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Concentraciones atmosféricas de CO2 del mioceno tardío y la expansión de las hierbas de C4

Pagani¹, Freeman, Arthur

¹Department of Geosciences, The Pennsylvania State University, University Park, PA 16872, USA.

Science (New York, N.Y.)

|August 7, 1999

Resumen

El dióxido de carbono atmosférico (CO2) no disminuyó durante el Mioceno tardío, al contrario de las teorías anteriores. En cambio, la expansión de los pastizales C4 probablemente fue impulsada por cambios en la aridez y los patrones de precipitación.

Área de la Ciencia:

Paleoclimatología Paleoclimatología
La paleobotánica es la paleobotánica.
La geoquímica es la geoquímica.

Sus antecedentes:

La expansión de las praderas de C4 durante el Mioceno tardío se atribuía previamente a la disminución de los niveles de dióxido de carbono (CO2) atmosférico.
Esta hipótesis se debate debido a la falta de evidencia directa de los cambios en el CO2 y la influencia conocida de otros factores ambientales en la distribución de las plantas.

Objetivo del estudio:

Investigar el papel de la presión atmosférica parcial de CO2 (pCO2) en la conducción de la expansión de las praderas del Mioceno C4 tardío.
Proporcionar evidencia directa de las fluctuaciones de pCO2 durante el Mioceno tardío.

Principales métodos:

Utilizó proxies geoquímicos basados en alquenonas para reconstruir los niveles pasados de pCO2 atmosférico.
Analizó núcleos de sedimentos para establecer una línea de tiempo de los cambios de pCO2 de hace 14 a 9 millones de años.

Principales resultados:

Las estimaciones de pCO2 basadas en alquenona revelan un aumento de hace 14 a 9 millones de años, seguido de una estabilización en los niveles preindustriales.
No se encontró evidencia significativa de una disminución importante en la pCO2 durante el Mioceno tardío.

Conclusiones:

La expansión del Mioceno tardío de los pastizales C4 no fue impulsada por una disminución en el CO2 atmosférico2.
Los factores alternativos, como el aumento de la aridez o la alteración de los patrones de precipitación, probablemente jugaron un papel más importante.

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