Has global warming modified the relationship between sunspot numbers and global temperatures?

摘要

We study time evolution of the relationship between sunspot numbers andglobal temperatures between 1880 and 2016 using wavelet coherence framework.The results suggest that the relationship is stable in time. Changes in thesunspot numbers precede changes in the temperatures by more than two years assuggested by the wavelet phase differences. This leading position of the sunactivity is stable in time as well. However, the relationship has beendisturbed by increasing $CO_2$ emissions since 1960s. Without controlling forthe effect of possible global warming, or more precisely the positiveconnection between increasing $CO_2$ emissions and the global temperatures, thefindings would have been quite different. Combination of the cointegrationanalysis and wavelet coherence framework has enabled uncovering a hiddenrelationship between the solar activity and global temperatures, and possiblyexplaining equivocal results in the topical literature.