This is an essay about sustainable intensification, a goal in farming whereby yields are increased without causing harm to the environment or cultivating more land. It’s one of many approaches that will help secure food for our future generations.
The essay explores its potential role and is divided into three parts. Part 1 provides some context, examining the complex, deeply interconnected and mutually reinforcing problems in our food system. Part 2 introduces the underlying concepts of sustainable intensification and its contribution to help address challenges in the food system. Part 3 critiques different approaches to food production, comparing the potential roles of industrial agriculture against diversified agroecological approaches.
This is an adapted version of an essay I wrote for a Food Security course I’ve been doing with Bangor University. Therefore it’s a little more formal and academic in style than my usual posts.
Part 1: Historical Context and Food System Challenges
In 1943 during the midst of World War II, a seminal event for the future of food and agriculture took place in Hot Springs, Virginia. Representatives of the United Nations gathered together for a conference comprising of 44 governments, representing 75 per cent of the world population. Their ambitious task was to reach agreement on certain plans for the production, distribution, transport and consumption of food across the world after the war (Lyon 1943). The delegates included diplomats, politicians, as well as experts in nutrition, economics and agriculture. The conclusion was that freedom from want of food, suitable and adequate for the health and strength of all peoples, can be achieved (FAO 1981).
During this period, substantial changes in agricultural practice were starting to spread across the world. Beginning in the 1940s and expanding significantly in the late 1960s, the ‘green revolution’ included new farm management practices, higher-yielding varieties of plants, synthetic fertilisers and pesticides, all of which contributed to increased yields. Worldwide, gross crop production grew from 1.84 billion tonnes in 1961 to 4.38 billion tonnes in 2007, an increase of 138% (Royal Society 2009). During this same period, global land for agriculture increased only 10%, from 4.46 billion ha to 4.92 billion ha (FAOSTAT 2016). While a huge achievement for increased yields, this intensification has been responsible for significant ecological degradation including water, air and soil pollution, causing sharp declines in biodiversity, increased greenhouse gas emissions contributing to climate change, and depletion of non-renewable resources (Foresight 2011; WWF 2016).
The increases in yield supported another substantial trend during the 20th century. Aided by advances in healthcare, the human population grew from 1.7 billion in 1900 to 7.3 billion in 2015 (UN 1999; UN 2015). It’s expected that population will level out at 8-10 billion by 2050 with the highest rate of growth expected in Africa (UN 2015).
Increased food demand is one of many pressures facing humanity today. While there’s been positive developments in the last 50 years such as a decline in the proportion of people suffering from hunger (FAO 2015), many major problems exist in the food supply chain:
- Many systems of food production are unsustainable, degrading the environment and compromising our future capacity to produce food (Foresight 2011): modern agriculture is causing problems such as overfishing, soil erosion, loss of soil fertility, salination, eutrophication and rates of water extraction exceeding replenishment. These practices are also contributing to climate change and biodiversity loss.
- Widespread hunger: an estimated 795 million people remain undernourished (FAO 2015).
- Over-consumption: over one billion people are substantially over-consuming, resulting in a public health epidemic of chronic health conditions such as cardiovascular disease and type-2 diabetes (Haslam 2005).
One significance of the 1943 Hot Springs Conference was that it laid foundations for the Food and Agricultural Organisation (FAO), an organisation dedicated to overcoming food and agricultural challenges through multilateral collaboration of governments and organisations. To respond to challenges in the food system, FAO developed the concept of food security, as defined below, which lies at the heart of its efforts today:
Food security exists when all people, at all times, have physical and economic access to sufficient safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life.
— 1996 World Food Summit (FAO 1996)
The evidence that substantial changes are required throughout the food system to meet food security and sustainability goals is overwhelming (Foresight 2011; IPES-Food 2016). These changes must be achieved from within a deeply complex food system comprised of a mostly self-organised set of interacting parts. Figure 1 provides a representation of the food system showing relationships between key drivers, activities and outcomes.
Figure 1 shows that food system activities determine various outcomes, including levels of food security and social and environmental welfare. The environmental challenge includes respecting and operating safely within planetary thresholds1 that safeguard our future by protecting ecosystem services. The social welfare challenge includes a variety of issues such as income, jobs, health, energy and food.
