A recipe for more reliable climate correlations with solar factors – use long temperature records such as Portugal for 140 years (from 1865 to 2005). Another study showing around half of decadal to centennial variations in temperature can be attributed to Cosmic Ray Flux.
Monthly averaged temperature series have been analyzed together with monthly North-Atlantic Oscillation (NAO) index data, sunspot numbers and cosmic ray (CR) flux intensity. The absolute values of the correlation coefficients between the temperature and the CR are higher than those between the temperature and the sunspot numbers. Our results are consistent with some of the proposed mechanisms that relate solar activity to Earth climate and could be explained through the effect of the solar UV radiation and stratosphere-troposphere coupling or/and through the effect of the CR particles on clouds and stratospheric and tropospheric conditions.