Ice cores are the time machines that allow us to investigate past climate. They preserve actual bubbles of air that mean that we can look at past concentrations of greenhouse gases in the atmosphere. They allow us to reconstruct past temperature and precipitation changes, and help us understand relationships between the composition of the atmosphere and changing climate. We can use ice cores to put modern climate change into an 800,000 year perspective, allowing us to investigate past rates and magnitudes of change. Learn more about ice cores in this section.