Organic farms tend to produce less food than non-organic ones Mint Images/Getty Images

Greenhouse gas emissions would go up if all farms in England and Wales went organic. Though the emissions of individual farms would go down, much more food would have to be imported as the amount they would produce would decrease substantially.

Yields would fall by nearly half if all food in England and Wales was produced organically. To meet this deficit, more farmland would be needed elsewhere in the world, which could double overall greenhouse gas emissions compared with those from farming in the two countries now.

“The key message from my perspective is that you can’t really have your cake and eat it,” says Laurence Smith, now at the Royal Agricultural University in the UK, who was part of the team that performed the analysis. Smith is a proponent of organic farming and says “there are a lot of benefits to the organic approach”. But his analysis shows organic farming has downsides too.


Read more: Is organic food better for you? Here’s the truth about the benefits

Farming and changes in land use – such as cutting down forests – are responsible for a third of all greenhouse gas emissions. That means reducing farming emissions and the land needed for farming is vital to limit further global warming.

According to the analysis by Smith and his colleagues, emissions per unit of food are on average 20 per cent lower for organic crops and 4 per cent lower for organic animal products.

The problem is that, on average, organic yields per hectare are lower, too. For wheat and barley, for instance, yields are just half of those of conventional farms. That means 1.5 times as much land would be needed to grow the same amount of food.

The estimated increase in emissions varies greatly depending on what assumptions are made about this extra farmland. If only half the extra land comes from turning grasslands into farms, the increase could be as low as 20 per cent. If grassland that would otherwise have been reforested is turned into farmland, emissions could nearly double.

“Organic farming has this greenhouse gas problem,” says team member Guy Kirk at Cranfield University in the UK. “You can’t ignore it.”

This doesn’t necessarily mean people should stop eating organic, says Smith. Individuals might choose organic for other reasons, such as to reduce their pesticide exposure (though contrary to popular belief organic farmers do use pesticides) or for the sake of wildlife.

Biodiversity

But going 100 per cent organic could harm global biodiversity. Again, this is because there would need to be more land used for farming and so the land available just for wildlife would be smaller and more fragmented.

Rob Percival at the Soil Association, which certifies organic farms in the UK, thinks the assumptions behind the analysis are “fundamentally flawed”.

“The study assumes no change in diet, which is clearly untenable,” says Percival. “Dietary change will benefit the public’s health and free up land, making an organic scenario entirely feasible.”

Third way

There is no doubt that reducing meat and dairy consumption would reduce emissions. Per kilogram, emissions from animal-based foods can be up to 50 times those from plant foods, so the kind of food we eat matters more than whether it is organic, or produced locally, says Hannah Ritchie at the University of Oxford.

Smith thinks there is a third way. “If we could combine the best of organic and the best of non-organic, we could get very high efficiencies.” For example, if organic farmers could use some non-organic fertilisers, that could greatly increase yields, while still retaining some organic principles. He also thinks organic standards should be revised to allow the use of gene-edited crops.

When it comes to emissions, he says that not all products are equal. Organic bread is the worst, because wheat yields are so much lower, but for vegetables the differences are much smaller.

Journal reference: Nature Communications, DOI: 10.1038/s41467-019-12622-7