How Does Our Modern Concentration of Atmospheric CO₂ Compare with CO₂

Multiple Choice

How does our modern concentration of atmospheric CO₂ compare with CO₂ during the past 800,000 years of Earth's history?

A) Atmospheric CO2 concentrations have been constant for the past 800,000 years.
B) It is lower today than at any time in the past 800,000 years.
C) It is greater today than at any time in the past 800,000 years.
D) There is too much variability in atmospheric CO₂ to describe any trends through time.