Carbon Dioxide Sources and Isotopic Evidence

What is a common argument made by some skeptics regarding the source of rising carbon dioxide levels?

• It is caused by oceanic evaporation.

• It is due to increased solar activity.

• It is mainly from volcanic activity.

• It is primarily from deforestation.

How do volcanic emissions differ from fossil fuel emissions in terms of carbon isotopes?

• Fossil fuel emissions have a higher oxygen content.

• Volcanic emissions have a different carbon isotope signature.

• Volcanic emissions have more carbon-12.

• Fossil fuel emissions have more carbon-13.

Why are fossil fuels depleted in carbon-13?

• Because they are formed from volcanic rocks.

• Because they absorb more carbon-14.

• Because organic life prefers carbon-12.

• Due to the high temperature of fossil fuel formation.

What would indicate that carbon dioxide is primarily from fossil fuels rather than volcanoes?

• An increase in carbon-14 levels.

• An increase in atmospheric oxygen levels.

• A stable ratio of carbon-13 to carbon-12.

• A decline in the ratio of carbon-13 to carbon-12.

What conclusion can be drawn from the scientific test on atmospheric carbon dioxide?

• Volcanic activity is the main source of carbon dioxide.

• Fossil fuel combustion is not a significant source of carbon dioxide.

• The volcanic hypothesis is false due to the decline in carbon-13.

• Carbon dioxide levels are decreasing due to natural processes.