrust.org

<footnote n="1">¹After these introductory remarks on the entire range of agricultural genetic resources, i.e., plant, animal, etc., only the partial aspect of plant genetic resources will be pursued in the following.</footnote>
advent of agriculture, and the need for it will only grow. The pressures on agriculture will increase in the future. The world population continues to grow, and grows richer and more demanding in the process. The climate is changing and, with it comes the likelihood of crop failure, including due to the emergence of new pests and diseases.

Meeting these challenges will only be possible if the genetic diversity contained in crops and their wild relatives remains available for use. This genetic diversity is the foundation of tomorrow's agriculture, allowing farmers and professional breeders to develop the new crop varieties that agriculture needs to adapt to changing conditions. The development of new varieties will be necessary for successful adaptation to climate change, and thus to secure the world's food supply in the future (Hawtin and Fowler 2012).

The maintenance of agrobiodiversity in situ, i.e., in nature and agricultural practice, remains indispensable, and is a task for protected areas and on-farm conservation efforts (Vincent et al. 2019). However, given the risks associated with this strategy, a second approach must be pursued consistently in parallel: the conservation of agrobiodiversity *ex situ* in genebanks.

## 2 Why *Ex-Situ* Conservation?

In view of the dramatic risk of loss of plant genetic diversity in nature and agricultural practice, its rescue before it is irretrievably lost is imperative. However, *ex-situ* conservation would make sense from a use point of view, even if there were no genetic erosion going on in the field at all.

This is because it would be tremendously complicated and expensive if, every time a plant breeder needed new genetic diversity, new material had to be collected from the wild or from farmers' fields, often in distant countries. It is true that there are many breeders who maintain their own working collections of germplasm, for short-term purposes. But there are clearly considerable efficiencies to be gained from collective efforts to build more comprehensive collections for long-term use in centralized genebanks at the national, regional and international levels. Such efforts are being made around the world, usually with the support of governments, and sometimes the international community. The values of conserving collections of plant genetic resources in genebanks are diverse and considerable (Hawtin and Fowler 2012):

* Having invested in collecting plant material from the wild or from farmers' fields – an expensive exercise – the cost of maintaining it in a genebank is often small by comparison.

* Samples are available from genebanks throughout the year, unlike plants growing in the wild or on farmers' fields that can generally only be collected in certain periods of the year, such as at harvest time.
* Genebanks are generally able to supply adequate quantities of good quality seed for research and breeding purposes. It is often difficult to collect adequate numbers of seeds of good quality from plants growing in the wild.

* Genebanks are generally able to supply samples that are free from pests and diseases. It is much harder to guarantee the health of material collected in the wild.

* Collections maintained in well-run genebanks remain genetically stable over time, unlike varieties maintained by farmers or populations under in situ conditions. This facilitates research and the generation of reliable information about samples, which, in turn, encourages their use in breeding programs.

* Genebanks offer a “one-stop” shop. Breeders are able to access a large range of diversity, often from many different countries, with a single request.

* Well-run genebanks have the facilities, administrative systems and experience not only to maintain samples, but also to distribute them nationally and internationally.

* Well-run *ex-situ* collections have reliable and readily available passport, characterization and evaluation data on samples, and, increasingly, data at the molecular level. Such data are critical to the ability of users to make informed choices about which materials to request, and how to use them.

* Over time, collections become ever more valuable as the data on the material in them become more comprehensive. Useful comparative data can be built up and made available for sets of samples grown across multiple environments.

* *Ex-situ* collections provide a “safety net” – a last resort – that enables locally adapted varieties and/or specific traits to be reintroduced into farming systems after they have been lost due to natural or human-induced disasters.

## 3 Status of *Ex-Situ* Conservation

The latest available data suggest that there are more than 1750 genebanks world-wide, of which about 130 hold more than 10,000 accessions each (FAO 2010). They are located on all continents barring Antarctica, though there are relatively few in Africa compared to the rest of the world. While it is estimated that about 7.4 million accessions are maintained globally, it is probable that, at most, only between 25% and 30% of these are unique, with the remainder being duplicates held either in the same or a different genebank. Clearly, there is a need for a measure of rationalization within and among collections (Hawtin and Fowler 2012).

