Ice/Sediment Cores
What do they show?
Ice cores show store several historical proxies for past climate conditions.
Atmospheric gases trapped in the ice can tell us about past GHG concentrations. Should be noted this is a direct measurement not a proxy.
The Oxygen isotope ratio can tell us the temperature at the time of snow fall, therefore giving us temperature records.
Sulphur Concentration shows volcanic eruptions
Calcium concentration shows atmospheric dust movements
Layer thickness can be used to determine the amount of precipitation.
About Ice cores
Ice accumulates layer by layer as more snow falls and is compressed, this leads to air bubbles and water being trapped under the new layers of snow. The oldest ice cores are in Antarctica and span 800,000 years and oldest in Greenland spans 130,000 years. Scientists hope to go further back to 1.5 million years in Antarctica soon.
Are there currently any scientists who are warning that such rapid change is imminent?