Coastline Changes: Interrelation of Climate and Geological Processes

Simulation of the Eemian interglacial and possible mechanisms for the glacial inception
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Published:January 01, 2007
A coupled ocean-atmosphere general circulation model was used to perform multi-centennial climate simulations of the Eemian interglacial and the subsequent glacial inception. The simulations were performed as equilibrium experiments with orbital parameters and greenhouse gas concentrations set to values of 125,000 and 115,000 yr before present (B.P.). These dates represent periods with enhanced and weakened seasonal cycles of insolation in the Northern Hemisphere. A consistent reaction of seasonal temperatures is simulated for most continental regions. Comparisons with pollen-based reconstructions of European temperatures show that the model simulates realistic spatial temperature patterns for the warm phase of the Eemian. In the case of the simulation for 115,000 yr B.P., the model reacts with a long-term cooling trend. This trend is associated with a continuous increase in Northern Hemisphere sea-ice volume and an expansion of the permanently snow-covered areas over North America. Although summer precipitation is reduced in this region, the changes in seasonality of temperature lead to significant higher amounts of summer snowfall. The strengthened North Atlantic circulation does not compensate the cooling of the Northern Hemisphere. The snow accumulation starts in northeastern Canada where southward winds transport cold Arctic air into the continent. The accumulated snow volume on the North American continent is equivalent to a reduction of sea level at a rate of ∼10 cm per century at the end of the simulation.
- Atlantic Ocean
- boundary conditions
- Canada
- Cenozoic
- circulation
- climate
- concentration
- cooling
- cycles
- Eemian
- gases
- greenhouse effect
- ice
- interglacial environment
- models
- North America
- North Atlantic
- Northern Hemisphere
- Pleistocene
- Quaternary
- reconstruction
- sea ice
- sea-level changes
- seasonal variations
- simulation
- snow
- upper Pleistocene
- ocean-atmosphere model