HUMAN POPULATION Noadswood Science, 2012

Human Population  To understand the impact of rapid growth in the human population Sunday, September 13, 2015

Developing & Developed  Look at the following – a recent scene from the Glastonbury festival and a shanty town in South America  What issues are involved with this many people?

Developing & Developed  In a given area if the population becomes this vast there is a huge strain on resources needed: space / shelter; food; water (and mates)  There is also a great strain on removal of waste  This impacts not only human populations, but any surrounding flora and fauna

Human Population Projection  Human beings compete with other living things for resources and space – as the world’s population continues to increase, and standards of living improve, there is serious danger of a permanent change to the global environment  Human activities have led to the pollution of the environment, and a reduction in the amount of land available for other animals and plants, which makes it difficult for some species to survive  There is a need to achieve a level of development that also sustains the environment for future generations…

Human Population Projection  Like all living things, humans exploit their surroundings for resources – before the beginning of agriculture about 10,000 years ago, small groups of humans wandered across large areas, hunting and gathering just enough food to stay alive  Population numbers were kept low because of the difficulty of finding food  The development of agriculture led to a population explosion that has accelerated enormously during the past 500 years – unlike other species, humans can adapt to and survive in almost all habitats and climates

Human Population Projection  Using the data in the table below plot a graph showing how the human population has changed over the last 10’000 years: - YearHuman Population Numbers (Thousands) 8’000 BCE5’000 6’000 BCE10’000 4’000 BCE20’000 2’000 BCE35’ ’ CE6’000’000

Human Population Projection  Human population graph over the past 10’000 years: -

Human Population  In the last 200 years or so the human population has grown very quickly – why?  We can grow more food  We can cure and prevent illness or disease  We have no natural predators  Standard of living has improved (electricity, fuel, heat, cars etc…)

Standards Of Living  People in the developed world enjoy a high standard of living, with abundant food, cars and comfortable housing  People in the developing world have a lower standard of living, but many countries are catching up quickly  Strains on the global environment include: -  Non-renewable energy resources (e.g. coal, oil and natural gas) are being used up rapidly  Raw materials are being used up rapidly  More waste is being produced  More pollution is being caused

Waste  Pollution is the addition of substances to the environment that may be harmful to living organisms  Population growth and increases in the standard of living cause more waste to be produced – If this waste is not handled correctly, it leads to pollution  Pollution can be categorised into the following: -  Land pollution  Water pollution  Air pollution

Land Pollution  Most rubbish is buried in landfill sites and not all of it comprises safe materials – even common household items can contain toxic chemicals such as poisonous metals (many smoke alarms contain radioactive americium)  Industrial waste is also discharged onto the land – many farmers apply pesticides to improve their crops, but these can damage living things (toxic chemicals can be washed from the land into rivers, lakes and seas causing eutrophication) Eutrophication in the Caspian Sea (turbidity in North)

Water Pollution  Water pollution is caused by the discharge of harmful substances into rivers, lakes and seas  Many aquatic invertebrate animals cannot survive in polluted water, so their presence or absence indicates the extent to which a body of water is polluted PollutantTypical Effect FertilisersDamage to aquatic ecosystems SewageDamage to aquatic ecosystems and humans Toxic chemicalsDamage to aquatic ecosystems and humans

Air Pollution  The most common source of air pollution is the combustion of fossil fuels PollutantEffect Smoke Deposits soot on buildings and trees, causing them damage – permeates the air, making it difficult for living creatures to breathe Carbon monoxidePoisonous gas Carbon dioxideGreenhouse gas that contributes to global warming Sulfur dioxideContributes to acid rain

Deforestation  Humans have been cutting down trees for thousands of years to clear land for farming and building, and for wood to use as a fuel or building material  Forestry is sustainable as long as forests are allowed to replace themselves, or are replanted after felling, but often this is not done – the result is that the world’s forests are steadily shrinking  Crops being grown for biofuels, based on ethanol, is now also playing a major part in deforestation

Deforestation  The world’s forests have changed greatly over the last 10’000 years

Deforestation  The world’s forests have changed greatly over the last 10’000 years

Deforestation  Deforestation leads to: -  Forest habitats being destroyed  Soil erosion increasing, which causes barren land, flooding and land slides  Atmospheric pollution is caused when forests are cleared by burning trees  Deforestation also leads to a loss of biodiversity – this refers not only to the number of different species, but also to all the variations within and between species, and all the differences between the habitats and ecosystems that make up the Earth’s biosphere

Deforestation

 The loss of forests reduces biodiversity and we run the risk of losing organisms that might have been useful in the future - for example as sources of new medicines  There is also a moral responsibility to look after the planet and its resources

Global Warming  The atmosphere is a thin layer of gases, surrounding the Earth  Certain gases in the atmosphere trap heat, reflecting it back to the Earth’s surface, warming it  This is similar to the glass in a greenhouse, which traps heat inside it (trapping of heat by the Earth’s atmosphere is known as the greenhouse effect)!  Without this atmosphere the Earth would be too cold for life to exist