This is the Environmental Protection Agency, Division of Answering Ignorant Questions from Belligerent Know-it-alls, Climate Sector. Can I help you?

Thanks to MT, for an even better way of labeling the on-going Eli used to be able to retire threads. Today we start the EPA blonks Plimer series

Comment (2-17):
A commenter (11454.1) provided quotes from Heaven and Earth (Plimer, 2009) claiming that CO2 was higher in 1942 than today based on the “Pettenkofer” method, and denigrating the use of infrared spectroscopy in modern CO2 analysis due to a lack of validation against the Pettenkofer method. Another quote provided from the same source disparaged the Mauna Loa data because only 18% of the raw data is used in statistical analyses.

Response (2-17):
We have reviewed Plimer’s book, and find that it has not been peer-reviewed or undergone any objective and thorough evaluation of its claims. The Pettenkofer method is a chemical method for determining CO2 concentrations in the atmosphere. Regardless of its accuracy, if used in inappropriate locations such as in or near towns or other areas that have high local CO2 concentrations, the Pettenkofer method will not result in a measurement of the global background concentrations (in contrast to the current measurement stations such as the Mauna Loa station, which are carefully placed in remote locations). See response 2-4 regarding CO2 concentrations reported by Beck (2007).

We find that the use of infrared spectroscopy for CO2 measurements has been validated extensively. Not only are infrared spectrometers used in scientific laboratories around the world, but the instruments used for measuring global background CO2 concentrations are regularly calibrated against CO2 samples that have been assessed by manometric measurements, involving condensing and separating CO2 and N2O from the remainder of the air and using a gas chromatograph to determine the CO2 to N2O ratio in the liquefied sample. This manometric procedure is estimated to have an accuracy of 0.07 ppm. Therefore, we find no support for the commenter’s objections to the use of infrared spectrometers.

With respect to Plimer’s claim that the Mauna Loa dataset was selectively edited in order to make an upward-trending CO2 curve, NOAA provides a rigorous description of the process used to measure, calibrate, and report the data from Mauna Loa at http://www.esrl.noaa.gov/gmd/ccgg/about/co2_measurements.html (Tans and Thining, 2008). The data are all archived, including any raw data that are not included in the final reporting. In contrast to Plimer, we find that 52% of the hourly data from 2008 were retained, consistent with the statement from NOAA that there is an average of 13.6 retained hours per day (57%) over the entire record. We also find that, with the exception of the 15% of the data that were recorded as “instrument malfunction,” the average of the included data in 2008 was within 0.2 ppm of the excluded data, contrary to the assertion by Plimer that selective editing was used in order to change the trend. These data have been extensively reviewed, published in the peer-reviewed literature, and ultimately also used by the broad climate change assessment community. In addition, the data from Mauna Loa are consistent with data collected at remote sites around the world, as well as with samples collected in air flasks and measured at a central site rather than on location (these flask data are on average within 0.11 ppm of the infrared analyzer data).

The confidence that the modern CO2 record gathered around the world represents accurate measurements of the global background CO2 concentration is therefore extremely high, in contrast to the northern European data collected by the Pettenkofer method in 1942. Therefore, we determined that the assertions of the commenter and the underlying source are not consistent with the current scientific literature.

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