While the majority of large collections are maintained at the national level, international collections are critically important because of their size and coverage, the availability of information on their contents and the ease of obtaining samples. Eleven of the CGIAR centers manage germplasm collections on behalf of the world community under Article 15 of the Plant Treaty, and, of these, the collections maintained by CIMMYT, ICARDA, ICRISAT and IRRI each comprises more than 100,000 accessions. Collectively, the CGIAR centers maintain more than
730,000 accessions of 3,000 species from 500 different genera. National genebanks managing more than 100,000 samples include those of Brazil, Canada, China, Germany, Japan, India, Russia, South Korea and the USA.

# 4 What Remains to Be Done

Unfortunately, many genebanks, especially in the Global South, are unable to guarantee the safety of the material they are responsible for, and valuable collections may be in jeopardy because their storage conditions and management are suboptimal. Further, the purpose of genebanks is clearly not just to conserve diversity, but also to create opportunities for plant breeding and more sustainable agriculture, i.e., for said diversity to be used. Much remains to be done. We focus here on three key interventions:

1. Strengthening the global system of *ex-situ* conservation

2. Making the global system fit for the purpose of caring for hard-to-conserve materials

3. Innovative funding of the global system

## 4.1 Towards a Stronger Global System of Ex-Situ Conservation

International and national genebanks operate within a worldwide community, or global system, that is made up not only of the institutes managing genetic resources, but also of a global plan of action, various technical standards, regional and crop networks and other instruments, all underpinned by the policy framework provided by the Plant Treaty, the Convention on Biological Diversity, the International Plant Protection Convention and the FAO Commission on Genetic Resources for Food and Agriculture.

The Crop Trust works with all parts of this community and has a unique role in helping to strengthen the global system so that it may become more effective, rationalized and collaborative. There are four main ingredients to strengthening the global system:

* A critical component in making the global system work is the availability of good quality data. It is only through good data that we know what is conserved, where and whether it is alive and available for use. Genesys, the online portal for accession-level data, provides a means for genebanks worldwide to share pass-port and characterization data on their collections, as part of the Plant Treaty's Global Information System. For such systems to reach their potential, genebanks require support to manage and share their data. For that reason, GRIN-Global
Community Edition is being developed for adoption by any genebank to help manage their data and their collections, and to build linkages with diverse data resources and systems that can enrich data holdings and help promote the use of diversity.

* Good quality data is intimately related to good operational practices and quality management. The Crop Trust, with CGIAR, has been developing a genebank quality management system (QMS) framework. Based on FAO genebank standards, the genebank QMS supports the documentation, review, improvement and sharing of genebank operations and practices. It provides a supportive tool for training and staff succession and an excellent vehicle for strengthening risk management and staff health and safety. Through QMS, new principles, protocols and research findings can be introduced into genebanks and spread among the global system as a whole.

* Armed with new data management tools and QMS, the Crop Trust has introduced new ways of building capacity through Genebank Operations and Advance Learning (GOAL) workshops, QMS Intensives, Genetic Resources on the Web (GROW) webinars, and communities of practice, each tailored for different levels of learning. The Crop Trust has also introduced performance targets to complement the FAO genebank standards, monitoring tools, audits and reviews, which are key to managing its long-term grants, but which can also apply to any genebank with an ambition to reach high standards of operation and fully participate in the global system.

* Finally, the global system has been growing and developing over several decades, and there is an opportunity now for different institutes to specialize and complement each other more coherently. The Svalbard Global Seed Vault, just over ten years old now, has already proven its worth in providing a unique mechanism for genebanks to deposit accessions for safe back-up. More institutions may be able to take up specialist roles on behalf of the community as a whole, whether it is conserving difficult crops and wild species, cryopreservation, or disease testing and cleaning for international germplasm movement. The Crop Trust would like to expand its work to help build capacity and partnerships to allow institutes to specialize and provide services for others.

## 4.2 Making the Global System Fit for the Purpose of Caring for Hard-to-Conserve Materials: Cryopreservation

The vast majority of crops have so-called orthodox seeds, which can be conserved relatively easily in cold stores if adequately dried. However, there are also other important crops – like bananas, cassava, cacao and coffee – that are propagated vegetatively, do not produce seeds or have seeds that are not orthodox. Their ex-situ conservation is therefore not possible through the typical drying and storage of seeds at –18 °C. Instead, these crops are usually conserved in field genebanks or in vitro,