World map on closing the “yield gaps” to 50 per cent of potential yields
Photo: © Science

“Global leverage points” for sustainable food security

Achieving sustainable global food security is one of humanity’s great challenges. A team of international scientists has identified key “global leverage points” that offer the best opportunities to improve both global food security and environmental sustainability.

A billion people around the world go to bed hungry every evening. Meanwhile, agriculture has become a major burden on the environment, whether through greenhouse gas emissions, harmful irrigation practices and over-fertilisation. And the challenges of food security and environmental sustainability will get even tougher as the world’s population grows by another two billion people by 2050. 

Yet it is clearly possible to provide much more food on a sustainable basis, concludes an international research team made up of experts come from the universities of Minnesota, Harvard and Bonn. Their study, published in June 2014 in the international science magazine Science, argues that a relatively small set of places and actions could provide enough new calories to meet the basic needs of more than three billion people, address a number of environmental impacts with global consequences and focus food waste reduction on commodities that impact most on food security. These “leverage points” in the global food system are intended as a guide to help non-governmental organisations, foundations, governments, citizen’s groups and businesses prioritise their activities.

The research team finds that the key to achieving food security is to grow more food on the existing land base and to do so in ways that limit additional pressure on natural ecosystems. The scientists look at the difference between potential and actual crop yield. These “yield gaps” are not evenly distributed around the world. They calculate that current yields are 50 per cent below realistically attainable potentials in many regions.

One of the study’s co-authors,  Stefan Siebert from the University of Bonn, Germany, suggests that in certain regions farmers could harvest up to ten times as much by adopting improved cultivation methods. In other words, these places have a huge “yield gap” of 90 per cent. “If we closed just 50 per cent of the gap, we could feed around 850 million more people,” Siebert believes. Efforts to achieve this should be concentrated on Africa, Asia and Eastern Europe, since these regions have the potential for producing food for an additional 780 million people.

The researchers also call for a halt to rainforest conversion into arable and pasture land. The trend towards rainforest destruction is headed by Brazil, a country that accounted for a third of global depletion between 2000 and 2012. Indonesia takes second place with 17 per cent. The consequences include dwindling biodiversity, accelerating climate change and widespread desertification – consequences that, as the research team warns, may push even more people into chronic hunger. 

The study also shows where the strategic use of water and fertiliser will make most sense. Moreover, the experts identify the regions in which, post-harvest, food is being used particularly inefficiently post-harvest. It is a problem that concerns not only the affluent societies of the industrialised world but also developing countries: between a third and half of the food produced is eaten by pests or goes bad due to poor storage and transport infrastructure. 

An important criticism raised in the study is that, on a global scale, vegetable foodstuffs are used less and less for human consumption. “We grow maize or soya to be fed to our livestock, but we could be eating this produce ourselves,” notes Siebert. The problem here is that no animal converts all the food it eats into meat, milk or eggs. In this respect, livestock is never efficient. The production of one animal calorie currently costs more than three plant calories – a loss of 70 per cent. As for using arable land to grow energy crops, this switch is entirely at the expense of human nutrition.

In this respect, the Western industrialised countries have a particular duty to change direction. The scientists calculate that Germany, for example, now uses only 40 per cent of calories produced on its arable land for direct human consumption. This contrasts sharply with a region like East Africa, where the figure for Kenya reaches almost 100 per cent.


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Publication:
P. C. West, J. S. Gerber, N. D. Mueller, K. A. Brauman, K. M. Carlson, E. S. Cassidy, P. M. Engstrom, M. Johnston, G. K. MacDonald, D. K. Ray, und S. Siebert (2014); Leverage points for improving food security and the environment; Science 345:325-328.

Participating institutes: Institute on the Environment, University of Minnesota (USA), Center for the Environment, Harvard University (USA), Environmental Working Group, Washington, D.C. (USA), Institute of Crop Science and Resource Conservation, University of Bonn (Germany).

(wi/Science/University of Bonn)