Jäätusaja

Jäätusaja, often translated as "ice age," refers to a prolonged period of significant global cooling that results in the expansion of continental ice sheets and polar ice caps. These periods are characterized by lower global temperatures, leading to the formation and growth of extensive glaciers and ice sheets that can cover vast areas of land. The Earth's climate system is dynamic, and ice ages are a natural, recurring phenomenon in its history.

The occurrence of an ice age is influenced by a complex interplay of factors. These include variations in Earth's orbital parameters, known as Milankovitch cycles, which affect the amount of solar radiation received by different parts of the planet. Changes in atmospheric composition, such as the concentration of greenhouse gases like carbon dioxide, also play a crucial role. Furthermore, geological events like continental drift and volcanic activity can influence long-term climate patterns.

During an ice age, sea levels drop significantly as water is locked up in ice sheets. This can expose land bridges, facilitating the migration of plants and animals. Conversely, interglacial periods, warmer phases within an ice age or between ice ages, are marked by glacial retreat and rising sea levels. Evidence for past ice ages is found in geological formations such as moraines, glacial striations, and sedimentary rock layers. Scientific research continues to study these past events to better understand Earth's climate and predict future changes.