Polar ice core and palaeo-environment
1989 Volume 98 Issue 5 Pages 535-561
Details
1989 Volume 98 Issue 5 Pages 535-561
In recent years it has become obvious that two large ice sheets in Antarctica and Greenland are most ideal medium for past some 100k year record of global climate and environment. Compared with deep-sea sediment, polar ice core has some following advantages as record medium for palaeo-environment.
1) High resolution because of high accumulation rale,
2) High Accurcay because of inactive chemical at ice sheet surface, and
3) Occulusion of air itself by the process of densification from firn to ice.
Recent polar ice core studies have revealed 100 k-year cycle of climatic change and the synchronism between Northern and Southern Hemisphere. French and Soviet co-studies on Vostok ice core suggest that CO2 change have had an important climatic role during the late Pleistocene in amplifying the relatively weak orbital forcing. Thus ice core studies have provided fundamental information for the interpretation of glacial and interglacial climatic cycle. Furthermore, such studies on long term climatic changes basis on ice cores show the necessity of interdiciplinary interpretation on atmosphere-ocean-cryosphere climatic system and its relation to earth's orbital movement.
Climatic cycle shorter than 100k-year shows regional characteristics. Hypsithermal, the warmest thousand years in Holocence appears in different ages; 8, 000-4, 100 years B. P. for Camp Century, Greenland core, 8, 000-4, 500 years B. P. for Byrd core, (9, 000)-5, 000 years B. P. for Mizuho core and 11, 000-8, 000 years B. P. for Dome-C core, Antarctica. So dose “little ice age”, the recent cold centuries. Polar ice cores reveal large volcanic eruption. Recent studies have suggested the climatic role of volcanic activities; The acidity of Byrd core indicates that a major volcanic event occurred for 150 years just when the transition period from the late glacial to the Holocence started.
Thus polar ice core studies release valuable informations on palaeo-climate and environmont. However, further studies are requested for the detailed, quantitative and interdiciplinaly interpretation of 102-105 year climatic variation with high quality deep ice cores. Japanese Antarctic Dome Program at the top of Dronning Maud Land, Antarctica and European Greenland Ice Program (GRIP) are expepected to provide by-polar “standard” cores which will cover more than last climatic cycle.
