9781422284926

Molly looked thoughtful. “Then without the trees here in this forest, there will be more car- bon dioxide in the air.” “And the more carbon dioxide, the warmer the climate,” Enzo concluded. Joaquin smiled again. “This is a simplified, small-scale look at what is happening. Carbon di- oxide is a greenhouse gas, responsible for trapping heat close to Earth’s surface. Carbon dioxide enters the atmosphere when fossil fuels are burned, or when massive forest fires destroy acres and acres of land. Forest fires mean fewer trees which are used to “clean” the atmosphere of car- bon dioxide. It’s a vicious cycle.” The group continued their walk in silence, wondering what the future held.

Try It Yourself

Climate change could result in a rapid melting of the polar ice sheets. If the ice sheet over Greenland melted, for example, sea level—across the plan- et—would rise by an estimated 20 feet (about six meters). If the ice sheet over Antarctica completely melted, sea level would rise 200 feet (about 60 meters)! How much water is really in ice? Try this experiment and find out.

Materials: • paper cup or liquid measuring cup • kitchen scale

• ice cubes • tap water

1. Use the kitchen scale to find the mass of the paper cup or measuring cup. 2. Add water to the cup and find the new mass. 3. Find the mass of 4–5 large ice cubes. 4. Add those to the water. 5. Allow the ice cubes to melt. 6. How much did the mass change? How much water was added to the cup when the ice cubes melted? Was it the same as the amount of water? Or was it more or less?

11