2023-09-13 06:00:07
Earth’s glacial cycles may be influenced more by precession than by the eccentricity of Earth’s orbit, according to a new study. This discovery challenges previous theories and offers new insight into the mechanisms that govern glacial and interglacial periods.
Image from Wikimedia Commons
Glacial cycles are often associated with three key factors: eccentricity, obliquity and precession (The mathematical formula that describes the precession of a quantity is written). Eccentricity concerns the shape of the Earth’s orbit (An Earth orbit is an orbit located around the Earth. The Moon, the only satellite…), obliquity relates to inclination (In celestial mechanics, the inclination is an orbital element of an orbiting body…) of the Earth’s axis (Earth is the third planet in the Solar System in order of distance…), and precession is the direction towards which this axis points.
Bethany Hobart, a doctoral researcher at the University of California, and her team modeled the impacts of the end of ice ages over 23,000 and 41,000 year cycles. Their study suggests that it is precession that would have the greatest impact on glacial cycles.
The researchers used oxygen isotopes to support their findings. Foraminifera, single-celled organisms, incorporate these isotopes into their shells. Analyzes of these isotopes in deep ocean sediment cores have identified rapid changes in the 18O/16O ratios. , indicating variations in temperature at depth.
Oxygen isotope ratios (18O/16O) from benthic foraminifera in the North Atlantic, compared with dating data from mineral deposits in caves and known cycles of obliquity and precession.
Credit: Hobart et al. 2023.
The dating data comes from mineral deposits in caves in China, providing an age model for the last 640,000 years. The research team identified nine end-of-ice-age events, with durations ranging between 90,400 and 115,500 years.
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