Multiple Choice
How has the CO₂ concentration in Earth's atmosphere changed over the past thousand years?
A) We have no means of measuring the CO₂ concentration in Earth's atmosphere for times so far past.
B) The CO₂ concentration has remained absolutely constant.
C) The CO₂ concentration has increased steadily.
D) The CO₂ concentration was relatively constant for about 800 years but has increased significantly since a.d. 1800.
Correct Answer:
Verified
Correct Answer:
Verified
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