So, your argument is that the CO2 values from one year taken from ice cores should not be compared to CO2 values from a different year taken from the same ice core because they represent<quoted text>
It means that the graph you are referring to represents data collected from one location on earth. Just like the temperature of yesterday in your area does not represent the temperature of the earth yesterday, the ice core data represents the values in antarctica, not the rest of the earh.
Yes, CO2 measured in the same place during the day will be higher than if measured at night. If measured in the summer, CO2 will be higher than if measured in the winter. CO2 values vary depending on the condition at the time of measurement.
In antarctica, it is winter all the time, so CO2 values will be lower when measured in winter. This is important because CO2 values in the ice core are no more indicative of worldwide CO2 values than the temps measured in the ice core represent world temps.
'Well distributed' is a relative value. It is well distributed at low elevations and low latitudes. It is not well distributed at high elevations and high latitudes. Vostok is both high elevation and high latitude. The result is that CO2 at vostok is not the same as CO2 values in Paris.
The ice core provides with a look at how climate has varied over the last 700,000 years. This is incredible information. The ice core shows us a pattern of activity, it does not show the world's temps over the last 700,000 years, it shows antarctica temps over the last 700,000 years.
And ice core data is different for the arctic. Greenland because it is impacted by precession is different from antarctica. Here's a quick look at the comparison. Notice how the antarctic temps lead the arctic temps.
- the same location
- the same time period
- the same climate
Guess what, if the CO2 at the Equator is increased 1000%, some of it is going to make its way to antarctica within a decade or two and show up in the ice cores.