Showing papers by "Sigfus J Johnsen published in 1970"
TL;DR: The stable isotope technique applied on the deep ice core gave an unbroken and detailed climatic record spanning probably 100,000 years, unlike other methods.
Abstract: THE idea of using the isotopic composition of glacier ice as a climatic indicator was proposed in 19541. The method is based on the fact that the concentration of heavy stable isotopes (deuterium and oxygen-18) in high polar snow increases with the temperature of formation of the snow1–3. This causes seasonal variations in the isotopic composition of accumulated snow and ice4, as well as long-term variations due to climatic changes5. A unique possibility for studying palaeoclimates was offered when the US Army Cold Region Research and Engineering Laboratory succeeded in recovering a 1,400 metre long surface-to-bottom ice core from Camp Century on the North Greenland ice sheet6. No physical dating method can be applied on the relatively small amounts of ice available, so the age of the various increments of the core had to be calculated by considering a simple ice flow model8. This procedure turned out to be successful, in so far as the climate record that resulted from plotting the δ(18O) data (δ is defined7 as the relative deviation of the 18O/16O ratio of a sample from that of standard mean ocean water) against the calculated ages depicted known climatic events dated by other methods5,9. In addition, unlike other methods, the stable isotope technique applied on the deep ice core gave an unbroken and detailed climatic record spanning probably 100,000 years.
76 citations