Your Turn
Ice cores are essential to our current understanding of historical temperatures and carbon sourcing. Answer the following questions to test your understanding of ice core extraction and analysis. Refer to the Ice Core Extraction and Analysis Learning Tool as necessary.
What information can be obtained from ice cores?
Click here to show answer
Ice cores provide information about past temperatures, atmospheric composition, concentrations of atmospheric gases such as carbon dioxide and evidence of volcano eruptions.
How is the age of an ice core determined?
Click here to show answer
The age of an ice core is determined by counting layers marked by differences in 18O composition; by calibration with events that leave evidence of their occurrence in the ice core (such as major volcanic eruptions), for which dates are known; or by determining the age of gas trapped in ice using 14C or 36Cl dating techniques.
How has the concentration of carbon dioxide changed over the past 400,000 years or so? How has temperature changed? Are these factors related?
Click here to show answer
The carbon dioxide concentration has fluctuated greatly over the past 400,000 years. The temperature has fluctuated at the same time as carbon dioxide. There appears to be a direct correlation between carbon dioxide concentration and temperature. However, this correlation alone is not sufficient to establish that fluctuation in one climatic variable caused fluctuation in the other. Additional evidence is needed to attribute causation.