The Influence of Human Activity on the Environment

Improvements in agriculture health and medicine have produced a dramatic rise in the human population

This increase in population size leads to an increase in pollution and higher demand for the world’s resources

Humans are using up the earth’s resources, including fossil fuels.

Burning fossil fuels in cars and power stations produces carbon dioxide, sulphur dioxide and other

greenhouse gases

• carbon dioxide traps heat in the atmosphere and causes the temperature of the earth to rise.

• This leads to disruption of the weather patterns eg drought, floods

• Some weeds may thrive on the extra carbon dioxide while other plants are killed

Sulphur dioxide will dissolve in rain producing Acid Rain

• Acid rain damages trees and pollutes rivers and lakes.

Acid rain causes erosion of buildingsand statues particularly if they are made of limestone

Deforestation

• In may countries people are chopping down forests to provide timber or space for agriculture for the growing population

This causes several problems

1. Burning the timber increases the level of carbon dioxide in the air

2. Less trees means less carbon dioxide absorbed for photosynthesis

3. Soil is eroded as it is exposed to the wind and rain

4. Less water is transpired into the atmosphere

5. Many animal and plant habitats are destroyed causing extinction of species

Intensive Farming

• Farming has become more intensive to provide a higher % yield from land

• Many people regard intensive farming of animals to be cruel

• In order to produce more food from the land farmers have to use more fertilisers and pesticides

Problems with Fertilisers

• Fertilisers enable farmers to grow more food as they are replacing the nutrients removed from the soil by plants

• However, if too much fertiliser is added and it then rains, the fertiliser finds its way into rivers and lakes

• This causes the water plants to grow and as there is competition for light, some will die

• Bacteria decay the dead plants and in so doing use up oxygen from the water

• This means the fish suffocate and die

• This process is called Eutrophication

• Raw sewage pumped into rivers has the same effect

Pesticides

• Pesticides kill insects that will damage crops

• They also kill harmless insects or can get washed into rivers and pollute the water

• They may even end up in the food chain

In the 1960s, DDT in the food chain threatened bird populations.Many birds of prey came close to extinction

What can we Do?

Organic Farming?

• This produces less food and is more expensive but it does not produce the pollution problems of intensive farming

Use farmyard manure as a fertiliser and set aside land for growth of wild plants

Biological Control of Pests

• This means using natural predators to eat pests instead of pesticides

• It does not have harmful effects

Develop alternative energy sources

• Conserve our rapidly diminishing fossil fuel reserves by using solar power or wind power

Benefits of conserving endangered species

• Ecotourism

• Agricultural benefits

• Species indicators

• Maintaining diversity in gene pool