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records, and improved knowledge about the geochemical behavior of 14 C and 10 Be can reduce the
uncertainties in radionuclide-based solar activity reconstructions. With new high-resolution 10 Be and 14 C
records there is the potential to track solar activity variations including the solar 11-year cycle more than
10,000 years back in time. In addition, there is the prospect that one can reliably reconstruct sustained
levels of high or low solar activity. Cyclic variations in cosmogenic radionuclide records might allow
researchers to estimate likely levels of future solar activity. For example, the suggestions of the dawn of a
new Maunder Minimum-type solar minimum are based largely on extrapolation of the cyclic behavior
visible in radionuclide records. However, without a better understanding of the solar dynamo these
predictions seem rather speculative at the moment.
FIGURE C.2 Two estimates of variations in the solar modulation function inferred from an ice core 10 Be record
(Vonmoos et al., 2006) and a tree-ring-based 14 C production record (Muscheler et al., 2004) together with the group
sunspot number record for the past 400 years (Hoyt and Schatten, 1998). The so-called Maunder Minimum, which
is characterized by an almost complete lack of sunspots, is highlighted with the grey shading. Both radionuclide-
based records are low-pass filtered with a cut-off frequency of 1/100 yr-1. See M. Vonmoos, J. Beer, and R.
Muscheler, Large variations in Holocene solar activity: Constraints from 10 Be in the Greenland Ice Core Project ice
core, Journal of Geophysical Research 111:A10105, 2006; R. Muscheler, J. Beer, G. Wagner, C. Laj, C. Kissel,
G.M. Raisbeck, F. Yiou, and P.W. Kubik, Changes in the carbon cycle during the last deglaciation as indicated by
the comparison of 10 Be and 14 C records, Earth Planet Science Letters 219(3-4):325-340, 2004; and D.V. Hoyt, and
K.H. Schatten, Group sunspot numbers: a new solar activity reconstruction, Solar Physics 179(1):189-219, 1998.
SOURCE: Raimund Muscheler, Lund University, “The Record of Solar Forcing in Cosmogenic Isotope Data,”
presentation to the Committee on the Effects of Solar Variability on Earth's Climate, September 8, 2011.
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