Ice cores are most useful for studying which aspect of Earth's history?

• A. Geologic plate movements
• B. Past climate and atmospheric conditions
• C. The origin of life
• D. Current weather forecasts

Answer: (B)

Ice cores give a record of Earth's past climate and atmosphere. As snow builds up year after year, it compresses into ice and traps bubbles of ancient air. Those trapped air bubbles provide direct samples of the atmosphere from long ago, letting scientists measure past greenhouse gas levels. The ratio of oxygen isotopes in the ice acts as a temperature proxy, showing how warm or cold it was in different periods. Layers may also contain volcanic ash and other particles that mark eruptions and climate events. All of this lets us reconstruct how Earth's climate and atmospheric conditions have changed over hundreds of thousands of years. They aren’t used to track current weather day to day, nor do they directly reveal plate movements or the origin of life.