Human-induced material flows from extraction to final disposal are kind of a conveyor belt that is associated with bundles of various environmental impacts. The magnitude of those impacts cannot be changed toward safe, i.e., acceptable low risk, level, without adjusting the flows accordingly.
5.1. Biotic Resource Use
In order to approach a balanced and sustainable bioeconomy, it seems important that food production should be first priority, that each hectare is cultivated in a sustainable manner, and that the number of cultivated hectares necessary to supply final demand is kept within a safe limit (Table 1
Micro management at the farm and forest level depends on criteria of good practice, which need to be provided for and monitored at the local level. Various certification schemes exist, and the proportion of certified cultivation schemes could be a target indicator. For fisheries, in particular marine harvest needs to be adjusted to sustainable levels to be determined for every commercial species and fishing grounds.
For macro management, it has been suggested to limit the cropland required for the final consumption of agricultural goods to 0.20 ha/person in 2030, corresponding to 0.16 ha/person in 2050. The rationale for the per-hectare basis was to contribute to halting the loss of global biodiversity by land-use change. At the same time, one has to consider that the productivity of agricultural land differs greatly from region to region, which is dependent on soil, weather, climate, and technology. Nevertheless, people are consuming an increasing variety of crop-based goods from various regions and cultivation schemes, so that this consumption-oriented target may be acceptable, in particular when applied for whole economies rather than at the level of the individual, and assuming an equal right to use goods produced on the same extent of cropland.
In order to control forest degradation by overuse, no more timber should be harvested than what is regrowing. Based on available data on the net annual increment of world and European forests up to 2014, [50
], assuming the current structure of existing forests to persist, suggested first orientation values for a safe limit of timber-based consumption. As Europe has highly productive forests and a larger endowment with forests compared to other regions, and has cultural roots to use timber products, the orientation for that continent could be rather the domestic supply capacity (1.2–1.4 m3
/person in 2050) than a global average (0.3–0.5 m3
/person in 2050).
Macro management of the consumption of fishery products may be performed in conjunction with the promotion of more healthy and sustainable diets.
When the overall harvest/extraction of biotic material resources shall be monitored to provide an orientation of possible risk levels, a compound value of 2 t/person of primary biomass could be taken as a proxy [20
]. This value results from keeping the global 21 Gt in 2000 rather constant, and attributing it to a world population of 9.55 billion in 2050, assuming that growing food demand could be compensated by reduced losses of food biomass. The order of magnitude applies both to total primary extraction and used harvest, comprising 85% to 90% agricultural biomass and 10% to 15% timber, with marine and wild fish catch vanishing in the rounded number. That data can be directly related to the economy-wide Material Flow Accounts database of the International Resource Panel (IRP) for benchmarking.
5.2. Abiotic Resources
Micro management for abiotic resources is related to minimizing the environmental (and detrimental social) impacts of mining and quarrying within the local context of extraction, beneficiation, and refining. Principles of good mining practice and lists of criteria to consider are available (e.g., 10 principles of the International Council on Mining & Metals, ICMM: https://www.icmm.com/en-gb/environment/managing-metals-sustainably
), and the IRP is going to provide a report on sustainable licensing to operate. Product certification schemes have been established that focus on their origin and the performance of primary production (e.g., to exclude “blood diamonds”).
For macro management, the long-term perspective of the socio-industrial metabolism (Section 3.1
) and the aggregated effects of abiotic resource extraction and their proximate and ultimate final disposal need to be considered. Even when micro management results in minimizing the local to regional impacts, mining and quarrying will still severely alter and degrade the excavated and surrounding area with larger impacts on hydrology, vegetation, and landscape, depending on the overall amount extracted. For Earth Systems functioning, looking at it with coarse grain, a certain number of these “scars” may be tolerable; single abandoned limestone quarries may even harbor some red-list species. However, continued at the high level or even growing volume flow, the extraction and disposal of mineral resources—which due to the nature of non-renewables proceed to devastate new areas—those scars will become deeper and larger, and they will become denser. With the number of extraction, refining, and disposal sites, the number of conflicts with the local population, agriculture, forestry, and nature conservation will increase.
Moreover, similar to environmental management at the company level, macro management also has to consider both orderly processes and accidents. With a certain frequency, depending on the stringency of governance in the world regions, mining operations are the cause of environmental disasters (e.g., hundreds of people killed or large rivers being severely polluted by breaking tailing dams).
The availability of mineral resources in the Earth crust seems to be rather sufficient. What is really scarce is conflict-free access to the deposits and low environmental risks of extraction, refining, and disposal.
As a consequence, also in view of the principle of precaution, the extraction of minerals from natural deposits should be reduced to the unavoidable minimum
For fossil fuels, the issue of climate change adds another pressing demand: the mitigation of climate change. It seems clear that the world has to phase out the combustion of fossil fuels. The energy can be provided by renewable sources. When carbon is needed, in particular to supply the chemical industry, the recycling of materials as well as using CO2
as raw material is possible, and will be an essential component of the future socio-industrial metabolism [51
], although technologies differ with regard to their footprints [52
For metal products, reuse, remanufacturing, and in particular recycling have already reached a significant level, while unused potentials still exist [20
For construction minerals, cascading the use of demolishing waste is widely practiced; urban mining becomes more and more state-of-the-art in order to proceed toward high-level recycling, including recycling aggregates from concrete and recycling even gypsum from plasterboard. Supplying construction activities from deconstruction will become easier, consequently, the closer societies will come to the saturation of their construction stock.
Industrial minerals represent a relative minor portion of total mineral extraction. For some minerals, such as kaolin for ceramics, it may be difficult to find mineral substitutes. Carbon fibers and polymers based on recycled carbon may provide some options, but feasibility will have to be researched.
