Several series of proxy climatic indicators (such as tree-ring widths, amounts of 10Be or 18O, ice cores,…) recorded in several regions have been processed since 500 A.D. Possible connections between climatic changes and the solar inertial motion (SIM) have been searched for.
The solar inertial motion is not negligible. The Sun moves in the circular area, up to 3.106 km from the centre of mass of the Solar System. The Sun moves along the orbit given by the variable positions of the giant planets. The SIM has two basic types, the ordered in trefoils (stable) one and the chaotic. The Sun returns to the ordered orbit always after 179 years. The ordered motion lasts about 50 years. The last trefoil appeared in the years 1906-1956. Sometimes, irregularities in this alternating pattern occur, last one between 870-1240 A.D., where the SIM is long-termed ordered (stable). The SIM in the years 1430-1520 A.D. is the most chaotic in the 2nd millennium.
Our results show that prolonged temperature maxima tend to coincide with the trefoil (stable) intervals of the SIM. The Medieval Warm Period approximately coincides with the exceptional, long-termed trefoil SIM. The results of our paper indicate that the SIM is the phenomenon which likely substantially contributes to climatic changes. The SIM is computable in advance. Predictive assessments of future climate development could be thus gradually established