Carbon 14 in tree rings

Abstract

In order to investigate how reliably the carbon 14 content of tree rings reflects that of atmospheric carbon dioxide, two types of determinations were carried out: (1) carbon 14 determinations in annual rings from the beginning of this century until 1974 and (2) carbon 14 determinations in synchronous wood from the North American bristlecone pine and from European oak trees, dendrochronologically dated to have grown in the third and fourth century B.C. The first series of measurements showed that bomb‐produced radiocarbon was incorporated in wood at a time when it was converted from sapwood to heartwood, whenever radiocarbon from bomb testing was present in the atmosphere. The second series showed that wood more than 2000 years old and grown on two different continents at different altitudes had, within the limits of experimental error, the same radiocarbon content. This work and other experimental evidence, obtained in part by other laboratories, show that tree rings reflect the average radiocarbon content of global atmospheric carbon dioxide accurately within several per mil. In rare cases, deviations of up to 10‰ may be possible. This means that a typical single radiocarbon date for wood or charcoal possesses an intrinsic uncertainty (viz., an estimated One‐sigma error' in addition to all the other errors) of the order of ±50 years. This intrinsic uncertainty is independent of the absolute age of the sample. More accurate dates can, in principle, be obtained by the so‐called method of ‘wiggle matching.’

A Novel Approach for Developing High-Resolution Sub-Fossil Peat Chronologies with 14C Dating

“…cities, industries) can show a locally enhanced Suess effect (Cain and Suess 1976). For the early 20th century, these local effects could create additional uncertainty that cannot be resolved with high precision unless a calibration data set from the same area is present or industrial areas are avoided.…”

Effects of human impact and climate change during the last 350 years recorded in a Swedish raised bog deposit

“…The atmospheric bomb pulse ('bomb peak') was used to wigglematch the post-1950 14 C dates (Levin et al, 1994;Goodsite et al, 2001;Goslar et al, 2005). Therefore the Excel-approach (Mauquoy et al, 2002b;Blaauw et al, 2003Blaauw et al, , 2004van der Linden and van Geel, 2006) updated with modern 'negative' radiocarbon years (Cain and Suess, 1976;Levin et al, 1994;Levin and Hesshaimer, 2000;van der Linden and van Geel, 2006) was used. In this approach, linear peat accumulation over limited stratigraphic intervals is preferred over a more complex accumulation model.…”

Regional Δ14C patterns and fossil fuel derived CO2 distribution in the Beijing area using annual plants

“…The 14 CO 2 level in the atmosphere depends on the production rate of atmospheric 14 C [14], and also on carbon cycling processes including rates of ocean mixing and air-sea gas exchange [15], carbon cycling within terrestrial ecosystems [16], re-entrainment of older stratospheric air in the troposphere [17], and human activities. The amount of atmospheric 14 CO 2 is disturbed by human activities via the ongoing emissions of fossil fuel CO 2 [18] and nuclear weapon tests that occurred in the late 1950s and early 1960s [19]. After the nuclear tests, the level of 14 C in plants surged up to twice the normal level [20,21].…”