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Climate Change Could Double Likelihood of Super El Ninos

The question of how global warming will influence El Niño has been a challenging one for scientists to answer. A new study suggests while the overall number of El Niños is unlikely to increase, particularly strong “super” El Niños are likely to occur twice as frequently in a warming world.

El Niño refers to a pattern of unusually warm water stretching across the surface of eastern equatorial Pacific that occurs every 3-7 years. That warm water influences climate patterns around the world, increasing the likelihood of wet and cool weather in the Southeast, heavy rain in California, warm and dry conditions in the Pacific Northwest, and host of other global impacts.

A map showing sea surface temperature anomalies leading up and during the 1997-98 super El Nino.
Credit: NOAA View

The strongest El Nino ever recorded occurred in 1997-98. It led to heavy rains across the southern U.S., landslides in Peru, wildfires in Indonesia, and the cratering of the anchovy fishery in the eastern Pacific. These and other impacts were responsible an estimated $35-45 billion in damage and 23,000 deaths worldwide.

Another “super” El Nino in 1982-83 wreaked similar havoc globally.

In a study published on Sunday in Nature Climate Change, researchers show that climate change could double the frequency of super El Nino events.

To obtain the results, researchers led by Wenjun Cai, a climate modeler at Australia’s Commonwealth Scientific and Industrial Research Organisation, used 20 climate models to simulate ocean temperatures and rainfall in the tropical Pacific with and without changes in greenhouse gases. Cai looked specifically at the period of December-February, when El Nino tends to peak and its impacts are the most widespread.

“Under greenhouse warming the eastern equatorial Pacific warms faster than the surrounding regions . . . making it easier to have maximum SST (sea surface temperatures) in the eastern equatorial Pacific, and hence more occurrences of extreme El Nino events,” Cai said in an email.

Surface waters in the eastern tropical Pacific averages around 72°F, about 10°F cooler than the western tropical Pacific. Cai said that makes it easier to warm, which reduces the overall temperature difference between the two regions and makes conditions more ripe for super El Ninos to develop.

Specifically, the results show that the likelihood of super El Ninos doubles from one every 20 years in the previous century to one every 10 years in the 21st century.

While the results show an increase in the number of abnormally strong El Ninos, they don’t show a change in the total number of El Ninos. The study also shows that the the current influence El Nino has on weather elsewhere is unlikely to change. Both are results that other studies have found as well.

The core of Cai’s results, that more super El Ninos are likely, was disputed by Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research.

He said some of the models used in the study overestimate the past number of El Nino events by a wide margin and do a poor job of representing them and their impacts.

A dust clouds descends on Melbourne on February 8, 1983, a super El Nino year. El Nino tends to increase the likelihood of drier than normal conditions in eastern Australia.
Credit: Trevor Farrar/Australia Bureau of Meteorology

“This seriously undermines the confidence that the models do an adequate job in ENSO (El Nino-Southern Oscillation) simulations and so why should we trust their future projections?” he said in an email.

Trenberth also said that some long-range climate models also fail to adequately simulate other natural climate patterns that influence El Nino let alone how they might also shift in a warming world.

Lisa Goddard, director of the International Research Institute for Climate and Society provided a similar assessment of some of the models used in the study. However, she said the methodology was sound and if the results are accurate, they could provide helpful information for scientists making seasonal forecasts around the globe and decision makers who rely on them.

“Since the majority of skill in seasonal forecasts is realized during El Nino events (and predictions become more skillful over more of the world's land areas), we would be able to prepare much better for the impacts of these events,” she said. “Adverse and costly climate happens in all years. We are just better able to predict that in years with strong El Nino and La Nina events.”

Though the the 1997-98 super El Nino caused extensive damage, decision makers in California poured an extra $7.5 million into flood preparedness based on seasonal forecasts that accurately predicted it months ahead of time. The state still suffered $1.1 billion in losses during the event, but that was half the total suffered during the 1982-83 super El Nino.

Water managers in Tampa Bay regularly use seasonal forecasts and the predictability of El Nino to plan for water availability in the coming months.

There is evidence that El Ninos has been changing already. Research published in January last year showed a roughly 20 percent increase in El Nino intensity over the course of the 20th century, though it didn’t specifically attribute that change to human greenhouse gas emissions.

