Global warming may double El Niño frequency

Study findings suggest more Australian heatwaves

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New study analyzes how global warming will affect El Niño events.

By Summit Voice

FRISCO — Strong El Niños — along with the extreme weather events that are driven by those warm Pacific ocean episodes — are likely to double as the globe heats up.

“During an extreme El Niño event countries in the western Pacific, such as Australia and Indonesia, experience devastating droughts and wild fires, while catastrophic floods occurred in the eastern equatorial region of Ecuador and northern Peru,” said  CSIRO Dr. Wenju Cai, lead author of a new study published in the journal Nature Climate Change.

“We currently experience an unusually strong El Niño event every 20 years. Our research shows this will double to one event every 10 years,” said Dr. Agus Santoso, a climate researcher with the ARC Centre of Excellence for Climate System Science. The international research team also included scientists with the National Oceanic and Atmospheric Administration.

“This research is the first comprehensive examination of the issue to produce robust and convincing results,” said NOAA researcher Dr. Mike McPhaden. “The question of how global warming will change the frequency of extreme El Niño events has challenged scientists for more than 20 years,” he added.

To achieve their results, the team examined 20 climate models that consistently simulate major rainfall reorganization during extreme El Niño events. They found a substantial increase in events from the present-day through the next 100 years as the eastern Pacific Ocean warmed in response to global warming.

“El Nino events are a multi-dimensional problem, and only now are we starting to understand better how they respond to global warming,” said Santoso.

Extreme El Niño events develop differently from standard El Ninos, which first appear in the western Pacific. Extreme El Nino’s occur when sea surface temperatures exceeding 28 degrees Celsius develop in the normally cold and dry eastern equatorial Pacific Ocean. This different location for the origin of the temperature increase causes massive changes in global rainfall patterns, Santoso explained.

The impacts of extreme El Niño events extend to every continent across the globe.The 1997-98 event alone caused $35 billion in damage and claimed an estimated 23,000 human lives worldwide.

In Australia, the drought and dry conditions induced by the 1982-83 extreme El Niño preconditioned the Ash Wednesday Bushfire in southeast Australia, leading to 75 fatalities.

“This latest research based on rainfall patterns, suggests that extreme El Niño events are likely to double in frequency as the world warms leading to direct impacts on extreme weather events worldwide.”

“For Australia, this could mean summer heat waves, like that recently experienced in the south-east of the country, could get an additional boost if they coincide with extreme El Ninos,” said co-author, Professor Matthew England from CoECSS.

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