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Teasing out El Nino's impact on climate change

The strength of the El NiƱo-Southern Oscillation (ENSO) climate system has varied substantially over the past 7,000 years according to an NSF-funded, multi-institution research team. Such high internal variability within the system may mean that the effects of climate change on ENSO will be difficult to tease out without longer-term records.

ENSO has a major impact on temperature and rainfall patterns across the globe. Understanding how greenhouse gas warming will affect this system is critical to developing climate change adaptation strategies. Model simulations are helping to predict climate change effects on ENSO, but this study suggests that the relationship may be more complicated than what current models can forecast.

To investigate past ENSO variability, the researchers used fossil corals from the Line Islands in the tropical Pacific Ocean. When these corals were living, their exoskeletons captured chemical information about the closely linked marine and atmospheric conditions that are associated with ENSO activity. Thus, the fossil corals allowed the scientists to look much deeper into the past than the time period for which we have direct measurements of ENSO behavior.

Nevertheless, the study suggests that because of ENSO's own internal variability, an even longer-term view may be needed to isolate its response to external forces like climate change resulting from human activity.

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  • fossil corals from the line islands in the pacific
Fossils corals from the Line Islands in the Pacific.
Kim Cobb, Georgia Institute of Technology

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