Over the past month, the University of Cambridge has been profiling research that addresses one of the biggest challenges of the 21st century – how to guarantee enough food, fairly, for the world’s rapidly expanding population. As part of this, we asked whether you had a question that you wanted us to answer, and put them to a panel of academics who specialise in research to do with food security. Here's what they had to say. Thanks to everyone who sent questions in!

I would suggest that the problem is less the number of people, than a particular kind of political economy that presents some people as a liability to the welfare of others.

David Nally

Should I use GM?

I live in Manipur, north eastern India. It’s a hilly area. The cropping system is a traditional terrace system and we sow once a year. We grow rice, some indigenous pulses, vegetables and fruit. Most of these crops are sown in the month of June and the rest of the year the land remains dry and unused. Nowadays cropping lands are reducing due to lack of water and growing of unwanted plants in the plot. So, I want to ask what measurement should we take either to adopt GM which we could not afford and is hardly available or should we focus on traditional recovery?

N G Ngashangva, Phadang Village Christian Compound, Manipur, India

Dear Mr Ngashangva, I do not think that there are GM varieties that would be useful to you – at least at present. However if you had herbicide-resistant crops then that might allow you to reduce weeds in your plots. It may also allow you to plant without ploughing or digging up the soil because you could drill holes to plant your herbicide resistant seed and then kill the weeds by herbicide application. Drought resistant GM crops are being developed but they are not available yet.

Professor Sir David Baulcombe

Can we tackle the financialisation of food?

I would like to ask what your analysis is of the impact of speculation in the food derivative markets on food prices. Bodies including the OECD and the G20 agriculture ministers are increasingly recognising the contribution of speculation in commodity derivative markets to food price spikes, which obviously has an immediate and negative impact on consumers everywhere, but especially in developing countries where food security is already a problem. Do you think we can tackle food security for the poorest people in the world without also tackling the financialisation of food globally?

Vicki Lesley, Brighton

The theory is that food derivatives help farmers to hedge the price risk they face. Demand for food has grown enormously in recent years, not the least with the 'emergence' of the Indian and Chinese economies. The supply of food has suffered erratically due to climatic calamities. Food prices have not only risen but have been volatile. Uncertain prospects of future food prices encourage farmers to hoard, and volatile prices stifle investments. Derivatives contracts allow the price risk to be traded so that speculators can take it on, induced of course by some probable return. A farmer who fears that the price of his crop will decline as it grows can hedge the price risk by entering into a futures contract to sell his crop in so many months’ time at a price determined now. This principle of transferring risk from hedgers to speculators is also the basis of option contracts which give holders the right to buy or to sell the commodity at an agreed price on or before a specified future date. If derivatives markets stayed true to principle, they should help in discovering price and encourage farmers to invest in the right crops. That is the theory! 

But as markets for food derivatives have grown, large buyers and sellers, attracted by the potential for speculative gains, have come to dominate the market, and physical hedgers are of much less significance. Demand and supply are now driven by speculative investment strategies in which commodities form one asset class in large portfolios.

Does this matter? The real price of food rises through changes in real demand and supply. Speculators never take physical delivery of the good. Can demand for futures contracts change real demand and their sales change real supply of food?

The markets for food and for food derivatives are linked of course. Speculators act upon small events that can potentially create price fluctuations in the real market, and amplify them in the derivatives market. Momentum traders render prices volatile. Volatility in turn drives more speculation. Volatile derivative prices that result can move real food prices when (at least some) farmers take them as signals of real prices in the future, and change their inventories accordingly. The risk management and price discovery functions of the derivatives market are ever at risk of being washed out by speculators. More often than not, the tail can wag the dog.

Furthermore, in the globalised world, commodity futures markets in different countries are linked. Returns and volatility spill over from rich country markets to emerging and developing country markets. Even in rich countries, futures contracts and the commodities they represent often do not converge to the same value at contract settlement. So even farmers and producers who do have access to the derivatives market cannot hedge efficiently using futures contracts.

The lives of large proportions of households in poor and developing economies depend on food prices. I agree with you that the need for the commodities futures market to be regulated more effectively, backed by careful research, is urgent.

Dr Paul Kattuman

How can we protect agricultural lands from urban spread?