One approach developed by Oxfam to frame humanity’s challenge is the ‘doughnut of social and planetary boundaries’, shown in Figure 2 (Oxfam 2012). This communicates a vision of prosperity that involves living within the ecological means of the planet while ensuring everyone has the resources required to meet their human rights. We need to design our food system to operate in this space and just space.
At an international policy level, there is a shared aspiration between UN Member States for achieving food security. Adopted in 2015, the goal to “End hunger, achieve food security and improved nutrition and promote sustainable agriculture” is one of 17 goals with associated targets, across a broad range of sustainable development issues (UN 2016a).
Part 2: Key Concepts in Sustainable Intensification
2.1. Definition and context
Sustainable intensification is a relatively new term that has been interpreted differently by different people (Garnett and Godfray 2012). The Royal Society (2009) defined sustainable intensification as a goal for agricultural production wherein “yields are increased without adverse environmental impact and without the cultivation of more land”. This definition frames sustainable intensification as an aspiration for raising productivity, not privileging or articulating any particular type of production (Garnett and Godfray 2012).
Sustainable intensification has been considered one component of action on a variety of fronts to achieve food security and sustainability goals, as shown in Figure 3 (Garnett and Godfray 2012). While this essay focuses on sustainable intensification, it’s recognised that action is required across multiple fronts to meet these goals.
2.2. An increasing demand for food?
As described in Part 1, a wave of agricultural intensification occurred during the 1960s. However in recent decades there has been increasing yield stagnation in the world’s major cereal crops (FAO 2002; Ray 2012). Studies project an increase in global food demand until 2050 and an increasing share of animal-based products in people’s diets, especially in rapidly industrialising countries such as China (Bodirsky 2015). These changing dietary preferences are influenced by multiple factors including income, climate, urbanisation, food prices and markets (Drewnowski 1997; Bodirsky 2015).
Studies forecasting future crop production demands fluctuate significantly. For example, the FAO has projected a need for a 60% increase by 2050 (FAO 2013) while a study by Tilman et al. (2011) suggested a 110% increase was required. While increased demand is probable, it is worthwhile recognising the influence of dietary preferences and inefficiencies. Figure 4 estimates the total food calories potentially available for human consumption if waste and the inefficiencies of animal production were removed. This highlights opportunities in demand management and food waste reduction. Lundqvist et al (2008) estimate that global food production is already theoretically sufficient to feed the planet twice.
2.3. Ecosystem services
Humans derive a range of benefits from ecosystems, without which we would not survive. One approach that helps recognise these benefits is known as “ecosystem services”. Figure 5 gives examples of these across a range of habitats, taken from the UK National Ecosystem Assessment (UNEP-WCMC, 2011). Ecosystem service assessments show how provisioning services such as food are just one of many benefits we derive from farmlands, making it a useful concept to draw from when we talk about sustainable intensification.
2.4. Land sparing and land sharing
Future food demands can be met by expanding the area of agricultural land available or increasing yields through intensification on existing farmland. Throughout history, increasing tracts of land have become managed by humans (Figure 6). Approximately 40% of land cover is now given to crops and pasture (Foley 2005) and there are recognised limits governing continued expansion of agricultural land:
- Remaining land usable for agriculture consists mainly of forests, wetlands or grasslands (Garnett 2013). Most of the highest quality land is already used for agriculture and much of the remaining areas are less suitable (Tilman 2002).
- Land conversion reduces rates of carbon sequestration, impacting climate regulation and other ecosystem services; rainforest clearance is a prominent example of this. Climate change is already affecting yields (Lobell 2007) and further climate change will particularly impact lower-income countries (IPCC 2014).
- Unsustainable biodiversity loss reduces our future capability to produce food (Scherr 2012). 35% of crops depend on pollination and the global decline in pollinators is driven by the use of pesticides and habitat loss from intensive agriculture (IPES-Food 2016).
- Competition for other land use such as built environment, culture and recreation.
- Freshwater availability and competition for water limits agricultural production. 70% of freshwater withdrawals are used in agriculture, mostly for irrigation (WRI 2005). Unsustainable water consumption has led to draining of aquifers and reductions in river flows. Currently, water stress affects more than 2 billion people around the world and this figure is set to rise (UN 2016b).
The choice between intensification or expansion of agricultural land is sometimes framed as a discourse in comparing two land management approaches, known as land sparing and land sharing:.
