Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse.
Proc Natl Acad Sci U S A
; 107(34): 14983-6, 2010 Aug 24.
Article
em En
| MEDLINE
| ID: mdl-20696937
ABSTRACT
Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO(2) (8 to 22x PAL preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan ("mixed layer") marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma) They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55 degrees -70 degrees S to approximately 40 degrees S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO(2) from a modeled Sandbian level of approximately 8x PAL to approximately 5x PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Atmosfera
/
Dióxido de Carbono
/
Clima
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article