El Niño

Dangerous Progress Toward Strong El Nino Continues as Extreme Kelvin Wave Rises in Eastern Pacific

Robertscribbler,

8 May, 2014

It’s happening. The most powerful sub surface warming of the Pacific Ocean on record is continuing to progress into the Eastern Pacific even as it rises toward the surface. As a result, risks for the emergence of El Nino during 2014 are spiking together with the potential for a host of global weather extremes.

Over the past month, trade winds remained weak even as west wind back bursts continued to push against the trades along the Equatorial Pacific. Moderate west winds emerged during mid-to-late April northeast of the Solomon Islands while cyclonic lows produced sporadic west winds in the Central Pacific. By May, consistent west winds were blowing over a large section of the Eastern Pacific.

Upper level easterlies had also emerged reinforcing a general pattern toward El Nino development.

The strong Kelvin wave that, in March, featured the highest sub-surface temperature anomalies on record entered its upwelling phase and began to push more and more of its heat potential toward the surface in the Eastern Pacific. This propagation is clearly visible in the sequence below:

(Kelvin Wave monitoring by NOAA. Image source: Climate Prediction Center.)

As of May 3, 2-3 C above average water temperatures had hit the surface of the Eastern Pacific and 3-6+ C above average temperatures lurked not far below.

The result of this rising warm water pulse was above average sea surface temperatures across the entire Equatorial Pacific with anomalies for the broader region hitting +.62 C on May 8th, 2014. It is worth noting that for El Nino to be declared, Equatorial Pacific water temperatures in the mid to eastern Pacific must remain above +.5 C for two months running. And, at this point, conditions appear primed for just such an event.

(May 7, 2014 Sea Surface Temperature anomaly map shows Pacific Ocean looking more and more like an El Nino. Image source: NOAA ESRL.)

These clear ongoing trends have resulted in yet one more upgrade of El Nino potentials by the Climate Prediction Center (CPC) this week. Chances for El Nino in the current three month period of May, June and July have now been adjusted to about 55% with probabilities continuing to rise throughout the summer and fall. Peak chances for El Nino, according to CPC, are now just shy of 80% by October, November and December of 2014.

All values now show a very high degree of certainty that El Nino will emerge exceeding even the high confidence predictions provided last month by both NOAA and Australia’s Bureau of Meteorology (BOM).

 

(El Nino Prediction Chart as of May 8, 2014. Image source: CPC/IRI.)

CPC notes:

The model predictions of ENSO for this summer and beyond are indicating an increased likelihood of El Niño compared with those from last month. Most of the models indicate that ENSO-neutral (Niño-3.4 index between -0.5°C and 0.5°C) will persist through part of the remainder of the Northern Hemisphere spring 2014, most likely transitioning to El Niño during the summer. While ENSO-neutral is favored for Northern Hemisphere spring, the chance of El Niño increases during the remainder of the year, exceeding 65% during the summer.

When El Nino Comes Early, Risks of a Strong Event Increase

It usually takes until Fall or even Winter for a typical El Nino event to emerge. When El Nino comes early — by late spring or summer — risks increase that the event will be far stronger than normal. In general, such events are thought to be preceded by very strong Kelvin waves like the one we’ve witnessed since January.

Many Ocean researchers such as Dr Wenju Cai, a climate expert at Australia’s Commonwealth Scientific and Industrial Research Organisation, now consider the ocean to be primed for such a strong El Nino event.

Dr. Cai explains:

“I think this event has lots of characteristics with a strong El Nino. A strong El Nino appears early and we have seen this event over the last couple of months, which is unusual; the wind that has caused the warming is quite large and there is what we call the pre-conditioned effects, where you must have a lot of heat already in the system to have a big El Nino event.”

Rising Potential for Very Bad Weather

With the world’s weather already pushed to extreme states by human warming, the emergence of a strong El Nino would likely have increasingly severe consequences. Weather events at both the flood and drought extreme would be further amplified as a portion of hottest ever Pacific Ocean heat content transferred back to the atmosphere. This transfer would push a hydrological cycle already amped by more than 6% due to human-caused warming to a greater extreme. It would also likely result in new global high temperature records worldwide as a Pacific Ocean that had sucked up so much of excess human warming during the past decade and a half again becomes a major heat source.

