The scientists, from the Potsdam Institute for Climate Impact Research and the University of Potsdam, also fear that the demand for animal feed will be so great that some regions will not be able to meet it.

Prajal Pradhan and his colleagues investigated the spatial distribution of embodied crop calories in animal products and found that, on a global scale, about 40% of the global crop calories are used as livestock feed. This proportion is set to rise to 48–55% by 2050. They also calculated that, on average, about 4 kcal of crop products are used to generate 1 kcal of animal products.

"In some regions the embodied crop calories can be as high as 10 kcal of crops used to generate 1 kcal of animal products," Pradhan told environmentalresearchweb. "This shows how inefficient the process of producing animal products can be, and I hope that our research will make people more aware of the environmental consequences of eating so many animal products."

The team estimated the future feed demand considering three scenarios: assuming diets would remain as they were in the year 2000 but population growth remains on its current trajectory; dietary changes as projected by earlier work, with the same population growth considerations; and changes in population, dietary patterns and feed conversion efficiency.

The researchers project that, when considering dietary changes, global feed demand will be almost doubled (increasing 1.8–2.3 times) by 2050 compared to 2000. This would force us to produce almost the same amount of, or even more, crops to raise our livestock than to nourish ourselves directly in the future.

"This is the first time that information on crop and animal products has been aggregated in a single comparable calorific unit," said Pradhan. "We felt this approach was important because human dietary requirements are generally measured in calorific values."

Using this approach, the work has highlighted that the current trend of an increasing share of animal products in our diet will have major consequences in the future, resulting in the need to grow more crops for animal feed than for direct human consumption.

"Some countries are already in the situation where they cannot produce enough crops to feed their animals and have to import feed," said Pradhan. "But in other countries, embodied calories in animal products are low because cattle simply graze on grass and do not consume any feed."

For example, the researchers predict that regions in Africa (apart from South Africa), South-East Asia and West Asia will not be able to meet their feed demand by 2050 without increasing their present crop production.

"Our research does not present answers to a potential future feed crisis, but it does show where there is room for alleviation," said Pradhan. "Some countries can adopt different kinds of livestock rearing systems to help avert a crisis, but one of the biggest factors in this trend is clearly the shift in dietary composition. Perhaps it is time to reverse the current trend and shift diets to include a smaller share of animal products?"

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