Nature Releases New El Niño Study by UMD ESSIC Scientist

For Immediate Release
June 24th, 2012
Contacts: Brian Compere,

Nature Releases New El Niño Study by UMD ESSIC Scientist

COLLEGE PARK, MD – Researcher Raghu Murtugudde, of the University of Maryland’s Earth System Science Interdisciplinary Center, and Nandini Ramesh, co-authored a new study billed as a breakthrough in the predictability of the El Niño effect, a process involving uncharacteristically warm ocean temperatures in the tropical Pacific.

The study, which Nature published today, finds that the Bjerknes feedback, a process that alters the volume of cold deepwater that rises in the East Pacific, is not an essential indicator of an El Niño, contrary to prior belief. The study instead finds that warm subsurface waters discharge up to 18 months before the warming occurs at the surface, thus activating the El Niño effect.

El Niños, which occur every 2-7 years, have significant global impacts, such as floods, droughts, forest fires, and even civil conflicts. This phenomenon has been known since Jacob Bjerknes’ work in 1969 pointed out that changes in equatorial Pacific winds have the most important effects on El Niños.

El Niño trends have changed throughout the past several decades, making it more difficult for researchers to determine definitively whether variability is related to climate change or if it operates through a more cyclic process. The study analyzed factors such as subsurface temperatures throughout different time periods in order to find any factors regular to the onset of an El Niño.

These new findings could provide a new paradigm for understanding, forecasting and predicting the impact of global warming on El Niños. It could even offer a way forward to predict El Niños with a lead time of more than a year. It is also a caution against simple models that use statistical approaches of surface expressions of El Niño to make El Niño predictions.

The exact processes responsible for initiating the warm subsurface water discharge so far ahead of the El Niño are still unclear.

Ramesh, currently at the Bangalore, India-based Divecha Centre for Climate Change, will attend Columbia University for her Ph.D. and will continue to collaborate with Murtugudde to explore these unanswered questions.

Media Contacts
Brian Compere
Earth System Interdisciplinary Center