1 THE EFFECTS OF THE POPULATION

EXPLOSION

p. 264

Objectives

Students should learn: that rapid growth in the human

population means that more waste is produced

that humans reduce the amount of land available for other animals and plants by building, farming, quarrying and dumping waste.

Outcomes

Most students should be able to: explain how human population growth has

occurred explain why raw materials are rapidly being

used up and more waste is being produced describe the effects of population growth on

land and resources.Some students should also be able to: analyse and interpret scientific data concerning

human population growth and environmental issues.

Specification

Rapid growth in the human population and an increase in the standard of living means that increasingly more waste is produced. Unless waste is properly handled, more pollution will be caused. [B3.4.1 a)]

Waste may pollute: – water, with sewage, fertiliser or toxic chemicals – air, with smoke and gases such as sulfur dioxide, which

contributes to acid rain – land, with toxic chemicals such as pesticides and

herbicides, which may be washed from the land into waterways. [B3.4.1 b)]

Humans reduce the amount of land available for other animals and plants by building, quarrying, farming and dumping waste. [B3.4.1 c)]

Workbook

P. 122-3

HOW BIG IS THE HUMAN POPULATION?

March 2015-

7,300,000,000

WHY?• Advancements made in medicine

• Developments made to the farming industry

• Heightened rate of natural increase

HOW FAST IS THE POPULATION GROWING?

http://www.worldometers.info/

Has doubled in 40 years, (1959- 3 billion 1999- 6 billion)

2015- increase of 1.14% per yearThe average population increase is currently

estimated at 80 million per yearEstimated to reach 8 billion by

2024

The changing population

HOW DO HUMANS AFFECT LAND?

Housing Shops Roads Industrial uses Farming Quarrying

Destruction of habitatsDisruption of eco-systems

Pesticides and herbicides may remain in soil for yearsPotentially impact the food chains within an eco-systemPollution may accumulate to toxic levels

The disposal of waste, (often containing toxic chemicals), also reduces the amount of land and resources available to other animals/plants. The removal of this waste can lead to air and water pollution.

Draining Earth’s finite resources(e.g. metal ores, fossil fuels)

HOW DO HUMANS AFFECT WATER?

Through the development of industry and rapid population growth, vast quantities of waste are being produced. This may lead to water pollution- sewage may pollute water supplies if not dealt with correctly, potentially resulting in disease outbreaks.

Through the discharge of harmful substances into bodies of water, food chains within the local eco-system may be severely affected.

What substances commonly pollute water? Excess nutrients from sewage/fertilisers

- may contain high mineral levels or harmful pathogens Toxic chemicals from industry

- may accumulate in food chains to toxic levels

The process of eutrophication can have major consequences on the eco-system.

HOW DO HUMANS AFFECT AIR?

The increased use of fossil fuels, (as a direct result of rapid population growth and a greater energy demand), has resulted in the increased production of pollutant gases. The combustion of fossil fuels is the most common source of air pollution.Air Pollutant Source Effect

Smoke Incomplete combustion of fossil fuels

Deposition of soot on buildings/treesPermeates air- breathing problems

Sulfur dioxide Sulfur impurities in fossil fuels Acid rain-Damages buildingsDisrupting aquatic eco-systems

Carbon dioxide Hydrocarbon fuels Greenhouse gas global warming

Methane Anaerobic decomposition of landfill wasteRice fieldsCows

Greenhouse gas global warming

THE FUTURE?

• By 2050, the human population is projected to reach 9.4 billion

• The rate of growth is expected to decrease, (to approximately 0.5%)

• Resources will continue to be used rapidly

• The continued disruption to the ecology of the planet will have massive consequences

Research is being carried out into alternative fuels/resources in order to supply our growing energy demand.

Computer models can be used to make predictions about population growth by using assumptions about birth rate.

Predicting future growth rate

Most analysts assume that birth rates will fall within the next 50 years. Why do you think this might happen?

How important do you think predictions about climate change and unsustainable development are in the analysts’ calculations?

decreased fertility lack of resources disease war

The human population is currently . This has occurred due to advancements made in medicine and developments made to the farming industry. As a result of various reasons, including building, farming and quarrying , humans are continuing to disrupt eco-systems by polluting and damaging the land. Excess nutrients and toxic chemicals from industry may wash from the land into waterways, contributing to the process of

7.3 billionmedici

nefarming

quarrying

nutrients

toxiceutrophication.

farming toxic quarrying eutrophication nutrients medicine 7.3 billion

Play odd man out with the classgive a reason in each case

1. Oil Coal Recycling2. Houses Rivers Trees3. Toxic chemicals Nutrients

Eutrophication4. Wind Petrol Sun5. Water Rubbish Sewage6. Hills Rivers Lakes7. Noise Air Cars

Biology B3 4.1The effects of the population explosion

Answers to in-text questions

a 6.8 billion. b By building houses and roads, by farming, by quarrying and by dumping waste. c i Water: excess nutrients from sewage and fertilisers from farms and by toxic chemicals from industry. ii Air: Carbon dioxide from the burning of fossil fuels, smoke and poisonous gases such as sulfur dioxide. iii Land: toxic chemicals from farming such as pesticides and herbicides, industrial waste, such as heavy metals.Summary answers

1 population, two hundred, farming, food, treat, diseases, predators, increase 2 a Any sensible suggestions, e.g. use of electricity for lighting, heating, TV etc.; use of fossil fuels for transport (cars, planes etc.); plastics.

b Any three suitable suggestions, such as fossil fuels, wood, land, metals, etc. 3 Look for clarity of explanation without copying the Student Book. Points covered should include: Growing human population increases the amount of waste: bodily

waste and the rubbish from packaging, uneaten food and disposable goods.

The dumping of waste produced by the ever-expanding human population makes large areas of land unavailable for other life.

Driving cars etc. leads to gases from exhausts. Farming leads to the use of pesticides and fertilizer sprays that

cause pollution.