C9 Greenhouse Gasses and Climate Change (page 158) Flashcards
Is carbon Dioxide a greenhouse gas?
yes
What is Greenhouse gasses?
Greenhouse gasses like carbon dioxide, methane and water vapour act like an insulating layer in the Earth’s atmosphere - this, amongst other factors, allows the Earth to be warm enough to support life.
What do greenhouse gasses absorb from the sun?
radiation from the sun.
All particles absorb certain frequencies of radiation. Greenhouse gasses don’t absorb the incoming short wavelength radiation from the sun, but they do absorb the long wavelength radiation that gets reflected back off the Earth.
Then they re-radiate it in all directions - including back towards the Earth.
The Longwave radiation is thermal radiation, so it results in warming of the surface of the earth. This is the greenhouse effect.
Some forms of human activity affect the amount of greenhouse gasses in the atmosphere, give some examples:
Deforestation: fewer trees means less Co2 is removed from the atmosphere via photosynthesis.
Burning fossil fuels: Carbon that was ‘locked up’ in these fuels is released as CO2.
Agriculture@ more farm animals produce more methane through their digestive processes.
Creating waste@ more landfill sites and more waste from agriculture means more CO2 and methane released by deomposition of waste.
Increasing carbon dioxide is linked to what?
Climate Change
The Earth’s temperature varies naturally, but recently the average temperature of the Earth’s surface has been increasing. Most scientists agree that the extra carbon dioxide from human activity is causing this increase and that this will lead to climate change.
Evidence for this has been peer-reviewed (see page 1) - so you know that the information out ther is reliable.
Why is it hard to fully understand the Earth’s climate?
this is because it’s so complex, and there are so many variables, that it’s very hard to make a model that isn’t oversimplified.
This has led to speculation, particulary in the media - where stories may be biased or only some of the information given. (see page 2 for more on science in the media).
Why is it important to make predictions about the Earth’s climate?
The Earth’s climate is complex, but it’s still important to make predictions about consequences of climate change so that policy-makers can make decisions now.
Examples:
An increase in global temperature could lead to polar ice caps melting - causing a rise in sea levels, increased flooding in coastal areas and costal erosion.
Changes in rainfall patterns (the amound, timing and distribution) may cause some regions to get too much or too little water. This along with changes in temperature, may affect the ability of certain regions to produce food.
The frequency and severity of stores may also increase.
Changes in temperature and the amount of water available in the habitat may affect wild species, leading to differences in their distribution.
Describe the greenhouse effect and how it affects global temperature ( 4 marks)
The sun gives out short wavelength radiation (1 mark), which is reflected back by the Earth as long wavelength/thermal radiation (1 mark). The thermal radiation is absorbed by greenhouse gasses in the atmosphere (1 mark). Greenhouse gasses give out the thermal radiation in all directions including back towards the Earth, causing the temperature to rise (1 mark).
