4 Population
4.3 Population–resource relationships Carrying capacity
Revised
Carrying capacity is a dynamic, as opposed to static, concept because advances in technology can increase the carrying capacity of a region or country significantly. The enormous growth of the global economy in recent decades has had a huge impact on the planet’s resources and natural environment. Many resources are running out and waste sinks are becoming full. Climate change will impact on a number of essential resources for human survival, increasing the competition between countries for such resources. The ecological footprint is an important measure of humanity’s demands on the natural environment. It has six components: l built-up land l fishing ground l forest l grazing land l cropland l carbon footprint An ecological footprint is measured in global hectares. Nations at different income levels show considerable disparities in the extent of their ecological footprint. In 1961, most countries in the world had more than enough biocapacity to meet their own demand. But by the mid-1980s humankind’s ecological footprint had reached the Earth’s biocapacity. Since then humanity has been in ecological ‘overshoot’.
Number of planet Earths
In many countries the carbon footprint is the dominant element of the six components that comprise the ecological footprint, while in some, other aspects of the ecological footprint are more important. In general the relative importance of the carbon footprint declines as the total ecological footprint of countries falls. l The ecological footprint is strongly influenced by the size of a country’s population. l The other main influences are the level of demand for goods and services in a country (the standard of living), and how this demand is met in terms of environmental impact. l International trade is taken into account in the calculation of a country’s ecological footprint. For each country its imports are added to its production while its exports are subtracted from its total. The expansion of world trade has been an important factor in the growth of humanity’s total ecological footprint.
Carrying capacity is the largest population that the resources of a given environment can support.
Biocapacity is the capacity of an area or ecosystem to generate an ongoing supply of resources and to absorb its wastes. Ecological footprint is a sustainability indicator that expresses the relationship between population and the natural environment. It takes into account the use of natural resources by a country’s population. One global hectare is equivalent to one hectare of biologically productive space with world average productivity.
Typical mistake Sometimes students think that the ecological footprint and the carbon footprint are the same. However, the carbon footprint is only one component of the ecological footprint, even though for many countries it is the most important component.
Carbon footprint is defined as ‘the total set of GHG (greenhouse gas) emissions caused directly and indirectly by an individual, organisation, event or product’ (UK Carbon Trust 2008).
1.8
Now test yourself
1.6 1.4 1.2 1.0
World biocapacity
0.8 0.6 0.4 0.2 0
1960
1970
1980
1990
2000 2005
19 Define carrying capacity. 20 What is the ecological footprint? 21 List the six components of the ecological footprint. 22 Define biocapacity. 23 Describe the trend illustrated in Figure 4.6.
Answers on pp.215–216
Figure 4.6 Global ecological footprint, 1960–2005 62
Cambridge International AS and A Level Geography Revision Guide
Tested
