BI 306 MIDTERM 1 What are the different measurements techniques allowing us to date atmospheric CO2 concentrations back 50 million years before present? What are some of the notable features of the Mauna Loa record for atmospheric CO2? What accounts for these features? Mauna Loa was originally chosen as a monitoring site because, located far from any continent, the air was sampled and is a good average for the central Pacific. Being high, it is above the inversion layer where most of the local effects are present and there was already a rough road to the summit built by the military. The contamination from local volcanic sources is sometimes detected at the observatory, and is then removed from the background data