700 year record of the 11 year solar cycle by planktonic foraminifera of a shallow water Mediterranean core

Abstract In this paper we present the δ 18 O and δ 13 C profiles of Globigerinoides Ruber measured in the GT90/3 shallow water Ionian sea core, dated with high precision. They are records respectively of the sea surface temperature (SST) and of the biomass amount present at the time of the planktonic forams growth. The profiles cover the period 1200–1900 AD, with a resolution of 3.87 years. The spectral analysis of the δ 18 O time series performed with different methods shows a dominant periodicity of 11.4 years with an amplitude of ∼0.07‰, in antiphase with the sunspot solar cycle, while the δ 13 C time series shows a dominant periodicity of 11.2 years with an amplitude of ∼0.04‰, in phase with the sunspot cycle. These components are identified at high significance level by Monte Carlo singular spectrum analysis (MC-SSA). These 700 year long records of δ 18 O and δ 13 C disclose the presence of a clear and statistically significant imprint of the solar cycle in a terrestrial archive.