Glaciers are massive bodies of ice that slowly move across Earth’s surface. Formed from accumulated snowfall over centuries, they carve deep valleys, shaping landscapes as they advance. Scientists study glaciers to understand conditions in the past and predict future changes. Ice cores, cylinders of ice retrieved from glaciers, contain layers of ice deposited over many years. These layers reveal information about past climates, including greenhouse gas concentrations in the atmosphere, temperature, and precipitation. The melting of glaciers because of global warming is a significant concern, as it contributes to rising sea levels and habitat loss.