Working at The Economist, I think that the advantages of free trade and comparative advantage are obvious. It makes sense for people from different countries to grow different things and trade. Yet a lot of people think that agriculture and food are things to which the laws of economics should not be applied. The Economist was set up in 1843 to campaign against the Corn Law and we’ve always taken a very firm line on free trade and food. We still think that’s the right thing to do.

I think looking forward, the big question for this century is a simultaneous climate, food and population crunch. The population will rise to about nine billion by 2070 before it starts to decline and so we need to have enough food to feed everyone at that point, and we need to be able to do that in the face of a changing climate. In fact, climate change will manifest itself as a food crisis for most people.

In most of the developing world, there are many people who are experiencing that crisis already. I was in Uganda a couple of months ago and the farmers there can’t rely on the usual rules of thumb about when to plant and when to harvest. This looks like it’s a consequence of climate change. So climate change is going to affect which parts of land are fertile, which crops grow where and how much rainfall there is. If good land and access to water are in short supply, there is likely to be conflict over these things and mass migration where agriculture becomes unable to support the number of people living in a particular area.

One of the things that happened after the ‘green revolution’ of the Sixties and Seventies was that lots of people thought that food was a solved problem. As a result, the problem of food production fell off the development agenda. The amount of research and development (R&D) money that was put into agriculture fell as governments thought that agriculture was old-fashioned and they needed to concentrate on building industry. The fact is that a country cannot industrialise, with the associated surge in the urban population, without first undergoing a massive increase in agricultural productivity - that is, producing more food with fewer people. A few countries can rely on imports, but someone, somewhere needs to produce the food.

In its annual report in 2008, the World Bank confessed that it had allowed food to fall off the agenda and that this was a mistake. The idea that you can leap from agricultural development and go straight to industry is obviously wrong. We should start to see more funds going into agricultural development as a result.

Another mistake has been the opposition of environmentalists in the West to the adoption of industrialised agriculture in the developing world. These groups don’t like the use of artificial fertilisers and corporate involvement. They think it is better to leave farmers with their traditional farming practices, and these ideas have influenced aid policies. This cult of the peasant farmer meant that the late Norman Borlaug, who understood the importance of modern methods, became a “tar baby” in Washington. Having been lauded as a hero for his part in the green revolution, suddenly he was the villain, encouraging global agricultural pollution. As a result, less emphasis was placed on agricultural aid for the reason that such aid in practice meant pursuing industrialised agriculture.

The food price crisis reflected these earlier mistakes. But it was also clearly influenced by the economic growth, not only in India and China, but also in Africa. That has meant that people want to eat more and they want to eat more Western-type diets. That means producing even more food to feed animals for meat, which in turn has pushed up the price of grain and soya. The shift in production toward biofuels was probably a factor in the price rises as well, along with some weak harvests around the world.

Anyone who tells you that the food price crisis was caused by a single one of these things is wrong. It was a combination of things, but in some ways it has been very helpful because it has put food back on the agenda. There was a big supply response last year and lots of investments made in places like Ukraine, which is a great place to grow wheat. Food prices came down, but a very bad monsoon in India is causing problems again this year.

Another environmental argument against food trade is the notion of ‘food miles’. I think most people recognise that the environmental impact of a particular foodstuff cannot simply be reduced to how far it has travelled. It is not as simple as that. It’s not just a matter of how far you ship things, but the amount of fuel per mile per tonne of food that matters. In truth, most of the at the carbon footprint associated with transport of most food in Britain is actually associated with driving two bags of groceries backwards and forwards in a three-tonne SUV rather than shipping it around the world.

The most striking numbers are those for New Zealand lamb, where the shipping emissions are actually a tiny fraction of the overall carbon footprint. Even when you transport New Zealand lamb halfway round the world for sale in the UK, the carbon footprint is still smaller than for home-produced lamb. That’s because New Zealand is a very good country for producing lamb, it’s relatively empty with few people, the lambs can graze and eat grass whereas in Britain they need to be reared in a heated shed and they’re fed processed feed delivered to them in lorries.

