Evidence for preindustrial variations in the marine surface water carbonate system from coralline sponges

Abstract

[1] Coralline sponge skeletons are excellent tools for reconstructing the carbon isotope history of dissolved inorganic carbon (DIC) in tropical surface waters. Carbon isotope records from coralline sponges clearly reflect the industrial 12 C increase in atmospheric CO 2 with a precision that permits quantitative interpretations. We find from a set of d 13 C records of four Caribbean sponge specimens that the isotopic response of surface water DIC to the changing isotopic composition of atmospheric CO 2 varied dynamically during the last century, depending on the rate of atmospheric change. Three of our sponges provide 600 year long d 13 C records. For the first time, we can reconstruct surface water d 13 C DIC for the full history of the industrial CO 2 release as well as the preceding preindustrial period back to the beginning of the Little Ice Age. This provides a well-founded estimate of the anthropogenically uninfluenced, preindustrial background level of surface water 13 C/ 12 C ratios. Our records show small but systematic variations that appear to be linked to the climate fluctuations of the Little Ice Age.

The Palaeocene–Eocene carbon isotope excursion: constraints from individual shell planktonic foraminifer records

“…13 C DIC of the surface ocean has decreased by 1.4‰ (figure 2), while the deep-sea d 13 C DIC has remained constant (Böhm et al 2002). Eventually, with continued anthropogenic carbon release and mixing, the deep-sea d 13 C DIC will decline, though more gradually.…”

Approaches to Estimating Marine Protein in Human Collagen for Radiocarbon Date Calibration

“…Since the onset of the Industrial Revolution and the mass burning of fossil fuels of infinite age, the atmospheric 14 C signal has been diluted by ~2% (Suess 1958). Isotope measurements on old shallow-water sponges record a decline in  13 C of 0.85‰ in the marine system (Böhm et al 2002), while tree rings and ice cores reflect a shift of 1.5‰ to 1.6‰ (Friedli et al 1986;Leavitt 1993). The carbon isotope value of marine CO 2 today is 0‰, while atmospheric CO 2 is 8‰, but for most of the Holocene, the period covered in this study, these values were closer to -1‰ for the marine system and -6.5‰ for the terrestrial system.…”

Extracting growth rates from the nonlaminated coralline sponge Astrosclera willeyana using bomb radiocarbon

“…In areas with similar radiocarbon surface water processes we can take advantage of the bomb curve from a well-dated coral to provide an age model for nonlaminated coralline sponges like Astrosclera willeyana (Benavides and Druffel 1986;Böhm et al 2002). Here we examine and determine the growth rate of the Indo-Pacific coralline sponge Astrosclera willeyana using high resolution ∆…”

“…Unlike corals, most coralline sponges do not exhibit any annual variations of density or skeletal structure, making it difficult to relate predicted environmental parameters to specific times. Previous studies have determined growth rates in coralline sponges by staining (Dunstan and Sacco 1982;Rosenheim et al 2004;Hartman 1985, 1999) (Benavides and Druffel 1986;Böhm et al 2000;Fallon et al 2003;Moore et al 2000;Wörheide 1998). The majority of paleo-reconstructions take a single linear extension rate extrapolated to the whole organism.…”