Linda F. Malanson
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Heat energy radiated from the sun warms the earth’s surface. The earth radiates heat back into the atmosphere and into space, but at much longer wavelengths. Some of this heat is absorbed by molecules of polluting gases such as water vapor, carbon dioxide, methane, chloroflourocarbons and nitrous oxide.
This process warms the air and is called the greenhouse effect. Many scientists feel that by releasing more gases, we may change world climates. There are many uncertainties, and evidence of global warming is interpreted differently by scientists.
EXPERIMENT: DROWNING IN MELTWATER
(figure available in print form)
If global climates become very much warmer because of pollution, the ice at the poles could begin to melt. It is unlikely that this will happen on a large scale, but if it did sea levels would rise as they did at the end of the ice ages. This experiment will allow you to see what the result would be for low-lying islands and coasts.
MATERIALS NEEDED:
1. baking dish
2. water
3. ice
4. modeling clay
Directions:
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1. Use some modeling clay to make a “continent” at one end of the dish, almost to the rim. Then make an “island“ in the middle of the dish, about half as high as the dish.
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2. Pour water into the dish to make a “sea”. It should be high enough to leave only the top of the island above water. The continent remains dry, well above the water.
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3. Pack as many ice cubes as you can on top of the continent, out of the water. Leave them to melt. The ice represents landlocked ice sheets, such as those over Antarctica. What happens to the sea level when the ice melts? What happens to the island as the water level rises?
(figure available in print form)
(figure available in print form)
(figure available in print form)
(figure available in print form)
(figure available in print form)
(figure available in print form)