Comment on: "Recent revisions of phosphate rock reserves and resources: a critique" by Edixhoven et al. (2014) – clarifying comments and thoughts on key conceptions, conclusions and interpretation to allow for sustainable action

Abstract

Abstract. Several recent papers deal with concerns about the longevity of the supply of the mineral phosphorus. The paper by Edixhoven et al. (2014), for instance, expresses doubts about whether the upward estimate of reserves by the IFDC (2006, 2010) and the USGS (2010) provides an accurate, reliable, and comparable picture, as it is based on reports that do not clearly differentiate between phosphate ore and phosphate products (i.e., marketable phosphate rock concentrate). Further, the indistinct use of the terms reserves and resources is criticized. Edixhoven et al. (2014) call for a differentiated inventory of world phosphate reserves including "guidelines which determine the appropriate drill hole distances and a detailed granularity". The claim that "humanity is on the safe side" with respect to future phosphate supply is doubted, as the validity of the IFDC's upgrading of the Moroccan data to 50 Gt phosphate is questioned. The main achievement of Edixhoven et al. (2014) is to elaborate that in the literature frequently used data on phosphate rock ore and phosphate concentrate are not properly distinguished, resulting in incorrect summary figures. In addition, it is commendable to raise the question how transparency concerning reserve and resources data and information on the geopotential of phosphate can be achieved because phosphorus is a special element. As fertilizer, it cannot be substituted and there are no unlimited resources as for the other main nutrients potassium in sea water and nitrogen in the air. However, the paper by Edixhoven et al. (2014) contains in the opinion of the authors some incorrect statements. Our comment elaborates first that several statements, such as that the upgrading of the Moroccan data is "solely based" on one scientific paper, are incorrect. Secondly, the paper comments on and illuminates a set of, in our opinion, misleading statements. These include the fact that the dynamic nature of reserves (which depend on price, technology, innovation for exploiting low-grade deposits, etc.) is acknowledged, but the right conclusions are not drawn, including the mixing of finiteness and staticness, and the way in which the critique of the USGS upgrading of the Moroccan reserves has been linked to Peak P. In particular, we clarify that reserves are primarily company data that serve mining companies for their strategic planning and may, by no means, be used as proxy data for providing global Peak P estimates. Likewise, we elaborate that drilling plans for assessing reserves have to be adjusted to site characteristics, in particular, in the case of four plateaus in Morocco and the Western Sahara comprising an area greater than 10 000 km2. We reconstruct the IFDC and USGS estimates and conclude that there is no evidence for considering the somewhat surprising increase to 50 Gt phosphate concentrate to be an unreasonable estimate for Moroccan reserves. However, the partial mixing of different units (e.g., phosphate ore and phosphate concentrate or marketable product) in the USGS data may be avoided by improving the database and using proper conversion factors. When applying these factors and assessing all reserves of marketable Gt of phosphate rock (PR-M), which is a common scale for measuring annual consumption, the magnitude of the 2014 USGS estimates of 67 Gt PR reserves does not change essentially but decreases from 64 (IFDC assessment) to 57.5 Gt PR-M (a worst-case calculation). We agree that a better harmonization of the (national) classification systems is meaningful. The discussion includes several ideas and thoughts that go beyond the paper by Edixhoven et al. (2014). We suggest that the discrepancies in the resource estimates are often caused by missing system understandings, different conceptions of sciences, and diverging world views. Finally, we suggest the establishment of a solidly funded, international standing committee that regularly analyzes global geopotential for assuring long-term supply security.

Although there is no Physical Short‐Term Scarcity of Phosphorus, its Resource Efficiency Should be Improved

“…The R/C ratio for phosphate is very high—higher than for nearly all other commodities; it grew from 90 in 1988 to 260 today, and there are discussions about whether this is a conservative estimate or not (Edixhoven et al. ; Scholz and Wellmer ). Other globally acknowledged experts on P have even stated, for example, that reserves and resources are so large that the term “reserves” has little relevance to the debate over long‐term phosphate rock (PR) accessibility (Mew )…”

Phosphorus Supply Chain—Scientific, Technical, and Economic Foundations: A Transdisciplinary Orientation

“…Ironically, much of the good work of spreading the discussion has come about through the scientifically incorrect notion that PR-ore reserves were becoming scarce and that a supply-driven peak in output would occur sometime in the 2030s [30,68,69]. The "peak phosphorus" theory was, in itself, flawed (e.g., [70][71][72]) as well as being based on data that, at best, needed revising and, indeed, were revised by the IFDC in 2011 [73]. However, "peak phosphorus" did capture headlines and continues to be referenced by some sources today.…”

Sustainable Mineral Resource Management—Insights into the Case of Phosphorus

“…Originally used to model the oil market, the concept was used for phosphate rock, and soon the term "peak phosphorus" was coined, raising great awareness. Much has been written about its highly controversial application to the case of P in recent years, for example [16][17][18][19][20], mostly around lack of availability of URR (ultimate recoverable resources) data and the comparability of oil and PR markets. However, this aspect is not within the scope of this special issue, and we point interested readers to the references mentioned above.…”