Carbon dioxide and global warming: the greenhouse effect
2 marks · HardExplain two reasons why an increase in the concentration of carbon dioxide in the atmosphere could lead to changes in Earth's climate.
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Also accept: CO2 is a greenhouse gas that absorbs infrared radiation; This leads to warming of the atmosphere (global warming); Melting of polar ice or rise in sea levels as possible consequences; More extreme weather events can result
Common mistakes: Only stating that CO2 is present, not describing its effect; Mixing up greenhouse gases with ozone depletion
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Marking points
B1 · 1 mark · CO2 is a greenhouse gas that absorbs IR radiation and warms the atmosphere
B2 · 1 mark · Describes a consequence of this warming, such as melting ice caps, rising sea levels, or more extreme weather
Worked solution
An increase in atmospheric carbon dioxide leads to more infrared radiation being absorbed by the atmosphere, which causes the Earth's atmosphere to become warmer (the greenhouse effect). This warming can result in melting of polar ice caps and rising sea levels, or can increase the frequency of extreme weather events such as floods and droughts.