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Present‐day and ice‐covered equilibrium states in a comprehensive climate model
Author(s) -
Marotzke Jochem,
Botzet Michael
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl028880
Subject(s) - snowball earth , atmosphere (unit) , climatology , climate model , climate state , solar irradiance , environmental science , sea ice , atmospheric sciences , climate change , geology , meteorology , physics , global warming , glacial period , effects of global warming , oceanography , geomorphology
We show that in a comprehensive climate model both the current climate and a completely ice‐covered Earth are stable states under today's total solar irradiance (TSI) and CO 2 level. We employ the Max Planck Institute for Meteorology coupled atmosphere‐ocean general circulation model ECHAM5/MPI‐OM, at relatively high resolution (horizontally T63 in the atmosphere and 1.5 degrees in the ocean). Setting TSI to near‐zero causes a transition from realistic present‐day climate to a completely ice‐covered state within 15 years; this state persists even when TSI re‐assumes today's value. A break‐up of the complete ice cover occurs with today's TSI and 100 times – but not with 10 times – today's atmospheric CO 2 level. While TSI is near‐zero, extremely strong meridional overturning ensues in both the Atlantic and the Pacific Oceans. Our results imply that a snowball Earth is possible, in principle, with inception possibly triggered by a brief dark spell.