Experiment

Greenland is mostly covered with snow and ice.

Global warming is causing a reduction in the amount of ice on the Earth. The world’s glaciers—the large masses of snow and ice found in the high mountains and on land in very cold parts of the Earth—are retreating, especially the massive ice packs of Greenland and Antarctica. Arctic sea ice—the cap of ice that covers the Arctic Sea at the North Pole year-round—is in decline. The legendary Northwest Passage, a shipping route across the top of the world, even opened in 2007 and 2008.

Although the melting of glaciers and sea ice is startling, only one of these phenomena results in rising sea levels. Here’s an experiment to help you see which one will cause coastal flooding and which one will not.

This experiment has two parts. First, you will simulate what happens when sea ice melts. Then you will simulate the melting of glaciers.

Arctic Sea Ice
The images below show the extent of the Arctic sea ice on two different days. Click on either image to see an animation of the sea ice day to day from September 28, 2003, to May 10, 2004. (The file is 21 MB.)

The gray areas are ice. Darker gray indicates older ice. The wispy white areas are clouds. The black dot is centered on the North Pole. There is no data for that area.

Tools and Materials

• A glass bowl
• Tape
• Ice cubes
• Water
• A flat rock

What to Do

Part 1: Sea Ice
Put some water in the bowl and add some ice cubes. You can put as much ice in as you want, but make sure it is all floating and not resting on the bottom. This is your Arctic Ocean with sea ice floating on it.

Mark the water level with a piece of tape.

Wait until the ice melts and check the water level. Has it changed?

Part 2: Glaciers
Put a flat rock in the bowl and add water. The top of the rock should be a bit above the water level. The rock is your landmass, like Greenland. Place some ice cubes on top of the rock. The ice is your glacier.

Again mark the water level with a piece of tape. Wait for the ice to melt. One or more ice cubes may fall into the water. This simulates the edges of glaciers breaking off and falling into the sea, a process called “calving.” This is a normal part of glacial melting.

After all the ice has melted, what happens to the water level?