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Crisis y impactos de la circulación termohalina durante la transición del Pleistoceno medio
Leopoldo D Pena1, Steven L Goldstein2
1Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, USA. leopoldo@ldeo.columbia.edu.
Science (New York, N.Y.)
|June 28, 2014
Resumen
La transición del Pleistoceno medio (MPT) interrumpió la circulación termohalina del océano (THC), debilitándola significativamente. Esta crisis de circulación facilitó el crecimiento de las capas de hielo y estabilizó los ciclos glaciales de 100.000 años.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- Oceanografía La oceanografía es la oceanografía.
- La geoquímica es la geoquímica.
Sus antecedentes:
- La transición del Pleistoceno medio (MPT, por sus siglas en inglés) cambió los ciclos glacial-interglacial de períodos de ~41 kyr a ~100 kyr.
- Este cambio se produjo sin cambios significativos en el forzamiento de Milankovitch, lo que sugiere que otras retroalimentaciones del sistema terrestre estuvieron involucradas.
Objetivo del estudio:
- Investigar el papel de la circulación termohalina oceánica (THC) durante el MPT.
- Para identificar los cambios en el THC relacionados con la aparición de ciclos de 100 kyr.
Principales métodos:
- Análisis de los isótopos de neodimio (Nd) en los sedimentos marinos.
- Reconstrucción de patrones de circulación oceánica del pasado.
Principales resultados:
- Se produjo una importante interrupción y debilitamiento del THC durante el MPT, específicamente entre las etapas de isótopos marinos (MIS) 25 y 21 (~950860 ka).
- Se observó un debilitamiento excepcional del THC durante el MIS interglacial 23 (~900 ka).
- La recuperación del THC después de la MPT se caracterizó por una debilidad sostenida durante los períodos glaciales.
Conclusiones:
- La crisis de la circulación oceánica MPT, marcada por el debilitamiento del THC, fue un factor clave en la transición a los ciclos de 100 kyr.
- Esta crisis facilitó la extracción atmosférica de CO2 y el crecimiento de las capas de hielo en latitudes altas, estabilizando los ciclos más largos.
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