- The idea behind a land sparing approach is to focus highly intensive agriculture on one piece of land, while ensuring there is associated land set aside for conservation.
- In a land sharing strategy, less land is set aside specifically for conservation, but less intensive production techniques are used to maintain biodiversity throughout agricultural land.
While this dichotomy offers a heuristic for thinking about trade-offs, it’s important to recognise that these strategies are not mutually exclusive and in reality, there are options in between. For example, farms can combine elements of land sparing and wildlife-friendly farming. Three challenges for land sparing are: 1) ensuring long-term food production is viable on the intensively managed land, 2) managing spillover, off-site negative effects such as
Three challenges for land sparing are: 1) ensuring long-term food production is viable on the intensively managed land, 2) managing spillover, off-site negative effects such as such as impacts from the production of agro-chemicals or water pollution and 3) land spared not being adequately tended to maximise ecosystem functions or have long-term protection assured (Fischer 2014). Fischer et al. (2014) identified how the discourse of land sharing vs sparing lends itself to polarisation and various frictions in the scientific community, recommending that an alternative, more holistic analytical framework may support better analysis.
2.5 Measuring what matters
In securing a long-term food supply, a common question when evaluating sustainable intensification concerns productivity. As an example, the question “can an organic farm be as productive as a non-organic farm?” is fraught with difficulties in measurement, such as:
- Which units of measurement? It is common for farm productivity to be measured as the production output against the land area (e.g. tonnes/hectare), production output against labour input, or the financial value of the output. Although useful, each measure offers a narrow view of productivity, not accounting for aspects such as the efficiency of inputs used in the production such as water, chemicals and energy. Measuring the “sustainability” with regard to productivity might also call for units such as “output per unit of water” or the carbon footprint (output per kg CO2e).
- Some inputs may be produced off-site, for example, the animal feed. Therefore measuring or comparing the efficiency of production becomes difficult without conducting detailed life-cycle assessments.
- Measuring multi-crop productivity: for example, some farms might practice intercropping with the aim of increasing total productivity. This is common in agroecological approaches to farming and makes comparisons against monoculture productivity difficult.
- Measuring ecosystem services beyond food provision: farms often provide a range of ecosystem services (see section 2.3) that are not explicitly valued financially.
- Other conditions affecting productivity: every farm will have its own climatic conditions (e.g. soil, weather, slope, water) that will greatly influence productivity. Therefore the question of productivity between two farms must take into account their site conditions. Only carefully conducted trials or aggregating data across a sector makes it possible to compare productivity across different types of agriculture.
These complexities in measurement explain why there is a limited evidence base and lively debate regarding the potential for different modes of agriculture to “feed the world”. The next section explores this in more detail.
Part 3: Approaches to food production
Adapted from IPES-Food (2016), Table 1 contrasts two ends of a spectrum for approaches to agriculture. While both share a goal of food provision, specialised intensive agriculture tends to focus on achieving a maximum volume of product, whereas diversified agroecological approaches tend to aim for multiple yields with less external inputs. There are of course, many farmers that operate in the middle, adopting practices from both approaches.
Figure 8 lists agricultural system outcomes that can be evaluated when comparing trade-offs between different modes of agriculture. While each outcome is important, it is not possible in this essay to provide a comprehensive critique of all outcomes. To explore the form of sustainable intensification, the following section focuses mostly on productivity and environmental outcomes.
3.1 Industrial agriculture
3.1.1 Productivity: Yields
Despite recent decades of yield growth stagnation (described in section 3.2), agri-tech firms suggest significant increases are still possible from a combination of biotechnology, advanced plant breeding and improved farm-management practices. Advances include genetic modification, resource efficiency through precision farming and improved herbicides and pesticides. One multinational company, Monsanto, has a goal to double yields of corn, soybeans and cotton between 2000 and 2030 using these techniques (Monsanto 2016).
Elsewhere, there is concern that focusing on maximising yields comes at the expense of future productivity as ecosystem services become degraded even further (Deguines 2014; Tilman 2002). Similar doubts are shared for the livestock sector which will be increasingly affected by competition for land, water, food and feed, as well as a low-carbon economy (Thornton 2010).
