More food, less climate change

Photo: flickr.com Gates Foundation cc by-nc-nd

Improved meat production in Latin America and higher crop yields in Africa are key measures to reduce greenhouse gas emissions from land-use change, while improving food security.

In large parts of the world there is a huge gap between actual agricultural production and what could be produced if modern technology and methods were applied. Minimising this gap and producing more food per hectare of arable land or per animal is usually recognised as a great way to both increase global food security and reduce greenhouse gas emissions, in particular from land-use change.

Reality is always a bit more complicated, and studies of historical developments have shown that the positive environmental effects are very dependent on how these productivity improvements are achieved. If more fertilisers are used, increased emissions of nitrous oxide can counteract the decrease in emissions from land-use change. More frequent use of machinery for tillage, harvesting and irrigation will burn more fossil fuels and give a similar effect. However, even if there are actual emission savings per produced unit, total emissions might not go down. When productivity is improved it is likely that costs per production unit will go down, food will be cheaper and demand for the product will increase. That is, the environmental benefits that come from more efficient production are offset by an increase in production volume. This phenomenon is known as the rebound effect.

In a recent study, three different pathways to increased productivity have been modelled to see what impact they would have on food security (calories per capita) and climate change (CO₂ equivalent per year):

• Conventional intensification – more of all inputs, e.g. fertilisers, pesticides, irrigation as well as investments in machinery.
• Sustainable intensification – productivity gains, without adding more fertilisers, using instead improved crop rotation, crop-livestock integration, precision farming (e.g. using satellite monitoring and GPS systems). For livestock this scenario is similar to conventional intensification.
• Free-tech is a third pathway relying more on innovation, through more public spending on research and development and infrastructure. For this pathway all input factors remain constant.

The researchers also compared different scenarios, one where productivity increases slower than the projected baseline. This could be the case if there is a failure in technology adaption, lack of investments, land degradation and increased pressure from climate change.

In another scenario, the productivity gap in Africa, Latin America and Asia is closed faster than projected. This scenario was also divided into two sub-scenarios; one where only livestock productivity is improved and the other where only crop productivity is improved.

When comparing the scenarios the result is quite clear – slow progress in productivity improvements will mean more hungry people and more greenhouse gas emissions regardless of the pathway chosen, while a more rapid improvement would have the opposite effect.

But there are still some significant differences between the pathways. The increase in nitrous oxide emissions from synthetic fertilisers in the conventional intensification pathway largely offsets the reductions in carbon dioxide emissions from reduced land use change within the crop sector.  Since the free-tech scenario doesn’t imply any extra costs for the farmer, it will result in lower food prices than the other two scenarios and thus a stronger rebound effect from increased food consumption. But the authors also note that these results are very sensitive to the price elasticity assumed. Thus, it may be that this effect is either highly overrated or highly underrated. However it is still possible to say from the results that sustainable intensification is the best option for reducing greenhouse gas emissions, and free-tech is preferable in respect of food security, even if it is difficult to predict how big the difference is.

The study also shows some interesting differences between different regions. An increase in livestock productivity would have a significant impact on emissions from land-use change in Latin America, where animal husbandry is one of the strongest forces behind deforestation. This despite the fact that productivity improvements would also result in Latin Americans eating significantly more meat.    

In Sub-Saharan Africa and South Asia, increased productivity in the livestock sector does not have such noticeable effects on greenhouse gas emissions or food security. In these parts of the world there are somewhat different drivers causing deforestation and land-use change. Higher crop yields per hectare would here be of greater importance in curbing deforestation, preventing degradation of soils as well as improving the population’s calorie intake.

Kajsa Lindqvist

Agricultural productivity and greenhouse gas emissions: trade-offs or synergies between mitigation and food security? By H Vakub, P Havlík, A Mosnier, E Schmid and M Obesrsteiner. Published in  Environmental Research Letters #8, 2013