[Previous posts of this series: 1, 2, 3]
As energy, matter is neither created nor destroyed, just transformed (the so-called law of conservation of mass). For producing the stuff we consume, we use the factors of production (labour, capital and energy) to transform raw materials into final goods. Along the production process, materials are first extracted and then transformed in industrial processes to create useful products. Then these products are purchased, used and disposed when they are no longer useful. Along this process matter is neither created nor destroyed, only transformed, but in each of these transformations part of the raw materials become dispersed and therefore no longer useful. In the worst case, the disposed products end up in nature again, dispersing all the materials embedded and potentially damaging local ecosystems. In the best case, the disposed products are recycled, in which case a fraction of the materials embedded is concentrated again and re-enters the production process as a raw material, and the other fraction is dispersed in nature in a controlled form (i.e. by minimizing the hazards to local ecosystems). Although theoretically 100% of products could be recycled with enough energy, this is not the case due to the enormous amounts of energy which would be required and due to technical constraints. In summary, the useful materials in the earth crust are limited and their use reduces their availability. Therefore, the only way to achieve infinite growth would be by decoupling economic growth from materials consumption.
Regarding material resources we can see the same trend as the one identified for energy and emissions: We find that although resource intensity has improved significantly over the last 30 years, material consumption has overall increased due to both economic and population growth (Figure 1).
Figure 1. Growth of GDP, material consumption, material productivity and intensity and population
Source: Dittrich et al. 2012
Figure 2 allows us to identify three groups of countries. Most of the countries have only achieved relative decoupling: improving material intensity while increasing the total material consumption. A few countries have increased both intensity and total consumption, and a third group of countries has achieved absolute decoupling: reducing both intensity and total material consumption. This third group of countries is mainly formed by developed countries and island states, which could suggest the same international trade effect identified in the previous posts of this series.
Figure 2. Worldwide trends in GDP and domestic material consumption growth (1980-2008)
Source: Dittrich et al. 2012
Some economists suggest that absolute decoupling could be achieved thanks to technological improvements. However, that seems unlikely to happen in a market economy due to the Jevons paradox or rebound effect, which states that increasing efficiency translates into lower prices and therefore higher demand, offsetting the resource gains of increased efficiency. Indeed, a recent MIT study (Magee and Devezas, 2017) analyzed 57 types of goods and services and found no evidence of dematerialization.
In conclusion, although material efficiency has consistently improved during the last 30 years, we have no evidence of absolute decoupling at a global scale. Although a few countries have achieved absolute decoupling, this might be triggered by a trade effect as seen in previous posts rather than a real drop in materials consumption. Moreover, when studying products individually there is no evidence of absolute decoupling for any of the individual items, since efficiency gains are offset by increase in consumption.
References
Magee, C.L., and Devezas, T. C. (2016). A simple extension of dematerialization theory: Incorporation of technical progress and the rebound effect. Technological Forecasting and Social Change. Technological Forecasting & Social Change.
Climate Footnotes 