Study Strengthens Link between El Niño and Climate Change
The cycle of Pacific Ocean surface water warming and cooling has become more variable in recent decades, suggesting El Niño may strengthen under climate change
Credit: Wikimedia Commons/NOAA
Predicting the behavior of the El Niño weather cycle is a challenge for forecasters and climate scientists, and the stakes are high.
El Niño and its counterpart La Niña, driven by changes in sea-surface temperatures in the tropical Pacific Ocean, can have major effects on weather conditions hundreds and thousands of miles away. Studies have linked catastrophic floods, droughts, disease outbreaks, wildfires and even social unrest to the weather cycle, known as the El Niño-Southern Oscillation.
Yet scientists have struggled to understand whether climate change is altering that cycle. Climate models have produced conflicting results, and reliable instrumental records of ENSO events begin in the early 20th century.
Now a new study, which builds on prior efforts to reconstruct El Niño's past behavior by examining coral growth, suggests that El Niño and La Niña events have become more variable and intense over the past several decades.
"We kind of answered the question, is El Niño changing with respect to recent natural variability?" said Kim Cobb, the Georgia Institute of Technology climate scientist who led the research published yesterday in the journal
Science. "The answer is yes, tentatively so."
The 7,000-year portrait painted by the corals she examined suggests El Niño may get stronger as the level of carbon dioxide in the atmosphere climbs, Cobb said.
But researchers will need to do more work -- including a concerted effort to fill gaps in the record of El Niño's past behavior -- to prove that connection, for now a tentative one, she said.
"It could be thrown out," Cobb said. "But whatever the result, we will have confidence with more data."
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https://www.scientificamerican.com/...hens-link-between-el-nino-and-climate-change/