Dusting for Fingerprints in the Holocene

Fingerprints are admissible evidence in criminal trials because of their uniqueness. The probability of two human beings having identical fingerprints is very low.

Measurements of δ13C depletion have often been cited as anthropogenic “fingerprints,” proving human culpability for the rise in atmospheric CO2 over the last 200 years or so…

Fig 1) The so-called Suess Effect from John Cook's "The Scientific Guide to Global Warming Skepticism"

While δ13C depletion certainly could be evidence of the Suess Effect, it is not a unique solution; therefore, not a “fingerprint.”

Examples of geologically recent δ13C depletion not of anthropogenic origin…

Fig 2) δ13C depletion during Holocene Climatic Optimum in the Thar Desert of Northwest India (Enzel et al., 1999).

Fig 3) δ13C depletion during Preboreal to Boreal in western Poland (Apolinarska, 2009).

Fig 4) δ13C depletion during last interglacial in the Indian Ocean (Banakar, 2005).

δ13C depletions were associated with warming events ~5,000 years ago in India, ~9,100 years ago in Poland and ~150,000 years ago in the Indian Ocean. It appears to me that δ13C depletion has been a fairly common occurrence during periods of “global warming.” It also appears that δ13C increases have occurred during periods of global cooling…

Fig 5) δ13C rise and depletion across the Little Ice Age in the Yucatan compared to recent δ13C depletion in the Coral Sea.

The red curve in Figure 5 is the Flinders Reef δ13C that was cited as “Human Fingerprint #1” in Skeptical Science’s The Scientific Guide to Global Warming Skepticism. The rate of δ13C depletion is quite similar to that of the lacustrine deposit on the Yucatan. The Flinders Reef data do not extend back before the Little Ice Age; so there is no way to tell if the modern depletion is an anomaly, if the δ13C was anomalously elevated during the 18th and 19th centuries and the depletion is simply a return to the norm or if δ13C is cyclical.

Is it possible that Skeptical Science’s “Human Fingerprint #1” is not due to the Suess Effect? Could it be related to the warm-up from the Little Ice Age?


Cook, J. et al., 2010. The Scientific Guide to Global Warming Skepticism.

Banakar V., 2005. δ13C Depleted Oceans Before the Termination 2: More Nutrient-Rich Deep-Water Formation or Light-Carbon Transfer? Indian Journal of Marine Sciences. Vol. 34(3). September 2005. pp. 249-258.

Enzel, Y. et al. High-Resolution Holocene Environmental Changes in the Thar Desert, Northwestern India. Science 284, 125 (1999); DOI: 10.1126/science.284.5411.125.

Apolinarska, K. δ18O and δ13C Isotope Investigation of the Late Glacial and Early Holocene Biogenic Carbonates from the Lake Lednica Sediments, Western Poland. Acta Geologica Polonica, Vol. 59 (2009), No. 1, pp. 111–121.

Hodell, D.A., M. Brenner, J.H. Curtis, R. Medina-Gonzalez, M.F. Rosenmeier, T.P. Guilderson, E.I.-C Can, A. Albornaz-Pat, and T.P. Guilderson. 2005. Climate change on the Yucatan Peninsula during the Little Ice Age. Quaternary Research, Vol. 63, pp. 109-121. doi:10.1016/j.yqres.2004.11.004

Pelejero, C., et al. 2005. Flinders Reef Coral Boron Isotope Data and pH Reconstruction. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2005-069. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.

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One Response to “Dusting for Fingerprints in the Holocene”

  1. pascvaks Says:

    “Could it be related to the warm-up from the Little Ice Age?”

    A Natural Warm Up vis-a-vis Post-LIC Return to Normal aka “Bounce Back”
    + A Natural Rise in Temp. vis-a-vis Normal Holocene Climate Variation aka “Solar Activity Blip”
    = Natural Bounce Back and Blip Temp Rise

    Rather than the culprits being the “Carbon Units Infesting Planet Earth” (a’la Star Treck fame) might the guilty, dispicable, insufferable entity responsible for all this paranoia be none other than… dare I say it?… Anthroprogenic Global Stupidity?

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