Friday, March 30, 2012

Milankovitch Cycles: An Astronomy - Climate Connection

Graph courtesy of

One of the fun things about teaching Earth Science is helping students understand connections between geology, astronomy, meteorology, and oceanography. One such connection is the link between ice ages and changes in the Earth-Sun relationship. This week's resource is a tutorial that will help students explore Milankovitch Cycles. CLICK HERE to go to the tutorial.

According to the Milankovitch Theory, the advance and retreat of "ice ages" (technically "glaciations, or glacial periods") over the past 3 million years have been caused (at least in part) by changes in the relationship between the Earth and Sun. The theory is named for Serbian astronomer Milutin Milankovitch, who painstakingly calculated how changes in Earth's orbit affected the amount of solar radiation that reached different latitudes at different seasons.

Though he did his work in 1920's, Milankovich's results weren't proven until the 1970s. A 1976 study, which examined deep-sea sediment cores, found that Milankovich's findings corresponded to periods of climate change. Although there is a consensus that Milankovitch cycles do influence the waxing and waning of ice ages, there are several problems. One mystery about the ice ages has to do with the change in frequency of glaciations that happened about 1 mya (see graph above). Why did the timing switch from once every 41,000 years to once every 100,000 years? To read more about Milankovitch Cycles and other mysteries related to ice ages, CLICK HERE. To watch, and listen to, an explanation (pencast), CLICK HERE.

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