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Concentración atmosférica de dióxido de carbono a lo largo de la transición del Pleistoceno medio
Bärbel Hönisch1, N Gary Hemming, David Archer
1Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory of Columbia University, NY 10964-8000, USA.
Science (New York, N.Y.)
|June 23, 2009
Resumen
Los ciclos glaciales del Pleistoceno cambiaron de 40.000 a 100.000 años. Este estudio revela niveles estables de dióxido de carbono atmosférico (CO2) antes de este cambio, desafiando la reducción de CO2 a largo plazo como la causa principal.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- La geoquímica es la geoquímica.
- Oceanografía La oceanografía es la oceanografía.
Sus antecedentes:
- La transición del Pleistoceno Medio (MPT) marcó un cambio significativo en la periodicidad del ciclo glacial de la Tierra.
- Los impulsores subyacentes de este cambio de ciclo de ~ 40,000 años a ~ 100,000 años siguen siendo incompletamente entendidos.
- Las hipótesis anteriores sugirieron una disminución a largo plazo en el CO2 atmosférico como un desencadenante potencial de MPT.
Objetivo del estudio:
- Para reconstruir un registro a largo plazo de los niveles de dióxido de carbono atmosférico (CO2) en todo el MPT.
- Investigar la relación entre la variabilidad del CO2 y la dinámica del ciclo glacial.
- Para probar la hipótesis de que la reducción de CO2 causó el MPT.
Principales métodos:
- Análisis de los isótopos de boro en las conchas foraminiferas plancticas para determinar la presión parcial de CO2 (Pco2) más allá de la superficie del mar.
- Construcción de un registro de Pco2 de 2.1 millones de años.
- Comparación de los niveles de CO2 antes y después del MPT con el comportamiento del ciclo glacial.
Principales resultados:
- La Pco2 atmosférica fue relativamente estable antes de la MPT.
- Los niveles glaciales de Pco2 eran aproximadamente 31 micro atmósferas más altos antes del MPT (>1 millón de años atrás).
- Los niveles interglaciales de Pco2 después de la MPT fueron similares a los del Pleistoceno tardío (<450.000 años atrás).
Conclusiones:
- Los hallazgos apoyan un fuerte vínculo entre el CO2 atmosférico y el clima global.
- La estabilidad del Pco2 interglacial antes del MPT contradice la teoría de una reducción gradual de CO2.
- Es poco probable que una reducción a largo plazo del CO2 atmosférico sea el principal impulsor de la transición del Pleistoceno Medio.
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