4.4 Climate Change Flashcards
What do greenhouse gases absorb/emit and what is the consequence of this?
Greenhouse gases absorb and emit long-wave (infrared) radiation, thereby trapping and holding heat within the atmosphere
What % of the earth’s atmosphere is greenhouse gases?
Greenhouse gases collectively make up less than 1% of the Earth’s atmosphere
Which greenhouse gases have the largest warming effect?
The greenhouse gases which have the largest warming effect within the atmosphere are water vapour (clouds) and carbon dioxide
How is water vapour created/removed?
Water vapour is created via evaporation of water bodies (e.g. oceans) and transpiration – it is removed via precipitation (rain)
How is CO2 made and removed?
Carbon dioxide is made by cell respiration and burning fossil fuels – it is removed via photosynthesis and absorption by oceans
What greenhouse gases have a less severe warming effect?
Other greenhouse gases include methane and nitrogen oxides – these have less impact on the overall warming effect
How is methane emitted?
Methane is emitted from waterlogged habitats (like marshes) and landfills – it is also a gaseous waste produced by ruminants
How are nitrogen oxides emitted?
Nitrogen oxides are released naturally by certain bacteria and also is emitted in the exhaust by certain vehicles
How does water vapour differ from other greenhouse gases?
Water vapour is the most abundant greenhouse gas in the atmosphere, but is not produced as a product of human activity
What two factors influence the warming impact of a greenhouse gas?
ability to absorb long-wave radiation
concentration within the atmosphere
How does the ability to absorb long-wave radiation affect the warming impact of a greenhouse gas?
Gases that have a greater capacity to absorb long-wave radiation will have a greater warming impact (per molecule)
How does the Concentration within the atmosphere affect the warming impact of a greenhouse gas?
The greater the concentration of a gas, the greater its warming impact will be within the atmosphere
What determines the concentration of a gas in the atmosphere?
The concentration of a gas will be determined by both its rate of release and persistence within the atmosphere
How can the overall impact of a greenhouse gas be determined?
The overall impact of a greenhouse gas will be determined by the combination of both these factors
How does methane compare to CO2 in terms of ability to absorb long-wave radiation?
Methane has a larger capacity to absorb long-wave radiation than carbon dioxide, but is significantly less abundant
How does water vapour differ from CO2?
Water vapour enters the atmosphere rapidly but only remains for short periods, while carbon dioxide persists for years
How is human activity affecting greenhouse gases?
Human activity is increasing the amount of greenhouse gases (except water vapour) and hence increasing their impact
What is the greenhouse effect?
The greenhouse effect is a natural process whereby the atmosphere behaves like a greenhouse to trap and retain heat
What is the purpose of the greenhouse effect?
This ensures the Earth maintains the moderate temperatures needed by organisms to maintain life processes (homeostasis)
What would happen without the greenhouse effect?
Without a greenhouse effect, Earth’s temperatures would drop significantly at night in the absence of direct sunlight
What does the greenhouse effect maintain?
The greenhouse effect functions to trap heat within the atmosphere and hence prevent rapid temperature fluctuations
What radiation is emitted by sun?
Incoming radiation from the sun is shorter wave radiation (ultraviolet radiation and the visible spectrum)
What radiation does the Earth absorb?
The surface of the Earth absorbs short wave radiation and re-emits it at a longer wavelength (i.e. infra-red / heat)
What do greenhouse gases absorb and re-radiate?
Greenhouse gases absorb and re-radiate this longer wave radiation and hence retain the heat within the atmosphere
What two human activities increase greenhouse gas concentration?
deforestation and increased farming
How does deforestation affect greenhouse gas concentration?
the removal of trees means that less carbon dioxide is removed from the atmosphere via photosynthesis
How does increased farming affect greenhouse gas concentration?
Increased farming / agriculture – this involves land clearing for cattle grazing, also ruminant cattle produce methane
What greenhouse gas is increasing most rapidly and why?
The greenhouse gas that is increasing most rapidly in the atmosphere is carbon dioxide and the main cause is combustion
What happens when fossil fuels are combusted?
When fossil fuels (e.g. coal, oil, gas) are combusted to release energy, carbon dioxide gas is released as a by-product
How have CO2 levels changed over time?
The increased reliance on fossil fuels following the industrial revolution has resulted in ~38% increase in CO2 levels
What are we doing to reduce CO2?
There are now efforts to reduce our reliance on fossil fuels by exploiting alternative energy sources (e.g. solar power)