While firms focusing on the industrial model of farming publicise impressive yield targets, maintaining its character presents some serious environmental risks such as:
- Loss of ecosystem services: farms provide a diverse set of ecosystem services, some of which are degraded by industrial practices. For example, removal of trees increase the risk of flooding, soil erosion and reduce biodiversity. The worldwide loss of pollinators is another example, closely linked with industrial farming practices and threatens future food production (Clermont 2015).
- Resilience and vulnerability: monocultures of genetically uniform species creates erosion of the gene pool, posing greater vulnerability in crop disease outbreaks. For example, of the 7,616 livestock breeds that exist, about 86% are local breeds present in one country and 20% of these are at risk of extinction (IPES-FOOD 2016). With the unpredictability of future stresses, the implications of genetic erosion could be huge. The reliance on pesticides also binds farmers financially to agri-tech companies, and weed resistance to pesticides fails to address underlying problems of pest resistance (IPES-FOOD 2016).
- Land degradation and soil erosion: intensive industrial agriculture has been considered the largest contributor to land degradation at a current rate of 12 million hectares per year (ELD Initiative 2015).
- Water contamination: chemical inputs result in particularly high risks of runoff leading to contamination of water courses (Boardman 2003). Furthermore, current trends estimate that 50% of irrigated arable land will be salinised by 2050 (Jamil 2011).
3.2 Diversified agroecological farming
3.2.1 Productivity: Yields
Long-term studies comparing yields between agroecological systems and industrial agriculture are limited (IPES-FOOD 2016) due to complexities such as comparing monocultural yields against polyculture yields, and comparing different farm types and sizes (see section 2.5). Studies that exist mostly focus on organic farming (described below) and tend to record lower yields when compared to industrial monocultures in developed countries, but higher yields in developing countries and on smaller farms (Kirchmann 2008):
- Badgley et al. (2007) analysed 293 yield comparisons between organic (or semi-organic) and industrial production and found that organic systems produced 8% lower yields than conventional in developed countries, while in developing countries, organic systems outperformed conventional approaches by far.
- De Ponti et al. (2012) analysed 362 paired sets of yield data across 43 countries, reporting organic yields as 80% of those obtained under industrial.
- Pettey et al. (2006) examined 286 interventions in developing countries and found that farmers adopting agroecological practices had an average of a 79% increase in yields (Pretty 2006). This was against a variety of baseline agricultural approaches.
- When comparing the productivity of polycultures, several studies demonstrate that “less land is required to produce in polycultures than to produce the same amount in monocultures, making yield per area higher in polycultures” (IPES-FOOD 2016).
Organic farming operates without pesticides, herbicides, antibiotics or inorganic fertilizers. It’s the most well known form of agroecological farming and various certification schemes exist for accreditation of organic practice. Organic practice involves elements such as crop rotations and diversification to maintain yields and manage pests. Factors limiting yields can include lower nutrient availability and weed control.
While the share of agricultural land being managed organically is increasing, globally it accounts for just 1% (FiBL 2016). The potential scope for organic farming is disputed. Some assessments have concluded that global food provision could be met by upscaling organic agriculture globally (Bagdley 2007) while critics believe that the amount of nitrogen fixation required to achieve necessary yields cannot be met sufficiently by animal and green manures (Halberg 2015; Kirchmann 2008).
Exploring the same environmental outcomes used in section 3.1.2, diversified agroecological approaches offer the potential to help achieve sustainability goals and longer term resilience:
- Ecosystem function and services: organic farms host greater biodiversity than industrial systems and this contributes to the delivery of ecosystem services. A meta-analysis found organic farms to have an average of 30% higher species richness than industrial systems, and 50% more species abundance (Bengtsson 2005).
- Resilience and vulnerability: agroecological farms tend to operate at smaller-scale with greater crop and livestock diversity. Practising year-round production and greater crop diversity can create a more resilient food supply during seasonal shortages (Powell 2015), environmental stresses and extreme weather events (IPCC 2014).
- Land degradation and soil erosion: the focus on building soil organic matter so that crops have the nutrients required supports better water-holding capacity and carbon sequestration.
- Water contamination: instances of water contamination are reduced as a result of less chemical inputs.
To secure a long-term sustainable food supply, sustainable intensification must occur within safe operating boundaries to preserve and enhance ecosystems (Figure 2). The required ‘intensity’ of production hinges on success across several fronts such as demand management, reducing waste, lower-impact diets and improved farming practice (Figure 3).
