Comment on “World Atmospheric CO2, Its 14C Specific Activity, Non-fossil Component, Anthropogenic Fossil Component, and Emissions (1750–2018),” by Kenneth Skrable, George Chabot, and Clayton French

DISCUSSION: PRESENTATION OF ATMOSPHERIC 14CO2 DATA

“…This discussion paper was stimulated by discussion among several authors (DA, RFK, HAJM, SES, JCT) arising out of comments (Andrews and Tans 2022;Schwartz et al 2022) on a publication that had misinterpreted the rate of decrease of atmospheric bomb 14 CO 2 as a measure of the rate of removal of anthropogenic CO 2 from the biogeosphere. SES prepared the initial draft and figures and led revisions.…”

Components of CO2 in 1750 through 2018 Corrected for the Perturbation of the 14CO2 Bomb Spike

“…The letter from Schwartz et al (2022) contains a figure that includes a curve from 1750 through 2015 of 14 C specific activities in our paper as well as a curve of their specific activities labeled as "No bombs" that is modeled to remove the perturbation of the increase in 14 CO 2 from atmospheric nuclear bomb tests in the 1950s and 1960s. The curve of specific activities from our paper appears to be about 2 dpm (gC) −1 higher than the "No bombs" curve throughout the entire period from 1750 to 2015 (traditional units are used here because they are used in 14 C dating and in each of the three references in this letter).…”

“…This letter relates to information in our paper (Skrable et al 2022) and to a letter that concludes our paper should be retracted from Health Physics in its entirety (Schwartz et al 2022). Our response to this letter counters those comments and conclusion.…”

Comments on “Components of CO2 in 1750 through 2018 Corrected for the Perturbation of the 14CO2 Bomb Spike”

“…A paper in this journal analyzing atmospheric radiocarbon specific activity by Skrable et al (February 2022) (hereinafter “Skrable 1”) attracted multiple critical letters by atmospheric scientists and others. One of those letters by Schwartz et al (2022) made four arguments against the paper, briefly summarized here as:…”

“…Plots of the bomb pulse specific activity, for example Fig. 1 of Schwartz et al (2022), indicate a time constant for the mixing of roughly a decade. In like manner, specific activity deficits in the atmosphere caused by injections of fossil fuel carbon are reduced by isofluxes of 14 C flowing toward the (lower specific activity) atmosphere.…”