Using wavelet decomposition method to retrieve the solar and the global air temperature signals from Greenland, Andes and East Antarctica δ18O ice core records

Abstract

The surface global air temperature (SGAT) and the solar activity presented near similar trends until approximately the 1980’s decade, when they start to diverge significantly. This divergence in both time series is attributed to the impact of addition players acting in the climate system as the greenhouse gas emissions and a more active ENSO (El Niño Southern Oscillation). For the period before this “turning point” we have made an exploratory investigation on the imprint of both SGAT and the solar activity (represented by the Sunspot Number – SSN) at δ18O isotopic ratios retrieved from ice cores, a proxy commonly used to describe past climate changes. In this work δ18O isotopic ratios, dated from 1861 to 1997, from three distinct global sites: (1) the Greenland Ice Sheet Project 2 (GISP2); (2) Quelccaya ice cap/Andes (Peru); and (1) Dronning Maud Land (DML)/East Antarctica were investigated. The wavelet decomposition method and regressions applied to these databases successfully allowed the isotopic reconstructions from both SGAT and SSN. We found that the reconstructions differ significantly depending on the geographical site.