Diagram of the Poles Apart experiment

Poles apart

Try this activity to see how melting ice and snow affect sea levels.

• 19 April 2007 | Updated 9 November 2012

• What you need
• What to do
• What's happening

What you need

• film canister filled with soil, with the lid on
• two clear plastic glasses
• water
• two ice cubes
• a marker pen.

What to do

1. Place the film canister upside down into one cup. This represents an island.
2. Half-fill each glass with water.
3. Place one ice cube on top of the ‘island’ and the other ice cube in the water in the second glass. Mark the level of the water on each glass.
4. Once both ice cubes have melted, see whether the water level has risen.

What’s happening

The ice cube floating in the water has already shifted, or displaced, the water in the glass; so when it melts, the level will barely rise. But the ice cube on the land (film canister) will not displace the water until it melts and drips into it, making the water level rise.

Only the melting of land-based ice and snow (like Antarctica) will increase the sea level. The melting of floating ice (like the North Pole) will not affect the sea level much.

For more hands-on activities, join CSIRO's Double Helix Science Club.