Christopher Doughty, Andrew Abraham, Joe Roman

Humans and natural systems face three pressing concerns: the loss of large animal biodiversity, eutrophication of many aquatic systems, and the need to better recycle phosphorus. Here we propose a mechanism to help alleviate these problems. Some have hypothesized that we are approaching “peak phosphorus,” where phosphorus may become more expensive as it becomes rarer, thus endangering the green agricultural revolution and the ability to feed ourselves. Animals play a key role in the recycling of phosphorus (P) from the ocean depths to the continental interiors, but this movement has declined by >90% over the past 10,000 years. Prior to this decline, animals played a critical role in the global P budget and the pre-Anthropocene P budget was in steady state only after accounting for animal P inputs. Recently a 5R strategy was developed by Withers et al (2015) to Realign P inputs, Reduce P losses, Recycle P in bio-resources, Recover P in wastes, and Redefine P in food systems. Here we suggest a sixth R, to Revitalize the natural phosphorus pump. Countries are starting to mandate P recycling, and here we propose a P-trading scheme based on REDD+, where a country could partially achieve its recycling goals through revitalizing the natural P pump. Accrued money from this scheme could be used to restore or conserve wild animal populations while increasing natural phosphorus recycling.