I wish to congratulate you on such an innovative initiative to research into the biggest global concern - Food Security. Having been exposed to some of the causes of Global Food Insecurity as a young academic with background training and experience in Human Settlement Planning, I have come to appreciate that, one major challenge to ensuring food security is the invasion of prime agricultural land by residential and other urban land uses. In Ghana for instance, the pace of invasion is so fast that large tracts of fertile lands have suffered from urban expansion and population growth particularly in the peri-urban interface. This has not only resulted in reduced food production but has also taken away the very sources of livelihood derived by residents of peri-urban areas.

Against this background, I wish to know what practical strategies could be adopted within the framework of Spatial Planning to ensure that agricultural lands are protected as a basic prerequisite to ensuring food security. Secondly, I will be glad if the group could expound on how a good balance can be achieved between efforts by national and international communities to reverse deforestation and the provision of suitable land for food production as well as the sustenance of rural livelihoods.

Ransford Antwi Acheampong, Kwame Nkrumah University of Science and Technology, Ghana

Thank you for these excellent questions. Although I am not an expert on spatial planning, my research deals with reconciling conflicting priorities for land, and as part of that work I spent a year in the forest zone of Ghana in 2006/2007.

Planners must consider a range of valid objectives (such as requirements for housing, commercial facilities, transport infrastructure, crop cultivation and biodiversity conservation) and attempt to find compromises between them to guide development without being overly prescriptive. To do this, a good place to start is in establishing very clearly what those objectives are, over an appropriate time horizon, by involving interested parties in a consultative process. Local plans need to be coherent with national policies, and national policies need to take account of local needs and constraints. If a particular group is excluded, there will be problems. For example, if only the needs of urban residents and businesses are considered in plans for urban expansion, and not those of peri-urban farmers (or of those who buy and eat the food they produce), any spatial plan will be built on a flawed foundation.

There is also a need for good information to inform decisions about zoning land for different uses. Here, communication and data-sharing between institutions is crucial. Which areas of land are most suitable for crop cultivation? Ghana has a Soils Research Institute which has produced detailed maps of crop suitability, but when I visited the country these were not accessible to planners. Which areas of land are most important for biodiversity conservation? Ghana has tropical forests internationally renowned for their diverse and endemic species, but while staff of the Forestry Commission might know this, many of those working within the Ministry of Food and Agriculture may not. These problems are not unique to Ghana: often here in the UK there is also poor communication between government departments.

How best to conserve forests while producing more food? My research in Ghana has persuaded me that the most promising approach is to grow more food on less land, while protecting (and in the long term, restoring) forests. Measures to increase food output while reducing food production can help too, such as reducing the amount of food that spoils before it can get to market. Increasing yields on existing farmland, while minimising pollution and other problems, will need the intensive application of both scientific knowledge and farmers’ knowledge. There is a role for planners here in synthesising information about the most appropriate lands for crop production (with good soils, low carbon storage and low biodiversity value) and directing agricultural development towards those areas.

In addition to targeting agricultural development towards existing croplands with the most potential, reducing deforestation will require zoning of land where further agricultural development is inappropriate. In Ghana, this might include all of the remaining high forests, many wetland areas, plus areas with potential for restoration, such as land dominated by shaded cocoa farms. Careful screening and regulation of any large-scale land acquisitions, particularly for biofuel crop cultivation, will be needed to ensure that they deliver real benefits for the nation and for local people, without damaging areas of high conservation value. Oil palm companies in Ghana have adopted a set of Principles and Criteria for responsible palm oil cultivation. Similar principles could be used to ensure that development of other crops, too, adheres to strict environmental and social safeguards.

Dr Ben Phalan

Should we instead address global overpopulation?

Thomas Malthus wrote. "Must it not then be acknowledged by an attentive examiner of the histories of mankind, that in every age and in every State in which man has existed, or does now exist, that the increase of population is necessarily limited by the means of subsistence, that population does invariably increase when the means of subsistence increase, and, that the superior power of population is repressed, and the actual population kept equal to the means of subsistence, by misery and vice."

While not suggesting we do nothing and thereby cause misery and vice, by working to produce more food for a growing population, are we not just compounding the problem because it will enable the population to grow even bigger, requiring even more food, and at the same time having an even greater negative impact on our planet? Why not address the root of the problem, ie global overpopulation, by better education, financial incentives from government, and other means to encourage people to have less children and therefore reduce the population back to a level that is naturally sustainable on Earth?

