[JustDoItAlways]

The older CO2 measurements are thought to be inaccurate due to the scientific instruments used, improper procedures etc.

[Robert A Cook PE]

Not true: This writer shows that they ARE NOT inaccurate and that they DID use valid procedures. Wiping them away by massively classifying them as inaccurate is the method used by Callender to promote HIS theory.

You statement is flatly contradicted by this research, and by Callender's prejudices.

[AFPhys]

I no longer trust anybody discussing items that would tend to be supportive of the CO2 Global Warming hypothesis ... after the shameful inclusion of Mann's "hockey stick" in the IPCC reporting.

[aruanan]

The older CO2 measurements are thought to be inaccurate due to the scientific instruments used, improper procedures etc.

This is not true. The chemical measurements of atmospheric CO₂ are accurate and they are extremely abundant. The problem is that they gave an unwanted baseline. This is why one of the global warming enthusiasts cherry-picked amongst those numbers to yield a 19th century CO₂ baseline of 280ppm when it was actually much higher. This is also why folks like Jones and Mann in building their chart used ice core CO₂ for preceding centuries and then grafted that (with some hacking to get things lined up) onto Hawaiian CO₂ readings to get a dramatic increase. It's already been demonstrated that ice cores lose a considerable amount of trapped CO₂. This is evident just in comparing 19th and 20th century ice core CO₂ measurements with measurements of atmospheric CO₂ measurements over the same period. The general contours are parallel but the ice-derived measurements are always considerably lower.