Illustrating the enhanced greenhouse effect
For the trial, this task was completed as a pencil and paper exercise using black and white versions of the images. If students have ready access to computer screens, you could consider allowing them to view the pictures to assist them in "reading" the colours of the images as the artist intended.
This task could be completed as a small group discussion, especially if extended as suggested below. In the trial, this task followed What do you know about the greenhouse effect?, which included a more traditional fully labelled diagram of the greenhouse effect. This was a deliberate attempt to ensure that students would not be disadvantaged if they had not encountered ideas about the greenhouse effect before.
| Y10 (08/2006) | ||
| a) | B – to increase an effect | very easy |
| b) |
Three key points in the artists' message are:
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difficult |
The most common combinations were of points 2 and 3 (refer to answers).
Greenhouse effect is good to a certain level. But if there is too much greenhouse gases it is bad and causes earth to get too hot.
The greenhouse effect is currently perfect, keeping the Earth warm and all of its creatures growing. If this effect was enhanced the Earth would be too hot and all of its organisms would die. At the moment the Earth is a very happy chappy. (This answer was unusual in not being focused only on human interests.)
Misinterpreting aspects of the images
- 12 percent of students gave answers that showed they did not "read" the images as the artist intended.
Misinterpreting the circles
A number of students thought the larger circles in each cartoon depicted the sun.
- The artist is making it clear that the more pressure you put on the sun the less heat it makes. When the greenhouse effect is enhanced there is too much heat getting bounced/reflected around for the sun to cope with. It is showing how the sun gets heat from the greenhouse's effects. But the enhanced greenhouse effects will be too much hard work for the sun.
It was possible for students to draw the correct "message" yet still think this was about the sun rather than Earth. (One student actually wrote beside the picture "is that the sun or the Earth?"):
- That the enhanced greenhouse effect is worse than the normal greenhouse affect [sic] because the sun is less happy. The message that the artist is giving us is that the greenhouse effect we have now (which is shown by the happy sun) is working and is fine how it is, but if we have the enhanced greenhouse effect that we could have in some years to come (which is shown by the tired and exhausted sweaty sun) it is not working and our world will slowly destroy itself.
Misinterpreting the arrows
Some students thought the arrows represented gases rather than energy.
- The message about the greenhouse effect is that we will all not be happy when the greenhouse effect is enhanced as it means that more gases will be entering and exiting the atmosphere so it really isn't a good idea.
- The pictures show the effects of how much of the greenhouse gas is being able to escape or not.
- They are conveying the idea that if our atmosphere let no gases out we would roast because the warm air has no way to escape.
- With global warming the heat cannot escape the earth's atmosphere because the ozone layer is blacked up maybe from pollution etc. It basically shows how the greenhouse effect works.
- If we have a relatively clean environment the earth will not get too hot because the sun's rays will go out of earth's ozone, but if we have a dirty environment the earth will get hotter and hotter.
This task revealed misconceptions in 21 percent of students' thinking, often occurring in combinations. As the above examples suggest, it is likely that existing misconceptions contribute to ways students misread the images.
Misconceptions about the atmosphere as a system
Misconceptions in this area were common. Some students do not seem to appreciate that it is the proportions of each gas that change, seeming instead to think that changes to actual volume of the atmosphere increases to cause the greenhouse effect. This is likely to be linked to thinking the arrows represent gases rather than energy flow (refer to "Misinterpreting the arrows" above.)
- When the atmosphere is thin and the heat rays can pass through easily the greenhouse effect is good, but when the atmosphere is thick and the heat rays get trapped inside, earth gets too hot.
- It is showing us that as the gases in the atmosphere build up the heat energy is trapped, causing the earth to become hotter and hotter.
- That the greenhouse effect is making the atmosphere thicker so that the gases can't escape like they naturally would be able to, so they are making the earth hotter than usual.
A few saw the atmosphere as a sort of two-way shield because it isolates the Earth, as well as incoming rays.
- In the enhanced greenhouse effect more gases are visible and this shows the sun's rays being trapped in the atmosphere, being bounced around, not being able to get through to the earth or back out, and the earth is struggling.
Some students seem to think that the greenhouse gases themselves are the source of heat energy, a misconception that, not surprisingly, also seems to combine with thinking the arrows represented the movement of gases rather than energy:
- The greenhouse gases will effect (sic) the earth by making it hotter, because they will not exit the atmosphere. They will just bounce off and come back. If this happens it will cause a domino effect of the earth increasing in heat until it is not longer habitat [sic]. Only a drastic reduction in greenhouse gases will reduce this.
- That at the moment the amount of heat coming into earth from the sun is just right but if something was to happen to the ozone layer (e.g. hole) the amount of heat going into or out of the earth will change and the earth will become dehydrated.
- That the ozone is getting holes in it from corrosive greenhouse gases. Earth is getting polluted and the suns heat cannot escape the earth.
- How the green house gases that don't escape can be harmful to the earth, making it over-heat, this is caused by to much CO2 which is polluting and destroying the ozone layer.
- When the atmosphere is clear, the suns rays, some are reflected off the ozone layer and others make it through and reflect off earth. When the atmosphere is cloudy and filled with gas, some rays are reflected off the ozone layer and others make it through to earth. The rays then get reflected off and hit the ozone layer which they are unable to go through as it is so thick. These rays are reflected back onto earth. The same happens over and over, heating up the earth.
- The enhanced greenhouse effect will be what happens when New Zealand gets sunnier.
- It is making the earth really hot like a greenhouse and doesn't let heat out. And more rays of sun get through so higher chance of skin cancer etc. etc.
Misconceptions about the solar system
There were a few examples of misconceptions about the solar system in general:
- If the sun gets any closer to the earth we could all die.
- I think the message is saying that the heat from the sun and the moon reflects onto the greenhouse to heat/warm the earth.
Issues with explanations 17 percent of students described the images rather than explaining them:
- The picture on the left is the normal greenhouse effect and the picture on the right is what the greenhouse effect will become.
Some wrote very vague answers, or essentially repeated the question:
- That it is alright in moderation but to [sic] much is a bad thing.
Some students missed the point of the message and thought any greenhouse effect was harmful:
- That narural greenhouse gases do some damage that nature repairs, but the enhanced gases that humans create can destroy it.
- We think the greenhouse effect is doing good to our planet but if we take a thorough look it is actually harming it.
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To support students in their first attempts at tasks of this type you could have groups discuss questions about any selected image such as:
What do the arrows represent?
What do the colours signal?
What is the artist showing by…? -
Before exploring the nature and effects of global warming consider whether you need to:
Check that the structure of the atmosphere is understood;
Differentiate the greenhouse effect from other types of atmospheric issues; and
Explore the range of greenhouse gases implicated and how they are generated in human activity (Farming and global warming) . - Impacts of global warming. You may want to explore students' ideas about actual effects of global warming. Do they think warmer = better? Do students appreciate that impacts are likely to be different in different parts of NZ? Again, resource What do you know about the greenhouse effect? could be used.
This resource was developed alongside item What do you know about the greenhouse effect? and they work well together. For a regularly updated source of media articles about the greenhouse effect see http://www.ghgonline.org.
NOTE: Every effort has been made to locate the owner of the graphic on the student page.