Renewable resources representing 45 per cent of global calorie intake have reached peak production levels

Peak oil has become a familiar term over the past decade, but the world will soon have to get used to peak rice, peak wheat and peak maize, according to new research from the Helmholtz Centre for Environmental Research.

‘Peak oil seemed believable because oil is a limited resource, but surprisingly our methodology in this study could not prove it,’ says Ralf Seppelt, a landscape ecologist working on the project. Money and innovation from the oil industry has seen peak oil recede as a risk, according to the research.

The Helmholtz study found that while peak oil is not a cause for concern, renewable resources have reached the limit for annual growth. Among the 20 renewables studied, 18 – including meat production and the global fish catch – peaked between 1988 and 2008.

‘People think these renewable resources are infinitely available because all plants needs are water and sunshine,’ says Seppelt. The study team looked at crops harvested from agriculture and used by humans for nutrition and feeding animals. Using figures from the Food and Agriculture Organization, the researchers found that renewable resources were already at production limits. Soya beans reached maximum production in 2009, milk in 2003, eggs in 1993 and fish in 1988.

Peak years for renewable resources (Image: Helmholtz Centre for Environmental Research )

‘We can’t hypothesis as to why so many resources reached a peak at the same time,’ says Seppelt. He suggests that changes in population and diet in India and China may have increased pressure on renewable resources.

‘In successful agricultural regions, like Europe and the US, we only see increases in renewable resource production of between 1–5 per cent per year,’ he says, adding that these are due to breeding or further increases in intensity. ‘Other regions in the world might be able to increase production, but there is no agreement as to whether this will be possible worldwide,’ he says.

‘It is highly debated as to whether Africa could reach American agricultural output levels. It might be the case that there are more increases possible, but you have to consider what is needed to achieve those levels,’ says Seppelt. Replicating the massive changes in irrigation and pesticide use outside intensively farmed regions could prove a challenge.

Fish obtained from aquaculture are one resource yet to peak, although there is a problem with fish caught in the ocean for aquaculture. ‘There is no substitute because different species are farmed than are caught in the ocean,’ says Seppelt.

‘Fish are one of the most efficient species for producing animal protein, while cattle or beef are the least efficient,’ he says. ‘This isn’t only about the yield gap; it’s also about closing the diet gap.’