Since the late 1700's, human activity has increased the concentration of carbon dioxide and other greenhouse gases. We tend to forget that there are natural sources of atmospheric carbon dioxide .
Can you identify the statements that correctly describe the natural sources of carbon dioxide in Earth's atmosphere? (Choose 4)
A. Human sources of carbon dioxide are much smaller than natural emissions
B. A large amount carbon dioxide is created by volcanic eruptions
C. About 43% of all naturally produced carbon dioxide emissions come from ocean-atmosphere exchange
D. The decomposition of organic life forms releases atmospheric carbon dioxide
E. An important natural source of carbon dioxide is photosynthesis carried out by autotrophs
F. Animal and plant respiration add carbon dioxide to the atmosphere
B. A large amount carbon dioxide is created by volcanic eruptions
C. About 43% of all naturally produced carbon dioxide emissions come from ocean-atmosphere exchange
D. The decomposition of organic life forms releases atmospheric carbon dioxide
F. Animal and plant respiration add carbon dioxide to the atmosphere