In 1969, the late Professor Albert Bartlett famously delivered a lecture, entitled “Arithmetic, Population and Energy”, which begins with the observation that, “The greatest shortcoming of the human race is our inability to understand the exponential function.” The truth of this is profound and irrefutable, as is further compounded by Bartlett’s averment, as the first law of sustainability, that “You cannot sustain population growth and/or growth in the rates of consumption of resources”. Nonetheless, exponential growth has continued, unabated, over the past half century, as is attested by an increase in the consumption of natural resources from 27 billion tonnes in 1970, to 92 billion tonnes in 2017, which corresponds to around 12 tonnes/year for every person on Earth. If recycled material is also included, the total rises to 100.6 billion tonnes, and hence 13 tonnes for every breathing human on the planet, and significantly, the proportion being recycled has fallen from 9.1% to 8.6% in the past two years. This rate of material consumption is expected to rise to between 170 and 184 billion tonnes by 2050, on the basis of a BAU, “take-make-waste” economic model, which equates to more than 18 tonnes per person, given an expected population of 9.8 billion by then.
Over the entire 1970-2017 period, a compound annual growth rate (CAGR) for resource consumption of 2.6% may be deduced, and hence we may infer that, by 2021, total annual demand for virgin natural resources will have exceeded 100 billion tonnes. The breakdown of this tally into individual components is interesting, and for 2017 amounts to: 24.06 billion tonnes [Gigatonnes (Gt)] of biomass, 43.83 Gt of non-metallic minerals, 15.05 Gt of fossil fuels, and 9.12 Gt of metallic ores; when these figures are compared with those for 1970 (9.00 Gt biomass, 9.20 Gt of non-metallic minerals, 6.21 Gt of fossil fuels, 2.58 Gt of metallic minerals), some patterns begin to emerge. Thus, the corresponding (2017/1970) ratios are: 2.67 (biomass), 4.76 (non-metallic minerals), 2.42 (fossil fuels), 3.53 (metallic ores). It is notable that all the other ratios are larger than that for the fossil fuels, which signifies that while use of energy is often taken as a proxy for overall economic growth, the latter does not depend only on energy, but all resources that are consumed in its wake, and which require increasing amounts of energy to place them into human hands.
Thus, the increased extraction and use of non-metallic minerals (4.76) is very striking, and represents mainly the mining and processing of sand and gravel, used to furnish concrete, glass and asphalt, but also silicone polymers, and electronic devices. An explosion in the use of these materials is being driven by urbanization and global population growth, especially in China, India and Africa, and according to one estimate, by 2060, annual demand will have risen to 82 Gt. In many parts of the world, sand mining is not regulated, and is the province of “sand mafias”; sand has also been described as a “conflict mineral”. The growth in metallic ore consumption represents, primarily, an increasing demand for iron and steel, aluminium, copper, zinc, lead and nickel, as are used for construction purposes, and to make an enlarging variety and number of consumer goods.
Perhaps the baseline metric for overall consumption is the increase in population, over a given time period, which was 3.70 billion (1970) and 7.55 billion (2017), thus giving a ratio of 2.04; hence, it is clear that the increased rate of consumption for all resource types has advanced greatly beyond this, demonstrating that the enlargement in resource use is not simply in step with the increasing number of feet on the planet, but reflects the expansion of industrialisation and development of a global consumer culture. The ratio for the consumption of biomass (2.67) is larger than that for fossil fuels (2.42), although, the additional fossil fuel ratio (use) drives all other production/consumption increases.
The term biomass includes crops, crop residues, grazed biomass, timber, and wild-caught fish, and in 1970, one third of all extracted materials could thus be accounted for. However, by 2017, the proportion of total natural resources being used in the form of biomass had fallen to around one quarter, even though the total biomass being consumed increased from 9.0 Gt to 24.1 Gt over the same period. In many ways this is little surprise, since countries depend more on biomass-based materials and energy systems in the earlier phases of their economic development, while the increasing industrialization of the global population during the 1970-2017 period has meant a rising demand for materials and energy systems that are based on mineral resources.
Nonetheless, despite its falling share of the total, the total amount of biomass used per capita has continued to grow, averaging at a global CAGR of 2.1%, to be compared with the global population CAGR of 1.5%. Some 40% of the total biomass extracted (9.5 Gt) was from crop harvesting in 2017, and a similar average growth rate was determined for grazed biomass to feed livestock animals, in reflection of the increased adoption of animal and dairy based food products by an expanding middle class in many parts of the world. The growth is shallowest for those kinds of biomass – such as wood, used to provide both fuel and building materials – which are most easily substituted by alternatives, and where yields cannot be readily enhanced through technological improvements – such as for wild-caught fish.
The expected, relentless increase in resource use is due to a current reliance on extracting virgin materials to fuel growth, rather than using those resources, already recovered, more effectively. For every tonne of resources that is reused, more than 10 are extracted, and no country is living within its own limits. Nearly half the materials that enter the economy are used in long-term products such as housing, infrastructure and heavy machinery.
However, through better design of products, so they can be reused, and an expansion of end-of-life reprocessing facilities, the consumption of virgin materials might be curbed, acting within the framework of a circular economy. Indeed, such circular design follows the example of nature, in which there is no waste: for example, in a forest, where the leaf litter from the previous season becomes nourishment for the soil from which new life is put forth in the next, and nutrients and water are cycled as an intrinsic part of its living mechanism. To recast the “take-make-waste” model to provide a system that is not only sustainable but regenerative is undeniably a sobering challenge, but really is the only viable course of action, since to even maintain, let alone grow, present levels of resource extraction is a patently untenable exercise.