Last updated October 10, 2018

Highly Variable El Niño–Southern Oscillation Throughout the Holocene

  • States that the sensitivity of the El Niño–Southern Oscillation (ENSO) to continued anthropogenic greenhouse forcing is uncertain
  • Analyzes fossil coral reconstructions of ENSO spanning the past 7000 years from the Northern Line Islands, located in the center of action for ENSO
  • Shows that corals document highly variable ENSO activity, with no evidence for a systematic trend in ENSO variance, which is contrary to some models that exhibit a response to insolation forcing over this same period
  • Finds that twentieth-century ENSO variance is significantly higher than average fossil coral ENSO variance but is not unprecedented
  • Results suggest that forced changes in ENSO, whether natural or anthropogenic, may be difficult to detect against a background of large internal variability