Paper finds another amplification mechanism by which the Sun controls climate

A paper published in Climate of the Past finds the position of the Southern Hemisphere Westerly Winds, "an important zonal circulation that influences large-scale precipitation patterns and ocean circulation," "is significantly correlated with reconstructed solar activity during the past 3000 years." The paper may represent another solar amplification mechanism by which small changes in solar activity are amplified to large effects on climate.

Horizontal axis is years before the present

Clim. Past, 7, 339-347, 2011 www.clim-past.net/7/339/2011/ doi:10.5194/cp-7-339-2011

Solar-forced shifts of the Southern Hemisphere Westerlies during the Holocene

V. Varma¹, M. Prange^1,2, F. Lamy^2,3, U. Merkel², and M. Schulz^1,2
1Department of Geosciences, University of Bremen, 28334 Bremen, Germany
²MARUM – Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen, Germany
³Alfred Wegener Institute for Polar and Marine Research, 27568 Bremerhaven, Germany
Abstract. The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation that influences large-scale precipitation patterns and ocean circulation. Variations in their intensity and latitudinal position have been suggested to exert a strong influence on the CO₂ budget in the Southern Ocean, thus making them a potential factor affecting the global climate. In the present study, the possible influence of solar forcing on SWW variability during the Holocene is addressed. It is shown that a high-resolution iron record from the Chilean continental slope (41° S), which is interpreted to reflect changes in the position of the SWW, is significantly correlated with reconstructed solar activity during the past 3000 years. In addition, solar sensitivity experiments with a comprehensive global climate model (CCSM3) were carried out to study the response of SWW to solar variability. Taken together, the proxy and model results suggest that centennial-scale periods of lower (higher) solar activity caused equatorward (southward) shifts of the annual mean SWW.