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Rapid Climate Change during the Last Glacial Cycle

Measurements of temperature variations that occurred during the last glacial cycle have been inferred from a number of geologic records. In particular, temperature variations deduced from analyzing oxygen isotope records from ice cores retrieved from Greenland and Antarctica have demonstrated that periods of extremely rapid global climate change have occurred in the Earth System during the last glacial cycle. The period know as Marine Oxygen Isotopic Stage 3 (MOIS3: ~60,000 to 30,000 years ago) is characterized by sawtooth millennial scale fluctuations in annually averaged temperature of 10°C to 15°C at high northern latitudes, with the most rapid changes occurring on the interannual timescale.  These temperature fluctuations known as Dansgaard-Oeschger (D-O) oscillations occurred with an almost periodic form during MOIS3. Understanding the nature of the dynamical mechanisms that underlie these oscillations will help validate models used for future climate change studies and to estimate the sensitivity of the Earth’s climate system to different internal and external perturbations. In this presentation I will discuss some numerical modelling results of the D-O phenomenon.