From the Scripps Institution of Oceanography comes excited
news on the climate conundrum that is El Nino, more correctly known as ENSO.
Anyone who has studied climate science will know that ENSO
has always been a bit of an enigma, especially when it comes to the role it is
playing in current climate change. More than other oscillations (such as the
North Atlantic Oscillation) ENSO affects global climate and its presence in
climate records can often be a smokescreen behind which the real climatic story
lies. A recent study may have gone a long way clarify ENSO in the context of
recent climate patterns.
The study, published in Science, processes data from fossil
corals – I use the term loosely, the oldest sample used was 7,000 years old
which is half a geological heartbeat – to reconstruct tropical climate in fine detail.
With over 15,000 samples analysed it hasn’t been a short term project but the
results would appear to have been worth it.
The data shows that 20th century ENSO events have
been of higher magnitude than those of the previous 7,000 years as preserved in
the coral samples. However it also reveals that a similar level was reached, albeit
for a short period of time, 400 years ago and that in general there is a high
degree of variability in ENSO magnitude (described as a ‘noisy background’).
On one hand this suggests that current ENSO levels may not
be linked to anthropogenic climate change. However there is also no denying
that, as the project’s lead scientist states ‘…the 20th century does stand out, statistically, as being
higher than the fossil coral baseline’.
What is important about this new work is not that it
confirms ENSO’s relationship to recent climate change (it doesn’t) but that it
has generated a record of ENSO variation of unprecedented detail which will be
invaluable in future work. It may be especially useful in helping to calibrate
climate models which have previously projected a different pattern for ENSO.
(Here is what Science has to say about the study and here isthe study itself, from the January 2013 issue of Science)
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