A Tropical Mechanism for Northern Hemisphere Deglaciation

• Main Authors: Keith B. Rodgers, Gerrit Lohmann, Stephan Lorenz, Ralph Schneider, Gideon M. Henderson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Canada; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.23.3766; http://www.palmod.uni-bremen.de/~gerrit/DEGLpaper.pdf

We investigate the role of the tropics in the melting and reforming of the Laurentide ice sheet on glacial timescales using an atmospheric general circulation model. It is found that warming of tropical sea surface temperatures (SST) from glacial boundary conditions, as observed at the end of glacial periods [Bard et al., 1997, Lea et al., 2000, Nurnberg et al., 2000], causes a large increase in summer temperatures centered over the ice-sheet-forming regions of Canada. This high-latitude response to tropical change is due to alterations in the vertical profiles of temperature and moisture in the extratropical atmosphere. This atmospheric bridge represents a mechanism for deglaciationxs which is consistent with timing constraints. In contrast, a cold perturbation to tropical SST for interglacial boundary conditions results in almost no cooling over the Canadian region. This implies that tropical SSTs could play a more important role in melting ice sheets in the northern hemisphere than in reforming them, possibly providing a mechanism which could help to explain the relative rapidity of deglaciation. 3 1.