Links:

NOAA’s Climate Prediction Center

NOAA ESRL

CPC/IRI

Ocean Data Points to Strong El Nino

Monster El Nino Emerging From the Depths

Hat tip to Colorado Bob

World is unprepared for major El Niño later this year

Wild weather is coming in 2014, with floods, storms and droughts expected around the Pacific, but little is being done to protect the people on the front line

by Michael Slezak

New Scientist,

May 2014

THE weather is preparing to go wild, and will wreak havoc and death around the globe later this year. An El Niño, a splurge of warm water in the Pacific Ocean, is coming. It will unleash floods in the Americas, while South-East Asia and Australia face drought. Yet little is being done to address these consequences.

"The tropical climate system is primed for a big El Niño," says Axel Timmermann of the University of Hawaii in Honolulu (see diagram).

An El Niño begins when warm water near Indonesia spreads eastwards and rises to the surface of the Pacific. The warm water carries rain with it, so El Niño takes rain from Asia and Australia and dumps it on the Americas .

The effects can be deadly. A big El Niño in 1997-98 killed 20,000 people and caused almost $97 billion of damage.

Meteorologists contacted by New Scientist all expect an El Niño at the end of this year. And it looks like a big one, says Wenju Cai of CSIRO, Australia's national research agency, in Melbourne. The more heat in the Pacific, the bigger the El Niño, and right now, 150 metres below the surface, a ball of warm water is crossing that ocean. "It's huge," says Cai.

Yet official forecasts remain cautious. As recently as 5 May, the US National Oceanic and Atmospheric Administration only said the odds of an El Niño would exceed 50 per cent this year.

Most El Niño researchers say forecasters are being too conservative. "One thing I hear over and over again is 'we do not want to create a panic'," says Timmermann. There is a reason: forecasting a big El Niño would cause a spike in food prices. "But it may be better to have this reaction at an early stage, when farmers can still adapt, rather than later."

The good news is that El Niño is a known quantity. "We already know what happens when a big El Niño hits," says Zafar Adeel of the United Nations University in Hamilton, Canada. That means vulnerable populations can be identified and emergency plans put in place. But not everywhere has a plan.

California, which faces floods, is well prepared for emergencies and has water rescue teams, says David McEntire of the University of North Texas in Denton. But Central and South America are more vulnerable (see "In the firing line") and it is unclear what will happen in Asia and Australia ). India has invested in water storage in case of drought.

Local forecasts are crucial, says Zafar, because large-scale predictions can get the fine detail wrong. In 1997, after a coarse-grained forecast, Costa Rica moved thousands of cattle away from an area where drought was expected. But they moved into an area of worse drought and died.

A big El Niño does not have to be a disaster. Impacts like shifting fish stocks and changes in rainfall can be handled, or even turned into benefits, if people are prepared for them. "But you need that trigger saying 'yes it's going to be a big one'," says Zafar.

Monsoon disruption

Asia and Australia will see less rainfall as a result of El Niño, leading to drought and wildfires. But many impacts depend on how El Niño affects the monsoons, which is hard to predict.

"There is no other phenomenon that can influence the monsoons like El Niño," says Krishna Kumar of the Indian Institute of Tropical Meteorology in Pune. If it weakens the Asian monsoons, it will threaten the food supply of billions of people.

Most El Niños weaken east Asian monsoons, but the Indian monsoon may survive. El Niños have caused the Indian monsoon to fail, however the 1997-98 El Niño didn't, despite being the biggest on record (Science, doi.org/fj7cbx). Kumar says the coming El Niño looks similar to the 1997-98 event, so India might be lucky.

Rising waters

The western US faces storms and floods from an approaching El Niño.

The sea level along California's coast may rise 30 centimetres, and then be pushed even higher by storm surges, says Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colorado. Extra water may sound good, because California has been hit by a severe drought. But the raised seas may combine with heavy El Niño rains to cause devastating floods, as happened to the San Francisco area in 1997-98.

El Niño also brings warmer weather, which melts ice. In 1997, extra river water in North Dakota and Minnesota may have contributed to the worst flood of the Red river since 1826.

In the firing line

When El Niño arrives, Central and South America face a mix of storms, floods and droughts.

These countries are more vulnerable to the effects of El Niño than the US, partly because they have less money. "Poverty is a major cause of vulnerability," says David McEntire of the University of North Texas in Denton.

However, more-developed regions are not always better off, says McEntire. Development causes its own problems, such as greater use of dangerous chemicals that can escape during disasters. And wealthier regions produce less of their own food, so can run short quickly.

As a result of all these issues, most countries in Latin America have become more vulnerable to El Niño, says Rodney Martínez of the International Research Centre on El Niño in Guayaquil, Ecuador. Even though many have El Niño response plans, the risks have grown thanks to population increases and crops being planted in high-risk zones. Such countries can also struggle to give each area a warning that is local enough.