Improvements in agriculture health and medicine have produced a dramatic rise in the human population
Trang 4Burning 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
Trang 6Acid rain causes erosion of buildings
Trang 7Deforestation
• In may countries people are chopping down
Trang 8This 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 atmosphere5 Many animal and plant habitats are
Trang 9Intensive 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
Trang 11Problems 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
Trang 12• 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
Trang 13Pesticides
• Pesticides kill insects that will damage crops• They also kill harmless insects or can get
Trang 14In the 1960s, DDT in the food chain threatened bird populations.
Trang 17Organic Farming?
Trang 19Biological Control of Pests
• This means using natural predators to eat pests instead of pesticides• It does not have
Trang 20Develop alternative energy sources
Trang 23This powerpoint was kindly donated to www.worldofteaching.com
http://www.worldofteaching.com is home to over a