Another good example is Kenyan flowers (and, most probably, Kenyan vegetables). Growing flowers in Kenya and then air-freighting them is still better in terms of carbon dioxide than growing flowers in greenhouses in western Europe. It makes sense for a country to grow the things it can grow particularly well. In the UK, we’re good at meat and wheat, but we’ll always be better off importing other products like coffee.

In terms of food production methods and innovation, I think there is a worthwhile analogy with energy here. When it comes to generating electricity, there is no one right answer; we’ll need wind, nuclear and a variety of other sources. And, just as with food, different countries will have different strengths. In Morocco, solar power will be abundant. In the UK, wind and wave power will be the predominant renewable energy sources. With food, too, I think what we need is a portfolio approach where we find the best solution for the local situation, whether it is no-till, GM soya in Argentina or organic methods elsewhere.

Where I have a big problem with the organic movement is with its fundamentalism. To say that the right amount of chemicals is always zero is wrong, but if you know tricks to reduce the amount that you need then that’s a good thing. We need the biggest toolbox we can possibly get, and organic methods should be included. For example, when I was in Uganda, people were making pesticides out of milk and fermented urine. That is, technically, an organic method although some of these homemade recipes for pesticides use substances that you’re not allowed if you want your production to be called ‘organic’. Fortunately, people in Uganda don’t care what the Soil Association thinks about these things.

In my book I go through some of the past crisis points in food production. For example, there was a crisis right at the beginning of the twentieth century because farming was starting to become dependent on fertiliser at that point and it wasn’t artificial fertiliser. This was before the invention of the Haber-Bosch process, so the necessary nitrates were coming from Chile. Indeed, there was a war in Chile over the nitrates in the 1870s and 1880s. It became clear that Chilean nitrate was not going to last forever, but there was little additional land that could be brought into production, so it looked as if the limits of output had been reached.

Indeed, the adoption of agriculture itself was in a sense a response to the increasing populations of settled communities not being able to support themselves from hunting and gathering. The industrial revolution in Britain was basically a response to agricultural crisis because we didn’t have enough land to grow food for all these people so we switched to producing industrial goods, exporting them and using the money to buy imported food. This was the model that Malthus was responding to when he claimed that we couldn’t sustain ourselves in the long run. The flip side of this equation was that the Industrial Revolution was not only a response to a food crisis, but helped to solve it by increasing agricultural productivity.

In fact, Britain did go too far down that road. By the end of the nineteenth century, the UK ended up importing 80 per cent of its wheat. Then the First World War happened and we realised this was a terrible situation to be in, so we frantically rowed back from that and we’re now 65 per cent self-sufficient.

Time and again through history, we have reached points where it looked like we wouldn’t be able to feed ourselves only for some technological change to appear that fixed the problem. We should never underestimate the ingenuity of the human race. I am an optimist and I think we’ll find a way to do it, but it won’t be easy.

I think genetic modification will be part of the answer and there is an interesting historical analogy with the potato, which was heralded as a wonder food in the seventeenth century when it first showed up in Britain. The Royal Society thought potatoes were great, that they were going to feed the poor and famine would be a thing of the past – pretty much all the things the Royal Society says about GM crops today. But people wouldn’t eat them because they didn’t know what they were, they thought they were devilish, they were unnatural, they weren’t in the Bible, they gave you leprosy, and so on.

It was only a series of wars and famines in the eighteenth century that forced people to eat potatoes because that was all there was. Once the French fry was invented in the 1770s, there was no looking back, you could say.

I suspect the same thing will happen with GM crops during this century. Already, resistance to GM in Africa is starting to weaken. It was essentially based on the idea that if you had GM crops in your country you wouldn’t be able to export anything to Europe because of the EU regulations about GM and the general anti-GM climate here. But African countries are suddenly much less keen on exporting to Europe and certainly much more keen on being more self-sufficient, so that’s less of a problem than it used to be.

I don’t know how much longer the Europeans will hold out against GM, but I suspect that once we get GM crops that do things that address the issue of sustainability, like being more efficient in the use of fertilisers and water, or grow well in salty soil, than that might change people’s perceptions of them.

Tom Standage is business editor at The Economist. His latest book, An Edible History of Humanity, is published by Atlantic Books. (Buy this book from Amazon(UK).)