“Meeting the food needs of people today and into the future while simultaneously decreasing the effects of agriculture on the environment is one of humanity’s grand challenges,” Paul West of the University of Minnesota, US, told environmentalresearchweb. “Currently, yield trends are not on track to meet these needs and agriculture is the main contributor of greenhouse gas emissions, water use and habitat loss, as well as a main contributor of water quality degradation.”

West and colleagues discovered that China, India, the US, Brazil, Indonesia and Pakistan could act as “global leverage points” for making improvements. A relatively small set of modifications to agriculture and food practices in a relatively small set of places could provide enough new calories to feed more than three billion people, according to the team.

“By pointing out specifically what we can do and where, it gives funders and policy makers the information they need to target their activities for the greatest good,” said West.

For example, closing 50% of the yield gap – the difference between actual and potential crop yields – in regions with the widest gaps could provide enough calories to feed 850 million people. Around half of these potential gains are in Africa, with most of the rest in Asia and Eastern Europe. Because these gains aren’t evenly distributed, changing just a small area of farmland could make a major difference.

“We found that increasing yields to only 50% of their potential in only 5–6% of cropland growing 16 major food crops could produce enough calories to meet the basic need of approximately 425 million people,” said West. “The same is true of efficiency – a few crops and countries explain most of the global impacts on climate, water use and water quality.”

Agriculture produces roughly 20–35% of global greenhouse gas emissions, through carbon dioxide released by tropical deforestation, methane from livestock and rice, and nitrous oxide from fertilizer use. The biggest opportunities for reductions are in Brazil and Indonesia for deforestation emissions, China and India for greenhouse gases resulting from rice production, and China, India and the US for emissions from fertilizer.

Rice, wheat and corn (maize) are the largest sources of excess nutrient use worldwide, while rice and wheat create the biggest demand for irrigation, the team found. India, Pakistan, China and the US accounted for the bulk of irrigation water use in water-limited areas. Boosting the efficiency of water use could cut water demand by 8–15% without affecting food production, the study showed.

As well as their examination of cutting yield gaps to get more out of existing farmland, reducing climate impact, and using nutrients and water more efficiently, the team also looked at how we could use crops themselves more efficiently.

Currently, the crop calories fed to animals around the world, particularly in the form of corn in the US, China and Western Europe, could meet the calorie needs of four billion people. Although cultural preferences and politics mean it could prove tricky to change this balance, the team suggest that shifting crops from animal feed to human use could act as a “safety net” if weather or pests created a shortage in any particular year.

What’s more, roughly 30–50% of food production is wasted worldwide. This is particularly significant in the case of meat – wasting 1 kg of boneless beef, for example, is equivalent to wasting 24 kg of wheat because feeding grain to a cow is not a particularly efficient way of creating food for humans. Reducing food waste in the US, China and India could provide enough food for more than 400 million people per year, the team says.

“We’d like to see governments, development banks, non-profits, foundations and companies target more of their food production and sustainability efforts on these issues, crops and regions,” said West. “These leverage points can ‘move the dial in the right direction’ both regionally and globally. Fortunately our team works with many global leaders on these issues, translating current science into more practical metrics to help guide actions.”

Now the team will fine-tune some of its analysis. “The larger next steps are to start assessing how risks related to these issues – and others – are changing to assess which areas are more vulnerable,” said West. The leverage points may alter as factors such as climate, diet, technology and markets change.

West and colleagues reported their work in Science.

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