A key food security issue went through without much comment in a recent Alloporus post on meat.

Via a calculation on the carbon footprint of omnivory, an estimate of the amount of productive land needed to provide all the humans on the planet with enough calories from plants to meet their daily needs came out at 4 million km2.

Next to this number we can put the FAO estimate that says there is roughly 48 million km2 of agricultural land on earth and a simple conclusion is reached: we should be fine.

All we have to do is eat plants.

According to this juxtaposition of area estimates, we have 10 times the land area we need to grow enough food to feed everyone. Surely all the chatter and concern about food security is unnecessary.

We grow more than we need, waste a whole bunch, and still have land to spare. Get over it.

There appears to be more than enough productive land to meet human needs. Perhaps as much as an order of magnitude more meaning we could go beyond needs towards our wants too… rib-eye and chocolate moose anyone?

Well perhaps.

Thanks to energy inputs, technology and a global supply chain there is remarkable capacity to feed people – the global requirement for roughly 14 trillion calories per day is a lot of food. That this happens every day with a declining failure rate is miraculous. Yet it happens and this supply seems to be keeping up with increasing demand. All the indices of poverty, hunger, the size and frequency of famines are heading in the right direction. Proportionally fewer people go hungry today than 5 years ago and serious regional famines are historical.

There is always more to do of course. Hunger and poverty still exist, even within wealthy societies, but the pragmatist will see food security as a social or political problem, not a problem of production.

So why does a Google Scholar search on food security pull up 729,000 research articles from the last 5 years alone with 60,000 of these published in the first 9 months of 2018?

Presumably a lot of researchers and the people behind the systems that fund their work believe we have a problem. Perhaps we need to go deeper than simple ratios.

The first confounding factor is in the 4 million km2 calculation where all the calories come from plants, the most energy efficient food source.

We know that people like to eat animal products in all their myriad forms. If a quarter of the required calories for each person’s daily needs come from animals (meat, milk and eggs) then the area requirement jumps dramatically thanks to the laws of thermodynamics. Meat contains calories but the animal also needed calories to maintain itself and grow before it gave up its tissues to the food chain.

This energy requirement is roughly 9 to 1.

So if a person eats 600 calories worth of meat and dairy products per day, then the animals that created this protein needed to consume 5,400 calories. They get this from plants (and the occasional meat based protein pellet).

If everyone consumed a quarter of their daily calories from animals instead of plants then the 4 million km2 requirement becomes 13 million km2. This is 27% of the available area.

Still plenty of buffer, right?

Well yes and no. The original calculation assumed that production was efficient. Crops produced predictable yields at near average levels. Averages are a useful metric in this type of calculation because they absorb the inevitable variation from one region to another, one landholding to another and even among fields.

Just as important though is the variance in production.

Suppose that the average yield of wheat is 3.0 t/ha, near enough the global average. However, in the low input, low output production systems of Australia the average is 1.9 t/ha, whilst the global average is 3.3 t/ha Yield is double. A drought or a widespread plant disease in Germany, where wheat production is over 24 million tonnes and the average yield over 9 t/ha, would have a disproportionate effect on global production than dry times in Australia.

Also averages can change over time. It happens that average grain yields have risen consistently for several decades at up to 1% per year for some commodities. More security you would think. Only there is a physical limit to yield, and, in time, averages could easily decline for any number of reasons. There is also the risk of catastrophe.

Among the many interesting numbers generated by the FAO is a critical one for our calorie count. The FAO report that 40% of soil in production systems is degraded. Below average in other words.

So let’s suppose than over the next decade yield averages decline on these degraded soils, let’s say by 50%. The 13 million km2 to grow enough calories becomes 15.6 million km2 and we are up to a third of the available area.

Then there are the climate change effects that will mess up average yields as well as increase catastrophic risk from drought fire and flood. If 2 million km2 of production area fails due to local catastrophe there is a 15% shortfall in calories. This amount will be hard to even out across the global supply chains.

These are enough production side challenges to tweak nerves. Next though we have to look at demand. First is the 1 billion or so people who consume far more than 2,400 calories per day; the average American ingests 3,600 calories. This pushes the area up to 19.8 million km2.

Not to forget the 8,000 new souls every hour of every day.

All this doom and gloom calculator craziness can go on and on. There is still a land buffer. At the moment there is land to spare and to absorb all the inevitable inefficiencies.

However, the 200 research articles per day on food security through 2018 is both reassuring and an alert. We need sharp minds on this real and present risk.

Think about all of this the next time you see a kilo of onions on sale for a dollar.