So what are the solutions? Here are the four important ones. Others are detailed in Julian Cribb's forthcoming book The Coming Famine (UCP, August 2010)

1. Redouble Knowledge

We need to redouble the global investment in agricultural science.  In my estimate we should lift the total agrifood R&D spend to at least $80 billion, twice what it is today.

Then, for every research dollar we need to spend another dollar getting the knowledge into the hands of the world's 1.8 billion farmers and food processors.

Science not applied is science wasted.

We must generate the greatest knowledge sharing effort in history - to reach not only farmers, but also consumers everywhere, because the farmers alone will not be able to solve the challenge.

Using the excellent mass communication and media systems now available and ramifying through the world, this is completely achievable.

It is essential that all national governments understand that agricultural science IS defence spending.

Devoting just a tenth of the world's current weapons spend to sustainable food production would secure both the food supply and enhance the prospects of world peace.

2. End Waste: re-use

An obvious way to enhance global food security is to reduce the colossal waste of half the food we currently produce. This will also spare water, nutrients, energy, soil and human labour.

However it means extensively redesigning both our diets, our cities and the food production and distribution systems that satisfy them.

It means greening our cities, mining and recycling the vast volumes of water and nutrients they presently collect, purifying them and designing entirely new urban-based food production systems.

These will turn what we now regard as organic waste back into food, fuel and a great many other essential things.

It will involve growing large quantities of fresh vegetables within urban areas by hydroponic, aquaponic and aeroponic methods. We need to design this new urban agriculture or mass permaculture from scratch and incorporate it into the buildings, landscapes and social milieu of our mighty cities.

It will also involve creating an entirely new food industry that uses waste to produce vegetable, microbial, fungal and animal cells in biocultures and turns them into healthy and novel processed foods - but also into fuel, fertilizer, stockfeed, pharmaceuticals and fine chemicals.

Above all we need a World War on Waste. Let us design farming and food systems that do not waste or, if they do, that then reuse.

3. A New Diet

Recognising that 11 billion people cannot all eat like Americans or Australians and hope to survive on this planet, we need to refashion the world diet.

To one that involves far less energy, land, water, nutrients and pollution.

To one that doesn't actually kill half the people who eat it, as does our present one.

Sounds hard?  Not really. It means returning to the sort of balanced nutrient intake our grandmothers would approve.

One way to do this is to double the amount of vegetables in the diet, many produced in these new urban systems using recycled water and nutrients

There are over a thousand "undiscovered" indigenous vegetables to make this a culinary adventure as well as a global awakening and a health revolution. The richness of nature has scarcely been tapped in this regard and our shops, supermarkets and restaurants are poor in diversity compared with what they will become.

To achieve this we should also embark on the world's most ambitious educational campaign - to install one full year, a food year, in every junior school on the planet.

A year in which every subject - maths, language, geography, science, society and sport - is taught through the lens of food, how precious it is and how it is produced, where it comes from, how to eat safely, thriftily and healthily. How to help ensure it never fails.

Teaching food is acceptable in all cultures, races and creeds. Teaching respect for food and how it is produced is equally so. The means already exist to share these principles and educational courses universally.

We must enlist the food processing industry, the supermarkets, the cookbook writers and nutritionists, the TV chefs and restaurants and the health departments to promote the same universal messages.

"Eat well but eat less. Eat more vegetables and less energy-intensive foods. Choose foods that spare our soil and water. Be happy to pay more for such good food, so our farmers can protect the precious environment that produces it."

4. Pay more for food

Today many people enjoy the cheapest food in human history. In rich countries it is one third the price our grandparents used to pay for it.

But it is destroying landscapes, water and farming communities worldwide and causing colossal wastage.

It is too cheap to last.

It is imperative in the coming decade that we do two things - first abolish all trade barriers so food production can go wherever it is most efficient and second, to start paying all farmers a fair price.

The prices that globalised food chains now pay farmers will end up destroying agriculture and its resource base. They will hollow out global food security.

Almost everyone in society now receives fair pay - except farmers. This has to end if we want to eat sustainably in future. There are many ways this can be done, which there is not room here to discuss in detail.

Julian Cribb is an award winning science writer with over 7000 published articles. He is a Fellow of the Australian Academy of Technological Sciences and Engineering (ATSE) and principal of Julian Cribb & Associates, consultants in science communication.

His forthcoming book The Coming Famine is about the global food crisis.