[Coral-List] El Ninos are highly unpredictable, coral evidence indicates

[Douglas Fenner]

We all know that some of the largest and most destructive mass coral
bleaching events occur during El Nino periods (like 1983 and 1989), so they
are important for coral reefs.  New evidence from coring corals indicates
that they are highly unpredictable, but also that variation in the 20th
Century was much higher than in most of the previous 7000 years (for
unknown reasons).

http://news.sciencemag.org/sciencenow/2013/01/el-ninos-are-highly-unpredictabl.html?ref=em
(open access)

The original Science article is at
http://www.sciencemag.org/content/339/6115/67

abstract:
The El Niño–Southern Oscillation (ENSO) drives large changes in global
climate patterns from year to year, yet its sensitivity to continued
anthropogenic greenhouse forcing is uncertain. We analyzed fossil coral
reconstructions of ENSO spanning the past 7000 years from the Northern Line
Islands, located in the center of action for ENSO. The 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. Twentieth-century ENSO variance
is significantly higher than average fossil coral ENSO variance but is not
unprecedented. Our results suggest that forced changes in ENSO, whether
natural or anthropogenic, may be difficult to detect against a background
of large internal variability.



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