Probing the impact of Solar System dynamics on Holocene North Atlantic cold events at the millennial-scale

In general, although the climate during the Holocene has been warm, nine well-recognized cold events with an average time interval of more than one thousand years have been highlighted. The forcing mechanism of these cold events with millennial-scale cycles is still widely discussed. In the present study, two different Solar System dynamical processes collectively driven by all eight planets were considered together: the solar inertial motion and the combined planetary tidal force acting on the Sun. In this context, an attempt was made to analyze their effects on solar activity and Holocene North Atlantic cold events at the millennial-scale. These two Solar System dynamical processes were proxied by the distance between the Sun and the Solar System barycenter (DS–S) and the intensity of the combined planetary tidal force (IP–S), respectively. Using the ensemble empirical mode decomposition (EEMD) method, time series data of Solar System dynamics proxies (i.e., DS–S, and IP–S), solar activity proxies (i.e., 14C and 10Be), and a proxy of Holocene North Atlantic cold events (i.e., hematite-stained grains) were decomposed into several intrinsic mode functions (IMFs). After extracting IMF components containing millennial-scale cycles, a correlation analysis was performed. As a result, it was found that the solar inertial motion had ~2,300- and ~1,000-year cycles and the combined planetary tidal force had a ~1,500-year cycle, while the solar activity and Holocene North Atlantic cold events proxies had ~2,300-, ~1,500-, and ~1,000-year cycles, respectively. The correlation analysis revealed that the millennial-scale periodic components of the two Solar System dynamics proxies were largely correlated with that of solar activity and Holocene North Atlantic cold events, suggesting that the solar inertial motion and combined planetary tidal force may work together to impact solar activity, and thus the climate in the North Atlantic. Consequently, solar activity was weaker and the North Atlantic temperature was cooler when the Sun was far from the Solar System barycenter and/or the combined planetary tidal force was weakened. This might indicate the involvement of Solar System dynamics on Holocene North Atlantic cold events at the millennial-scale.