Phenomenon:
When ice floating in a glass of water melts, the water level stays the same (Fig. 1).

Fig. 1. Ice melting in a glass. What do you notice about the water level?
Image by Sebastian Stewart.
Inquiry:
What happens when ice on Earth melts?
Why are scientists worried that melting glacier ice will cause sea level to rise?
Guiding Questions:
- How does the atmosphere interact with the hydrosphere to influence sea level?
- How do glaciers and icebergs differ in contributing to sea level?
- How are climate change and sea level linked?
- Why should we be worried about warming melting glaciers and/or icebergs?
Activity:
Investigate the difference between melting of icebergs and melting of glaciers on land and explore the relative effects on sea level rise.
Materials:
- A clear container (ex. tupperware tub)
- Clay, silly puddy, or large rocks
- Ice cubes
- Water
- Ruler
- Tape
- Marker
- Student Worksheet and Teacher Guide (attached below)
Procedure:
- Follow your worksheet to set up your model and conduct your trials. Read the background information below before begining the activity:
Background:

An iceberg is a large piece of ice that is floating freely in the water (Fig. 2a). Icebergs form when chunks of ice break off of glaciers, ice shelves, or larger icebergs.

A glacier is a large piece of ice on top of land (Fig. 2b). Glacier ice forms by the accumulation and compaction of snow. Glaciers typically occur on mountains or near the poles.
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- Mold your clay into an island and stick it to the bottom of your container. If you are using rocks, place them in the container. Make sure the island has a flat surface for your ice cubes (glaciers) to balance on.
- Tape your sea level gauge (ruler) to the inside of the container so that you can measure the height of the water (sea level).
- Add water to the container. Make the top of your island is above the water level!
- Make some predictions based on your model:
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Imagine that you put an ice cube directly in the water. What does the ice represent?
- What will happen to the water level as the ice cube melts?
- Imagine that you put an ice cube on top of your
island. What does the ice on top of the island
represent?
- What will happen to the water level as the ice on
top of your island melts?
- Conduct your trials.
Trial #1: Icebergs
- Place ice cubes in the water near your island. These ice cubes represent icebergs. Note the number of ice cubes used.
- Measure and record the water level BEFORE the icebergs melt in the data table below.
- Measure and record the water level AFTER the icebergs melt in the data table below.
- Calculate the difference in water level before and after.
Trial # 2: Glaciers
- Reset your ocean in the same container, or use a separate container.
- Add the same number of cubes as above, but this time place them on the island to represent glaciers.
- Measure and record the water level BEFORE the glacier melts in the data table below.
- Measure and record the water level AFTER the glacier melts in the data table below.
- Calculate the difference in water level before and after.
- Record the data in your data table:
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Placement of ice cubes |
Starting height of water level (mm) |
Height of water after ice melts (mm) |
Change in water level (mm) |
Trail#1 (Iceberg)
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Trial #2 (Glacier) |
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Activity Questions:
- What do each of your supply items represent in your model? (tub, clay (or large rock), ice cubes, water, ruler)
- How was sea level change different between the iceberg and the glacier trial?
- How does this experiment model sea level rise in the real world?
- What is the atmosphere?
- What is the hydrosphere?
- How does warming of the Earth's atmoshpere affect the hydrosphere?
- What causes sea level rise?
- How do you think rising sea level will affect people where you live?
- Bonus! Follow the link below to do your own research to help Dr. Humuhumunukunuku Apuaʻa investigate the future impact of climate on Pacific Island environments and resources!
- Bonus! Test your newfound knowledge to see if you can spot the error on the newspaper story in the Further Investigations below: