10. HUMAN INFLUENCE ON ECOSYSTEMS & HOW TO MAKE IT BETTER

Natural ecosystems everywhere have been affected by humans, either directly or indirectly. The serious implications of this have become increasingly apparent, and considerable action is required. The new generation will feel the consequences more strongly than anyone previous. Their understanding and involvement is essential from the outset because the repercussions, though not their fault, will most certainly be their problem.

Basic background information for some serious human threats to the living world, and some possible solutions, are outlined below as guidance for teacher-pupil discussions. Only environmental problems that are easily observable and resolvable within Britain have been included. For example, rainforest destruction, though of major importance, has not been described. The problems, in general, are caused by humans altering natural ecosystems, which then affect other ecosystems around the world.

To get the children thinking about the issues, the problems and potential solutions, tell them a few of the things that humans do, e.g. drop litter, drive cars, farm intensively. What effects do they think these will have on the local ecosystem and more remote ones? What could we do differently to reduce, or eliminate, these problems?

Emphasise roles the children can play themselves. Involve them. They can help to change things by altering what they do, or by telling others about the problems and solutions. Perhaps they could be assisted in writing a letter to the government or local council, saying what they think should be done, asking what is being done and how they can help.

Ask the children what they think the area of their school looked like one million years ago, before there were any humans. Almost certainly, it would have been forest, with a great abundance of wildlife. What has changed in the area since then? Why has it changed?

In the Introduction to ecosystems section it was learned that the waste from one living thing is always used by another. However, humans are different, because they produce a lot of waste that is not easily used by other living things and will not easily rot (decompose or biodegrade) in the environment. This waste becomes harmful to living things, and so is called pollution.

A lot of rubbish is dropped as litter... Crisp packets, Big Mac cartons, aluminium cans, glass bottles, plastic bags, bus tickets. Most litter is from food and drink containers. Because it decomposes only very slowly, or not at all, it will remain in the environment for a long time.

Instead of dropping litter, a lot is thrown away in dustbins. [The average household produces 20kg of waste per week (Waste Watch, 1993)]. This gets taken away by dustmen and we never see it again. But, where has it gone? Is it still a problem?

Household rubbish is sometimes burned, which puts a lot of smoke and poisonous gases into the air, causing air pollution. However, it is usually dumped at landfill sites - large areas of land piled up with rubbish, ruining the areas' ecosystems. So, even though this rubbish isn't dropped as litter, it is still harmful.

Rubbish that is dropped as litter, dumped or burned cannot be re-used. This means that more resources have to be used up to make new items and packaging. Resources include trees, metals and minerals from underground, chemicals, etc. Using more resources requires more energy (or electricity - see below), has harmful effects for the areas they are taken from and means that less and less will be available in stock.

...10.2.2 Recycle

. . .

...10.2.3 Reuse

...10.2.4 Reduce

...10.2.5 Composting

If a third of household rubbish can be easily recycled, a further third composted, and most of the remainder reused or recycled with difficulty, why does so much waste get produced? How can this be changed?

Pollution is contamination by poisonous or harmful substances. Air can become polluted by smoke or harmful gases, e.g. from factories and (mainly) car exhausts. Water can become polluted by the dumping of waste from households and factories at sea or in rivers, and by the spread of chemicals used on farms, e.g. pesticides and chemical fertilisers.

Air and water pollution spreads far from its source, harming ecosystems in other areas. Furthermore, when one ecosystem is damaged, they cannot interact usefully with others. Consider the two ecosystems given as an example in Ecosystems connected to other ecosystems. If the first ecosystem is destroyed, then it will not form clouds, giving less rain to the second ecosystem. All the organisms in the second ecosystem will be affected. This will transfer to further ecosystems.

10.3.1 Air pollution and the "Greenhouse effect"

Breathing polluted air can make animals, plants and humans ill. It also causes the "Greenhouse effect," whereby Earth's atmosphere cannot get rid of enough of the Sun's heat, and so gets hotter and hotter [global warming]. The immense masses of ice at the North and South Poles could melt, releasing a massive amount of water into the oceans. Sea levels will rise all over the world, leaving a lot of land underwater. How far above sea level do the children think their school is? Is it safe from rising water?

Air pollution comes mostly from car exhausts. Have the children noticed a difference between air near a busy road and air in the countryside? How can we reduce the number of cars?

Often when people drive, there is only one person in the car. If all the people in five different cars used only one, then four cars could be left at home. So, people could drive together, when going on similar journeys.

Public transport could be used whenever possible. Many more people can travel on buses and trains, for the same amount of pollution, than in cars.

Bicycles produce no pollution at all. They also provide good exercise. Cycling or walking should be used whenever possible.

What prevents people from using fewer cars? How can this be resolved?

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