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How do changes in Earth’s orbit affect climate over thousands of years?
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Global warming
A series of photographs of the Grinnell Glacier taken from the summit of Mount Gould in Glacier National Park, Montana, in (from left) 1938, 1981, 1998, and 2006. In 1938 the Grinnell Glacier filled the entire area at the bottom of the image. By 2006 it had largely disappeared from this view.
Changes in Earth’s orbit, known as Milankovitch cycles, influence long-term climate by altering the seasonal and latitudinal distribution of incoming solar radiation. These cycles operate on three primary timescales:
- Eccentricity (approx. 100,000 years): The shape of Earth’s orbit shifts between nearly circular and elliptical, which slightly affects the total annual solar energy received.12
- Obliquity (approx. 41,000 years): The tilt of Earth’s axis varies between 22.1° and 24.5°. A greater tilt increases the intensity of seasonal contrasts, leading to warmer summers and colder winters in both hemispheres.12
- Precession (approx. 26,000 years): The "wobble" of Earth’s axis and the rotation of its orbital ellipse change the timing of the seasons relative to Earth’s position in its orbit.12
By interacting, these cycles pace major climate phenomena, such as the advance and retreat of continental ice sheets during the Pleistocene Epoch. While these orbital variations are fundamental to understanding past glacial-interglacial cycles, they have had little impact on climate over the past few millennia and are not considered significant drivers of present-day global warming.23