The leading theory for the occurrence of periodic ice ages …

The leading theory for the occurrence of periodic ice ages on Earth is known as the Milankovitch theory, named after Serbian scientist Milutin Milanković, who proposed it in the early 20th century. The theory suggests that variations in Earth's orbital and rotational parameters, collectively known as Milankovitch cycles, cause changes in the amount and distribution of solar radiation reaching the Earth's surface, leading to long-term climate changes and the onset of ice ages.
The Milankovitch cycles consist of three main components:
1. Eccentricity: The shape of Earth's orbit around the sun varies from nearly circular to slightly elliptical on a cycle of about 100,000 years. This variation affects the distance between the Earth and the sun and, consequently, the amount of solar radiation received by the Earth.
2. Axial tilt (obliquity): The angle between Earth's rotational axis and the perpendicular to its orbital plane varies between 22.1° and 24.5° on a cycle of about 41,000 years. This change in tilt affects the intensity of the seasons and the latitudinal distribution of solar radiation.
3. Precession: Earth's rotational axis wobbles like a spinning top, completing a full cycle approximately every 26,000 years. This wobble, combined with the precession of Earth's orbital ellipse, changes the timing of the seasons relative to Earth's orbit and the distance from the sun.
According to the Milankovitch theory, when these orbital variations align in a way that reduces the amount of summer solar radiation received in the Northern Hemisphere, particularly at high latitudes, it allows snow and ice to persist through the summer and accumulate over time. This increase in snow and ice cover reflects more of the sun's energy back into space (the ice-albedo feedback), further cooling the Earth and leading to the growth of continental ice sheets and the onset of an ice age.
The Milankovitch theory is supported by evidence from various sources, including the analysis of ice cores, deep-sea sediments, and other paleoclimate records. However, it is important to note that while the Milankovitch cycles are the primary drivers of long-term climate change, other factors, such as greenhouse gas concentrations, ocean circulation patterns, and tectonic activity, also play important roles in shaping Earth's climate on various time scales.