Global ice-sheet system interlocked by sea level
Denton and Hughes postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during later Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75/sup 0/N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet. But factors other than areal changes of the grounded Antarctic Ice Sheet may have strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate, but another potential influence was high-frequency climatic oscillations. It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm-high frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 /sup 14/C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide. Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.
- Research Organization:
- Univ. of Maine, Orono (USA)
- OSTI ID:
- 6578049
- Journal Information:
- Quat. Res. (N.Y.); (United States), Vol. 26
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
CARBON DIOXIDE
ENVIRONMENTAL EFFECTS
CLIMATES
VARIATIONS
SEA LEVEL
GLOBAL ASPECTS
ICE CAPS
NORTHERN HEMISPHERE
QUATERNARY PERIOD
SOUTHERN HEMISPHERE
CARBON COMPOUNDS
CARBON OXIDES
CENOZOIC ERA
CHALCOGENIDES
EARTH PLANET
GEOLOGIC AGES
ICE
LEVELS
OXIDES
OXYGEN COMPOUNDS
PLANETS
580100* - Geology & Hydrology- (-1989)
500200 - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)