16
January 2003
Cenozoic climate: Out of the greenhouse
The widespread glaciation of Antarctica and the associated cooling 34 million years ago at the Eocene/Oligocene boundary is one of the most fundamental global climate events recorded. The trigger for this glaciation is generally assumed to be the opening of the Tasmanian Passage between Antarctica and Australia and the Drake Passage between Antarctica and South America. New simulations, using coupled general circulation and dynamic ice sheet models, suggest that though the opening up of Southern Ocean gateways would have caused marked cooling in southern latitudes, other factors must have been at work to cause the observed switch from a 'greenhouse' to an 'icehouse' climate. The main factor could have been the decline in atmospheric CO2 at the end of the Cenozoic.
Rapid Cenozoic glaciation of Antarctica induced by declining
atmospheric CO2
ROBERT M. DECONTO &
DAVID POLLARD
Nature 421, 245–249 (2003); doi:10.1038/nature01290
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Palaeoclimatology: Cooling a continent
PETER
BARRETT
The effect of greenhouse gases on climate is underscored by modelling
work showing that formation of the Antarctic ice sheet, 34 million years ago,
occurred largely because of a fall in atmospheric CO2 concentration.
Nature 421, 221–223 (2003); doi:10.1038/421221a
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