ísheimsins

ísheimsins is an Icelandic term that translates to "ice age" in English. It refers to prolonged periods of significant climatic cooling characterized by the expansion of continental ice sheets, mountain glaciers, and sea ice. These ice ages are a natural and recurring feature of Earth's climate history, occurring over geological timescales, typically lasting for millions of years.

During an ísheimsins, global average temperatures drop considerably, leading to widespread glaciation. This glaciation has profound effects on Earth's geography, including the carving of valleys, the formation of fjords, and the lowering of sea levels as water is locked up in ice. The most recent major ice age, the Pleistocene epoch, ended around 11,700 years ago.

The causes of ísheimsins are complex and are thought to involve a combination of factors. These include variations in Earth's orbit (Milankovitch cycles), changes in atmospheric composition (such as greenhouse gas concentrations), and tectonic activity. Scientists study ice cores, geological formations, and climate models to understand the past and predict future ice age cycles. The term is primarily used in geological and climatological contexts to describe these major climatic shifts.