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Evidencia isotópica de la glaciación durante el super invernadero del Cretácico
André Bornemann1, Richard D Norris, Oliver Friedrich
1Scripps Institution of Oceanography, University of California, San Diego, Geosciences Research Division, 9500 Gilman Drive, La Jolla, CA 92093-0244, USA. a.bornemann@uni-leipzig.de
Science (New York, N.Y.)
|January 12, 2008
Resumen
Durante el cálido período turónico, la evidencia sugiere que se produjo una glaciación significativa. Esto desafía la idea de que los polos siempre estuvieron libres de hielo durante eventos anteriores de calentamiento global.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- Geología Geología Geología.
Sus antecedentes:
- La época turoniana (93,5 89,3 Ma) fue un período excepcionalmente cálido en la historia de la Tierra.
- La evidencia sugiere posibles eventos de glaciación durante este clima de super invernadero.
Objetivo del estudio:
- Para investigar la ocurrencia y la extensión de la glaciación durante el período turónico.
- Reevaluar las suposiciones sobre la presencia de hielo polar durante eventos pasados de calentamiento global.
Principales métodos:
- Análisis de los datos del isótopo del oxígeno (delta18O) de las calizas marinas en el Atlántico tropical.
- Reconstrucción de la superficie del océano y los cambios de temperatura de aguas profundas.
Principales resultados:
- Los desplazamientos sincrónicos del delta18O en la superficie y los océanos profundos alrededor de 91.2 Ma indican un evento de glaciación de ~ 200,000 años.
- Se estima que las capas de hielo eran aproximadamente la mitad del tamaño de la moderna capa de hielo antártica.
- La glaciación ocurrió a pesar de las condiciones de super invernadero prevalecientes.
Conclusiones:
- Las grandes capas de hielo pueden formarse incluso durante períodos de calentamiento global extremo.
- Se desafía la suposición de polos libres de hielo durante los climas de invernadero pasados.
- La glaciación del Turón proporciona datos críticos para los modelos climáticos y la comprensión de la dinámica climática pasada.
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