Apr. 6, 2010 In an analysis of the past 1.2 million years, UC
Santa Barbara geologist Lorraine Lisiecki discovered a pattern
that connects the regular changes of Earth's orbital cycle to
changes in Earth's climate. The finding is reported in the
scientific journal Nature Geoscience. Lisiecki performed her
analysis of climate by examining ocean sediment cores. These
cores come from 57 locations around the world. By analyzing
sediments, scientists are able to chart Earth's climate for
millions of years in the past. Lisiecki's contribution is the
linking of the climate record to the history of Earth's orbit.
It is known that Earth's orbit around the sun changes shape
every 100,000 years. The orbit becomes either more round or more
elliptical at these intervals. The shape of the orbit is known
as its "eccentricity." A related aspect is the 41,000-year cycle
in the tilt of Earth's axis. Glaciation of Earth also occurs
every 100,000 years. Lisiecki found that the timing of changes
in climate and eccentricity coinci