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| Activity Resources
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| Activity 3 |
Click on the Web icon above and read Information Sheet 2, ‘Causes of climate change’, from the website of the Climatic Research Unit.
Which of the potential causes are influenced by human activity?
Click on the Text icon above and compare the charts for greenhouse gases (carbon dioxide, nitrous oxide and methane) and temperature over the last 1000 years.
- Discuss the key features and implications of these two sets of information.
- Compare the radiative forcing for the human influences – what does this suggest?
- You may like to prepare a worksheet to help pupils analyse and understand the information in these charts.
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Evidence suggests that global temperature is beginning to rise. There are several factors that could cause this. Only one is affected by human activity.
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Up to this point we have been primarily concerned with evidence and trends, with ‘what has happened’. This sort of analysis does not tell you ‘why’ something happened. To understand ‘why’, we need some sort of explanatory model that works on a global scale. The starting point of ‘why’ for climate change, is to consider energy flows in the climatic system. Click on the thumbnail to see a chart showing the rates of energy gain and loss by the Earth’s surface and atmosphere.
Rates of energy gain and loss by the Earth's surface and atmosphere.
Note that even though the arrows starting and stopping in the atmosphere do so in small region in the centre, the atmospheric energy gains and losses that they represent take place throughout the atmosphere. 100 units represent the rate at which solar radiation is intercepted by the Earth. The width of each arrow is proportional to the rate of energy transfer.
If you would like a full explanation of the energy flows in the diagram, click on the icon here, to read more.
So what determines the GMST?
Activity 3 explores the possible causes that may be disturbing the equilibrium of such a model, and the evidence of human influence.
The models being used in research take such simple energy flows and increase the ‘granularity’ of the components used, to build complex time sequences.
You may like to see Information Sheet 8 at the website of the Climatic Research Unit for a summary of how these have developed.
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Unit Resources
