it influences weather patterns across
the world from America to Antarctica to
Australia from the Spanish for little
boy it's known as El Nino it's other
cycle is La Nina or little girl with the
in-between phase called neutral the
swing between these phases forms the El
Nino Southern Oscillation or ENSO one of
the most important climate drivers in
the world ENSO is a major influence on
Australia's climate El Nino and La Nina
events can cause natural extreme events
such as bush fires droughts heat waves
floods and cyclones
as the Earth spins tradewinds stream
across the planet driving warm surface
sea waters across the vast Pacific Ocean
these sea surface temperatures create
predictable patterns of circulation in
the atmosphere and ocean climate
scientists gather data from ships
weather stations ocean robots and
satellites to measure the swing between
the three phases of ENSO neutral El Nino
and La Nina a La Nina event tends to
bring above-average rainfall to eastern
Australia during an El Nino event there
is a greater chance of droughts and bush
fires each El Nino and La Nina event
lasts about 6 to 12 months it takes on
average four years to cycle from El Nino
to La Nina and back again but no to El
Ninos are the same the strong 1997-98 El
Nino impacted every continent in the
world causing widespread devastation
worldwide this story begins in the
eastern Pacific here trade winds blowing
from east to west push warm surface
waters across the planet piling up more
water in the western Pacific above the
ocean warm air rises driving atmospheric
circulation patterns known as Walker
circulation cold nutrient-rich waters up
well in the coastal ocean replacing the
warm water pushed away by the trade
winds like an athlete pumping iron the
La Nina is the muscled-up version of the
neutral phase trade winds become strong
and more warm water builds up in the
West Pacific
the excess of warm water increases
evaporation and precipitation causing
floods and forming tropical cyclones of
the northeastern Australian coast this
warm water escapes through the gap
between Indonesia and Australia to
supercharge the lewin current a 5500
kilometer long flow of warm waters along
the Western Australian coast but like an
athlete
the winds can't keep pumping at this
speed forever sometimes the winds weaken
and warm water sloshes back across the
ocean to the East Pacific the Walker
circulation breaks down weakening or
even reversing the trade winds warming
of the eastern Pacific accelerates
setting off a feedback loop that keeps
most of the rain producing evaporation
in the middle of the Pacific due to the
movement to the east of warm surface
waters northern and eastern Australia
experienced clearer skies higher
temperatures heat waves and increased
risk of drought off the coast fewer
tropical cyclones form as tropical
activity is concentrated further east
off the coast of South America upwelling
of cold waters is suppressed and warmer
surface waters result in higher than
normal rainfalls and sometimes flooding
and hurricanes in Western Australia the
lewin current tends to be weaker and
cooler during El Nino events
during the 2010-2011 Lenina marine
waters that were up to five degrees
warmer than usual caused mass deaths of
marine life as well as coral bleaching
along the western australian coast
however wall Milania waters are
generally beneficial for species such as
the western rock lobster whose larvae
ride the lewin currents southwards
inland in young years more lobster
larvae settle to the ocean floor meaning
greater numbers are available to
fisheries 2015 is the first strong El
Nino in 18 years in the future
understanding when how and why these
events happen will help us to manage the
risks that they bring