The contribution of ice core studies to the understanding of environmental processes

Oeschger, H. (1985). The contribution of ice core studies to the understanding of environmental processes. In: Langway Jr., C.C.; Oeschger, H.; Dansgaard, W. (eds.) Greenland Ice Core: Geophysics, Geochemistry and the Environment. Geophysical Monograph Series: Vol. 33 (pp. 9-17). American Geophysical Union 10.1029/GM033p0009

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Data obtained from the studies of polar ice cores supplement the records available from tree rings, peat bogs, lake and ocean sediments, and provide a relatively new data source to understand processes of the complex climatic and global cycles. The main sources of ice core data are stable and radioactive isotopes, soluble and particulate matter, and the composition of the gases occluded in the ice. Such information can be used to investigate the history and the variability of carbon dioxide and the climate system.

Temperature and other climatic data obtained from δ18O measurements of polar ice cores can be correlated with similar information obtained from carbonate lake sediments. Comparison of the δ18O profiles of the Dye 3 ice core and central European lake sediments show distinct similarities such as the identification of the Older Dryas-Bolling/Allerød-Younger Dryas-Preboreal sequence.

Measurements of the cosmic ray produced isotope 10Be on only 1 kg polar ice samples are possible by accelerator mass spectrometry. The resulting data reveals the 11-year solar modulation cycle and the Maunder Minimum of solar activity from 1645 to 1745 AD. The 10Be concentration values for the Maunder Minimum are a factor 1.6 higher than the average for the past 800 years. Using a carbon cycle model these 10Be variations can be compared to the 14C variations found in tree rings. The relatively good correlation suggests a common origin of the 10Be and 14C fluctuations and serves as a check of carbon cycle models. During the Wisconsin stage all of the Dye 3 ice core parameters measured to date (δ18O, CO2/air, SO4 −, NO3 −, Cl−, dust) show values fluctuating between two different boundary conditions. This suggests that the climate system existing at that time oscillated between a cold and a warm state, probably strongly influenced by different ocean circulations and ice cover. During the Wisconsin stage a cold system dominated; the transition to the Holocene is considered as the final transition to a warm state. Thereafter the boundary conditions did not allow the systems to switch back to a cold state.

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