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Solar Activity and Precipitation in Newfoundland Over the Course of the Holocene
Reference
Hughes, P.D.M., Blundell, A., Charman, D.J., Bartlett, S., Daniell, J.R.G., Wojatschke, A. and Chambers, F.M. 2006. An 8500 cal. year multi-proxy climate record from a bog in eastern Newfoundland: contributions of meltwater discharge and solar forcing. Quaternary Science Reviews 25: 1208-1227.

Background
"Over the last decade," according to the authors, "evidence suggesting a link between solar irradiance and sub-Milankovitch-scale palaeoclimatic change has mounted," and they say that this "solar hypothesis, as an explanation for Holocene climate change, is now gaining wider acceptance."

What was done
Hughes et al.'s paper, as they describe it, "presents a multi-proxy palaeoclimate record from a coastal plateau bog in Newfoundland called Nordan's Pond Bog," based upon "analyses of plant macrofossils, testate amoebae and the degree of peat humification," which enabled them to create "a single composite reconstruction of bog surface wetness (BSW)" that they compare with "records of cosmogenic isotope flux."

What was learned
The seven researchers report that "at least 14 distinctive phases of increased BSW may be inferred from the Nordan's Pond Bog record," commencing at 8270 cal. years BP, and that "comparisons of the BSW reconstruction with records of cosmogenic isotope flux ... suggest a persistent link between reduced solar irradiance and increased BSW during the Holocene."

What it means
Hughes et al. conclude that the "strong correlation between increased 14C production [which accompanies reduced solar activity] and phases of maximum BSW supports the role of solar forcing as a persistent driver of changes to the atmospheric moisture balance throughout the Holocene," which finding further suggests that the sun likely orchestrated the Little Ice Age to Current Warm Period transition, which altered precipitation regimes around the globe. Consequently, variable solar activity is likely also largely responsible for the temperature change associated with that transition, which leaves little room for increasing greenhouse gas concentrations to have had much of an impact on the planet's temperature over this period, which includes the so-called unprecedented warming of the last quarter century.

Reviewed 4 October 2006