Page 33 - 新思维科学学生用书9 样章
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1 Photosynthesis and the carbon cycle
1.4 Climate change
In this topic you will:
• find out how the Earth’s climate has changed in the past
• learn what happened when an asteroid collided with Earth
• consider how the increase in carbon dioxide in the atmosphere affects climate
today and also in the future, and describe some of the predicted impacts of
climate change.
Getting started
In Stage 8, you learnt how carbon dioxide concentration in the atmosphere has been
steadily increasing. Carbon dioxide is a greenhouse gas, which traps heat energy in
the atmosphere and keeps the Earth warm.
Look at this diagram. It is similar, but not identical, to one that you may remember.
3
atmosphere
4
2
Earth
1
Sun
With a partner, match each of these statements to one of the numbers on the diagram.
A Some of the reflected energy passes back out through the atmosphere and is lost
to space.
B Energy from the Sun passes through the atmosphere and warms the surface of
the ground.
C Some of the reflected energy is blocked by carbon dioxide in the atmosphere, so
it stays close to the Earth.
D Some of the energy that reaches the ground is reflected.
Key words
mass extinction meteorites meteoroids meteors slush
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