Biomass extraction is distributed unevenly around the globe – to a large extent due to different endowments of land suitable for agricultural production – and trade in biomass products is required as a balancing mechanism for supply
and demand. High population density areas are characterized by low per capita biomass harvests and by small amounts of per capita land suitable for agricultural production. Areas of low population density, on the other hand, have large availability of potential agricultural land and harvest high amounts of biomass in per capita terms. Therefore, biomass trade flows
Figur e 36
4.2 Metals trade and upstream requirements from sparsely populated countries (North and
South America, Oceania, the FSU and parts of Sub-Saharan Africa) to areas of high population density (Asia and Europe).
Biomass trade has grown at comparable rates to other material categories, but upstream requirements of biomass materials have grown faster than directly traded biomass. The faster growth in upstream requirements mainly results from the growing share of higher-processed biomass products in trade. Higher-processed products have, by definition, higher upstream material requirements, compared to goods at lower processing stages. For agricultural products, the growing share of animal products in the trade mix can serve as an example of this trend (Regmi, 2001).
At the global level, Asian and European countries are close to maximum productivity for their available land. Intensification is at a maximum and does not leave much space for further increases
in productivity. These densely populated areas are depending on imports from other regions, i.e.
regions of low population density. Latin America, North America, and some areas in Sub-Saharan Africa are focussed on high per capita biomass extraction, and thus make use not only of the availability of land but also of the high productivity of the available land area. In terms of future capacities, these regions have additional and productive land available for biomass harvest.
However, expanded biomass production in these regions has resulted in the cutting down of forests, land degradation and ecosystem changes (Foley, 2005; Krausmann et al., 2013;
Lambin and Meyfroidt, 2011; UNCTAD, 2012;
Zika and Erb, 2009). Moreover, high inefficiencies in harvest technologies have aggravated these effects (UNCTAD, 2012). In terms of future potential, increases in efficiencies can, to some degree, compensate for the environmental problems. However, increasing land degradation and loss of forest area can be expected.
4.2 Metals trade and upstream requirements
Metals play a central role in economic
development. The ability to forge and use metals has enabled humans to construct more efficient tools and instruments for agriculture, construction and military purposes.
Until the nineteenth century, humans processed only a limited number of metals, such as copper, tin and iron. Today, however, almost every element in the periodic table is extracted and used on an industrial scale for producing specific materials and high-tech commodities. Out of the more than sixty different metals existing in nature, mass flows in human economies are made up of iron and manganese (used mainly for structural steels), aluminium (primarily required in transportation), lead (for use in batteries), and copper (essential for the transportation of power, and energy) (Graedel, 2010). With the exception of lead, these metals are used widely in mass applications such as infrastructure and buildings.
According to Allwood and Cullen (2012), out of the more than 1 billion tons of steel produced
14 per cent in infrastructure, with a further 16 per cent being used in electrical and mechanical equipment and a further 12 per cent in cars, trucks and ships. Out of the 45 million tons of aluminium products produced every year, around 26 per cent is used in transportation equipment (cars, trucks and planes), 24 per cent in buildings, 20 per cent is required in industrial equipment and 13 per cent is used in packaging (Allwood and Cullen, 2012). Other metals, such as indium and platinum, are increasingly used in small or even microscopic amounts, especially in the electronics industry. Graedel (UNEP, 2010) concludes that hardly any chemical element can currently be eliminated from the list of those that are important to modern society and to cutting-edge technology.
Thus, metals are mainly a flow from extraction to processing and eventually to stocks, which are accumulated in societies for years, if not centuries. The history of economic development reflects countries’ use of metals and the per
4. Trade flows by type of resource and their environmental impacts
countries have naturally accumulated larger per capita stocks of various metals, compared to less developed countries (Graedel, 2010). Copper stock per capita, for example, is around four to ten times higher in developed countries than in less developed countries, while stainless steel stock is between five and twelve times higher, again in favour of developed countries.
Metals are a non-renewable material, each extraction reducing and depleting the respective
deposit. Worsening ore grades partly reflect the current degree of depletion of accessible resources (Figure 38). Continuing metals extraction and depleting deposits means that more gross ore has to be broken out, with potential impacts on local and global ecosystems and with higher input requirements of energy, water and chemicals. Metal ores and metal products are highly diverse - both in terms of price per tons and in metal content per ton of gross ore.
The declining ore grades of metals
Source: (Mudd, 2010)
Although not a renewable resource like biomass, metals can be recycled and used several times.
However, less than one-third of existing metals have an end-of-life recycling rate above 50 per cent, and thirty-four of these register a recycling rate below 1 per cent. Clearly, boosting recycling rates is still a global challenge (Graedel et al., 2011).
The extraction and processing of metals contribute to a multitude of environmental problems. The recently published UNEP International Resource Panel Report on
“Environmental Risks and Challenges of Anthropogenic Metals Flows and Cycles” (van der Voet et al., 2013) provides a comprehensive synthesis of existing knowledge on the
environmental impacts of metal use by humans.
The environmental problems caused by metals use depend, among other things, on the respective metal, the specific characteristics of the deposit, and the technologies of extraction and processing. Examples of environmental problems include:
}
} Removal of ecosystems and human settlements for the installation of mines and access roads to the mines
}
} Dust and noise pollution, as a result of open-pit mining operations such as blasting and haulage
}
} Damage resulting from crushing and grinding operations
}
} Disposal or release of toxic substances (if not used properly) and their impacts on local populations
Figur e 37
4.2 Metals trade and upstream requirements
}
} General contamination and overexploitation of soil and water reserves near the mines or processing locations.
Deposits of metals are geographically
concentrated, in contrast to biomass resources.
Even though a large variety of metals exist in the earth’s crust everywhere on the globe, these sources are considered to be deposits only if extraction is economically viable.
Economic viability, in turn, depends on several factors, such as concentration, accessibility, available technologies, by-products and price expectations. Thus, the geographical distribution of metal deposits is fixed from a geological point of view but is changing over time, in terms of accessibility, according to improvements in technology and exploration as well as through depletion of sources.
For different reasons and on the basis of current knowledge of deposits, some countries such as China and Australia are well endowed with various deposits, while other countries have found very few deposits to date. Commercial grades of some metals, such as copper, cobaltand tin, are concentrated among a handful of countries. In 2010, the three leading tin- producing countries were responsible for 78.4 per cent of global tin extraction and contained around 58 per cent of global reserves (BGR, 2012).
The uneven geographical distribution of deposits
and their limited substitutability (considered impossible in some industries and applications) drive international trade in metals. Countries without sufficient domestic sources have to depend on imports of metals. Compared to biomass, where average import dependencies are low (the global average share of biomass imports in DMI was around 8 per cent in 2008), average global import dependencies for all metals is fairly high, with a 24 per cent imports share in DMI. When measured in raw material equivalents, this share rises to 62 per cent of imports
(Wiedmann et al., 2013).