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Monster
El Nino Emerging From the Depths: Nose of Massive Kelvin Wave Breaks
Surface in Eastern Pacific
(A monster Kelvin wave, possibly more powerful than the 1997-98 event, is now rushing toward the surface of the Eastern Pacific. Image source: NOAA/ESRL.)
24
March, 2014
We
are observing an extraordinarily powerful Kelvin Wave, one that was
likely intensified by factors related to human global warming,
traveling across the Pacific. It appears to be an epic event in the
making. One that may be hotter and stronger than even the
record-shattering 1997-98 El Nino. What this means is that we may
well be staring down the throat of a global warming riled monster.
*
* * * *
Ever
since the early 2000s very strong east to west trade winds have been
blowing across the Pacific. By around 2010, the force of this wind
pattern had risen to never before seen records. Over the years, these
record winds piled very warm waters in a region of the world east of
the Philippines and Australia. As the pool grew warmer, evaporation
increased and salinity levels in the hot water pool spiked.
Increasing salinity in the zone resulted in a down-welling current
that transferred heat into the ocean’s depths.
By
2013, this hot water pool had grown into a vast abyss of heat.
Cyclones forming over this zone experienced a kick in intensity as
the typical upwelling force of their winds only dredged more hot
water from the ocean deeps. It was a pattern that is contrary to
typical tropical storm dynamics in which cooler waters drawn up by
intense storms tend to limit their peak strength. Not
so with mega-typhoon Haiyan, the strongest storm ever to strike land.
The cyclonic wind pattern only dredged more heat from the
extraordinarily deep hot water. And
so the storm only grew stronger and stronger, knowing little in the
way of limits before it barreled into an already storm-battered
Philippines.
After
Haiyan’s passage, the heat pool remained, only growing deeper and
more intense, waiting for a change in the wind. And by January of
2014, that wind change was already well on its way.
In
Deep, Hot Water
Like
an enormous bag waiting to burst eastward, the hot water pool
contained temperatures of 29-30 degrees C or hotter and sagged deep,
extending up to 150 meters below the ocean surface. A vast stretch of
explosive heat that had been held in check from an equatorial surge
only by the strongest trade winds on record. But by January, those
trade winds had faded. The east-west flow first weakened, then it
fluttered, then it died, allowing the wind direction to reverse.
(Did
strong trade winds intensify the current Kelvin Wave by piling hot
water into the Western Pacific? Top graph shows ocean heat content
rise, bottom graph shows zonal wind strength of the trade winds
through 2011. Note that IPO divergence roughly correlates with trade
wind intensity fluctuation. Image source: England
Study.)
This
trade wind reversal has, since January, been facilitated by a string
of explosive low pressure systems that developed in the vicinity of
the Western Pacific both south and north of the equator. Northern
hemisphere storms circulate in a counter-clockwise fashion while
southern hemisphere storms circulate clockwise. When the storms line
up, they kick storm winds out along the equator, providing strong
reversals to the trade winds and further shoving our hot, monster
Kelvin Wave to the east.
And
as the trade winds fell and reversed due to this sporadic assault of
countervailing storms, the hot, deep pool of water surged eastwards.
To those on the surface, the motion was invisible. And but for a
series of floats spread throughout the Pacific, we would never know a
monster thing was rushing along toward the east at a depth of about
150 meters below.
But
the floats did their work and by late February it looked like a
rather strong heat pulse was on its way across the Pacific Ocean.
Risks began to dramatically increase that the heat would breach the
surface of the Eastern Equatorial Pacific and set in place the
globe-altering weather pattern called El Nino. In a world where human
warming was already having serious impacts, the emergence of a new,
potentially strong El Nino was not at all a welcome sign. For one, it
meant new global high temperature records were likely to soon follow.
It
also meant that world food security may well be about to receive yet
one more staggering blow.
First
Warnings
As
the signal for a new El Nino began to appear in the models during
late February,NOAA
started to issue watches and predictions.
Initial estimates were for a 52% chance of El Nino by late 2014.
These
warnings caused a ripple of concern through the global food markets.
Already
reeling under the insults of a series of severe, climate change
induced, droughts from Brazil and Argentina, to California and Texas,
to the Middle East, to China, the world’s growers were hardly
prepared for another series of anomalous weather events. Russia
rolling into bread-basket Ukraine further set anxieties alight.
But the threat of even a moderate El Nino and its associated droughts
and extreme weather seemed to be a rising perfect storm for what was
already a terrible year.
Southeast
Asia often experiences an interruption of the annual monsoon in
association with El Nino. So the region, which was already suffering
from ground water shortages, lowering glacial outflows and sporadic
periods of intense drought — all conditions related to growth,
over-consumption and climate change — could ill afford yet one more
strike against it.
Still,
the strike appeared to be gathering heat and steam.
A
Rising Monster Pushing the Tip of Its Nose up in the
Eastern Pacific
Eastern Pacific
As growers and states with marginal or bad food security grew more anxious, the hot water surge intensified. Researchers independent of NOAA began to issue estimates for a 60, 70 even 80% probability for the emergence of El Nino. Others, tracking what now appeared to be the hottest Kelvin wave ever seen, began to issue warnings that a monster event may well be on the way.
(Most
recent NOAA Kelvin Wave assessment. Top panel shows deep water high
temperature anomalies telegraphing across the Pacific and pushing
toward the surface. Large, deep pool of hot water providing energy to
for the wave is visible in the bottom panel. Image source: NOAA.)
At
issue were deep ocean temperature anomalies that were now rushing
across the Pacific and beginning to rise toward the surface. The zone
in late February that had indicated temperature anomalies in the
range of +4-6 C was over an area of approximately 48 degrees of
longitude. By March 19, the hot zone of 4-6 C above normal
temperatures had expanded to cover about 62 degrees of longitude, and
contained a hotter 5-6 C anomaly zone that was now larger than the
4-6 C zone from late February. The deep, hot water pool in the
Western Pacific was now beginning to set up a kind of bridge in which
it could transfer east, dump its heat into the atmosphere and disrupt
global weather. Perhaps, somewhat more disturbing, it was linking to
a deep pool of warmer water off the coast of South America (also see
animation at the top of this post).
By
comparison, the monster El Nino of 1997 featured a Kelvin Wave
covering about the same area but whose high temperature anomalies
only peaked out at about 4.5 C above average. So the current Kelvin
wave is of approximately the same size but, based on current
observations, appears to contain more heat.
The
Kelvin wave had also begun to tilt up in the front with its ‘nose’
just starting to break the Pacific Ocean surface at between 120 and
100 West Longitude. This put the tip of the rising heat spike almost
due south of Baja California and almost due west of the Peru and
Ecuador border as of yesterday, March 23.
(Monster
El Nino pokes the tip of its nose through Pacific surface waters
between 120 W longitude and 100 W longitude along the equator. Image
source: NOAA/ESRL.)
In
the above ocean temperature anomaly measure for March 23, 2014, we
can see a hot pool in the range of 1 to 2 C above average beginning
to emerge between 120 and 100 West Longitude. It is a heat pulse that
has eliminated all but the closest near-shore cool upwelling along
the west coast of South America.
Should the rest of the Kelvin wave follow, temperature anomalies in this region will spike well above 4 C and possibly has high as 5-6 C. Such an event would be even stronger than the one seen in 1997-98, drive global temperatures about .05 to .2 C hotter than previous records in a single year, and set off a series of extreme weather that, when combined with the already severe conditions set in place by human-caused warming, may well be far in excess of those seen during past events.
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