Humans and their environment

Humans and their Environment

Human impact on the environment

• The population of the world is currently rising very quickly and isn't slowing down.
• It is mostly due to medicine and farming methods which reduce the number of people who die from disease and hunger.
• This is good for humans but we have a big impact on the environment we live in.
• When there were less people, the effects of human activity were small and local but now they have a far more widespread effect.
• We put pressure on the environment as we take resources we need to survive.
• People around the world are also demanding a higher standard of living so we use more raw materials but we also use more energy when making things. It means that we are taking more resources from the environment more quickly.
• Many raw materials are being used up faster than they can be replaced so one day we will run out of these materials.

Slide 3

• We produce a lot of rubbish which uses a lot of land.
• As we make more things we produce more waste. This causes harmful pollution.
• Sewage and toxic chemicals from industry can pollute water.
• This affects the plants and animals that rely on the water for survival including humans.
• Chemicals used on land (fertilisers) can be washed into water.
• We use toxic chemical for farming and this causes land pollution.
• We bury nuclear waste underground and dump household waste in landfill sites.
• Smoke and gases released into the atmosphere can pollute the air.
• Humans reduce the amount of land and resources available to other animals and plants.
• Building, farming, dumping waste and quarrying for metal ores are the four main activities that do this.

Carbon dioxide and the greenhouse effect

• Carbon is present in the atmosphere as carbon dioxide.
• Many processes lead to CO2 being released such as burning fossil fuels.
• Too much CO2 in the atmosphere causes global warming.
• CO2 can be sequestered (locked up) in natural stores including oceans, lakes and ponds; green plants where it's stored as carbon compounds and remove CO2 from the atmosphere during photosynthesis; and peat bogs.
• Storing it like this is important as it means carbon dioxide is removed from the atmosphere.
• The temperature of the Earth is a balance between the heat it gets from the sun and th heat it radiates back into space.
• Gases in the atmosphere acts as an insulation layer. They absorb the heat that would normally be radiated into space and re-radiate it in all directions including towards the Earth.

Slide 5

• If this didn't happen then it heat wouldn't be kept in at night and it would be very cold. We've recently started to worry that this effect is getting out of hand.
• There are different gases that keep the heat in. They are called greenhouse gases and the main ones we worry about are carbon dioxide and methane because they levels of these two are rising quickly.
• The Earth is gradually heating up because the levels of green house gases are increasing - this is global warming. It is a type of climate change and causes other types of climate change.

Deforestation + destruction of peat bogs

• Trees and peat bogs trap CO2 and lock it up. The problem starts when it escapes.
• Deforestation is the cutting down of forests. This causes big problems when it's done on a large scale such as cutting down rainforests.
• It is done to provide timber as a building material.
• It is done to clear land for farming to provide more food or grow crops to make biofuels.
• It produces paper from wood.
• Rice is grown in warm, waterlogged conditions ideal for decomposers. They produce methane that is released into the atmosphere.
• Cattle produce methane so more cattle means more methane.
• Carbon dioxide is released when trees are burnt to clear land.
• Microorganisms feeding on dead wood release carbon dioxide when they respire.