Our phosphorus future - an introduction

The global phosphorus sustainability challenge - present concerns and future outlook

By the mid- to late-20th century, the sustainability of the global anthropogenic phosphorus cycle for the long-term provision of food and fresh water was brought sharply into focus. In his early assessment of the anthropogenic P cycle, Stumm (1973) concluded:

“By mining phosphorus in progressively increasing quantities, man disturbs the ecological balance and creates undesirable conditions in inland waters, estuaries and coastal marine waters… Our present agricultural practice of excessively fertilizing land needs to be re-examined; our present agricultural technology must not without modification be exported to tropical areas.”

The suggestion here is that, if unchecked, unsustainable phosphorus use would create environmental conditions that are unacceptable for humanity. Rockström et al. (2009) termed this concept, ‘the Planetary Boundaries’; and as Stumm correctly surmised, humanity was fast approaching the phosphorus boundary in the mid- to late-20th century. Despite Stumm’s warning, the global anthropogenic phosphorus cycle continued on its trajectory of increasing flows through the early 1970s (Chapters 2 and 3). The net result is that global phosphorus input to fresh waters doubled by the end of the 20th century. The planetary boundary for phosphorus has been exceeded for freshwater eutrophication, but not yet for the extraction of phosphate rock. The issue of balancing heterogeneity in phosphorus demand for food and emissions to fresh waters remains a major future challenge.

The global outlook for anthropogenic phosphorus emissions to fresh waters is of great concern. Phosphorus demand in the agricultural sector is predicted to double, again, by 2050 (from 2006 levels), further increasing risk of emissions to fresh waters. Phosphorus losses from food production for domestic consumption will impact directly on catchments that have been ‘set-aside’ for agriculture. Losses of phosphorus from wastewater to fresh waters could increase globally by up to 70% by 2050. Yet, as is widely acknowledged (see Chapters 2-9), sustainable phosphorus management remains largely ignored in the food and environmental policy agendas of many countries, despite the social and economic burden it carries.

Geographic variation in phosphorus consumption

Recent estimates indicate that phosphate rock reserve supply does not represent a near term risk for global food security, with a projected lifetime of phosphorus reserves of around 320 years. However, national exposures to such risk are variable, especially where countries are reliant on either fertiliser exports as their economic foundation or fertiliser imports to maintain food security (Chapter 2). The challenges of price spikes and export controls, such as experienced in 2008 (Chapter 3) and in 2021 are expected to continue.

The geographic concentration of phosphate rock reserves risks impacting food security for countries and regions dependent on imported phosphate rock and/or fertilisers (e.g. Sub-Saharan Africa, India, the EU, Australia and Brazil). Unsurprisingly, wealth is an important determinant of whether a nation's farmers have access to phosphorus fertilisers. When describing phosphorus fertiliser consumption patterns, most countries can be classified in - or are transitioning between - one of three broad categories, each with different phosphorus sustainability issues:

• Countries that consume too little phosphorus. Typically less economically developed countries, e.g. some nations in Sub-Saharan Africa and parts of Asia. In these countries, insufficient access to phosphorus fertiliser can constrain agricultural production, impacting food security. Often these countries have a growing population, increasing urbanisation and poor sanitation. This can create ‘hotspots’ of phosphorus loss from human wastes in and around cities, contributing to eutrophication.

• Countries that are significantly increasing phosphorus consumption. Typically large countries with emerging economies, e.g. Brazil, India, and China. In these countries, increasing mineral phosphorus fertiliser use is contributing to rapid increases in agricultural output. However, low phosphorus use efficiency (and in some cases, insufficient sanitation), often cause substantial phosphorus losses, resulting in increasing and/or significant eutrophication issues.

• Countries levelling off or reducing phosphorus consumption. Typically more economically developed countries, e.g. most nations in the EU, and the USA. In these countries, long-term high consumption of phosphorus fertiliser has fuelled agricultural sectors. However, typically high and/or improving phosphorus use efficiency - combined with improved access to legacy phosphorus stores in soils - is allowing a levelling off or reduction in phosphorus fertiliser use. Good sanitation mitigates some phosphorus losses from human wastes in comparison to less economically developed countries. Historic poor phosphorus management has however left widespread chronic eutrophication issues, representing a financial, environmental and human health burden.

Towards a sustainable phosphorus future

Under the business as usual scenario; as the global population continues to rise, so demand for food will increase (Chapter 3). In addition, as economic development progresses, so the consumption of high phosphorus foods will increase (Chapter 8). Both of these drivers will tend to increase phosphorus losses from the food system (Chapter 5), as well as representing an economic loss to farmers (Chapters 4 and 9). Phosphorus losses from the food system will further degrade the ecosystems into which it flows, contributing to biodiversity loss and reducing ecosystem capacity to deliver services essential for sustaining life on earth (Chapter 5). Unless action is taken, global phosphorus demand will remain buried within national economic development plans and undetected across the global sustainability policy arena (Chapters 2 to 9).

It is being increasingly acknowledged that the world cannot afford to continue on its current path for phosphorus. In 2019, over 500 scientists signed ‘The Helsinki Declaration’; calling for transformation across food, agriculture, waste and other sectors, to deliver much needed improvements to global phosphorus sustainability.

This report considers the evidence required to underpin a more sustainable phosphorus future. It reflects on the need for improvements across the entire phosphorus value chain, from mine to fork, and from field to freshwater and coastal ecosystems. It considers the roles and opportunities for stakeholders in delivering such gains, and the need to deliver a long-term process to track progress. Finally, an analysis of the existing policy arena is provided alongside a proposal for improved international coordination for phosphorus sustainability, identifying country-level opportunities to align phosphorus with actions on other nutrients. In doing so, a clear message emerges – that the green shoots of change are upon us. Innovation and the application of trans-disciplinary thinking are already leading to pockets of more sustainable phosphorus use, as is evident in the many pioneering case studies presented across all of the OPF Pillars.

The challenge now lies in connecting opportunities into a coherent package of measures designed to address the ultimate societal goal: to deliver global food security for a growing population, whilst reversing and preventing the destruction of the natural environment. If society is to meet this goal, then sustainable phosphorus use must be at the heart of the solution.

Executive Summary

Chapter 2 →

Phosphorus reserves, resources and uses