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Pruebas isotópicas de controles múltiples de los oxidantes atmosféricos durante las transiciones climáticas
Lei Geng1,2,3, Lee T Murray4, Loretta J Mickley5
1Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, USA.
Nature
|May 18, 2017
Resumen
Los oxidantes troposféricos como el ozono (O3) y el hidroxilo (HOx) son cruciales para la química atmosférica. Este estudio encontró que las relaciones O3/HOx aumentan en climas fríos, contrariamente a las suposiciones anteriores, lo que sugiere nuevos mecanismos de retroalimentación climática.
Área de la Ciencia:
- Química atmosférica y paleoclimatología
- Estudio de los oxidantes troposféricos y su respuesta al cambio climático
Sus antecedentes:
- Los oxidantes troposféricos (ozono, hidroxilo, radicales peroxílicos) controlan el tiempo de vida de los gases traza y la formación de partículas.
- El conocimiento actual sugiere una disminución del ozono en climas fríos, con HOx relativamente estable.
- Faltan los registros paleológicos para restringir los niveles de oxidantes anteriores durante las transiciones climáticas.
Objetivo del estudio:
- Para investigar el comportamiento pasado de los oxidantes troposféricos utilizando registros de núcleos de hielo.
- Para restringir la respuesta de los oxidantes atmosféricos a los cambios climáticos pasados.
- Identificar posibles mecanismos de retroalimentación climática relacionados con la química de los oxidantes.
Principales métodos:
- Análisis del exceso de oxígeno-17 en el nitrato de un núcleo de hielo de Groenlandia.
- Reconstrucción de la relación ozono/HOx durante el último ciclo glaciar-interglacial y los eventos de Dansgaard-Oeschger.
- Utilizó datos de núcleos de hielo como un sustituto para la abundancia de oxidantes atmosféricos del pasado.
Principales resultados:
- Se observó un aumento de la relación ozono/HOx durante los períodos de clima frío.
- Este hallazgo contradice la hipótesis prevaleciente de menor ozono en climas fríos.
- La evidencia sugiere un transporte mejorado de la estratosfera a la troposfera de ozono y química reactiva de halógenos en climas más fríos.
Conclusiones:
- Los oxidantes troposféricos son sensibles al cambio climático, con una respuesta inversa en climas fríos en comparación con los modelos actuales.
- El transporte mejorado de ozono desde la estratosfera y la química de halógenos son factores hipotéticos.
- Estos procesos pueden representar mecanismos de retroalimentación climática significativos y poco explorados.
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