For about 50 years Milankovitch's theory was largely
ignored (Kaufman, 2002). But in the 70s a revival of the concept
began. This next revolution came when scientists began trying to
reconstruct past climates with data from ocean cores called ocean proxy
data. Analyzed as part of this data was forams (fossilized sea species)
and delta-0-18 ratio (percentage of an oxygen isotope found in sediments and
microorganisms) (Mysak, 1997). It was found that variations in climate
were closely associated with changes in the geometry of Earth's orbit. The
Ice Ages had occurred when the Earth was going through different stages of
orbital variation (Kaufman, 2002).
Other work has continued into the 1990s. SPECMAP (Spectral Mapping Project) work has refined the tools and data needed to unravel the role of the Milankovitch theory and has facilitated a better understanding of how the Earth's climate system works . Another group, COHMAP (Cooperative Holocene Mapping Project), is putting efforts into mapping out climate changes using proxy data sources. (American Geophysical Union, 1995).
Despite all the progress toward understanding the internal and external forcing of the climate system of the late Quaternary, many puzzles remain(American Geophysical Union, 1995). The Milankovitch theory is one piece, put there are many pieces yet to be found and understood.
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