Feeding the world: Can we preserve forests, go organic and eat meat?

§ “Zero-deforestation”

Whether for growing crops, grazing or building on, 75% of the Earth’s ice-free surface is used in one way or another by humans, today’s study begins. Put another way, only a quarter is left in something resembling its natural state.

Land-based ecosystems house a large fraction of the world’s biodiversity, as well as providing food, fuel, energy, air and water purification, and protection against the elements for humans.

Forests, in particular, also play an important role in mitigating climate change. The paper notes:

The starting point for the study is a hypothetical world in which the global population recognises the intrinsic value of our remaining forests and halts to deforestation.

The authors look at the projected global population in 2050 and work out what options exist for ensuring the supply of food meets demand, without encroaching on any forested land.

As well as a global average, the study considers whether supply meets demand in 11 distinct regions of the world. These include, for example, sub-Saharan Africa, North America, Western Europe and Southeast Asia.

The authors express food demand in kilocalories per capita per day and the base projections are in line with estimates from the UN Food and Agricultural Organisation (FAO).

Regarding the consequence of a growing population on demand for cereals, roots, sugar crops, pulses, oil crops, and fruit and vegetables, the paper explains:

§ Options on the table

The study examines how various different factors combine to affect whether or not demand is met in 2050. These include the expansion of farmland (ranging between 11-70% compared to 2000), the size of crop yields (high, low or business-as-usual) and the composition of human diet (ranging from heavy meat consumption through to veganism).

Of 500 pathways, each featuring a unique combination of these factors, 289 are likely to produce enough food while still staying within the study’s “zero-deforestation” limits.

According to the study’s results, 100% of scenarios that exclude all livestock manage to supply enough food to meet demand in 2050. In other words, if the whole world becomes vegan, the global population in 2050 could eat enough without another tree being cut down.

The same would be true if the whole world turned vegetarian, assuming the area available for crops expands more than about 22% compared to 2000 levels. The paper says:

Assuming the world neither turns vegan nor vegetarian, what options are left? The study explores various options for continuing to eat meat, while still keeping our forests in tact.

The many permutations of different types of livestock (cows, pigs, chickens etc), what they’re fed on and the grazing intensity make for a pretty complex picture.

Broadly-speaking, if the diet of North America in 2000 were to prevail globally in 2050, only scenarios in which technological advancements produce very high yields or where a large share of high quality grazing land is given over to cropland provide enough food.

Scenarios that see global food demand and diets in different regions rise in line with FAO forecasts for 2050 – representing a “business-as-usual” scenario – provide enough food in all but the lowest yielding scenarios with little cropland expansion.

§ Climate impact

The study does not explicitly model the impact of climate change on food production, or how it affects the results presented above. This was a deliberate choice because the severity of the consequences is uncertain, says lead author Prof Karl-Heinz Erb from Alpen-Adria University in Vienna. He tells Carbon Brief:

Erb explains that where nutrients and water are freely available, higher atmospheric CO2 could increase plant growth – an effect known as CO2 fertilisation. Lengthening growing seasons could be another consequence of rising temperature. But, Erb adds:

Instead, the paper makes a general point about the consequence of low yields, saying:

As a reasonable approximation to climate change, the authors point to their “organic” scenario, in which crop yields per harvest are 40% lower compared to industrial agriculture. Erb explains:

The study’s organic route is only likely to be able to support the FAO’s business-as-usual meat-eating scenario out to 2050 if cropland expands at least 20% on 2000 levels. No scenarios allow for an organic approach to food production and global adoption of a North American style diet, the study suggests.

On the climate-benefits of organic agriculture more generally, the paper explains:

§ Understatement

While the study attempts to discuss the impacts of climate change in its vision of a zero-deforestation world, the real situation will be far more complicated, says Prof Andy Challinor, professor of climate impacts with expertise in food security at the University of Leeds. He tells Carbon Brief:

Simply comparing organic agriculture to climate change impacts misses the very important impacts of extreme weather events on crop production. Challinor adds:

Erb acknowledges the shortcoming in his study’s discussion of climate change, telling Carbon Brief the comparison with the organic pathway is “guess-working”.

There are other simplifications and elements that make the study purely hypothetical, too. For example, it assumes that shortfalls in regional food production can be met through international trade. As the paper explains, the reality is likely to be quite different:

As such, the study is intended more as a vehicle to provoke conversation than to elicit concrete recommendations. Indeed, the authors say the paper:

The simple point the authors make is about the trade-offs between quality and quantity of food production in a deforestation-constrained world.

Main image: Agriculture on hills in the Burundian countryside. The green patches are tea. Until recently most of these hills were completely forested. Credit: Jane Boles/Flickr.