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)
Responses
A Human sources of carbon dioxide are much smaller than natural emissions.Human sources of carbon dioxide are much smaller than natural emissions.
B A large amount carbon dioxide is created by volcanic eruptions.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.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.The decomposition of organic life forms releases atmospheric carbon dioxide.
E An important natural source of carbon dioxide is photosynthesis carried out by autotrophs.An important natural source of carbon dioxide is photosynthesis carried out by autotrophs.
F Animal and plant respiration add carbon dioxide to the atmosphere.