This paper reviews the latest information and perspectives on global phosphorus scarcity. Phosphorus is essential for food production and modern agriculture currently sources phosphorus fertilizers from finite phosphate rock. The 2008 food and phosphate fertilizer price spikes triggered increased concerns regarding the depletion timeline of phosphate rock reserves. While estimates range from 30 to 300 years and are shrouded by lack of publicly available data and substantial uncertainty, there is a general consensus that the quality and accessibility of remaining reserves are decreasing and costs will increase. This paper clarifies common sources of misunderstandings about phosphorus scarcity and identifies areas of consensus. It then asks, despite some persistent uncertainty, what would it take to achieve global phosphorus security? What would a ‘hard-landing’ response look like and how could preferred ‘soft-landing’ responses be achieved?

Phosphorus security is emerging as one of the twenty-first century's greatest global sustainability challenges. Phosphorus has no substitute in food production, and the use of phosphate fertilizers in the past 50 years has boosted crop yields and helped feed billions of people. However, these advantages have come at a serious cost. Mobilizing phosphate rock into the environment at rates vastly faster than the natural cycle has not only polluted many of the world's freshwater bodies and oceans, but has also created a human dependence on a single nonrenewable resource. The 2008 phosphate price spike attracted unprecedented attention to this global situation. This review provides an updated and integrated synthesis of the biophysical, social, geopolitical, and institutional challenges and opportunities for food security. Remaining phosphorus resources are becoming increasingly scarce, expensive, and inequitably distributed. All farmers require fertilizers, yet a sixth of the world's farmers and their families are too poor to access fertilizer markets. Inefficient use of this fossil resource from mine to field to fork calls for substantial reduction in demand through efficiency and recycling. Phosphorus governance at global, regional, and local scales is required to stimulate and support context-specific sustainable strategies to ensure all the world's farmers have sufficient access to phosphorus to feed the world and ensure ecosystem integrity and farmer livelihoods.

This paper reviews the drivers, development and global deployment of intelligent water metering in the urban context. Recognising that intelligent metering (or smart metering) has the potential to revolutionise customer engagement and management of urban water by utilities, this paper provides a summary of the knowledge-base for researchers and industry practitioners to ensure that the technology fosters sustainable urban water management. To date, roll-outs of intelligent metering have been driven by the desire for increased data regarding time of use and end-use (such as use by shower, toilet, garden, etc.) as well as by the ability of the technology to reduce labour costs for meter reading. Technology development in the water sector generally lags that seen in the electricity sector. In the coming decade, the deployment of intelligent water metering will transition from being predominantly “pilot or demonstration scale” with the occasional city-wide roll-out, to broader mainstream implementation. This means that issues which have hitherto received little focus must now be addressed, namely: the role of real-time data in customer engagement and demand management; data ownership, sharing and privacy; technical data management and infrastructure security, utility workforce skills; and costs and benefits of implementation.

Phosphorus underpins the world’s food systems by ensuring soil fertility, maximising crop yields, supporting farmer livelihoods and ultimately food security. Yet increasing concerns around long-term availability and accessibility of the world’s main source of phosphorus—phosphate rock, means there is a need to investigate sustainable measures to buffer the world’s food systems against the long and short-term impacts of global phosphorus scarcity. While the timeline of phosphorus scarcity is contested, there is consensus that more efficient use and recycling of phosphorus is required. While the agricultural sector will be crucial in achieving this, sustainable phosphorus measures in sectors upstream and downstream of agriculture from mine to fork will also need to be addressed. This paper presents a comprehensive classification of all potential phosphorus supply- and demand-side measures to meet long-term phosphorus needs for food production. Examples range from increasing efficiency in the agricultural and mining sector, to technologies for recovering phosphorus from urine and food waste. Such measures are often undertaken in isolation from one another rather than linked in an integrated strategy. This integrated approach will enable scientists and policy-makers to take a systematic approach when identifying potential sustainable phosphorus measures. If a systematic approach is not taken, there is a risk of inappropriate investment in research and implementation of technologies and that will not ultimately ensure sufficient access to phosphorus to produce food in the future. The paper concludes by introducing a framework to assess and compare sustainable phosphorus measures and to determine the least cost options in a given context.