Phosphorus footprint? Shifting dietary habits are complicating a sustainable supply, warn researchers.
Rising consumption of meat products, coupled with ever increasing caloric intakes since the early 1960s has fuelled a sharp increase in the amount of mined phosphorus that is now complicating efforts to conserve a sustainable supply of the essential mineral, according to researchers writing in Environmental Research Letters.
Led by Geneviève Metson from McGill University, Canada, the research team found that rising meat consumption and increases in total calorie intake have underpinned a 38% increase in the world's per capita 'phosphorus footprint’ between 1961 and 2007.
“Our results indicate that dietary choices, especially those related to meat consumption, have a large impact on the demand for phosphorus in food production,” explained Metson and her colleagues.
“Approximately 28% of the total increase in phosphorus demand between 1961 and 2007 was due changes in the global average diet, including increasing meat consumption.
"It is really remarkable how much influence changes in diet have had on our demand for this very limited resource," said Professor Elena Bennett – who also worked on the study.
"As research in this area proceeds, it would also be interesting to learn how much of the phosphorus used in food production is able to be recycled and how much is currently reused,” she said. “Food waste and human waste generally aren't reused today, but can be a valuable resource if turned into fertilizer or compost for use on nearby agricultural fields."
Metson and her colleagues noted that in recent years, many researchers have explored how human activity has altered the phosphorus cycle in the environment and how management of phosphorus could be altered to ensure long-term sustainability.
They said the new study sheds more light, in particular, on how diet choices have affected the intensity of phosphorus use around the world.
To do this, the team computed phosphorus-footprint values based on annual country-by-country diet composition data from the Food and Agriculture Organization. They calculated the total amount of phosphorus applied to food crops for humans and animals by using fertilizer-application rates available through the International Fertilizer Association, among other sources.
The authors also examined the statistical relationship between economic development and phosphorus-footprint values, and developed scenarios to consider the relative importance of diet changes.
Meat consumption was found to be the most important factor affecting phosphorus footprints; where it accounted for 72% of the global average phosphorus footprint.
"Our results demonstrate that changes in diet can be a significant part of the strategy for enhancing sustainability of phosphorus management," said Metson, who suggested that reduced consumption of meat, and especially beef, in countries with large phosphorus footprints “could put a big dent in demand for mined phosphorus.”
Source: Environmental Research Letters
Volume 7, Number 4, doi: 10.1088/1748-9326/7/4/044043
“The role of diet in phosphorus demand”
Authors: Geneviève S Metson, Elena M Bennett, James J Elser