gyokuro
Eventually she revealed that the reason that she feels this way is because she is a pretty serious Christian who is trying to reconcile her creationist upbringing with modern science. Since historical CO2 levels are obtained from a "fossil record" of arctic ice cores and geological samples, the evidence for the historical correlation between global warming and CO2 presupposes a certain age and history of the earth which contradicts the creationist myths.
I am sure that this is a common issue among such people, since if such a person is to accept the geological evidence for anthropogenic global warming, they have to face a deep contradiction to a long-held worldview and belief system (a contradiction that is actually tangential to the issue of global warming.)