Jacqueline Garget, Cambridge

The term ‘overpopulation’ makes a normative claim about population size, so we might begin to answer your question by first positing another one: what constitutes an ‘ideal’ or ‘naturally sustainable’ population?

A few statistics might help us frame this discussion. According to the United Nations, Somalia, Sudan, and Mozambique, three African countries severely affected by hunger and malnutrition, have between 14 to 29 inhabitants per sq km. These figures contrast sharply with 400 people per sq km for the Netherlands, 351 for Belgium, and 255 for the UK. Ghana, which is twice the size of the UK, has nearly a third of the population of the latter. Yet, we are unaccustomed to thinking of the UK or Belgium as ‘overpopulated.’ Why? Well, clearly the long-term carry-capacity of an area, rather than the overall population density, is what matters most. But that point aside, I do not think that one needs to delve too deeply to see that the tendency to single out the developing world for attention expresses a deep and abiding fear of the other. We all know that we would need several additional planet Earths if everyone adopted the consumption patterns of the average America; and yet that knowledge does not tend to diminish the perception that it is ‘their’ prolificacy that threatens ‘our’ existence. Historian David Arnold puts this very well when he writes that ‘too many people’ usually means ‘too many of the wrong sorts of people.’

Of course, Malthus’s own account of the population problem was saturated in this kind of moral reasoning. The poor, especially the non-European poor, were creatures of nature that bred without any consideration of the consequences. Malthus believed that in the ‘southern climates’, where virtue was absent and the inhabitants lived in a ‘degraded state’, the perennial threat of war, pestilence and famine was necessary to sharpen faculties, force improvements, and prevent additional population increases. The ‘four horsemen of the apocalypse’ were thus seen as a ‘positive check’ on human improvidence – a last resort to discipline the intractable and restore balance in the human and natural world.

The latent racism of Malthus’ worldview is frequently ignored. Instead arguments tend to concentrate on his more general point that famines are caused by a decline in food availability brought on by an increase in human numbers. We might ask, then, if this is a helpful way to think about the aetiology of subsistence crises?

Unfortunately, measuring aggregate food supply against population totals – as Malthus did – is profoundly misleading, because it gives little consideration to the ways in which resources are unequally apportioned. This is one of the major contributions of Amartya Sen’s classic work on famines as ‘entitlement failures’ (Sen’s book, Poverty and Famines: An Essay on Entitlement and Deprivation, was first published in 1981). According to Sen, people starve when either their ‘endowments’ (by which he means their resources) or their ‘entitlement set’ (by which Sen means the bundle of goods and services that a person can legally utilise) change to such a degree that they can no longer obtain adequate sustenance.

Sen offers many examples to think about how shifts in resources and entitlements can lead to starvation. For example, a farmer and his family may starve because they find themselves unable to pay rent and are forced of the land. Alternatively they may starve or undergo severe hardship because the cost of labour or price of inputs (for, say, seeds and fertilisers) increases to such a degree that they are unable to undertake the usual cultivation the land. The point is that people ‘command’ food through a variety of mechanisms, and thus analysing the ‘entitlement set’ is much broader than looking only at, say, income or indeed food supply, as the determining factor in precipitating a subsistence crisis. 

I spend some time discussing Sen’s Nobel Prize winning research because it demonstrates how the ‘famine question’ involves so much more than the ‘population question’. Or as Sen has put it himself, ‘the most important denial made by the entitlement approach is ... the simple analysis in terms of ‘too many people, too little food.’ The Malthusian ‘food availability decline’ model, as Sen calls it, presupposes that starvation deaths result from a severe interruption in the supply of food (caused by an environmental catastrophe, like a drought, or arising from the effects of overpopulation), whereas the ‘entitlement’ approach focuses attention on the allocation of resources within a market-based economy.

I find the latter approach to be a more helpful method to analyse the problem of global hunger. It is a well-established fact that there is enough food to feed the world’s present population – indeed by some estimates there is 20% more food than the world currently needs. Yet hunger persists and future famines seem very likely. I would suggest that the problem is less the number of people, than a particular kind of political economy that places food in some hands and not others.

Dr David Nally

How do we reclaim nutrients from water?

How long have we got to develop massive systems of nutrient reclamation from the world's sewers (before phosphate or potassium, or perhaps boron becomes limiting) and how much energy might such a system, require - energy that has to be added to our energy budget for the future? Agriculture exports nutrients to the cities of the world with every tonne of food supplied. Until mankind finds ways of returning those nutrients to the cropland (instead of flushing them out to sea) no system of farming can be described as sustainable. There is an added challenge here: we need those nutrients returned, but without the pollution that the cities inevitably mix with them - particularly heavy metal contamination.

