You freeze water and you get ice. During the freezing process some of the air that is around or dissolved in the water gets frozen too. However, when the ice melts, the frozen air goes too. See?
Back to my key credible source of information on global warming and climate change. Page 33 of the IPCC Summary for Policymakers in the Climate Change 2001 reports has a great chart which illustrates the CO2 levels found in core ice which they somehow worked out was formed as far back as the year 1000. This shows very even concentrations of CO2 right up until more recent times when the scientists used direct atmospheric measurements (ie they used some real air).
This is very impressive evidence that CO2 concentrations in the atmosphere were incredibly stable until the 20th century. When I read this graph I wondered what the ice core readings would show compared to the atmospheric readings for the past few decades. That would be really interesting! Hmmm. Maybe the ice core data isn't available because the polar ice caps have been melting, not building up to provide evidence for us to study?
Ahhhh! That's why the CO2 concentration levels in ice cores are so consistent for the past thousand years! When there was more CO2, the world was warmer, the ice melted a little, and didn't build up. There is no evidence in the ice of higher CO2 concentrations because the evidence melted!
What interesting item will I find in these reports next?