A paper published in Nature Climate Change yesterday looks at El Niño/Southern Oscillation (ENSO) patterns in recent years, and their effect on tree-rings.
Author Jinbao Li from the University of Hong Kong and his colleagues (including Shang-Ping Xie of the Scripps Institution of Oceanography) examined a seven-century long ENSO reconstruction based on 2,222 tree-ring chronologies from places as far apart as Indonesia, New Zealand and South America. In places where there is a lot of rain, the tree-rings grow wider in El Niño years, but narrower in places that dry up.
There is an increase in the effect of El Niño events on the tree-ring widths in recent years according to Li, who attributes this to global warming.
"There will be more severe drought and more widespread forest fires during La Niña years," says Li. "And there will be more storm floods during El Niño years in Southern California."
The 1997 El Niño cycle was one of the worst Li observed. He said years like '97 are becoming the new normal as climate change accelerates.