MILLENNIAL CYCLES OF MEAN SEA LEVEL EXCITED BY EARTH'S ORBITAL VARIATIONS

The millennial climate cycles are an important factor of global environmental changes. These cycles change the polar ice thickness during ice ages, what results in the Mean Sea Level (MSL) changes. The main cause of ice age periods are the so called Milankovich orbital cycles, generated by variations of climatic precession, eccentricity of the Earth's orbit and Earth's axial tilt with respect to its orbital plane with main periods of about 23 ka(1), 40 ka and 100 ka, respectively. The common millennial cycles of MSL and Earth's orbit variations are studied by means of reconstructed MSL time series for the last 800 ka and insolation data of the latest orbital solution of Laskar et al. (2011). The models of the common millennial cycles of MSL and insolation variations are based on partial Fourier approximations with different period bands around 23 ka, 18ka, 11.5 ka, 7.5 ka, 6 ka and 2.3 ka, respectively. These models may help to analyze the Earth's rotation cycles caused by millennial solar activity cycles, such as Hallstatt cycles, and to point out new possible millennial cycles of the solar activity.