Internal oscillations of the thermohaline circulation and abrupt climate changes during the last Ice Age and perhaps in the future ...

• Main Author: Yang, Ming
• Format: Thesis
• Language: English
• Published: The University of North Carolina at Chapel Hill University Libraries 2006
• Subjects: North Atlantic; Sea ice
• Online Access: https://dx.doi.org/10.17615/3ncv-0n23; https://cdr.lib.unc.edu/concern/dissertations/n009w2632?locale=en

The first half of this dissertation presents a hypothesis to explain the abrupt climate changes that occurred during the last ice age. The Dansgaard-Oeschger (DO) oscillations are a prime example of abrupt climate changes in the paleoclimate record, clear evidence that large and extremely rapid climate fluctuations have repeatedly happened in the recent past. There is wide agreement that a likely driver for the DO oscillations may involve changes in the strength of the Atlantic thermohaline circulation (THC). A 3D coupled global atmosphere-ocean-sea-ice model of intermediate complexity, ECBilt-Clio, is used here to study the natural variability of the THC and associated climate changes in the North Atlantic. Under boundary conditions appropriate for the last glacial period the model simulations produce large amplitude, DO-like oscillations. Since no varying external forcing is applied, this is an internally driven, self-sustained, nonlinear free oscillation of the THC. It is argued that the free oscillation ...