On RealC02 summarizing Ernst-Georg Beck's work, this history of CO₂ levels are posted for the 19th century:
SkepticalScience, on its "How reliable are CO₂ measurements?" page says "CO₂ levels are measured by hundreds of stations scattered across 66 countries which all report the same rising trend." and shows a far different history for the 19th century:
What explains the wide discrepancy before the Mauna Loa samples compared to Enst-Georg's for the 19th century, and which set is most accurate?
The discrepancy is detailed on A Different Perspective by Dr. Tim Ball, quoting Edgar Gartner:
Due to his immense specialized knowledge and his methodical severity Ernst very promptly noticed numerous inconsistencies in the statements of the Intergovernmental Panel on Climate Change (IPCC). He considered the warming of the earth’s atmosphere as a result of a rise of the carbon dioxide content of the air of approximately 0.03 to 0.04 percent as impossible. And he doubted that the curve of the CO₂ increase noted on the Hawaii volcano Mauna Loa since 1957/58 could be extrapolated linear back to the 19th century. (Translated from the German)
What is the scientific consensus? Is it correct that scientific consensus agrees that CO2 record for the 19th century should be reconstructed from the Law Dome Ice Core, or are Ernst-Georg Beck's results correct?
Mixing & altitudes
"coby" on ScienceBlogs claims "You can go here to see dozens of CO₂ sampling station records from sea level to mountain top, from pole to equator, that show unequivically that CO₂ spreads very evenly throughout the global atmosphere, all theory or prediction aside.", "here" being a collection of research held at the "Carbon Dioxide Information Analysis Center".
While it's obviously true that CO₂ is well mixed by infrared spectroscopy analysis at high altitudes
I can find no research invalidating samples taken at sea level; however, the source of anthropomorphic CO₂ production, coal fired power plants, are located nearer to population centers and not carbon sinks
My inexperience tells me that it seems Beck's research should be fully invalidated before it can be concluded that his research invalidates the Law Dome ice core.