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Respuesta climática al forzamiento orbital a través de la frontera entre el Oligoceno y el Mioceno
J C Zachos1, N J Shackleton, J S Revenaugh
1Earth Sciences Department, Center for Dynamics and Evolution of the Land-Sea Interface, University of California, Santa Cruz, CA 95064, USA. jzachos@es.ucsc.edu
Science (New York, N.Y.)
|April 17, 2001
Resumen
Este estudio revela que los ciclos de Milankovitch influyeron en el clima de finales del Oligoceno y principios del Mioceno y en la química de los océanos. Un importante evento de glaciación (Mi-1) coincidió con una rara configuración orbital que favorecía la expansión de la capa de hielo antártica.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- Oceanografía La oceanografía es la oceanografía.
- Ciencias del clima Ciencias del clima Ciencias del clima Ciencias del clima
Sus antecedentes:
- El clima del Oligoceno tardío y el Mioceno temprano y la química del carbono oceánico son cruciales para comprender la dinámica climática a largo plazo.
- Se sabe que los ciclos de Milankovitch influyen en el clima de la Tierra en varias escalas de tiempo.
Objetivo del estudio:
- Para analizar las propiedades espectrales del clima y la química del carbono oceánico durante un período de 5,5 millones de años.
- Para investigar la relación entre las variaciones orbitales y los eventos climáticos, incluida la glaciación.
Principales métodos:
- Análisis espectral de núcleos de aguas profundas del Atlántico ecuatorial occidental.
- Reconstrucción cronológica que abarca 5,5 millones de años (Mi).
- Examen de la varianza en las frecuencias de Milankovitch.
Principales resultados:
- La variación climática se concentró en todas las frecuencias de Milankovitch.
- Potencia espectral excepcional en la banda de excentricidad de 406 mil años (ky) (20-23,4 Ma).
- Potencia espectral significativa en las bandas de 125- y 95-ky durante niveles sospechosos bajos de gases de efecto invernadero (21.7-23.0 Ma).
- La glaciación Mi-1 (aprox. 23 Ma) vinculado a la congruencia orbital (nodo de oblicuidad, mínimo de excentricidad).
- Período extendido (aprox. 200 ky) de órbitas de baja estacionalidad que favorecen la expansión del hielo antártico.
Conclusiones:
- Los ciclos de Milankovitch impactaron significativamente el clima de finales del Oligoceno y principios del Mioceno y la química del carbono oceánico.
- Las configuraciones orbitales jugaron un papel clave en el desencadenamiento de grandes eventos climáticos como la glaciación Mi-1.
- Los bajos niveles de gases de efecto invernadero pueden haber amplificado el forzamiento orbital sobre el clima.
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