We know that carbon dioxide levels were in the atmosphere millions of years ago through ____.
A) radioisotope dating
B) measuring carbon dioxide levels in fossil fuel samples
C) measuring carbon isotope ratios in fossil fuel samples
D) measuring carbon dioxide levels in air pockets in ice cores
E) measuring carbon isotope ratios in air pockets in ice cores

Question

Quizplus · Accepted Answer

Scientists measure carbon dioxide levels in air pockets trapped in ice cores to determine past atmospheric CO2 levels.

We Know That Carbon Dioxide Levels Were in the Atmosphere