Even while promising improved yields with approaches such as biotechnology and GM, the analysis in section 4.1.2. suggests that by maintaining its character, the industrial model will continue to degrade numerous ecosystem services. This is a dangerous tract, threatening long-term human survival.
Agroecological approaches offer significant potential for addressing sustainability goals including resilience. Yield comparisons can be comparable but vary significantly and evidence on capacity for increased yields is limited and disputed. For approaches such as organic farming, studies suggest there are significant productivity gains possible in developing countries. Yield improvements may occur through better knowledge-sharing, precision technologies and increased intercropping (Halberg 2015).
The natural question is whether there is scope for convergence. As shown in Figure 8, can industrial agriculture integrate agroecological practices while continuing to intensify? Some form of convergence seems imperative to meet sustainability goals. In its form, the convergence needs to be transformational. Several reports suggest that just “tweaking practices” in industrial agriculture is not enough and won’t deliver the change required to respond properly to sustainability challenges (Foresight, 2011; IPES-FOOD 2016).
Transforming the industrial agricultural sector is challenged by “lock-ins” that act as barriers to change. For example, industrial agriculture often requires significant financial investment (e.g. machinery for monoculture production) and once that investment has been made, it is difficult for a farmer to change course. IPES-FOOD (2016) have identified eight “lock-ins” and solutions that could help unlock industrial agriculture to become more agroecological, as shown in Figure 9. This shows the important role of governance, food policy and further research to help realise sustainable intensification.
Sustainable intensification is one of several paths that will improve resilience and efficiency in the food system. The degraded state of ecosystems and the sense that “time is running out” to effectively mitigate climate change impacts demand urgency in response. Industrial agriculture is challenged with maintaining yields while diversifying and significantly reducing its inputs and widespread environmental impacts; “tweaking” practices is not enough. While diversified agroecological modes of production must be scaled-up with further innovation to improve yields. A convergence of thinking is needed however several “lock-ins” for industrial agriculture extending beyond food production make this transition difficult, highlighting the role of further research, improved governance and policy.
This essay provides an overview of key issues for sustainable intensification and is not a comprehensive assessment. Many important agricultural outcomes such as livelihood, income, and employment conditions were not discussed. Further reading is encouraged by exploring the references used in this essay.
1. The notion of ‘planetary thresholds’ relates to estimates of how close to a threshold the global human community can act, without seriously challenging the continuation of the current state of the planet. It includes nine Earth system processes that include biodiversity, nitrogen cycle, climate impacts, land system change and atmospheric aerosol loading. (Galaz et al. 2012).
Badgley, C., Moghtader, J., Quintero, E., Zakem, E., Chappell, M.J., Avilés-Vázquez, K., Samulon, A., Perfecto, I. (2007). Organic agriculture and the global food supply. Renewable Agriculture and Food Systems 22, 86–108. doi:10.1017/S1742170507001640
Bengtsson, J., Ahnström, J., Weibull, A.-C., 2005. The effects of organic agriculture on biodiversity and abundance: a meta-analysis. Journal of Applied Ecology 42, 261–269. doi:10.1111/j.1365-2664.2005.01005.x
Boardman, J., Poesen, J., Evans, R. (2003). Socio-economic factors in soil erosion and conservation. Environmental Science & Policy 6, 1–6. doi:10.1016/S1462-9011(02)00120-X
Bodirsky, B. L., Rolinski, S., Biewald, A., Weindl, I., Popp, A., & Lotze-Campen, H. (2015). Global food demand scenarios for the 21st century. PLoS One 10(11) doi:http://dx.doi.org.ezproxy.bangor.ac.uk/10.1371/journal.pone.0139201
Clermont, A., Eickermann, M., Kraus, F., Hoffmann, L., Beyer, M. (2015). Correlations between land covers and honey bee colony losses in a country with industrialized and rural regions, Science of The Total Environment, Volume 532, p. 1-13, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.05.128.
Deguines, N., Jono, C., Baude, M., Henry, M., Julliard, R. and Fontaine, C., (2014). Large-scale trade-off between agricultural intensification and crop pollination services. Frontiers in Ecology and the Environment 12(4):212-217.
