Age difference between polar ice and the air trapped in its bubbles

• Published in: Nature
• Main Authors: Schwander, J., Stauffer, B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 1984
• Subjects: 530 Physics; Siple; Antarc*; Antarctica
• Online Access: https://boris.unibe.ch/158254/1/schwander84nat.pdf; https://boris.unibe.ch/158254/

Air entrapped in bubbles formed in cold ice has essentially the same composition as that of the atmosphere at the time of bubble formation. The analysis of dated ice samples therefore enables the history of atmospheric composition to be investigated. (1–3) The age of the entrapped air is, however, not the same as that of the surrounding ice because air bubbles only become isolated from the atmosphere during the transition from firn to ice. Typically the age of the ice at this transition is between 100 and 3,000 yr, depending mainly on firn temperature and snow accumulation rate. The mean age difference between ice and enclosed air, as well as the age distribution width for a given sample, are especially important for the investigation of the anthropogenic increase of CO2 and trace gases in the atmosphere over the last centuries, and for the comparison of climatic parameters recorded in the ice with parameters recorded in the bubbles. For Siple Station (Antarctica), this age difference and age distribution width were deduced from the bubble volume measured as a function of depth. The values are 95 yr and 22 yr respectively.