Carbon tree rings

Though measurements of solar output have been taken only for the past eighteen years, longer trend patterns can be derived from indirect data sources, such as ice cores and tree rings. Cosmic rays, which fluctuate with the sun s activity, also strike constituents of the atmosphere, creating radioactive versions of certain elements. Beiyllium, in particular, is ionized to "Be by cosmic rays. The "Be then gets incorporated into trees as they grow, and is trapped in bubbles in ice masses, as is carbon dioxide. 

Leavitt, S.W. and Long, A. 1991 Seasonal stable-carbon isotope variability in tree rings possible palaeoenvironmental signals. Chemical Geology (Isotope Geoscience Section) 87 59-70. 

Saurer, M., Siegenthaler, U. and Schweingruber, F. 1995 The climate-carbon isotope relationship in tree rings and the significance of site conditions. Tellus 47B 320-330. 

Figure 10. Carbon-14 production as calculated from tree-ring 14C concentrations by means of the...

Radiocarbon years are calibrated from determinations of the 14C activity and stable isotopic carbon ratios of dendrochrono-logically dated tree rings [4]. The stable isotope data are required to normalize the dates to average wood with 613C value of -25 per mil (13C/12C fractionation relative to PDB reference standard). Photosynthetic and other plant physiological processes may produce differential isotopic fractionation between species, within the same species in different localities and even within the same tree under changing environmental conditions. 

As for the carbon isotope ratios in tree rings, these derive from and reflect carbon isotope ratios in atmospheric carbon dioxide. There is some evidence suggesting that the ratio 13C/ 12C in atmospheric carbon dioxide varies seasonally in such a way that the isotope ratio is large in the summer. For example, figure 4 shows monthly variations in the stable carbon isotope ratio in atmospheric carbon dioxide at Spitsbergen, on the Pacific... 

The conclusions of Hurt s study of year-by-year oxygen isotope ratios in 72 years of S. gigantea are thus supportive of the conclusions of the CIAP study [49] that solar variations influence the abundances of many kinds of chemical species in the stratosphere, and therefore influence the.amount of solar energy they absorb and re-radiate to earth, and therefore influence the surface temperature of the earth and especially the surface temperatures of the oceans. It is the surface temperature of the oceans which produces the phenomena we have discussed the isotope ratio variations in rain and hence in tree rings, the isotope ratio variations in the Greenland ice cap, in the organic carbon and uranium concentrations in sea cores, and furthermore variations of the sea surface temperature produces variations in the carbon-14 to carbon-12 ratio fractionation at the sea air interface and hence in the carbon-14 content of atmospheric carbon dioxide and hence in the carbon-14 content of tree rings. 

If the stable isotope ratio of 13C/12C is to be further measured in tree rings and interpreted as an indicator of climate variation, (and we have barely begun to initiate its use as a thermometer in the present work, confining our measurements to the stable isotopes in water, because water is so abundant compared to carbon dioxide and because the dependence of its isotope ratios is relatively simple compared with those of carbon dioxide), some more sophisticated considerations must be given to the distribution of carbon dioxide among the reservoirs on the surface of the earth. 

In the process of making bio-organic matter, plants store carbon depleted with respect to carbon dioxide by about 2.7 percent in carbon-13 [56-58]. If the total amount of depleted carbon stored in the biosphere in the past has been different from what it is now, interpretation of 13C/12C variations in tree rings as caused solely by temperature changes will reflect an error. 

Freeman KH, Hayes JM (1992) Fractionation of carbon isotopes by phytoplankton and estimates of ancient CO2 levels. Global Biogeochem Cycles 6 185-198 Freeman KH, Hayes JM, Trendel JM, Albrecht P (1990) Evidence from carbon isotope measurements for diverse origins of sedimentary hydrocarbons. Nature 343 254-256 Freyer HD (1979) On the C-record in tree rings, I, C variations in northern hemisphere trees during the last 150 years, TeUus 31 124-137... 

Biological samples are potentially excellent records of their environment and are being examined by inorganic and biomolecular mass spectrometry to an increasing extent. Biomaterials such as carbonate shells, fish otoliths and fish scales or tree rings that increase their mass regularly on an annual basis may record changes in their environment via the concentrations of metals or non-metals and the isotopic composition of elements.2... 

Hemming D. L., Switsur V. R., Waterhouse J. S., and Heaton T. H. E. (1998) Chmate variations and the stable carbon isotope composition of tree ring cellulose an intercomparison of quercus robur, fagus sylvatica and pinus silvestris. Tellus SOB, 25-33. 

A cypress beam from the cliff dwellings of Mesa Verde in southern Colorado was determined by carbon-14 dating to be about 700 years old. This date was confirmed by counting the annual tree rings in samples of old trees that came from the same area. The Anasazi Indians had moved to Mesa Verde and lived there from around 1100 to 1300 a.d. ... 

The carbon dioxide level in the atmosphere today is often compared with that in preindustrial days. Explain how scientists use tree rings and air trapped in polar ice to arrive at the comparison. 

Freyer, H. D. (1978). Prelimary evaluation of past C02 increase derived from l3C measurements in tree rings. In Carbon Dioxide Climate and Society (J. Williams, ed.), pp. 69-78. Pergamon, New York. 

Wagener, K. (1978). Total anthropogenic C02 production during the period 1800-1935 from carbon-13 measurements in tree rings. Radial. Environ. Biophys. 15, 101-111. 

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