Natural resources, including minerals, water, energy and arable land, are the basis of human society. However, the levels of consumption of these resources are rising rapidly. As a consequence, Earth's climate is changing, fish stocks and forests are shrinking, the prices of energy resources and critical materials are rising, and species are becoming extinct.

According to many scholars, population size and economic prosperity are the two main drivers of human impact on natural resources and ecosystems. Consider the following equation, originally presented by Ehrlich and Holdren (1971), which is often used to describe the relation between human impact and these drivers:

Impact = Population × Affluence × Technology

The equation suggests that if the world's population grows from the present 7 billion to some 9 billion in 2050, the impacts on natural resources and ecosystems are likely to increase considerably, especially if global economic growth results in a rise in the mean level of per capita consumption. Technological innovation may weaken the combined effects of population growth and economic growth if it enables the more efficient use of natural resources.

We should mention that the equation itself has engendered heated debate, especially regarding the relative importance of the three factors. Neo-Malthusians such as Paul Ehrlich believe that population is the number one problem. Ecological economists, like Herman Daly, believe that exponential population growth combined with increased consumption is the real culprit. Biologist Barry Commoner, however, focused on the amount of pollution resulting from economic growth, and concluded that population and affluence would contribute much less pollution than the technology of production (Commoner et al., 1971). Other commentators argue that economic growth is not the problem but the solution. One of them is Julian Simon (1980), who suggests that increasing populations and decreasing resources will boost technological innovation.

Drivers of resource use

Although opinions differ as to the precise relation between population, affluence and technology, the overall conclusion stands. Throughout the 20th century, the growing population has led to an increase in the use of fossil fuels by a factor of 12, and to the extraction of 34 times more material resources. If the population grows as expected and the mean per capita consumption doubles by the year 2050, it is most probable that humanity will experience the limits to growth.