For example, melt layers are related to summer temperatures. More melt layers indicate warmer summer air temperatures. Other ways of dating ice cores include geochemisty, layers of ash (tephra), electrical conductivity, and using numerical flow models to understand age-depth relationships.
Snow falls over Antarctica and is slowly converted to ice.
This section contains 11 annual layers with summer layers (arrowed) sandwiched between darker winter layers.
From the US National Oceanic and Atmospheric Administration, Wikimedia Commons.
Through analysis of ice cores, scientists learn about glacial-interglacial cycles, changing atmospheric carbon dioxide levels, and climate stability over the last 10,000 years. This picture shows a traversing field camp from December 2010.
From top to bottom: * Levels of carbon dioxide (CO2). High rates of snow accumulation provide excellent time resolution, and bubbles in the ice core preserve actual samples of the world’s ancient atmosphere.