In 2010, all the anthropogenic mineral extractions were estimated to reach 135 to 150 Gt, thus exceeding the natural mass flows modeling the Earth’s crust such as by volcanism by four or five times (if only the extrusive magma flows are accounted for, the difference would be 68 to 75 times [20
]). Against that background and reviewing earlier target proposals for sustainable mineral extraction, [20
] suggested a target corridor of 6 to 12 t/person for 2050. The range was determined in a constructive approach: return to half to a full level of extraction in 2000. These values can be interpreted as aggregate proxy values of orientation, reflecting that for landscape changes and orders of magnitude of local conflicts, it may be less determinant whether ores or construction minerals, fossil fuels, or industrial minerals are extracted and refined rather than the magnitude of those operations that relate to the overall extraction and translocation of natural materials on the surface of the Earth’s crust.
In the absence of detailed specific cause–effect relationships and their overall impacts, considering mainly the general aspect that the mass turnover of primary materials is the basic determinant of related environmental pressure and regarding the risk of societal conflicts with mining, quarrying, and final deposition, those values may be regarded as precautionary values for orientation. If they are trespassed by the overall production and consumption of a country, this may be regarded as an early warning that some adaptation of the policy framework would be needed in order to adjust those patterns toward a more sustainable performance.
If such macro targets are to be implemented at the micro level, the environmental management of companies could do so by controlling the material footprint of their products [53
]. For that purpose, indicators can be used that are already reported. For example, at EU level, there are the raw material input (RMI) and raw material consumption (RMC) [54
]. Both comprise the biotic and abiotic used
extraction of raw materials (without the unused part of total extraction). The former is the material flow basis for production and accounts for domestic extraction plus imports including their raw material equivalents, while the latter reflects the material flows for final domestic consumption and subtracts exports and their raw material equivalents from the RMI. Based on the possible compound targets for biotic and abiotic material resource extraction (used and unused) shown in Table 1
and Table 2
] derived a range of 3 to 6 t RMC per person in 2050, comprising 2 t/person biotic harvest. For purposes of easy communication, a concrete value of 5 t RMC per person in 2050 was suggested as a possible target for global RMC. Considering that the EU industry produces both for domestic and foreign consumption (via exports), assuming that the relation of RMI/RMC remains unchanged (19.6 t per person/14.2 t per person in 2016), and that the EU´s population will remain rather constant and 150 million persons will be further employed by business, a possible target for the material footprint of 24 t RMI per employeebusiness
could be derived for 2050. Compared to the 67 t RMI per employeebusiness
in 2016, this would require a reduction of nearly two-thirds (64%). The consideration of the material footprint of the purchases of companies is already foreseen in the 2017 update of the Eco-Management and Audit Scheme (EMAS) [55
is a relevant industrial mineral that is also indispensable as a fertilizer in agriculture. Due to its dispersive way of application, there are unavoidable losses, so that a certain amount of phosphate mining will remain indispensable in the foreseeable future; the recycling of phosphorous from waste water is going to be conducted to a growing extent, but will only be capable of recycling smaller flows compared to those being managed in agriculture. Phosphorus mining and refining is challenged as the remaining larger deposits have relatively high amounts of contaminants such as cadmium, and may require a significant amount of water for refining. The bundle of those impacts may be reduced when keeping the extraction to the necessary minimum by well-described measures including measures to reduce food waste [56
] (see also http://phosphorusfutures.net/phosphorus-sustainability/
Consumption-oriented measures and targets aiming to stabilize global biomass harvest, i.e., the biotic part of resource use, may have not only a profound effect to mitigate the necessity of phosphorous mining. Such reduction will also help to mitigate the eutrophication of aquatic ecosystems, which is largely caused by phosphor compounds leached from fertilized fields.
Another major cause of global eutrophication is the input of nitrogen to natural ecosystems. Crop production is the single largest cause of human alteration of the nitrogen cycle. Mineral fertilizer represents nearly half of the nitrogen input, while nearly two-fifth of the nitrogen input is being lost in natural ecosystems [57
]. While farming can manage to supply nitrogen by cropping systems integrating nitrogen-fixing plants, conventional agriculture is still bound to chemical nitrogen fertilizer. The ammonia part is coming from the Haber–Bosch process, which transforms inert molecular nitrogen from the atmosphere to chemically-active nitrogen
compounds. This activation process had not only been the basis of the green revolution, improving food supply for many people, it also remains the starting point of the nitrogen-based eutrophication of many terrestrial and aquatic ecosystems worldwide. The limit suggested by [6
] based on [58
] is 62 Tg N/a from industrial and microbial fixation. From a macro management point of view, in the end, such a target would require a limitation of industrial production of activated nitrogen worldwide. The adequate level will have to be determined by dedicated modeling, including scenarios considering technical development and varying agricultural practice.
For freshwater use
, targets at the global level would seem inadequate in view of the varying water availability of river basins around the world. While a future convention on the sustainable use of natural resources may formulate general goals such as “not to use more water than what is sustainably available for humans and the natural environment”, the management will basically have to be performed on the river basin scale. There, it would rather be a kind of a meso management, because the various actors of the region have to be addressed and included in integrated water management. Nevertheless, macro management by national governments could help monitor water use and the effectiveness of water management in the river basins, issuing targets of water quality and adjusting the incentive framework if necessary, e.g., to promote water-use efficiency or limit the number of cattle per farm hectare to reduce eutrophication. Governments could also monitor the water footprints of their country based on the AWARE approach in order to reveal which parts of their production and consumption are coming from regions with high water scarcity [59
], and if so, provide incentives for change.