Our ability to predict El Niño/Southern Oscillation (ENSO) activity is hampered by the relatively short length of the instrumental record. An annually resolved record of ENSO variability over the past millennium based on tree rings indicates that ENSO amplitude varies on a 50–90 year cycle, providing an important constraint for improving predictions.
- Jinbao Li
- Shang-Ping Xie
- Xiao-Tong Zheng