Milankovitch Cycles
First published: 2023
Brief summary
National Geographic Education introduction to orbital cycles and ice-age pacing.
Article
Milankovitch cycles are periodic changes in Earth’s orbital characteristics that alter when and where solar energy reaches the planet. They arise from gravitational interactions within the Solar System and operate over tens of thousands to hundreds of thousands of years.
Eccentricity changes the shape of Earth’s orbit from more circular to more elliptical. Obliquity changes the angle of Earth’s axial tilt, affecting the intensity of the seasons, while precession changes the direction of the axis and the timing of the seasons relative to Earth’s position in its orbit.
The combined cycles alter summer sunlight at high latitudes, where the survival or melting of snow and ice strongly affects ice-sheet growth. Lower summer insolation can allow snow to persist and ice sheets to expand, whereas stronger summer insolation promotes melting.
Geological records preserve repeated glacial and interglacial changes that correspond with orbital timescales. Orbital forcing helps pace ice-age cycles, while feedbacks involving ice reflectivity, greenhouse gases and ocean circulation amplify the climatic response.
Source details and credits
- Source / publisher: National Geographic Education
- Source type: Educational article
- URL type: WWW
- Credits: National Geographic Education
- URL: https://education.nationalgeographic.org/resource/milankovitch-cycles/