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You can download this bookmark as a PDF and the activity text as a Word document

Background:

The ocean plays a huge role in climate change. Covering 70% of the globe, they store 1,000 times more heat than the atmosphere (water can store four times more heat per unit mass than air). Ocean surface temperatures worldwide have risen on average 0.9 degrees Fahrenheit, or 0.5 degrees Celsius, and ocean waters in many tropical regions have risen by almost 2 degrees F (1 degree C) over the past century. These warming oceans make hurricanes stronger and cause sea level to rise slightly because water expands when it warms. Without the oceans climate would change much faster. Once the oceans come to equilibrium with a greenhouse-gas warmed earth however, they will keep us hotter for a long time.

Directions:
1. Print out this bookmark on heavy paper if possible.
2. Ask students to cut out both pieces and glue them back to back.
3. Assign this as a take home experiment.
4. Discuss results in class.

After students do this simple experiment at home, discuss their results:

• Which glass was warmer? (The one with the water in it.)
• Why does the glass with water take longer cool down? (Water holds onto heat longer than air.)
• How does this affect global warming? (Ocean water warmed by increased temperatures will stay warm longer than the air. The warmer the oceans get in the summer, the warmer they are in winter. Ocean water warms the air and that causes climate change.)

Students who leave their glasses in the refrigerator for longer than 15 minutes may have two cold glasses!