Tree rings can be used to improve El Nino predictions in climate models, climate scientists have discovered.
The annually resolved tree-ring records from North America, particularly from the US Southwest, give an account of the intensity of El Nino events over the past 1100 years.
"Our work revealed that the towering trees on the mountain slopes of the US Southwest and the colorful corals in the tropical Pacific both listen to the music of El Nino, which shows its signature in their yearly growth rings," said Jinbao Li, International Pacific Research Center, University of Hawai'i at Manoa.
"The coral records, however, are brief, whereas the tree-ring records from North America supply us with a continuous El Nino record reaching back 1100 years," he added.
The tree rings reveal that the intensity of El Nino has been highly variable, with decades of strong El Nino events and decades of little activity.
Scientists found that tree rings in the US Southwest, agree well with the 150-year instrumental sea surface temperature records in the tropical Pacific.
The study has been published in the current issue of Nature Climate Change.