TOPIC 3: HUMAN POPULATION, CARRYING CAPACITY AND RESOURCE USE 3.1.1. Describe the nature and explain the implications of exponential growth in human populations •
Human population is growing exponentially
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Predicted to reach 9 billion in 2070, then fall again…
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Lower fertility rates + longer life expectancies = larger population size
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Exponential growth - a growth rate which is increasingly rapid or an acculturating rate of growth.
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Huge amount of extra resources needed to feed, house, and clothe people.
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High population growth more common in LEDCs - less educated / believe they need more children to help them make a living and take care of the family in the future.
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The debate: over-consumption vs. over-population? - those in MEDCs consuming the most.
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Government policies e.g. China - One Child Policy.
3.1.2 Calculate and explain, from given data, the values of cure birth rate, crude death rate, fertility, doubling time and natural increase rate CRUDE BIRTH RATE CBR = (total number of births / total population) x 1000 Number of live births per thousand people in a population CRUDE DEATH RATE CDR = (total number of deaths / total population) x 1000 Number of deaths per 1000 people in a population FERTILITY Fertility rate - average number of birth/children per woman of child bearing age •
Total fertility rate (TFR)
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General fertility rate (GFR)
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Age-specific fertility rate (ASFR)
ASFR = total number of births / 1000 women of any specified year group(s) Generally, fertility rates tends to be higher in LEDCs, very few have made the transition from high birth rates to low
DOUBLING TIME Doubling time (years) = 70 / % growth rate How long it will take for the population number to double. NATURAL INCREASE (CBR - CDR) / 1000 x 100% •
Infant Mortality Rate (IMR) - total number of deaths of children aged under 1 year per 1000 live births
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Life expectancy - average number of years that a person can be expected to live, given that demographic factors remain unchanged
3.1.3 Analyse age/sex pyramids and diagrams showing demographic transition models Population pyramids - show how many individuals are alive in different age and sex groups in a country for a given year. Wide base
High birth rate
Narrowing base Falling birth rate Straight sides
Low death rate
Concave slopes
High death rate
Bulging slopes
High immigration rate
Deficits slopes
High emigration rate
Demographic transition model - change in population structure from LEDCs to MEDCs (country undergoes economic and social development). Pattern of decline in mortality + fertility of a country. Stage 1: High birth rate; high death rate; short life expectancy Stage 2: High birth rate; falling death rate; slightly longer life expectancy Stage 3: Declining birth rate; low death rate; longer life expectancy Stage 4: Low birth rate; low death rate; long life expectancy
3.1.4 Discuss the use of models in predicting the growth of human populations There are MANY factors that affect population growth, therefore making accurate predictions is extremely difficult. Factors also change over time. Factors affecting birth rate
Factors affect death rate
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age structure
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age structure
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female emancipation
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availability of clean water
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type of economy
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sanitation
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wealth
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adequate housing (place of residence)
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religion
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reliable food supply
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social pressure
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prevalence of disease
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educational status / sex education
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provision of health-care facilities
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availability of contraceptives
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type of occupation
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desire for children / fertility
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natural hazards / civil conflict and war
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provision of child-care measures
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social class
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provision of pensions
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child mortality and IMR
GENERAL FACTORS •
Economics - standard of living
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Legislation/politics - objectives of the state
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Heath care - provision by govt? affordable?
CHANGING PROJECTIONS •
Models may be very generalised and simple to use, or so complex that they are difficult to use.
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They should serve to help us make predictions and sense of the real world.
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There are various population growth models including computer models - technology.
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Extrapolation of population curves is often rather inaccurate but doe serve to assist us in making predictions and while they often over-exaggerate the problem this often serves to inspire quicker action and solutions.
Malthusian Theory •
Human population increases geometrically
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BUT food supply increases arithmetically
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“Laws of nature” limit growth
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Checks - limitations to population growth
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Pessimistic view of the future
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Diminishing returns and famine will be reached
Boserup theory •
As population increases, demand for food increases, tech will also develop to produce more
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“Necessity is the mother of invention”
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Optimistic reliance on technology
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Innovation will catch up with population demands
3.2 Natural Capital 3.2.1 Explain the concept of resources in terms of natural income Natural capital - resources (goods/services) that are not man-made but have value to humans - yield natural income. Natural income - yield or harvest of services provided by the environment (natural capital). Income from natural capital may be in the form of goods or services •
Goods - marketable commodities such as timber and grain
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Ecological services - flood and erosion protection, climate stabilisation, maintenance of soil fertility.
