4.4 Climate Change

Question 1

What are the most significant greenhouse gases

Answer 1

• Carbon dioxide: released by heterotrophs and autotrophs when they respire and through the combustion of biomass and fossil fuels
• Water vapour: released through the evaporation of bodies of water

Question 2

What does the impact of the gas depend on?

Answer 2

• It’s ability to absorb long-wave radiation: gases that have a greater capacity to absorb long-wave radiation will have a greater warming impact
• It’s concentration on the atmosphere: the greater the concentration of a gas, the greater its warming impact will be within the atmosphere. The concentration of a gas will be determined by both its rate of release and persistence within the atmosphere

Question 3

Is the greenhouse effect a natural process?

What would happen without the greenhouse effect?

Answer 3

Yes!
- The green house effect is a natural process where the atmosphere behaves like a greenhouse to trap and retain heat
- This ensures the Earth maintains the moderate temperatures needed by organisms to maintain life processes (homeostasis)
- Without a greenhouse effect, Earth’s temperatures would drop significantly at night in the absence of direct sunlight

*The greenhouse effect functions to trap heat within the atmosphere and hence prevent rapid temperature fluctuations

Question 4

How does the greenhouse effect work?

Answer 4

• Incoming radiation from the sun is shorter wave radiation (ultraviolet radiation and the visible spectrum)
• The surface of the Earth absorbs short wave radiation and re-emits it at a longer wavelength (infra-red)
• Greenhouse gases in the atmosphere absorb and re-reflect this longer wave radiation and hence retain the heat within the atmosphere
• This causes the green house effect and results in an increase in average mean temperatures on earth.

Question 5

What human activities increase greenhouse gas emission?

Answer 5

• Deforestation
• Increased farming/agriculture
• Industrial practices (combustion of fossil fuels)

Question 6

What will happen if the concentration of greenhouse gases increases?

Answer 6

The greenhouse effect will increase.
- Therefore: global temperatures will increase, more frequent extreme weather conditions, the sea level will rise, loss of habitat (ice caps and glaciers are melting), droughts and floods, changes to circulating ocean currents.

Question 7

What correlation is there since the industrial revolution?

Answer 7

There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial
revolution 200 years ago and average global temperatures.

Question 8

Case study: coral reefs

Climate Change

Answer 8

• When the carbon dioxide dissolves into water, it makes it acidic because of the H+ ions.
• The acidity can make shells and coral exoskeletons dissolve.
• An increase in H+ ions means there is less free carbonate ions for calcification.
• Therefore, the production of coral skeletons will slow or form at a lower density than usual causing a weakness in
  the reef framework. This can make erosion levels exceed reef growth destabilising coral reef structures.

Question 9

Claims for and against climate change

Answer 9

For:
- Global temperatures are rising
- Sea levels are rising
- Glaciers/ice caps are melting
- Ocean acidification
- Carbon dioxide levels are increasing

Against:
- Climate change is being caused by solar activity
- Certain changes in climate conditions cannot be linked to greenhouse gas emissions
- Climate has changed in the past and current trends merely reflect the Earth’s natural climatic cycle (counter argument: climate changes do occur naturally, but usually not as abruptly as what is seen currently)

Question 10

What are some other greenhouse gases that have less of an impact?

Answer 10

Methane and nitrogen oxides