This graph shows the changes in the level of carbon dioxide in Earth’s atmosphere over the past 400,000 years. Many scientists agree that the change shown in the last 200 years or so has been caused by human activities that release carbon dioxide gas. During this period the temperature on Earth’s surface has increased by about 1.1 degrees Celsius.

Question

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Which argument best uses evidence to link human activities that release carbon dioxide gas to changes in Earth’s climate?

A.
The recent increase in atmospheric carbon dioxide is so much greater than past changes that it must be caused by human activity rather than natural forces.

B.
Computer models predict that Earth’s climate will continue to warm as human release of carbon dioxide continues, so the relationship between human activities and climate change is well established.

C.
Experiments show that carbon dioxide gas traps and radiates heat, so a big enough increase in atmospheric carbon dioxide will cause Earth’s atmosphere to warm.

D.
Increases in Earth’s climate have occurred at the same time that its atmospheric carbon dioxide has increased significantly.

Answer 1

D. Increases in Earth’s climate have occurred at the same time that its atmospheric carbon dioxide has increased significantly.

This argument uses direct evidence that shows a correlation between the increase in atmospheric carbon dioxide and the increase in Earth's surface temperature. This correlation strongly suggests that human activities releasing carbon dioxide gas are contributing to changes in Earth's climate.