Milankovitchcycli

Milankovitch cycles, named after the Serbian astronomer Milutin Milanković, describe long-term variations in the geometry of Earth’s orbit and axis. These orbital changes affect the amount and distribution of solar radiation received on Earth, providing a natural pacing mechanism for long-term climate shifts, including glacial and interglacial cycles.

The three main components are eccentricity, obliquity, and precession. Eccentricity refers to changes in the shape of Earth’s orbit around the Sun, with cycles around roughly 100,000 years and 413,000 years. Although the overall distance variation is modest, eccentricity modulates the solar energy Earth receives and interacts with other cycles. Obliquity is the tilt of Earth’s axis relative to its orbital plane, varying between about 22.1° and 24.5° with a ~41,000-year period. This tilt controls the contrast between seasons and the latitudinal distribution of insolation. Precession is the wobble of Earth’s axis, shifting the timing of seasons in relation to the perihelion and aphelion of the orbit, with a primary period of about 19,000 to 23,000 years.

The combined effect of these cycles alters summer insolation at high northern latitudes, a key factor in the growth or melting of continental ice sheets. They are inferred from geological records, including ice cores, marine sediments, and loess, and are incorporated into climate models to explain the pacing of late Cenozoic glacial cycles. Milankovitch theory acknowledges that orbital forcing interacts with greenhouse gas concentrations and feedbacks, so the cycles act as a framework rather than a sole driver of climate change.