Increase in extreme El Niño events is unavoidable

El Niño – a climate pattern characterized by the unusual warming of surface waters in the eastern tropical Pacific Ocean – is affecting the climate, ecosystems, and societies all over the world. A new study led by the University of Exeter has found that the global weather fluctuations caused by El Niño will become more frequent by 2040, regardless of the climate change mitigation effects that we might undertake in the near future.

By using state-of-the-art climate models, scientists examined the “time of emergence” of changes in the tropical Pacific related to El Niño – i.e., the moment when the signal of climate change emerges from the usual background noise of natural climate variability. They took into account four possible scenarios for future greenhouse gas emissions and found that, in all the four scenarios, the best estimate of the time of emergence of changes converged on 2040.

“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 after the next two decades,” said study lead author Dr. Jun Ying, a visiting scholar at the University of Exeter.

“What surprised us is that changes emerge regardless of the scenario we look at,” added study co-author Matthew Collins, a professor of Climate Science at the University of Exeter. 

“Because rainfall in the tropics is associated with the warmest sea surface temperatures (SSTs), it is the relative changes in SST that are more important than the absolute change. This leads us to the rather stark conclusion that these changes are essentially unavoidable.”

Although the study results suggest that El Niño events and associated climate extremes are more likely regardless of any significant mitigation actions to reduce emissions, this should not lead to complacency from policy makers and federal agencies. If no immediate actions are taken to curb global warming, the negative effects associated with increases in temperatures will most likely escalate to unprecedented levels, highly endangering life on our planet.

The study is published in the journal Nature Climate Change.

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By Andrei Ionescu, Earth.com Staff Writer