Phosphorus emissions from changing phosphorus supply chain networks in China

Phosphorus (P) is widely used in food production and is essential to human beings. China's rapid socioeconomic transition, including economic development, population growth, and dietary changes, has led to significant changes in P supply chain networks and P emissions. Revealing the critical socioeconomic factors that influence P emissions from the consumption side is essential for P emission reduction. Here we explored the key sectors influencing P emissions in the P supply chain networks from the consumption side during 1949–2012 based on the physical input-output (PIO) model. Results showed that food processing sectors (e.g., coarse grain processing) were the dominant demand-side drivers. Subsequently, we applied structural decomposition analysis (SDA) to reveal critical socioeconomic factors influencing P emissions from the changing P supply chain networks based on the consumption perspective. During 1949–2012, emission intensity change was the primary factor leading to P emission increments, contributing 6.0 million tons (Mt), followed by the increased per capita final demand (3.4 Mt), population growth (1.4 Mt), and the change in production structure (1.2 Mt). The change in the final demand structure was the only factor that contributed to P emission reductions (2.9 Mt). It is worth noting that the impact of the change in P emission intensity on P emission increments has gradually diminished in recent years, but the incremental effect of production structure changes has gradually increased. This indicated that, in addition to end-of-pipe control measures (e.g., reducing P emission intensities), structural optimization actions are urgently needed to reduce P emissions. For example, the production efficiency of P supply chain networks should be improved, particularly by reducing food loss in food processing sectors. Moreover, promoting green consumption and optimizing the export structure would have significant potentials of reducing P emissions.