Abstract
Based upon coupled climate simulations driven by present day and glacial boundary conditions, we demonstrate that although the ice sheet topography modifications during the glacial period are primarily placed in the Northern Hemisphere (NH), a climate simulation that employs the ICE-5G glacial topography delivers significantly enhanced climate anomalies in the Southern Hemisphere (SH) as well. These conditions, in association with climate anomalies produced by the modification of the atmospheric CO² concentration characteristic of the Last Glacial Maximum (LGM) interval, are shown to be the primary forcing of the SH climate during this epoch. Climate anomalies up to -6°C over the Antarctic region and -4°C over South America are predicted to occur in respect to present day conditions. Accompanying the SH cooling in the LGM simulation there exists a remarkable reduction in the specific humidity, which in turn enforces the overall Southern Hemisphere cooling due to the weaker greenhouse capacity of the dry atmosphere.
Highlights
An important motivation to simulate past climatic conditions is that such experiments provide a unique opportunity to study the importance of climate feedbacks
Our results pointed out that the Southern Hemisphere (SH) glacial t2m was more strongly influenced by the reduction of the atmospheric CO2 concentration, which confirms the results of previous studies (e.g. Broccoli and Manabe, 1987; Rind, 1987)
Based upon coupled climate simulations subject to present-day and Last Glacial Maximum conditions, we have investigated the individual impact of including LGM boundary conditions on the Southern Hemisphere climate
Summary
An important motivation to simulate past climatic conditions is that such experiments provide a unique opportunity to study the importance of climate feedbacks. They may help, to assess the validity of future-climate predictions. Justino et al, 2005; Vettoretti et al, 2000; Broccoli and Manabe, 1987), and oceanic circulation changes (Peltier and Solheim, 2004; Shin et al, 2003; Hewitt et al, 2001). It has been demonstrated that the presence of Laurentide and Fennoscandia ice sheets in the Northern Hemisphere has both a topographic and a thermal effect which occur simultaneously and lead to a greater stationary eddy forcing of the zonal mean flow ( Justino et al, 2005; Shin et al, 2003; Vettoretti et al, 2000).
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