Bruce Danckwerts, Choma, Zambia

Many of the world's larger communities are exploring the option of nutrient recovery, although often in the context of recovering the energy content of the organic matter in sewerage. For example the city of San Diego in California is producing such as system, in part in response to recovering energy content and in part to recover the water. Nutrient recovery has tended to be a side benefit. You are, however, correct that nutrient recovery will become increasingly important in the future, not only because the raw materials of nutrients are being depleted, but because the energy required to make these into useful materials such as fertilisers is quite large, and so contributes to the greenhouse gas emissions of nations.

Dr Douglas Crawford-Brown

Can we afford the energy input? Do we have adequate water resources?

Someone once said that modern agriculture is the conversion of fossil fuel calories into edible calories, due to the reliance on mechanisation. If oil prices continue to rise as predicted, the cost of farming will increase markedly, as will the cost of the food produced. Since it seems we can no longer control oil prices in a sustainable fashion, except by recession, it would appear that permanent food price rises are now a reality. How can we give people access to affordable food when we rely so heavily on expensive fossil fuel to produce it? Also, we know that water tables in the Middle East, China and Australia are already severely depleted, mainly due to the demands of agriculture. If this issue turns out to be more widespread, how on earth can we expand agriculture further?

Tristan Collier, Cambridge

Your comments are right on the mark. In fact, the Foreseer Project we are involved in aims to study the physical linkages between energy, agriculture and water resources to inform discussions like this on a local, regional and global level. The aim of the project is to develop an online visualisation tool to help the policy makers, industry and the general public understand the importance of future resources such as energy, land and water. 

The major physical linkages between food production and energy occur through the production and use of fertiliser (which uses about 2% of world energy production) and the use of fossil fuels for mechanisation of food production and transportation of food. Decreasing this physical reliance might make food prices less linked to energy prices. One possible strategy to do this would be to avoid the use of excess fertilisers.

Agricultural yields in developing countries could potentially increase without adding much mechanisation, fertilisation and irrigation. Yields and productivity can be improved by better informing the local farmers about the use of new practices, such as agro-forestry and soil moisture conservation practices, including minimum tillage, depending on local conditions.

Water scarcity is probably the biggest limitation to expansion of agricultural production, as you correctly point out. There is some room for improvement, such as better irrigation technologies, rainwater harvesting and increase use of wastewater in agriculture production. However we agree that agricultural production cannot be expanded infinitely.  Using desalinated water is also an option, though today it is still much too expensive to be used for irrigation – and it comes at energy price. One of the main goals of The Foreseer tool is to include this kind of energy, water and land interactions into the analysis.

Grant Kopec, Bojana Bajzelj and Liz Curmi

Is GM the answer?

How can GM technologies serve enough food for the human population which is growing rapidly every year and if we compare with sosiocultural aspect of human, poverty and planting areas? Maybe we can increase the quality and quantity of food with genetically modified food, but it can’t compare with population growth. I come from Indonesia, most people said my country is a high biodiversity country, evergreen and we can grow up every vegetable and rice, but it can serve for Indonesian (for about 200 million people), there are many malnutrition children, hungeroedema and etc. What do you think about the connection between population growth, poverty and quantity of foods?

Rikhsan Kurniatuhadi, University of Tanjungpura, Pontianak City, Indonesia

To feed the growing population we will likely need a whole array of approaches. This will include, but will not be limited to strategies like traditional breeding, enhanced breeding strategies (including making use of genetic information that is not currently residing in the genepool of the crop in question), as well as improvements in engineering aspects of agriculture, and the supply chain itself. All of these areas have the potential to be important. Whether any one part of the process, including genetic modification, is the most important will only be clear when we look back.

However, there are traits that one could engineer into crops to improve tolerance to stresses, including pest and pathogen attack. There are also the approaches currently being taken to improve nutrition of crops. There is also the possibility of using natural variation in photosynthesis to increase the potential yield of crops. There is growing support for the argument that, to maintain biodiversity, we need to ensure the agricultural land that is in use is used as efficiently as possible. The hope is that multiple technologies will be combined and this will contribute to sustainable food production in the future.

Dr Julian Hibberd

And finally….

