Jäätusajad

Jäätusajad, also known as ice ages, are prolonged periods of reduced global temperatures during which large-scale ice sheets and glaciers cover significant portions of Earth's landmasses. These periods are characterized by a general cooling trend that leads to the expansion of ice from the polar regions towards the equator.

The Earth's climate has experienced numerous ice ages throughout its geological history. These ice ages are not continuous; they are punctuated by warmer interglacial periods, during which ice sheets recede. The most recent glacial period, often referred to as the Pleistocene epoch, lasted from approximately 2.6 million to 11,700 years ago. During this time, massive ice sheets covered much of North America and Eurasia.

The causes of ice ages are complex and are thought to involve a combination of factors. Astronomical factors, such as variations in Earth's orbit (Milankovitch cycles), play a significant role by altering the amount and distribution of solar radiation reaching the planet. Geological factors, including changes in atmospheric carbon dioxide levels due to volcanic activity or tectonic shifts, also influence long-term climate trends. Furthermore, changes in ocean currents and albedo (the reflectivity of Earth's surface) can create feedback loops that amplify cooling or warming trends.

The effects of ice ages are profound, shaping landscapes through erosion and deposition by glaciers, influencing sea levels, and driving evolutionary changes in flora and fauna as species adapt to altered environmental conditions. The study of past jäätusajad provides crucial insights into Earth's climate system and helps scientists understand potential future climate change scenarios.