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nccted with ihe cycles of solar radiation. Since the MilanJumich cffcct is loo slow for ibese periodicity, ihey suggest to look for the reasoo in sołar produc -tu m . They point on the evidencc that the carbon-14 concentration inauno-spheric carfoon dioxide has vaned in a non-random way in the past that its Holocene variations are in antiphase with climatic temperaturę changes including the 2550 year cycle They aJso point out that the Benlium-10 con-centration. which is a cosmogenic isotope, in the ice is in antiphase with that of the oxvgen-18- They thus speculate that Iow solar activity in terms ofparticie emissions, is connected with cold ciimates.

H. Oeschger et al. (1984) suggest that the vanations in the Berilium-10 concentratioiis tnainly reflect changes of the precipitation ratę. although they notę that solar induced variadons of this isotope by a factorof 15, have been found for the Maunder minimum ofaquiet son lastmgfrom 1640to 1710 AD.

The cold period, which occurred between ca 850 and 760 BC was caused according to B. V'an Geel and H. Renssen (1998) by reduced solar activity_ esideneed by the high er levels of T in the aimosphcre. This can be coochided ftom the divergence between the dates arrived by carbon 14 dating methods and those calculated by dendto-chronologica] methods, namely the mmiber of tree rings. The reduced solar activity, which means reduced ultrasiolet radiation. may also lead to a decline in ozme production in the lower strato-sphere. This could have resulted in a decrease of the larmidmal extenston of the Hadiey Celi ciiculation, which may lead to a weakening of the monsoons, as wei! as ;o an cxpansion of the Polar Cells and the displacemem towaids the south of the cyclonic tracks.

The rapid carbon dtoxide changes and the fact that the oceans form the mair. carbon dioxide reservoirs afTectmg climate changes on the time scalę of ten thousand of years, brought H. Oeschger et aL (1984) to suggest that the cor-relation between carbon dtoxtde concentratton and palaeo-łetnperatures are connected «::li the upwelling phenotnena which tegnlates the eunchment of the surface water by phosphate. They suggest that durmg penods of morę rapid vertical mixtng. tbere is enrichment in biolosica! productivity. which tesuhs in higher carbon dioxideconcentratton On the othet hand t: be upwdling of deep water is reduced the organistns will have time to coosume all the phos-phate. which will result in the lowcnng of carbon dioxide concentratton.

E.T. Degcm et al. (1984) suggested that tbere might be a few sjmultaneous drńring fort es. which act as triggers. mosłly efłectne when they happen to-gether with an orbita! in sola t ton signal. for example sm-spots DJ Schnt (1984) cfatmed that the relationship of sunspots and climate depends on the