Drewnowski, A., & Popkin, B. M. (1997). The nutrition transition: New trends in the global diet. Nutrition Reviews, 55(2), 31-43. Retrieved from http://search.proquest.com.ezproxy.bangor.ac.uk/docview/212306420?accountid=14874
Ericksen, P.J. (2007), Conceptualizing food systems for global environmental change research. Global Environmental Change, doi:10.1016/j.gloenvcha.2007.09.002
FAO (1981). FAO: its origins, formation and evolution 1945–1981. Food and Agriculture Organisation of the United Nations. Available at: http://www.fao.org/docrep/018/p4228e/p4228e.pdf. Accessed: 31 December 2016.
FAO (1996). Rome Declaration on World Food Security and World Food Summit Plan of Action. World Food Summit 13-17 November 1996. Rome.
FAO (2002). World agriculture: towards 2015/2030. Food and Agriculture Organisation of the United Nations. Available at: http://www.fao.org/docrep/004/Y3557E/Y3557E00.HTM. Accessed: 31 December 2016.
FAO (2008). An introduction to the basic concepts of food security, FAO, 2008 EC – FAO Food Security Programme. Available at: http://www.fao.org/docrep/013/al936e/al936e00.pdf
FAO (2013). Climate-smart agriculture sourcebook. Food and Agriculture Organization of the United Nations, Rome.
FAO (2015). The State of Food Insecurity in the World 2015. Meeting the 2015 international hunger targets: taking stock of uneven progress. Rome, FAO. Available at: http://www.fao.org/3/a-i4671e.pdf
FAOSTAT (2016), Land Use [online]. Available at: http://www.fao.org/faostat/en/#data/RL. Accessed: 3 January 2016.
FiBL, (2016), The World of Organic Agriculture: Statistics and Emerging Trends 2016. Research Institute of Organic Agriculture, Switzerland. Available at: http://www.fibl.org
Fischer, J., Abson, D.J., Butsic, V., Chappell, M.J., Ekroos, J., Hanspach, J., Kuemmerle, T., Smith, H.G. & von Wehrden, H., (2014). Land sparing versus land sharing: moving forward. Conservation Letters, 7, 149-157.
Foley, J. A., DeFries, R., Asner, G. P., Barford, C., & al, e. (2005). Global consequences of land use. Science 309(5734), pp. 570-574. Retrieved from http://search.proquest.com.ezproxy.bangor.ac.uk/docview/213600813?accountid=14874
Foresight (2011). The Future of Food and Farming. Final Project Report: Executive Summary. The Government Office for Science, London.
Galaz, V et al. (2012). Global environmental governance and planetary boundaries: An introduction. Ecological Economics 81 (2012) 1–3.
Garnett, T. and Godfray, C. (2012). Sustainable intensification in agriculture. Navigating a course through competing food system priorities, Food Climate Research Network and the Oxford Martin Programme on the Future of Food, University of Oxford, UK.
Garnett, T., Appleby, M. C., Balmford, A., Bateman, J., Benton, T. G., Bloomer, P., Burlingame, B., Dawkins, M., Dolan, L., Fraser, D., Herrero, M., Hoffmann, I., Smith, P., Thornton, P.K., Toulmin, C., Vermeulen, S.J., Godfray, H.C.J. (2013). Sustainable Intensification in Agriculture: Premises and Policies. Science 341 (6141), pp.33-34.
Halberg, N., Panneerselvam, P., Treyer, S. (2015). Eco-functional Intensification and Food Security: Synergy or Compromise? Sustainable Agriculture Research 4 (3).
Haslam, D. W. & James, W.P.T., (2005). Obesity. Lancet 366, 1197-1209.
IPCC (2014): Climate Change 2014: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L.White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1-32.
IPES-Food (2016). From uniformity to diversity: a paradigm shift from industrial agriculture to diversified agroecological systems. International Panel of Experts on Sustainable Food systems. Available at: http://www.ipes-food.org/reports
Jamil, A., Riaz, S., Ashraf, M., Foolad, M.R., (2011). Gene expression profiling of plants under salt stress. Critical Reviews in Plant Sciences 30, 435–458. doi:10.1080/07352689.2011.605739
Kirchmann, H., Bergström L., Kätterer, T., Andrén, O., & Andersson, R. (2008). Can organic crop production feed the world? In: Kirchman and Bergström: Organic Crop Production – Ambitions and Limitations. (Chapter 3, pp. 39-72). Springer.
