by Charles the moderator, May 7, 2019 in WUWT
University of New South Wales
Melbourne: Australian scientists have developed an innovative method using cores drilled from coral to produce a world first 400-year long seasonal record of El Niño events, a record that many in the field had described as impossible to extract.
The record published today in Nature Geoscience detects different types of El Niño and shows the nature of El Niño events has changed in recent decades.
This understanding of El Niño events is vital because they produce extreme weather across the globe with particularly profound effects on precipitation and temperature extremes in Australia, South East Asia and the Americas.
The 400-year record revealed a clear change in El Niño types, with an increase of Central Pacific El Niño activity in the late 20th Century and suggested future changes to the strength of Eastern Pacific El Niños.
“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.”
This extraordinary result was teased out of information about past climate from coral cores spanning the Pacific Ocean, as part of Dr Freund’s PhD research at the University of Melbourne and the Centre of Excellence for Climate Extremes. It was made possible because coral cores – like tree rings – have centuries-long growth patterns and contain isotopes that can tell us a lot about the climate of the past. However, until now, they had not been used to detect the different types of El Niño events.