Multiple choice

Increased carbon dioxide may cause global warming by 

  1. reflecting sunlight from Earth's surface

  2. trapping more heat in the atmosphere

  3. reducing the amount of oxygen in the air

  4. allowing more sunlight into the atmosphere
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Carbon dioxide is a greenhouse gas that absorbs infrared radiation. This traps heat in the atmosphere that would otherwise escape into space.

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