Lobell D.B., Field C.B. (2007), Global scale climate-crop yield relationships and the impacts of recent warming. Environmental Research Letters, 2:014002.
Lundqvist, J., de Fraiture, C., Molden, D. (2008). Saving Water: From Field to Fork – Curbing Losses and Wastage in the Food Chain. SIWI Policy Brief. Stockholm International Water Institute. Available at: http://www.siwi.org/publications/saving-water-from-field-to-fork-curbing-losses-and-wastage-in-the-food-chain
Lyon, D.M. (1944) ‘The Hot Springs Conference’, Proceedings of the Nutrition Society, 2(3-4), pp. 163–176. doi: 10.1079/PNS19440010.
Monsanto (2016). Working to maximise yields [online]. Available at: http://www.monsanto.com/improvingagriculture/pages/producing-more.aspx. Accessed 4 January 2016.
Oxfam (2012), A Safe and Just Space for Humanity: can we live within the doughnut? Oxfam Discussion Paper. Available at: https://www.oxfam.org/en/research/safe-and-just-space-humanity
Powell, B., Thilsted, S.H., Ickowitz, A., Termote, C., Sunderland, T., Herforth, A., (2015). Improving diets with wild and cultivated biodiversity from across the landscape. Food Security 7, 535–554. doi:10.1007/s12571-015-0466-5.u
Pretty, J.N., Noble, A.D., Bossio, D., Dixon, J., Hine, R.E., Penning de Vries, F.W.T., Morison, J.I.L. (2006). Resource-conserving agriculture increases yields in developing countries. Environmental Science & Technology 40, 1114–1119. doi:10.1021/es051670d
Ray, D.K., Ramankutty, N., Mueller, N.D., West, P.C., Foley, J.A., (2012). Recent patterns of crop yield growth and stagnation. Nature Communications 3, 1293. doi:10.1038/ncomms2296
The Royal Society (2009). Reaping the benefits: science and the sustainable intensification of global agriculture, London.
Rockström, J. (2009). A safe operating space for humanity. Nature, 461(7263), 472-475. Retrieved from http://search.proquest.com.ezproxy.bangor.ac.uk/docview/204470082?accountid=14874
Scherr, S.J. & McNeely, J.A. (2008). Biodiversity conservation and agricultural sustainability: towards a new paradigm of ‘ecoagriculture’ landscapes. Philosophical Transactions of the Royal Society B 363, 1491, 477–494.
Smil, V. 2000. Feeding the World: A Challenge for the Twenty-First Century. MIT Press, Cambridge, MA, USA.
Thornton, P.K., 2010. Livestock production: recent trends, future prospects. Philosophical Transactions of the Royal Society of London B: Biological Sciences 365, 2853–2867. doi:10.1098/rstb.2010.0134.
Tilman, D., Cassman, K.G., Matson, P.A., Naylor, R. and S. Polasky., (2002). Agricultural sustainability and intensive production practices. Nature 418: 671-677. Doi: 10.1038/nature01014.
UN, (1999). The World at Six Billion. United Nations, Department of Economic and Social Affairs, Population Division. Available at: http://www.un.org/esa/population/publications/sixbillion/sixbillion.htm
UN, (2015). World Population Prospects: The 2015 Revision. United Nations, Department of Economic and Social Affairs, Population Division. Available at: https://esa.un.org/unpd/wpp/Download/Standard/Population
UN, (2016a). Goal 2: End hunger, achieve food security and improved nutrition and promote sustainable agriculture [online]. Available at: http://www.un.org/sustainabledevelopment/hunger. Accessed: 2 January 2017.
UN, (2016b). The Sustainable Development Goals Report 2016. United Nations, New York.
UNEP-WCMC, (2011). The UK National Ecosystem Assessment: Synthesis of the Key Findings. UNEP-WCMC, Cambridge.
WRI (2005). The wealth of the poor: managing ecosystems to fight poverty. World Resources Institute. Washington, DC, USA. Available online at: http://www.wri.org/publication/world-resources-2005-wealth-poor-managingecosystems-fight-poverty
WWF, (2016). Living Planet Report 2016. WWF International, Gland, Switzerland. Available at: http://wwf.panda.org/about_our_earth/all_publications/lpr_2016