Topic 8Human Systems and Resource Use

8.4 Human population carrying capacity

Human Population Growth• Carrying Capacity– The maximum number of individuals of a species that

can be sustainably supported within a habitat. It occurs when birth rate is equal to death rate

• But does this really apply to human populations?• Do human populations actually have a carrying

capacity?• Well, there are many examples of direct and

indirect effects of drought, famine and war which act to reduce populations when they grow too large

Human Population Growth• Size of population isn’t the only factor which impacts

on natural resources• Other factors include:– Wealth (MEDC or LEDC)– Resource desire– Resource need (or use)– Age distribution– Rural or urban populations– Time (it is dynamic)

80% of the world’s population lives in MEDCs where birth rate is falling (or negative, e.g.Japan)20% of the world’s population lives in LEDCs where birth rate is increasing

Human Population Growth

• It is very difficult to assess a carrying capacity for a human population (or even if one exists):– We produce non-biodegradable waste which can cause

environmental degradation and reduce the ability of an area to provide resources

– The resources we use are far more varied and there are necessities and luxuries to take into account

– Human populations have the capacity to move goods around the world – we can import food from another region if there isn’t enough where we live

– We employ technology to change the environment.

Malthusian Theory

• Malthus believed that human populations grow exponentially, but resources only grow arithmetically (limited by land availability and existing technology)

• Food production can only therefore increase to a certain level

• Above this level, soil erosion and decreasing soil fertility cause productivity to decrease

• A natural check on population occurs

Thomas Malthus

Boserup Theory• An increase in population will simply stimulate

scientists to come up with ideas to increase food production

• “Necessity is the mother of invention”• Productivity has been increased by:

– Reclaiming land from the sea– Selective breeding and cross breeding– Developing high-yield plants – Genetic modification– Terracing– Hydroponics– Greenhouses– Irrigation– Artificial fertilisers– Switching to new crops (e.g. soya)– Fish farming

Ester Boserup

Norman Borlaug

Environmental Demands of Human Populations

• An ecological footprint (EF) is the hypothetical area of land needed by an individual, group or society to fulfil its resource needs and assimilate all waste

• An ecological footprint is not necessarily sustainable. It may refer to an unstable equilibrium

Ecological Footprint

• A country with a total ecological footprint greater than its available land is in theory living beyond its means (It has an ecological deficit)

Factors affecting ecological footprint• A large footprint could be caused by:

– Reliance on fossil fuels– Increased use of technology (depending on its use)– High levels of importation– Large production of carbon waste– High food consumption– Meat-rich diets

• Footprint could be reduced by:– Reduced resource consumption– Recycling and reuse of resources– Improved efficiency of resource use– Reduced pollution– Exportation of waste– Use of technology (to increase carrying capacity and efficiency of land use)– Reduced population

Approximate Ecological Footprints (2003)• USA – 10.3 ha cap-1

• Australia – 9.0• Canada – 7.8• Germany – 5.3• UK – 5.2• Switzerland – 5.1• Mexico 3.0 (2007 data)• China – 1.6• India – 0.8

In 2003, there were approx. only 1.8 ha available per person (including productive marine areas). Therefore many of us are living beyond the Earth’s ability to sustain the population

Which country do you think currently has the largest ecological footprint?

Calculations

• Ecological footprint is usually calculated in hectares• 1 hectare = 10 000m2

• This is aproximately the size of a football field (0.6-0.8 ha) or the field inside a 400m athletics track (about 1.2 ha)

• The 2 basic calcs usually carried out are1. Per capita land (and water) required for food consumption2. Per capita land (and water) required for carbon waste absorbtion

• They are are added together to give the total footprint

Calculations

Per capita land requirement for food production (ha cap-1) = per capita food consumption per year (kg cap-1 yr-1) mean food production per hectare per year (kg ha-1 yr-1)

Per capita land requirement to assimilate carbon waste (ha cap-1) = per capita CO2 emission per year (kg cap-1 yr-1) total CO2 fixation by vegetation per year (kg ha-1 yr-1)

+Food given as kg equivalents of grain

The 6 components of a national footprint

• Footprint of built-up land– Infrastructure, housing, paved land – produces CO2 and in many cases

unable to recycle waste • Footprint of national fishing grounds

– Estimated area of primary production at sea and in fish-farms on land• Footprint of forestry

– Estimated land required to produce paper pulp, timber for wooden products and wood for fuel

• Footprint of grazing land• Footprint of cropland• Carbon uptake footprint

– Estimated green area required (other than areas of ocean )to absorb the CO2 produced by the other five components