We have be provided with a wealth of resources, which mankind tends to “exploit” and gain profit from. This is okay, so long as it is done sustainably. 3.2.2 Define the terms renewable, replenishable, and non-renewable natural capital Renewable - living species and ecosystems which can be replaced by natural productivity (photosynthesis - biotic process) as fast as they are used (e.g. food, crops, and timber). •
Sustainable yield/harvest = (or less than) natural productivity
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Natural capital is not diminished
Replenishable - non-living resources which are continuously restored by natural processes (e.g. rivers, streams and the ozone layer) as fast as they are used up. •
Provide sustainable natural income
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Natural capital is not diminished
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Depends on abiotic processes
Non-renewable - natural resources which cannot be replenished within a timescale of the same order of which it is used up e.g. fossil fuels and minerals. •
Depletion of stock
3.2.3 Explain the dynamic nature of the concept of a resource Depend on cultural, economic, technological and other factors that influence the status of a resource over time and space. E.g. Uranium which had no use (value) until humans discovered nuclear power. •
Different societies value resources differently
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Increase in demand may increase the value of a resource
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Supply of resources may influence the value of a resource
3.2.4 Discuss the view that the environment can have its own intrinsic value •
Economic - Determined from the market price of the goods or services a resource produces
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Ecological - Value that have no formed market price but are essential to humans e.g. photosynthesis. Doesn’t really have a monetary value but things like soil erosion control, nitrogen fixation and photosynthesis and all essential for human existence
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Aesthetic - No market price, similar to ecological value (basically things that look good) e.g. appreciation of the landscape for its visual attraction.
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Intrinsic - Ethical, spiritual and philosophical views. Valued regardless of their potential use to humans. Not determined by their potential use to human, their value is given vary by culture, religion, etc. e.g. statue
Different use values •
Direct - ecosystem g/s that are directly used by humans
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Consumptive - includes harvesting food products, timber for fuel or housing..
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Non-consumptive - recreational, and cultural activities that don’t require harvesting
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Indirect - derived from ecosystem services that provide benefits outside the ecosystem itself (e.g. natural water filtration which may benefit people downstream)
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Optional values - potential future use of ecosystem g/s not currently used either by yourself (optional value) or future offspring (bequest value)
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Non-use values - include aesthetic and intrinsic values. Sometimes called existence values
3.2.5 Explain the concept of sustainability in terms of natural capital and natural income Sustainability - use of global resources at a rate that allows natural regeneration and minimises damage to the environment. This can be encouraged by: • Ecological land-use to maintain habitat quality and connectivity for all species. • Sustainable material cycles, (ex carbon, nitrogen, and water cycles). • Social systems that contribute to a culture of sufficiency that eases the consumption pressures on natural capital. CASE STUDY Over fishing e.g. Chesapeake Bay / Chimbote Peru •
Tragedy of the commons - problems arise when people exploits common access goods such as international waters. People take advantage; unsustainable fishing.
• Tipping point - point of no return • Trawling - using a large net dragged behind a boat to catch fish (unsustainable) • Long-line fishing - using baited hooks on a long line cast from a boat • Quota - set amount of fish, fishers are permitted to catch • Relate to environmental values…role of politics…sustainability. 3.2.6 Discuss the concept of sustainable development Sustainable development - development that meets the needs of the present without compromising the ability of future generations to meet their own needs. (Improving quality of life while considering environmental, social and economic factors). 3.2.7 Calculate and explain sustainable yield from given data Sustainable yield - rate of increase in natural capital (i.e. natural income) that can be explored without depleting the original stock or its potential for replenishment.
t = time of the original natural capital t+1 = the time of the original capital plus yield SY = (total biomass at t+1) - (total biomass at t) SY = (total energy at t+1) - (total energy at t) SY = [total biomass at t / total energy] - [total biomass at t / total energy] SY = (annual growth and recruitment) - (annual death and emigration) Maximum sustainable yield (MSY) - largest yield (or catch) that can be taken from the stock of a species over an indefinite period. 3.3 Energy resources 3.3.1 Outline the range of energy resources available to society • ORIGIN: THE SUN • Oil is our greatest source of energy at the moment, supplying 37% of all energy demands. • Coal is the next with 25% and then natural gas with 23%. • Fossil fuels therefore power 80% of the world’s economy. • The other energy comes from nuclear (about 5%) and renewable resources (about 15%). • Of the 15% of renewable energy 3% comes from burning biomass, 3% from hydro-electric power, and the other sources (solar, wind, geothermal) provide the remainder. How long will these last? • Oil – 50 years • Natural gas – 70 years • Coal – 250 years These are just estimates, they all dependent on how much we use and how fast we use them, as well as technological development. They will eventually run out.