Watch out for the following events at the University of Cambridge’s Festival of Ideas:

Is the future of food GM?

Saturday 22 October 3.30pm – 4.30pm, Faculty of Law, Sidgwick Site

What are the challenges and solutions to the global food crisis? Are genetically modified crops a natural progression in efficient agriculture or are we playing God with nature?

Can we afford not to embrace GM? Join Professor Sir David Baulcombe, Regius Professor of Botany; Tony Juniper, Sustainability Adviser; David Nally, Department of Geography and the chair, Jack Stilgoe, University of Exeter for the debate.

Seven billion: the crowded planet

Tuesday 25 October, 6pm – 7pm, Mill Lane Lecture Rooms, 8 Mill Lane

The world’s population will reach seven billion this year. Can the Earth sustain this many people and is reproductive freedom a fundamental liberty? What will the future hold for a crowded planet? Panel discussion with Professor John Guillebaud, Population Matters; Sara Parkin, Forum for the Future; Dr Rachel Murphy, University of Oxford; Fred Pearce, author of Peoplequake and the chair, Sir Tony Wrigley, Cambridge Group for the History of Population and Social Structure.

Energy policy: should scientists be in charge?

Thursday 27 October, 5.30pm – 6.30pm, Judge Business School, Trumpington Street

The Electricity Policy Research Group lift the lid on the long-standing dispute between engineers and economists. Who knows best and whose contributions should be used to solve the problems of energy usage in the UK today?

For more information about these and many other events, please visit

Panel contributors

Professor Sir David Baulcombe

Sir David Baulcombe is Regius Professor of Botany, a Royal Society Research Professor and Head of the Department of Plant Sciences. His research interests include genetic regulation, disease resistance and gene silencing; he discovered small interfering RNA and the importance of this molecule in epigenetics and in defence against viruses. In 2008, he chaired a Royal Society Working Group on how biological approaches can enhance global food crop production. In 2009, he was knighted by Queen Elizabeth II for services to plant science.

Dr Douglas Crawford-Brown

Douglas Crawford-Brown is Executive Director of the Cambridge Centre for Climate Change Mitigation Research in the Department of Land Economy. He is interested in all aspects of research related to the development of policies for mitigating the risks of environmental change, including - but not restricted to - climate change, and has provided expertise to government bodies and businesses.

Dr Julian Hibberd

Julian Hibberd is a plant scientist in the Department of Plant Sciences.  His research interests lie in the evolution and assembly of photosynthetic apparatus in plants. In 2008, he was named by Nature magazine as one of ‘Five crop researchers who could change the world’ for his research, which would greatly increase the efficiency of photosynthesis and create a rice cultivar that could ‘have 50% more yield’.

Dr Paul Kattuman

Paul Kattuman is a Reader in Economics at Cambridge Judge Business School and Director of Studies in Economics and a Fellow of Corpus Christi College. Dr Kattuman’s research interests include: applied econometrics and statistics; industrial organisation; distribution dynamics methods and applications; online markets; the software industry; co-operative game theory applications; system dynamics; India. He is a member of the Business & Management Economics subject group at Cambridge Judge Business School and is on the editorial board of the B.E. Journal of Economic Analysis & Policy. Prior to beginning his academic career, he was an economist in the Indian civil service.

Dr David Nally

David Nally is political geographer in the Department of Geography. His research focuses on the relationship between famine and society and the politics of disaster relief, as well as the historical origins of development geographies and theories of political violence. Nally has also worked on the political economy of agro-biotechnologies. His latest book Human Encumbrances: Political Violence and the Great Irish Famine (2011) traces the causes of the Irish Famine of 1845-50.

Dr Ben Phalan

Ben Phalan is a conservation biologist in the Department of Zoology and a junior research fellow at Churchill College. His current research is concerned mainly with understanding the impacts of agriculture on tropical faunas and identifying land use strategies to minimise those impacts. He works in collaboration with BirdLife International, the RSPB and the UNEP World Conservation Monitoring Centre.

Grant Kopec, Bojana Bajzelj, Liz Curmi

Grant Kopec, Bojana Bajzelj and Liz Curmi are researchers on the University of Cambridge's Foreseer Project, a cross-departmental project which examines current and future interactions between the supply and demand of regional energy, land and water resources. Collectively, they have expertise in water economics, energy systems, land-use issues and climate change mitigation.

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