Published in Nature Climate Change, a new study finds that rainfall variations associated with the global climate phenomenon El Niño are likely to become more frequent in the next 20 years.
El Niño – the unusual warming of surface waters in the eastern tropical Pacific Ocean –affects climate, ecosystems and societies worldwide. El Niño and its cool counterpart La Niña alternate on timescales of years, leading to shifts of the tropical atmospheric circulation, known as Southern Oscillation and shifts in global rainfall patterns. The combined atmosphere-ocean phenomenon is referred to as the El Niño-Southern Oscillation (ENSO).
The study examined four possible scenarios for future carbon emissions and found an increased risk for intensifying tropical rainfall fluctuations in all four.
This means El Niño events and associated climate extremes are now more likely “regardless of any mitigation actions” to reduce emissions, the researchers warn.
Lead author Dr Jun Ying, from the Second Institute of Oceanography, Ministry of Natural Resources in China and the University of Exeter, said: “We know from previous studies that, when measuring El Niño changes in terms of rainfall shifts in the eastern equatorial Pacific, models predict an increase in the frequency of events.”
“This study shows that those changes could happen in the next two decades.”
The study, published in Nature Climate Change, examines the “time of emergence” of changes in the tropical Pacific, using state-of-the-art climate models. The time of emergence is defined as when the signal of climate change emerges from that usual background noise of natural climate variability.
When looking at changes in the range of El Niño-La Niña-related rainfall fluctuations, the best estimate of the time of emergence converges on 2040 in all the four emissions scenarios considered.
Co-author Professor Axel Timmermann, from the IBS Center for Climate Physics, South Korea, added: “Interestingly, we find a much earlier emergence of the anthropogenic signal in ENSO-related rainfall than in ocean temperatures, which highlights the strong non-linearity and robustness of the atmospheric response.”
“We previously identified in another study the physical mechanisms that cause the increase in rainfall variability associated with ENSO, but our team was quite surprised to see that this effect will become visible and detectable against the background of natural climate variability so soon.” The study was performed by an international team of scientists from China, the UK, South Korea and Australia.
Notes for Editors
Reference
Ying J., M. Collins, W. Cai, A. Timmermann, P. Huang, D. Chen, K. Stein, 2022: Emergence of climate change in the tropical Pacific. Nature Climate Change, doi: 10.1038/s41558-022-01301-z.
Media Contact
For further information or to request media assistance, please contact: Jun Ying, State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources (+86 0571 8980 7121, yingjun@sio.org.cn), or U-Jeong Seo, IBS Center for Climate Physics, Pusan National University (+82-51-510-7328, u_jeongs@pusan.ac.kr), or University of Exeter press office: a.morrison@exeter.ac.uk (+44 (0) 7920 278762)
Researcher contacts
Axel Timmermann, axel@ibsclimate.org
Jun Ying yingjun@sio.org.cn
About the Institute for Basic Science (IBS)
IBS was founded in 2011 by the government of the Republic of Korea with the sole purpose of driving forward the development of basic science in South Korea. IBS has 32 research centers as of July 2021.
About ICCP
The IBS Center for Climate Physics (ICCP) seeks to expand the frontiers of earth system science by conducting cutting-edge research into climate dynamics and utilizing high-performance computer simulations, with the goal of improving decadal Earth system forecasts and long-term projections. See more on http://ibsclimate.org