Problems with the Calculation

• It doesn’t consider the effects of pollutants other than CO2

• It doesn’t consider land (or water) needed to assimilate wastes other than CO2

• It doesn’t consider land lost through urbanisation

http://wwf.panda.org/how_you_can_help/live_green/footprint_calculator/

MEDCs vs LEDCsmore/less economically developed countries

1. Which has the higher ecological footprint?2. Why does North America have a particularly high

per capita grain consumption?3. Which are more dependent on fossil fuels?4. Which has higher CO2 fixation and why?5. Use the data to calculate per capita footprints:

Area Per capita grain consumption kg cap-1 yr-1

Grain production kg ha-1 yr-1

Per capita CO2 emissions kg cap-1 yr-1

Net CO2 fixation by vegetationkg ha-1 yr-1

Africa 300 6000 200 6000

North America 600 300 1500 3000

Environmental Value Systems (EVSs)• A set of paradigms which shapes the way individuals or societies

perceive and evaluate environmental issues

• This is affected by:– Cultural concerns– Religious concerns– Economic issues– Whether a society belongs to an MEDC or an LEDC

• As with any system, they have – INPUTS (e.g. education, media, religious doctrines)– OUTPUTS (e.g. environmental mediation)– PROCESSING (e.g. political decisions)– FEEDBACK LOOPS (e.g. scientific advice)

Rather than being based on energy and/or matter, environmental value systems are based on the flow and processing of information

Environmental Value Systems• Since EVSs vary, different cultures, societies, and special-

interest groups often come into conflict over them

• e.g. The U.N. moratorium on whaling is seen very differently in Japanese society compared to European nations

• e.g. The oil lobby in the U.S. sees attempts to switch to a greener economy differently to environmental groups

Environmental Value Systems• There are 3 general categories:– Ecocentric (centred on the environment) – Technocentic (centred on technology)– Anthropocentric (centred on humans)

ecocentrism anthropocentrism technocentrism

Ecocentrism• Ecocentrists are likely to distrust technology• They would stand against large-scale production and corporations• They would view nature as having control over human society

rather than the other way round• They would view the world as having very finite natural capital

which should be protected rather than exploited• They believe that ecology is too complex for humans to fully

understand and therefore be able to manage it• Some believe that nature has more value than humanity (an

extreme view referred to as “deep-ecology”)

Technocentrism• Technocentrists trust in technological advances to

solve environmental problems• They trust in the resourcefulness of humans• They believe that humans are able to control nature• They believe that scientific thinking and scientific

research is important in making public policy• Extreme technocentrists are referred to as

‘cornucopians’. They believe that the world has infinite resources to support a growing population and that this is achievable through a free-market and reliance on technology

Anthropocentrism• Anthropocentrists would include aspects of both

ecocentrism and technocentrism and in their worldview

• They would view humans as managers rather than controllers of nature

• They believe that population control is as important as use of natural capital

• They believe that government has an important role to play in regulating human action in relation to the environment

Silent Running, 1972

Religion• The Abrahamic religions (Christianity, Islam and Judaism) set out a

concept of ‘dominion’ and ‘stewardship’ of nature in the Book of Genesis

• This is an extreme version of anthropocentrism in which nature has value in terms of its usefulness to humans and the pleasure and profit it can provide

• However, a belief in creationism also endows the responsibility on humans to look after God’s creation

• It could be argued that this is a religious responsibility rather than a moral one

Deep-Ecology

• A school of philosophy (ethics) founded by Norwegian intellectual Arne Næss(1912-2009)

• He believed humans should do nothing unless they are fully aware of the outcomes of an action and can take responsibly for it

• He was profoundly influenced by Gandhi and the book ‘Silent Spring’ by Rachel Carson

Deep-Ecology• The tenets of deep-ecology are:

– The well being of human and non-human life has no value in itself which is independent of the usefulness of the non-human world to humans

– The richness and diversity of life contributes to these values– Humans have no right to reduce this richness and diversity except to

satisfy vital needs– For human (and non-human) life to flourish a substantial reduction in

human population is required– Human interference with the non-human world is excessive– A substantial change in world policy is needed in terms of economics,

technology and ideology– Humans should appreciate the quality of life rather than aspire towards

higher standards of living– People with ecocentric views need to constantly work to make these

changes to improve the well-being of the Earth

Can Carrying Capacity Change?• If we cut down on our use of natural resources• It may be achieved by:– Recycling (reprocessing materials into new

products)– Re-use (returning materials to the manufacturer of

processor, or finding new uses ourselves)– Reduction (using less energy or resources)– Substitution (switching to renewable resources

from non-renewable)

https://www.youtube.com/watch?v=E8dkWQVFAoA