What are the three primary Milankovitch cycles and together how are they thought to control climate change over time?
The correct answer and explanation is :
The three primary Milankovitch cycles are:
- Eccentricity (100,000-year cycle)
- The shape of Earth’s orbit around the Sun changes from nearly circular to more elliptical and back over approximately 100,000 years. A more elliptical orbit leads to variations in solar energy received by Earth, intensifying or reducing seasonal contrasts.
- Obliquity (Axial Tilt) (41,000-year cycle)
- The tilt of Earth’s axis changes between 22.1° and 24.5° over about 41,000 years. A greater tilt increases the intensity of seasons, making summers hotter and winters colder. A lesser tilt reduces seasonal differences, promoting ice sheet growth.
- Precession (Axial Wobble) (23,000-year cycle)
- Earth wobbles like a spinning top, shifting the timing of seasons relative to its orbit. This alters the position of solstices and equinoxes, affecting the contrast between seasons in each hemisphere.
How They Control Climate Change
Together, these cycles influence Earth’s climate over tens to hundreds of thousands of years by altering the amount and distribution of solar energy. When these cycles align to reduce summer insolation in high latitudes, ice sheets grow, leading to glacial periods. When they increase summer warmth, ice sheets melt, triggering interglacial periods like the current Holocene epoch. These orbital variations help explain past Ice Ages and warm periods observed in Earth’s history.