Humans and the environment

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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.

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standards of living

Standards of living

People in the developed world enjoy a high standard of living, with sufficient food, cars and comfortable housing. People in the developing world have a lower standard of living, but many countries are catching up quickly.

Impact of humans

The world’s human population has passed 6 billion and continues to increase. The growth in the human population and the increase in the standard of living are putting strains on the global environment. Here are some of the ways in which this is happening:

  • non-renewable energy resources, such as 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
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population growth

Population growth

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

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population growth

the population has rapidly increased since 1500 CE, from less than 1 million in 1500 CE to over 6 billion today. (

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waste and land pollution


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. The most obvious form of pollution is often simply just litter on the ground, but pollution can affect the air and water too.

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.

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water pollution

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.

some common water pollutants and their effects:

  • fertilisers - damage aquatic ecosystem
  • sewage - kills aquaticorganisms and harm human health
  • toxic chemicals - kill aqustic organisms and harm human health
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Air Pollution

Air pollution

The most common source of air pollution is the combustion of fossil fuels. This usually happens in vehicle engines and power stations.

Some common air pollutants and their effects:

  • smoke - Deposits soot on buildings and trees, causing them damage. Permeates the air, making it difficult for living creatures to breathe.
  • carbon monoxide - poisonous gas
  • carbon dioxide - greenhouse gas that contributes to global warming
  • sulfur dioxide - contributes to acid rain
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air pollution

Indicators of air pollution

Lichens are plants that grow in exposed places such as rocks or tree bark. They need to be very good at absorbing water and nutrients to grow there, and rainwater contains just enough nutrients to keep them alive. Air pollutants dissolved in rainwater, especially sulfur dioxide, can damage lichens, and prevent them from growing. This makes lichens natural indicators of air pollution. For example:

  • bushy lichens need really clean air
  • leafy lichens can survive a small amount of air pollution
  • crusty lichens can survive in more polluted air

In places where no lichens are growing, it's often a sign that the air is heavily polluted with sulfur dioxide.

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Humans have been cutting down trees for thousands of years. We do this 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.

This process is called deforestation. It has some important consequences:

  • forest habitats are destroyed
  • soil erosion increases, which causes barren land, flooding and land slides
  • atmospheric pollution is caused when forests are cleared by burning trees
  • loss of biodiversity
  • loss of some species of plants and animals
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( forests 8000 BC

(   worlds forests 2000 CE

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greenhouse gases

Greenhouse gases

Methane and carbon dioxide are greenhouse gases. They absorb heat energy and prevent it escaping into space. This keeps the Earth warmer than it would be without these gases. Remember that the Moon and the Earth are the same distance from the Sun. The Moon has no atmosphere and has an average surface temperature of –18ºC, while the Earth has an average surface temperature of 14ºC. So you can see that greenhouse gases are not a bad thing in themselves, but too much of them in the atmosphere leads to global warming.

Extra Methane: produced by rice paddy fields and cattle, as these things incrase so does the amount of methane in the atmosphere

Extra carbon dioxide: resleased into the atmosphere bu burning fossil fuels. As deforestation increases there are less trees to take in the exra Carbon dioxide.

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global warming

The percentage of carbon dioxide in the atmosphere has risen from 0.028 in 1700 to 0.035 in 1990. ( these graphs you can see that as the amount of caron dioxide has rises, genrally so has the temperature of the earth. This is calleg Global Warming.

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global warming

The earth's global average temperature has risen from 13.5º C in 1860 to 14.4º C in 1995 (temperatures over a 5 year average).  (

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sustainable development

Sustainable development

Humans reduce the amount of land and resources available for plants and animals. This happens because of farming, quarrying, dumping waste and building.

Sustainable development means improving our quality of life without damaging the quality of life of future generations. It is important to all of us, not just the other inhabitants of the planet, that sustainable development is achieved. This involves each of us as individuals, and careful planning at local, regional and global levels.

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Urbanisation means the growth of cities. About half the world’s population live in cities, and most of the population growth in the future is expected to take place in cities. It is predicted that by 2015, the world’s six largest cities will each have more than 20 million inhabitants. These are some of the effects of urbanisation:

  • increased pollution
  • increased energy consumption
  • land no longer used for food production
  • loss of natural habitats
  • decline of rural towns and villages as people leave them to live in cities
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