Milankovitch forcing

Though an important part of the Quaternary climate puzzle, this view of the ice-age cycles is by itself quite incomplete. If Milankovitch forcings alone govern climate change then ... 

Crowley TJ, Kim K-Y (1994) Milankovitch forcing of the last interglacial sea level. Science 265 1566-1568... 

Imbrie J. (1992) On the structure and origin of major glaciation cycles I. Linear responses to Milankovitch forcing. Paleoceanography 7, 701—738. 

A knowledge of past lake-levels may be used to interpret variations in precipitation/evaporation - commonly called effective precipitation - and which is clearly dependent upon air temperature. Evaporite mineralogy is a key component of such studies. For example, in Death Valley, California, the interpreted dry periods are associated with glauberite, gypsum and calcite in palaeo-mudflat deposits, whereas abundant calcite, scarce CaS04 minerals and halite with mud layers, typify wet periods, including a perennial-lake phase (Li et al., 1997 Lowenstein et al., 1999). A crude lOOka cyclicity is noted, possibly related to Milankovitch forcing. 

Harvey, L. D. D. (1989b). Milankovitch forcing, vegetation feedback, and North Atlantic deep-water formation. /. Climate 2, 800-815... 

Berger, A. (in press). The role of CO, and of the geosphere-biosphere interactions during the Milankovitch-forced glacial-interglacial cycles. In Workshop on Geosphere-Biosphere Interactions and Climate. Pontifical Academy of Sciences, Vatican City. 

Kutzbach, J. E. and Street-Perrott, F. A. (1985). Milankovitch forcing of fluctuations in the level of tropical lakes from 18 to 0 kyear B.P. Nature 317, 130-134. 

Milankovitch and albedo forcing of the tropical monsoons a comparison of geologic evidence and numerical simulations for 9000 y BP. Trans. R. Soc. Edinburgh 81, 407-427. 

Farley and Patterson (1995) and Patterson and Farley (1998) interpreted the variability of the He accumulation in deep-sea sediments to directly reflect the cyclicity of the accretion rate of IDPs, i.e. changes in delivery of IDPs from space. This interpretation supports a recent hypothesis by Muller and MacDonald (1995, 1997a,b,c) that the accretion rate of cosmic dust to the earth varies with the 100 ka cycle of Earth s inclination and may be responsible—in contrast to the widely accepted Milankovitch theory—for forcing the 100 ka climate cycle. 

This takes into account the hypotheses of Milankovitch and J. Croll requiring that the Earth s climate must respond to orbital forcing (Imbrie 1985). Suitable models include spectral and cross-spectral, gain-and-phase, and dynamic, but cannot be discussed here. However, the first involved four of the main Milankovitch frequencies, i.e., at 100,000, 41,000, 23,000, and 19,000 years, the second including two attempts. One aimed at simulating the entire 782,000-year record, again using the Milankovitch four, which are 100,000 = eccentricity, 41,000 = obliquity, 23,000 and 19,000 = processional factors (O Fig. 16.4). 

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