What if... we all ate organic?

If you've spent five minutes in the aisles at M&S, you'll know that organic food is big business. 'It's better for the environment' claim the marketers, 'It's healthier' and 'think of all those poor animals'. But is it worth splashing extra cash on organic? What would happen if everyone decided it was?

It's worth giving a little thought to the huge benefits industrial agriculture has brought to the world. At the turn of the 20th century, an agricultural apocalypse was looming. ‘unless the chemistry world manages to turn the nitrogen of the air into fertilizer' German chemist Karle Engler told the British Association for the Advancement of Science in 1898 'the western world will starve’.

A few years later Fritz Haber and Carl Bosch came up with a method for the industrial scale production of ammonia, the basis of modern fertilisers. It's difficult to overstate the impact of the Haber-Bosch process. Since 1950 the relative abundance of cheap food has allowed global populations to expand from 2.5 billion to today's seven. Without it, you probably wouldn't be here reading this article.

But intensive agriculture has many side effects. Fertilisers and pesticides can contaminate hydrological and ecosystems in unexpected ways. It is here that organic agriculture, with its reduced reliance on chemicals has clear advantages. You might have also seen claims that organic food is healthier. But extensive studies have found that organic food offers no additional nutritional value. And whilst it might expose you to less pesticides, the levels of pesticides permissible in our food in the UK are so tightly controlled, they pose no measurable risk to health.

Now remember - this blog is about climate change! So does organic food produce fewer greenhouse gases? The evidence is often conflicting but overall the balance seems to point to yes. Nitrate fertilisers used in industrial farming are broken down by bacteria in the soil, which release nitrous oxides into the atmosphere. And the techniques used in organic farming mean that carbon is held, or sequestered, in the soil for longer, keeping it out of the atmosphere.

Comparing emissions across types of agriculture is tricky. Different values are arrived at depending on whether you're calculating emissions per kg of produce or per hectare of land. And figures vary wildly depending on whether you've accounted for the sequestration effects of organic farming or not.

An eight year study by scientists at Michigan State University to measure gas fluxes from agriculture found that, once sequestration effects were taken into account, emissions from organic were 64% lower. Modelling studies show similar reductions. So, if we take the most optimistic predictions, emissions from agriculture could reduce by 64% if we all ate organic (or about 9% of total emissions). But this is likely to be a long way off the actual figure. Far more research is needed to establish the true impact of going organic. 

Comparison of soil carbon gains and losses in different farming systems in long term field experiments
Source: Low Greenhouse Gas Agriculture, FAO (2009)

What is clear is that the social implications would be huge. The reduced yields of organic compared to industrial farming mean it's unclear whether it's even possible to feed the global population entirely on organic. And food prices would undoubtedly rise. In a world where nearly a billion people go hungry, I think we're best sticking to industrial practices for the foreseeable future.