ABSTRACT
We conducted the first synchronously coupled atmosphere-ocean general circulation model simulation from the Last Glacial Maximum to the Bølling-Allerød (BA) warming. Our model reproduces several major features of the deglacial climate evolution, suggesting a good agreement in climate sensitivity between the model and observations. In particular, our model simulates the abrupt BA warming as a transient response of the Atlantic meridional overturning circulation (AMOC) to a sudden termination of freshwater discharge to the North Atlantic before the BA. In contrast to previous mechanisms that invoke AMOC multiple equilibrium and Southern Hemisphere climate forcing, we propose that the BA transition is caused by the superposition of climatic responses to the transient CO(2) forcing, the AMOC recovery from Heinrich Event 1, and an AMOC overshoot.
ABSTRACT
Most of the last 100,000 years or longer has been characterized by large, abrupt, regional-to-global climate changes. Agriculture and industry have developed during anomalously stable climatic conditions. New, high-resolution analyses of sediment cores using multiproxy and physically based transfer functions allow increasingly confident interpretation of these past changes as having been caused by "band jumps" between modes of operation of the climate system. Recurrence of such band jumps is possible and might be affected by human activities.
