28/10/2011 10:02 BST | Updated 28/12/2011 05:12 GMT

Can we Feed Seven Billion People?

Around the world, 200 million children's growth is stunted. That is one-third of all children in the world under the age of five years old. In some African countries, the proportion of children stunted is as high as 50%. These are shocking statistics. As US Secretary of State, Hillary Clinton has said, "these deaths are intolerable because they are preventable." We have known how to prevent them for a long time: the answer lies in a combination of breastfeeding and better diets, including adequate minerals and vitamins, along with various medical interventions.

These are immediate problems which we urgently need to tackle. But we also need to worry about how we are going to feed a planet that by 2050 will have an extra two or more billion mouths to feed.

The arithmetic challenge of increasing food production by a third or more is not too difficult, at least technically. The current rates of increase in yields should do it. However, the problem is much greater than this. Incomes per capita are rising, especially in the emerging nations of China, India and Brazil. This means diets are changing: more people are eating meat and consuming milk, cheese and other dairy products. To rear the livestock requires more grain and oil seeds. There is also increasing demand for crops as the feedstock for a growing biofuels sector.

Added to these increasing demands are difficulties with supply. Rising oil prices mean greater transport costs and higher prices for fertilisers and pesticides. We do not have significantly more land to cultivate so we will have to do more with what we have by producing higher yields on the same land area. Water is also getting scarcer. By 2025, three billion people will live in water stressed countries, having less than 1,700 m3/person/year - the threshold for meeting the water requirements for agriculture, industry, domestic purposes, energy and the environment. Land and water are becoming increasingly polluted and otherwise degraded.

On top of all of this, we have to worry about global warming. This is already leading to shorter growing seasons in the developing countries and reduced yields cause by high temperatures and lack of rainfall. Climate change also means more extremes of weather, more frequent and more intense tropical cyclones and droughts.

We will have to have the capacity to respond rapidly when weather disasters strike. Altogether,

this requires a doubling of food production by 2050.

How do we do it? First, we need all the technologies we can lay our hands on:

Traditional technologies - such as cultivating local varieties, so-called land races;

Intermediate technologies - for example, using treadle pumps to irrigate land;

Conventional technologies - but used more precisely, such as fertilisers in a cola bottle cap placed in the planting hole with the seed;

Modern platform technologies - such as nanotechnology, biotechnology and information and communication technology, which Africans are already using in innovative ways.

But there is no magic bullet. Technology, even if productive and environmentally friendly, will not be enough on its own. Farmers need access to seeds, fertilisers and other inputs. The thousands of agro dealers - small village stores - that are springing up in Africa are part of the answer. They, in turn, will have to rely on the innovative small seed and fertiliser companies that are being created. Micro-credit is also a challenge. African banks have the funds but we need to find ways of helping them provide inexpensive loans to farmers, backed up with forms of micro-insurance.

At the other end of the chain, farmers need to access markets for their grain and other products. Village cooperatives, various forms of contract farming and use of mobile phones to enable farmers to get the best prices can all help.

Farmers are part of the private sector. They are often entrepreneurial and innovative. But their farms are are usually very small. 80% of African farmers are smallholders with less than two hectares of land. They can only be innovative if they have access to inputs, either subsidised or at a cheap cost, and if they get a fair price for their products in the local or regional markets.

In the end it comes down to good governance and committed political leadership. I am an optimist, partly because there are good examples of success. Notably, Ghana has already achieved the Millennium Development Goal of halving poverty and hunger. Former President John Kufuor received the World Food Prize earlier this month for his leadership in Ghana's journey to food security.

Maybe the 7th billion person will be born lucky - in Ghana?