Geophysical Research Abstracts, Vol. 7, 01910, 2005 SRef-ID: 1607-7962/gra/EGU05-A-01910 © European Geosciences Union 2005 Does Solar Irradiance Caused the Time Shifting of Termination-II? Y. Shopov, D. Stoykova Faculty of Physics, University of Sofia, James Bouchier 5, Sofia 1164, Bulgaria (YYShopov@phys.uni-sofia.bg/ FAX +359(2) 8512838) Glaciations were attributed to variations of the Earth’s orbit (Milankovitch cycles). But the best dated paleoclimatic record (from a Devils Hole, Nevada speleothem) demonstrated that the end of the last glacial period (Termination II) happened 10 000 years before the one suggested by the orbital variations (Winograd et al, 1992), i.e. the result appeared before the reason. This fact suggests that the theory do not completely reflect the real variation of the solar insolation. The Orbital theory presumes that the solar irradiance was constant during geological periods of time. Recent studies demonstrated that this presumption is not precise. Di- rect satellite measurements of the solar constant demonstrated that it varies with time as much as 0.4% during the observation time span (Hickey et al., 1980), but there are experimental data suggesting that it varied much greater during geological periods. Stuiver & Braziunas (1989) demonstrated that longer solar cycles are more than one order of magnitude stronger, than the solar cycles covered by direct measurements. Increasing of the ice volume and the related sea level change during glaciations pro- duces changes in the inertial moment of the Earth and resulting changes in the speed of Earth’s rotation (Tenchov et al., 1993). Orbital variations cause also some defor- mation of the solid Earth and redistribution of the Ocean masses (Morner, 1983). In result theoretical Milankovich curves can be used only for qualitative reference. For quantitative correlation it is necessary to use experimental records of the solar insola- tion, because they contain also variations of the solar irradiance and number of others not covered by the Orbital theory.