A team of Australian researchers have produced a 400-year record of El Niño that shows dramatic changes in the phenomena, a task previously deemed ‘impossible’ by coral experts.
A team of Australian scientists have produced a 400-year record of El Niño weather events with a specialised method of analysis that uses cores drilled from coral reefs.
The paper published in Nature Geoscience shows the nature of these phenomena, which are a driver of extreme weather weather events across the globe, has changed over time and suggests that the streength of Eastern Pacific El Niños was likely to increase in future.
“We are seeing more El Niños forming in the central Pacific Ocean in recent decades, which is unusual across the past 400 years,” said lead author, Dr. Mandy Freund.
“There are even some early hints that the much stronger Eastern Pacific El Niños, like those that occurred in 1997/98 and 2015/16 may be growing in intensity,” she said.
“By understanding the past, we are better equipped to understand the future, especially in the context of climate change.”
At the heart of the novel method to identify seasonal patterns in El Niños was the understanding that coral records could contain sufficiently granular data to document such changes. This had never been done and had previously been labelled ‘impossible’ by experts in the field.
Dr. Freund took her proposed technique to a group of climate scientists and coral experts: Dr Ben Henley, Prof David Karoly, Assoc Prof Helen Mcgregor, Assoc Prof Nerilie Abram, and Dr Dietmar Dommenget.
The team worked to refine the process, which leverages machine learning to reconstruct El Niño events in time and space, and Dr. Freund found agreement in the results of this technique and existing instrumental records.
After three years, the team has found an unprecedented increase in the number of El Niños forming in the Central Pacific over the past 30 years, compared to all 30 year periods in the past 400 years, and that the stronger Eastern Pacific El Niños were the most intense El Niño events ever recorded.
The results also represent a world-first 400-year El Niño record, and a novel new methodology that may well form the basis for future climate research.
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