Related content 
Global Warming-El Nino Link Stronger but Still Not Proven
NOAA’s New Cool Tool Puts Climate on View for All
Global Warming May Worsen Effects of El Niño, La Niña Events
El Nino May Be On the Way, Altering Weather Patterns
Forecasts Call for Weak-to-Nonexistent El Nino This Winter
Drought Has Ties to La Nina, with Global Warming Assist


By ReduceGHGs (Albany/Oregon/97321)
on January 19th, 2014

There’s no reasonable doubt in the scientific community and hasn’t been for years.  So we should each ask ourselves… “What am I doing about it?”  Apathy only advocates more of the same destructive behaviors.  Future generations will suffer needlessly if we don’t do more to curb global emissions.  Please join the efforts.  Our children are worth the effort.

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By RUSerial
on January 20th, 2014

What is the perfect global mean temperature in your view?  Are you 100% certain that a few degrees above that which is currently observed over the course of a hundred years, for example, will have a NET negative impact on our race?  Because there could certainly be some positive effects of warmer temperatures.  The fact is that you don’t know, and no one does.  But, you’re pressuring others to impose negative economical measures upon themselves now, which also impacts future generations negatively.  So, could it be that the ideas you are selling are creating the exact outcome that you are warning against?  I think so.

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By Steven Blaisdell
on January 21st, 2014

“Are you 100% certain that a few degrees above that which is currently observed over the course of a hundred years, for example, will have a NET negative impact on our race?”
Yes. It is certain. The effects of a 2 degree celsius rise in global mean temperature will have extensive adverse effects on human life and civilization, including at least 1 m sea level rise (dislocating hundreds of millions), desertification of the American South, West, and Midwest in addition to Russia’s grain belt, the Amazon, and all currently tropical and subtropical areas, the disappearance of mountain glaciers and fresh water for tens or hundreds of millions, severe disruption of agriculture and animal husbandry (ask California farmers and Texas cattlemen how they’re doing these days), the cumulative effects of overfishing and ocean acidification and warming resulting in collapsing fish stocks….all these effects are ALREADY occurring and documented.
“Because there could certainly be some positive effects of warmer temperatures.”
Of course there will. And will be far outweighed by the costs. We stand to lose far more than we’ll gain (see above).
“The fact is that you don’t know, and no one does.”
No. Wrong. While noone can precisely tell the future, the net effects of global warming have been predicted with increasing precision for decades. Further, we are seeing these effects as we speak.
“’re pressuring others to impose negative economical measures upon themselves now, which also impacts future generations negatively.”
Either we in the first world shift to a much lower rate of resource consumption and massive and immediate reduction of greenhouse gas emissions, or “future generations” will have a lot more to worry about than switching to an easily achievable and accommodated sustainable standard of living. 
“...could it be that the ideas you are selling are creating the exact outcome that you are warning against?”
No. You’re being warned that if the First World and emerging economies don’t sharply reduce overall resource consumption and GHG emissions, “future generations” will be struggling against forces far out of their control, with the least of their worries being accepting a more sustainable standard of living.

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By Philip S. Wenz (Corvallis, Oregon, 97333)
on April 10th, 2014

Very well said, Steven. Thank you. For all the deniers there is a simple message — no matter what you read or don’t read in the mainstream media, climate change is writing its own story, easily read by all but the scientifically illiterate. It’s upon us, and carbon persists in the atmosphere for decades. Will we react in time?

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By kermit freehand
on January 27th, 2014

Nothing is science is 100% sure, but we are as sure of this as we are of anything we know. With only about 1°C rise since the beginning of the industrial age, we are seeing hotter, longer droughts, torrential downpours, sea level rise, a spread of invasive species, climate refugees, and political instability (e.g. the Arabian Spring was largely a result of increasing food costs from poor harvests world wide). Also the increasing acidity of the ocean - another result of greenhouse gases - will likely lead to a mass extinction - 80% of marine species lost is a mainstream prediction.

Quite a few people know these things; their development is observable and explainable.

As for “negative economic measures” you will hear the same kind of complaints from anyone who is maxing out their credit card past their ability to pay. There will be a reckoning, and we will have to pay our bills with interest. but perhaps you are hoping to pass the consequences on to your children. They will certainly suffer the brunt of the storm.

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