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Imágenes de gases atmosféricos de hace dos millones de años del hielo antártico
Yuzhen Yan1, Michael L Bender2,3, Edward J Brook4
1Department of Geosciences, Princeton University, Princeton, NJ, USA. yuzheny@princeton.edu.
Nature
|November 1, 2019
Resumen
Los antiguos núcleos de hielo revelan que los niveles de gases de efecto invernadero y las temperaturas de la Antártida fueron más bajos durante el
Área de la Ciencia:
- Paleoclimatología
- Investigación de núcleos de hielo de la Antártida
- Análisis de los gases de efecto invernadero
Sus antecedentes:
- El clima de la Tierra ha experimentado ciclos glaciales-interglaciales, con un prominente ciclo de 100,000 años ('mundo de 100k') que ha dominado los últimos 800,000 años.
- Antes del 'mundo 100k', un 'mundo 40k' (hace 2.8 a 1.2 millones de años) exhibió ciclos glaciales más débiles, con una sugerida menor variabilidad de dióxido de carbono atmosférico.
- Los datos directos de gases de efecto invernadero atmosféricos del "mundo 40k" han estado faltando, lo que limita nuestra comprensión de este estado climático anterior.
Objetivo del estudio:
- Para reconstruir el dióxido de carbono atmosférico, el metano y la temperatura de la Antártida durante el 'mundo de los 40K' usando antiguos núcleos de hielo.
- Para comparar la variabilidad climática en el "mundo de los 40 mil" con el más reciente "mundo de los 100 mil".
Principales métodos:
- Recuperación de hielo antiguo y discontinuo estratigráficamente del Área de Hielo Azul de Allan Hills, en la Antártida Oriental.
- Análisis de las concentraciones de dióxido de carbono y metano en muestras de núcleos de hielo prístino.
- Medición de la temperatura de la Antártida mediante el uso de la proporción de isótopos de deuterio/hidrógeno (δDhielo).
Principales resultados:
- Los núcleos de hielo prístino de más de dos millones de años proporcionaron datos atmosféricos directos del "mundo 40k".
- Las propiedades climáticas del "mundo 40k" cayeron dentro del rango del "mundo 100k", pero mostraron amplitudes glaciales e interglaciales reducidas.
- Las temperaturas más bajas de dióxido de carbono, metano y Antártida durante los períodos glaciales del "mundo 40k" fueron más altas que las del "mundo 100k".
Conclusiones:
- El estudio confirma amplitudes reducidas de las variaciones glaciales-interglaciales en los gases de efecto invernadero y el clima antártico durante el "mundo 40k".
- La transición al "mundo 100k" se asoció con una disminución de las concentraciones mínimas de dióxido de carbono durante los máximos glaciales.
- Los antiguos núcleos de hielo proporcionan una evidencia directa invaluable para comprender la dinámica y las transiciones climáticas del pasado.
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