Composition and consequences of the IntCal20 radiocarbon calibration curve

Abstract

Radiocarbon calibration is necessary to correct for variations in atmospheric radiocarbon over time. The IntCal working group has developed an updated and extended radiocarbon calibration curve, IntCal20, for Northern Hemisphere terrestrial samples from 0 to 55,000 cal yr BP. This paper summarizes the new datasets, changes to existing datasets, and the statistical method used for constructing the new curve. Examples of the effect of the new calibration curve compared to IntCal13 for hypothetical radiocarbon ages are given. For the recent Holocene the effect is minimal, but for older radiocarbon ages the shift in calibrated ages can be up to several hundred years with the potential for multiple calibrated age ranges in periods with higher-resolution data. In addition, the IntCal20 curve is used to recalibrate the radiocarbon ages for the glaciation of the Puget Lowland and to recalculate the advance rate. The ice may have reached its maximum position a few hundred years earlier using the new calibration curve; the calculated advance rate is virtually unchanged from the prior estimate.

A manifesto for palaeodemography in the twenty-first century

“…Nonetheless, advances in methods that are on the horizon, which capitalize on Bayesian frameworks to overcome the intrinsic limitations of frequentist approaches, are highly promising for accurately resolving palaeodemographic parameters [32]. The recent publication of the IntCal20, SHCal20 and Marine20 curves will probably lead to further refinements, particularly in Pleistocene settings where dates are sparser [33].…”

MOSAIC (Modern Ocean Sediment Archive and Inventory of Carbon): a (radio)carbon-centric database for seafloor surficial sediments

“…Radiocarbon databases or data collections have been established for the atmosphere (e.g., University Heidelberg Radiocarbon Laboratory, 2020), ocean waters (Global Data Analysis Project (GLODAP); Key et al, 2004), and most recently soils (International Soil Radiocarbon Database (IS-RaD); Lawrence et al, 2020), with tree rings, corals and other annually resolved archives providing information on historical variations in 14 C in the atmosphere and surface reservoirs (Friedrich et al, 2020;Reimer, 2020). At present, no such radiocarbon database exists for OC residing in ocean sediments.…”

“…At present, no such radiocarbon database exists for OC residing in ocean sediments. As a sensitive tracer of carbon sources and carbon cycle perturbations, there is a clear imperative to fill this information void given that ongoing anthropogenic activities directly and indirectly influence ocean sediment and resident OC stocks (Bauer et al, 2013;Breitburg et al, 2018;Ciais et al, 2013;Keil, 2017;Regnier et al, 2013;Syvitski et al, 2003). Materials accumulating in modern ocean sediments also provide a crucial window into how ongoing processes that are observable through direct instrumental measurements and remote sensing data manifest themselves in the sedimentary record.…”

“…As the interface between land and ocean, continental mar-gins comprise a key juncture in the carbon cycle (Bianchi et al, 2018), provide crucial habitats for unique marine ecosystems (Levin and Sibuet, 2012), support a major fraction of the worlds fisheries (Worm et al, 2006) and participate in exchange processes with the interior ocean (Dunne et al, 2007;Jahnke, 1996;Rowe et al, 1994). These ocean settings and their underlying sediments are also amongst those most vulnerable to change (Keil, 2017) through direct perturbations such as contaminant and nutrient discharge from land; loci of intense resource extraction, such as bottom trawling (Pusceddu et al, 2014) and mineral and hydrocarbon recovery (e.g., Chanton et al, 2015); and indirect effects such as ocean warming (Roemmich et al, 2012), acidification (Feely et al, 2008;Orr et al, 2005) and local or large-scale deoxygenation (Diaz and Rosenberg, 2008;Keeling et al, 2010). Such influences may change not only the amount of carbon sequestered in marine sediments but also its character, with radiocarbon serving as a key metric to detect such change.…”

Bone need not remain an elephant in the room for radiocarbon dating

“…48 000 years) due to sample type (inorganic versus organic carbon), pretreatment chemistry and efficiency to remove contaminants [ 16 ]. The development of calibration curves (IntCal20, SHCal20, Marine20) allows the calibration of 14 C dates up to 55 000 calendar years before present (BP, where present is 1950 AD [Anno Domini]) [ 17 ].

Figure 1.

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