The Earth's climate has changed many times in
the past. Subtropical forests have spread from
the south into more temperate (or milder, cooler
climates) areas. Millions of years later, ice
sheets spread from the north covering much of
the northern United States, Europe and Asia with
great glaciers. Today, nearly all scientists believe
human beings are changing the climate. How can
that be?
Over the past few centuries, people have been
burning more amounts of fuels such as wood, coal,
oil, natural gas and gasoline. The gases formed
by the burning, such as carbon dioxide, are building
up in the atmosphere. They act like greenhouse
glass. The result, experts believe, is that the
Earth heating up and undergoing . How can you show the
- Two identical glass jars
- 4 cups cold water
- 10 ice cubes
- One clear plastic bag
- Thermometer
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