The Pacific weather phenomenon known as El Niño has
attracted a lot of attention this year as forecasters have puzzled
over its 'will it or won't it' behaviour.
In May, scientists were confidently predicting a
90 per cent chance of an El Niño materialising by the end
of the year. But it's proved elusive, with the odds of even a weak
event dropping to 58 per
cent earlier this month.
El Niño brings extreme rainfall to some parts of the
world and drought to others. So predicting when one will make an
appearance and how big the effects will be is important.
A new study just published in Nature uses a diverse
array of different data sources, from corals to computer modelling,
to unravel what's been driving changes in El Niño over the past
Pinning down this
enigmatic phenomenon is tricky, the study concludes. But
there's reason to believe climate change could lead to stronger El
Niño's in the future, say the scientists.
El Niño and climate-readiness
Every five years or so, a change in the winds causes a
shift to warmer than normal ocean temperatures in the
equatorial Pacific Ocean - a phenomena known as El
Together, El Niño and its cooler counterpart La Niña
are known as the El Niño Southern Oscillation (ENSO). Cycling
between the two phases is responsible for much of the variation we
see in global climate from one year to the next.
Knowing if and how climate change will affect El Niño
and La Niña is an important scientific question, says Professor Kim
Cobb, co-author on today's paper. She
told us recently:
"Preparing for large swings in temperature and
rainfall is critical to adaptation strategies, especially if such
variability will increase in the future."
In theory, human-caused warming could increase the
strength of ENSO events, Cobb continues:
"It is important to remember
that climate change is much more than "global warming" … Because
ENSO involves feedbacks between the wind strength, ocean
temperature, and circulation, a change in any related climate
parameter would arguably have some effect on ENSO strength".