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4.3 Population–resource relationships
Carrying capacity
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.
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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’.
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.
0.8 0.6 1.4 1.6 0 0.2 0.4 1.2 1.8 1.0 1960
Number of planet Earths
1970 1980 World biocapacity
1990 2000 2005
Revised
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).
Now test yourself
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
Tested
Figure 4.6 shows how humanity’s ecological footprint increased from 1960 to 2005. The global ecological footprint now exceeds the planet’s regenerative capacity by about 30%. This global excess is increasing and as a result ecosystems are being run down and waste is accumulating in the air, land and water. The resulting deforestation, water shortages, declining biodiversity and climate change are putting the future development of all countries at risk.
The causes and consequences of food shortages
About 800 million people in the world suffer from hunger. The problem is mainly concentrated in Africa. Food shortages can occur because of both natural and human problems. The natural problems that can lead to food shortages include: l soil exhaustion l drought l floods l tropical cyclones l pests l disease
However, economic and political factors can also contribute to food shortages. Such factors include: l low capital investment l rapidly rising population l poor distribution/transport difficulties l conflict situations
The effects of food shortages are both short and long term. Malnutrition can affect a considerable number of people, particularly children, within a relatively short period when food supplies are significantly reduced. With malnutrition people are more prone to disease and likely to fall ill. Such diseases include beriberi (vitamin B1 deficiency) and kwashiorkor (protein deficiency). People who are continually starved of nutrients never fulfil their physical or intellectual potential. Malnutrition reduces people’s capacity to work. This is threatening to lock parts of the developing world into an endless cycle of ill health, low productivity and underdevelopment.
Revised
The role of technology and innovation in resource development
The global usage of resources has changed dramatically over time. Technological advance has been the key to the development of new resources and the replacement of less efficient with more efficient resources. Examples of technological development in the UK include: l the development of the nuclear power industry, which found a new use for uranium, significantly increasing its price l renewable energy technology, particularly the construction of offshore wind farms, which is now beginning to utilise flow resources in a significant way
Innovation in food production has been essential to feeding a rising global population. The package of agricultural improvements generally known as the Green Revolution was seen as the answer to the food problem in many parts of the developing world. India was one of the first countries to benefit when a high-yielding variety seed programme (HVP) commenced in 1966–67. The HVP introduced new hybrid varieties of five cereals: wheat, rice, maize, sorghum and millet.
Revised
The Green Revolution refers to the introduction of high-yielding seeds and modern agricultural techniques in developing countries.
Table 4.3 The advantages and disadvantages of the Green Revolution
Advantages Disadvantages
Yields are twice to four times greater than traditional varieties High inputs of fertiliser and pesticide are required to optimise production; this is costly in both economic and environmental terms The shorter growing season has allowed the introduction of an extra crop in some areas HYVs require more weed control and are often more susceptible to pests and disease Farming incomes have increased, allowing the purchase of machinery, better seeds, fertilisers and pesticides Middle- and higher-income farmers have often benefited much more than the majority on low incomes The diet of rural communities is now more varied Mechanisation has increased rural unemployment Local infrastructure has been upgraded to accommodate a stronger market-based approach The problem of salinisation has increased with the expansion of irrigation Employment has been created in industries supplying farms with inputs Some HYVs have an inferior taste Higher returns have justified a significant increase in irrigation HYVs can be low in minerals and vitamins
The role of constraints in sustaining populations
There are a significant number of potential constraints in developing resources to sustain changing populations. Figure 4.7 illustrates the factors affecting the development of a particular resource body. The factors included in the diagram are those that operate in normal economic conditions.
Quantity Quality Location Physical conditions (Political stability of area)
Price Cost of extraction
Revised
Level of demand Resource ‘body’ State of relevant technology
Level of economising on use and efficiency
Substitute resources Availability and price of Cost of extraction
Alternative suppliers of the same resource
Figure 4.7 Factors affecting the development of a particular resource body
War is a major issue for development. It significantly retards development and the ability of a country to sustain its population. Major conflict can set back the process of development by decades. Trade barriers form another significant constraint. Many developing countries complain that the trade barriers erected by many developed countries are too high. This reduces the export potential of poorer countries and hinders development. Climatic and other hazards in the short term and climate change in the medium and long term impact seriously on the utilisation of resources.
The idea of optimum population has been mainly understood in an economic sense (Figure 4.8). At first, an increasing population allows for a fuller exploitation of a country’s resource base, causing living standards to rise. However, beyond a certain level rising numbers place increasing pressure on resources and living standards begin to decline. The highest average living standard marks the optimum population or, more accurately the economic optimum. Before that population is reached, the country or region can be said to be underpopulated. As the population rises beyond the optimum, the country or region can be said to be overpopulated.
Economic optimum population
Optimum population is one that achieves a given aim in the most satisfactory way. Economic optimum is the level of population that, through the production of goods and services, provides the highest average standard of living. Underpopulated – when there are too few people in an area to use the resources available efficiently. Overpopulated – when there are too many people in an area relative to the resources and the level of technology available.
Figure 4.8 The optimum population
The most obvious examples of population pressure are in the developing world but the question here is: are these cases of absolute overpopulation or the results of underdevelopment that can be rectified by adopting remedial strategies over time?
The ideas of Thomas Malthus
l The Rev Malthus produced his Essay on the Principle of Population in 1798. l He maintained that while the supply of food could, at best, only be increased by a constant amount in arithmetical progression (1–2–3–4–5–6…), the human population tends to increase in geometrical progression (1–2–4–8–16–32…). l In time, population would outstrip food supply until a catastrophe occurred in the form of famine, disease or war. l These limiting factors maintained a balance between population and resources in the long term.
Malthus could not have foreseen the great advances that were to unfold in the following two centuries. However, nearly all of the world’s productive land is already exploited. Most of the unexploited land is either too steep, too wet, too dry or too cold for agriculture.
Population
Population increase 2 Resource optimists (e.g. Boserup)
Population increase
Increased demand for food
Less food per person Increased demand for food
Increased mortality
Decreased fertility Decrease in population growth Improvement in technology
Population growth continues unchecked
Expanding population means increasing food production causing environmental and financial problems. People are the ultimate resource – through innovation or intensification humans can respond to increased numbers.
Source: Advanced Geography: Concepts & Cases by P. Guinness & G. Nagle (Hodder Education, 1999), p.35
Figure 4.9 The opposing views of the neo-Malthusians and the anti-Malthusians
Figure 4.9 summarises the opposing views of the neo-Malthusians and the resource optimists such as Esther Boserup. Neo-Mathusians argue that an expanding population will lead to unsustainable pressure on food and other resources. In recent years neo-Malthusians have highlighted: l the steady global decline in the area of farmland per person l the steep rise in the cost of many food products l the growing scarcity of fish in many parts of the world l the continuing increase in the world’s population
The anti-Malthusians or resource optimists believe that human ingenuity will continue to conquer resource problems. They have highlighted: l the development of new resources l the replacement of less efficient with more efficient resources l the rapid development of green technology, with increasing research and development in this growing economic sector
The concept of a population ceiling and population adjustments over time
Studies of the growth of animal and fungus populations show that population numbers may either crash after reaching a high level or reach an equilibrium around the carrying capacity. These contrasting scenarios are represented by S and J growth curves. Both incorporate the concept of a population ceiling beyond which a population cannot grow because of the influence of limiting factors such as lack of food, limited space and disease.
S-curves begin with exponential growth, but beyond a certain population size the growth rate gradually slows, eventually resulting in a stable population. J-curves illustrate a ‘high growth and collapse’ pattern: l The population initially grows exponentially. l Then the population suddenly collapses. Such collapses are known as
‘diebacks’. Often the population exceeds the carrying capacity (overshoot) before the collapse occurs.
Now test yourself
24 List four natural problems that can lead to food shortages. 25 State two advantages and two disadvantages of the Green
Revolution. 26 Define optimum population. 27 Show in numerical form how arithmetical progression differs from geometrical progression. 28 State the three limiting factors identified by Malthus.
Answers on p.216
Tested
