Question

which of the following explains how scientists know that current global warming is related to human activities. there wasn't carbon dioxide in the atmosphere in the past, there was more methane in the atmosphere 6,000 years ago, increased carbon dioxide in the atmosphere is not carbon-14, there is more water vapor in the atmosphere today than the past

Answer 1

Answer:

Scientists know that recent climate change is largely caused by human activities from an understanding of basic physics, comparing observations with models, and fingerprinting the detailed patterns of climate change caused by different human and natural influences.

Answer 2

C.  Increased carbon dioxide in the atmosphere is not carbon-14.

Explanation: Scientists know the increased carbon is from human activities because it is not the normal carbon 14 released by natural process. When we burn coal, oil, and natural gas, we leave an imprint on the atmosphere of what we call negative carbon-14, or less carbon-14. Because fossil fuels are so old, there's no carbon-14 left, it's all decayed away.