Saturday, 10 May 2014

2014/15 - Most Hyped El Nino in History?

It would be hard to have missed all the hype surrounding the predicted El Nino this summer, the odds of which happening have recently been increased to 65% according to NOAA. The buzz surrounding it has been going on for 18 months or so now but has recently hotted up - in tandem with the waters of the equatorial Pacific - with speculation now reaching fever pitch in some quarters.

The boys and girls over at SkS were at the forefront of such speculation in April, suggesting that, though it was early days, 2014/15 might rival 1997/98 in intensity:

"Every now and then a very large event occurs, such as the one in 1997-1998 which broke surface temperature records at the time and caused worldwide disruption and damage. . . .

A powerful El Niño is by no means guaranteed, but should one develop mid-2014 to mid-2015 would likely be the hottest 12 months ever recorded. . . . .

As stated earlier, we only have just over two decades worth of reasonably detailed observations, so it is by no means guaranteed that a powerful El Niño will develop. But, based on what we have observed and our current physical understanding of the phenomenon, the evolution of an intense El Niño event is possible. It's true the models are not yet predicting a large event, but they did fail to predict the magnitude of the 1997-1998 event, so are not necessarily a reliable indicator of scale this far in advance. . . ."

Though they are at pains to stress that the arrival of a powerful El Nino later this year "would entail widespread weather-related disruption and suffering around the world" and so is not to be welcomed, it is not difficult to read between the lines to see that the authors would indeed in many ways welcome such an event because, besides being a Pause Buster par excellence, it would lend credibility to the idea mooted for years now by warmists that the 'missing heat' from anthropogenic global warming (not) these past 17 years 9 months has been lurking in the deep ocean.

"The hottest 12 months ever recorded" might coincide with such a Super El Nino if it were to form, says SkS. Goodness me, no wonder warmists are getting feverish with anticipation. Imagine the CAGW propaganda coup! Imagine the funding! So, when world temperatures suddenly accelerate as a direct result of the anticipated powerful El Nino, they can sit back smugly and say, 'We told you so':
'Be afraid, be very afraid'
'Climate change is happening', they will say.
'Gaze upon it in awe all ye non-believers and pesky anti-science, pseudo-sceptic deniers. Look and weep - 4 Hiroshimas per second, every second for nearly 18 years, suddenly unleashed upon the globe in just a few months courtesy of the Pacific belching out a big menacing cloud of AGW  Awesome! Trenberth et al were right, so stick that in your Faux Pause and smoke it! Only Big Green can save us now'.

So much for the hyperbole. Let's look at the facts as we understand them. A more sober and informative look at the prospects for a 2014/15 El Nino can be found at this Wattsupwiththat post by Bob Tisdale which compares the evolution of the powerful 1982/83 and 1997/98 El Ninos with the current one. Bob Tisdale points out that the Nino3.4 regional anomalies for 2014 are within "spitting distance" of the +0.5C threshhold to declare an official El Nino. Comparing water temperatures across the entire equatorial Pacific, Tisdale notes that:

 ". . . . warm water volume is lower and depth-averaged temperatures are less in 2014 than they were in 1997. Then again, they’re higher than they were in 1982".

So, in theory at least, 2014/15 could be slightly more powerful than 1982/83, but probably not quite as intense as 1997/98. Tisdale ends the post on a cautionary note:

"That feedback will eventually kick in to allow the 2014/15 El Niño to strengthen, if it hasn’t started already. The only questions now are how strong the El Niño will become and how long El Niño conditions will last. Everything depends on the weather in the tropical Pacific, which is why no two El Niño events are the same."

Joe Bastardi, in his excellent Saturday Summary gives his own personal take on the evidence (or not, as the case is) for 2014/15 being a Super El Nino here. He is in no doubt whatsoever that 2014/15 is being hyped like crazy at the moment by those who have an 'agenda'. It's hard not to agree with him.

On the subject of El Ninos in general and their effect upon the global climate, Judith Curry recently ran an excellent and very interesting guest post on Climate etc. authored by Donald Rapp. Rapp begins by questioning whether there is a link between rising levels of CO2 in the 20th Century and the prevalence of El Ninos:

"Why after 400 years of La Niña precedence, did periods of El Niños dominance start in the 20th century? And why did the two periods of strong El Niño dominance in the 20th century occur during a period when the CO2concentration was rising? Is there a link between rising CO2 and the El Niño – La Niña balance? But if there is such a link, why did El Niños become less prevalent than La Niñas from 1941 to 1976 and be in balance after 1998?"

Bob Tisdale thinks there is probably not a link between CO2 and ENSO. With reference to Tisdale's views on El Nino/La Nina Rapp says:

"The Pacific periodically goes through transitions from El Niño to neutral to La Niña, and vice versa. In an El Niño, warm waters cover a sizable portion of the Pacific, which heats the atmosphere. Tisdale has shown that at least in the 20th century, one can correlate durations of increase in global temperature with periods of El Niño dominance. Actually, the global warming of the 20th century correlates better with Niño indices than it does with CO2 concentration. He has therefore argued that a substantial part (if not all) of the global warming of the past ~120 years can be attributed periods of imbalance in favor of El Niños, rather than the effect of rising CO2concentration."

