A glacial cycle refers to the natural fluctuations in Earth's climate that lead to the advance and retreat of glaciers over thousands of years. These cycles are primarily driven by changes in Earth's orbit, solar radiation, and atmospheric composition, which influence global temperatures. During colder periods, known as glacial periods, ice sheets expand, covering large areas of land. In contrast, during warmer periods called interglacial periods, glaciers melt and retreat, leading to rising sea levels. The most recent glacial cycle began around 2.58 million years ago and continues today, with the last major glacial period ending approximately 11,700 years ago.