Atmospheric carbon dioxide levels are shown below.This graph was developed by measurements that were obtained by

Question

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The graph was developed by measurements obtained through direct measurements on Mauna Loa, Hawaii, and from air bubbles trapped in ice. The other options, such as studies on plant tissues and structures or carbon isotope levels in sea floor sediments, may provide useful information about historical CO2 levels, but they are not the sources for this specific graph. The option about measurements from bat droppings in caves on a South Pacific island is not relevant to measuring atmospheric CO2 levels.

Atmospheric Carbon Dioxide Levels Are Shown Below