So we have two opposing theories. Firstly, global warming via increasing concentrations of CO2 causes there to be a predominance of El Ninos, which release excess heat stored in the Pacific resulting in rapid global warming, superimposed upon a more general warming trend, we might suppose. Very little or none of it natural. Secondly, we have the natural climate change hypothesis which says that warming per se is due to the prevalence of El Nino type conditions in the Pacific and cooling happens when La Ninas predominate. The most obvious question here of course is what, if anything, drives the pendulum swing from La Nina dominance to El Nino and vice versa? It's probably been happening for many thousands of years, so we can eliminate CO2 emissions, at least prior to the industrial era. Again, the most obvious candidate is solar activity.

But getting back to Rapp on Climate etc., he says:

"Starting in year 1900, and continuing to about 1941, El Niños were more prevalent and stronger than La Niñas. Also during this period, the earth warmed significantly. From about 1941 to about 1976, El Niños and La Niñas were fairly balanced, although there was a slight excess of La Niñas. The earth cooled slightly during this period but the prevalence of La Niñas was weak. From 1976 to 1998, El Niños strongly dominated over La Niñas. This 23-year period included the very strong El Niño of 1982-3 and culminated in the very strong El Niño of 1997-8. The earth warmed rapidly during this period from 1976 to 1998. In fact, about half the warming of the 20th century occurred during those 23 years. With the termination of the great El Niño of 1997-8, we entered a period of balance between El Niños and La Niñas and the earth’s temperature remained essentially unchanged from 1998 to 2014."

The implication is that the much talked about 'Pause' is caused by a neutral La Nina/El Nino balance. If 2014/15 produces a very powerful El Nino, this might kick start global warming again and end the current phase of ENSO neutrality with a return to a more general warming trend overlying a predominance of El Ninos. Personally, I think this scenario is unlikely, but we shall see.

Trenberth's view is that CO2-based global warming is mediated via heat stored in the oceans and periodically released via the incidence of El Ninos. Rapp questions this hypothesis:

"Trenberth’s view is that the earth is out of balance (acquiring more heat from the Sun than it can reject to space) and this excess heat finds its way into the oceans. When enough heat is stored in the surface waters, it eventually comes out as in the form of an El Niño. But, we have had El Niños on and off for hundreds of years without rising greenhouse gases, and there was very significant El Niño activity between 1900 and 1942 when CO2 concentrations were much lower. The regime shift at year 1900 was just as dramatic as the regime shift of 1977, and the persistence of El Niños from 1900 to 1942 was just as pervasive as that from 1977 to 1998. Any proposed explanation would have to deal with this widely ignored early phase of high El Niño activity."

So the 'small' issue of past natural La Nina/El Nino activity is actually a major stumbling block for those who argue that there are grubby black carbonaceous anthropogenic fingerprints all over the 20th Century warming period and the observed dominance of El Ninos throughout much of that time. But I am sure that this will not stop Trenberth and others loudly trumpeting that they have been vindicated if El Nino 2014/15 does indeed turn out to be the powerful "pause buster" which they are all hoping for. Certainly, it will provide added impetus for Obama's mad rush to green energy generation in the States and lend wholly artificial credence to loony Ed Davey's plan to push all of us here in the UK into energy poverty by reliance upon wind energy, whilst at the same time gobbling up large tracts of virgin US forest to feed Drax during periods of calm weather when each 350 foot turbine barely produces enough juice to boil a kettle.

Though the odds have shortened considerably on the incidence this summer of an El Nino, it is still by no means a certainty and there is no real way of predicting with any degree of accuracy the intensity or duration of any event. What strikes me though is the pattern of the Pacific Decadal Oscillation (PDO) throughout the 20th Century, which mirrors closely the shorter period ENSO oscillations throughout.

One can clearly see the intrinsic periodic oscillatory nature of PDO. One can clearly discern the various 'regime shifts' in the Pacific Ocean from positive (warm, El Ninos dominating) to negative (cool, El Ninas more prevalent). Though it is argued that the PDO is distinct from ENSO in that ENSO is a feature of the tropical pacific whereas PDO represents a spatial pattern of temperature anomalies across the North Pacific and occurs over decadal time-scales rather than months, there is reasonable evidence to suggest strongly that the oscillatory PDO modulates to some extent the behaviour of ENSO. To see that this is the case, one has only to look at the graph of smoothed Nino3.4 SST anomalies and compare it with the graph of PDO to immediately notice that the two are correlated, with positive Nino3.4 anomalies occurring largely within the envelope of the positive phase of the PDO.

Here is another plot of the PDO taken from climate4you:

Note the clearly defined regime shift in 1977 and the decline post 2000. The PDO has gone into negative phase. For this reason particularly, I suspect that, if we do see an El Nino this year and on into next, it probably will not be very intense. I personally would be most surprised if it got anywhere near the strength of the1997/98 El Nino or even the lesser 1982/83 event. The next few months will tell. Whatever the case, besides being probably the most hyped El Nino in human history, 2014/15 will no doubt also be the most intensively studied.

Correction 5th July 2014:

Latest data on PDO indicates that it moved into positive territory at the beginning of the year and has been increasing ever since. 

As can be seen from the above graph, it is in fact quite normal for PDO to go positive or negative in contrast to the predominant 'regime', but the magnitude of the positive shift looks to be quite unusual. So maybe there is indeed a chance that a moderate strength El Nino will form later this summer/autumn, though it still looks very doubtful that it will ascend 'super Nino' status. 

There is still the fact that subsurface warm anomalies in the Eastern Pacific have tailed off and unusually warm surface waters across the entire basin are tending to neutralise conditions favourable to the formation of El Nino. Latest assessment from NOAA: