Unit 7: Resources – Natural Capital 7.3 Human Carrying Capacity and the Ecological Footprint
Human Carrying Capacity What is carrying capacity?
Human Carrying Capacity Carrying capacity is defined as the maximum number or load of individuals that an environment can sustainably carry or support.
Human Carrying Capacity By examining the requirements of a given species and the resources available, it should be possible to estimate the carrying capacity of that environment for the species. But this is problematic in the case of human populations for a number of reasons.
Human Carrying Capacity Why?
Human Carrying Capacity Humans use a far greater range of resources than any other animal. We also replace resources with others if they run out. We may burn coal instead of wood, use solar energy instead of oil, or eat mangoes instead of apples.
Human Carrying Capacity 2. Depending on our lifestyles , culture and economic situation, our resources use varies from individual to individual, country to country.
Human Carrying Capacity 3. Developments in technology lead to changes in the resources we use.
Human Carrying Capacity 4. We import resources from outside our immediate environment.
Human Carrying Capacity While importing resources increases the carrying capacity for the local population, it has no influence on the global carrying capacity. It may even reduce the carrying capacity by allowing cheaper imports of food and forcing farmers to reduce their costs to compete with imports and so reduce incentives for conservation of the local environment.
Human Carrying Capacity Example – if the environment becomes degraded by soil erosion, the land may become less productive and so not produce food for as many people. These variables make it practically impossible to make reliable estimates of carrying capacities for human populations.
Human Carrying Capacity What do people think about this? What can we do?
Human Carrying Capacity Some may try to reduce their use of non-renewable resources and minimize their use of renewable ones. Some may argue that the human carrying capacity can be expanded continuously through technological innovation and development. Its just a matter of being more efficient and inventive.
Human Carrying Capacity Conventional economists argue that trade and technology increase the carrying capacity. Ecological economists say that technological innovation can only increase the efficiency with which human capital is used. Technology may appear to increase productivity but it cannot be sustainable and long-term carrying capacity may be reduced.
Reuse, recycling, remanufacturing and absolute reductions How can humans reduce their environmental demands and thereby increase human carrying capacity?
Reuse, recycling, remanufacturing and absolute reduction Humans can reduce their environmental demands by:
Reuse, recycling, remanufacturing and absolute reduction
Ecological footprints Humans can exceed their local carrying capacity by several means including trade to import resources. Thus human carrying capacity can also be viewed as the maximum load (rate of resource harvesting and waste generation) that can be sustained indefinitely without reducing productivity and functioning of ecosystems wherever those ecosystems are.
Ecological footprints So human carrying capacity depends not only on population size but also on the areas of land that support that population.
Ecological footprints The ecological footprint of a population is an area of land (and water) that would be required to sustainably provide all of a particular population’s resources and assimilate all its wastes (rather than the population that a given area can sustainably support).
Ecological footprints An ecological footprint is therefore the inverse of carrying capacity and provides a quantitative estimate of human carrying capacity.
Ecological footprints How does the cartoon show this?
Ecological footprints Personal ecological footprints A fair Earthshare is the amount of land each person would get if all the ecologically productive land on Earth were divided evenly among the present world population.
Ecological footprints On average, some ecological footprints are: Canada – 7.8 hectares (78,000 m²) USA – 10.3 (103,000 m²) Australia – 9.0 India – 0.8 (8,000m²) China – 1.6 UK – 5.2 Germany – 5.3 Switzerland 5.1
Ecological footprints The ecological footprint of a country depends on several factors: Population size and consumption per capita-how many people and how much land each one uses. Cropland and any other land that is needed to grow food, grow biofuels, graze animals for meat, produce wood, dig up minerals, and the area of land needed to absorb wastes (solid, liquid, and gaseous).
Class work The diagrams represent the area inhabited by, and the ecological footprint of, two human populations, A and B. One population is from an MEDC and the other is from an LEDC. The diagrams are drawn to the same scale.
Class work = Area = Ecological Footprint Population A Population B
Class work Which country is most likely to be an LEDC? Explain your answer. State four pieces of information that would be necessary to calculate the ecological footprint of any human population. Explain two ways in which the latitude of a country might affect the size of an ecological footprint.
Class work 5. Which of the populations, A or B, is exceeding the carrying capacity of its local area? 6. Explain your answer. 7. Suggest two ways in which food production of the two populations might differ. 8. Explain how these differences in food production could influence the size of the ecological footprints of these two populations.