Will global warming survive a strong La Nina?

Guest post by Frank Lansner

A global temperature stagnation despite warm El Nino year 2010?

After the warm El Nino period 2009-2010, global temperature trends starting 1998 has generally turned positive:

The period starts out with a strong El Nino in 1998, however a strong La Nina lasting 3 times longer also has a strong effect on temperature trends starting 1998.

Temperature trends from 2002:

Thus removing the 1998 El Nino and 1999-2001 La Nina significantly cools the trends. The overall picture is now temperature stagnation 2002-2010 9 years.

The global warming theory generally suggests heating, but one can say that a period of roughly a decade with no temperature rise might be an expected deviation from the general trend.

However, things get worse for the global warming idea. Problem is that 2010 in the very end of the shown period is in fact a rather warm El Nino year. And still, the trends 2002-2010 are just… flat. Even now after the warm 2010. As if the global warming idea just barely holds on in the months just after a warm 2010.

However, things get even worse for the global warming idea. The powerful La Nina is now showing its strength as we have witnessed temperature dive in the latest months. The NCEP prognoses roughly indicates a further drop of probably more than 0,1 K from dec 2010 to jan 2011. And the La Nina – allthough predticed to weaken during spring time – is by many predicted to match the 1999-2001 La Nina.

IF the present La Nina will resemble the magnitude and effect of the 1999-2001 La Nina, how would this affect the temperature trends from 1998 that already seems to have stagnated for a decade?

A “simulated” La Nina 1999-2001 by just assuming the same temperature flow repeated starting Januar 2011 to get a rough idea. Now suddenly we have a full 16 years period of no warming. In fact we mostly see cooling trends. (If we imagine yet an El Nino to occur thereafter, then after 17 – 18 years, perhaps we will still just have a flat curve??)

And “Uhh Ohh” whats going to happen if we simulate a 1999-2001 La Nina on the graph starting at 2002??

In this view, we see 12 yeas of strongly falling temperature trends.

La Nina is upon us, and that it won’t help the global warming message.

—– * ——

Method used above is basically saying:

“How many years can we go back and still see temperature trend stagnation or trend decline?”

If we want to have an answer to this question, typically the year 1998 or 2002 will be the start year of the new stagnating (or falling) temperature trend.

The classic alarmist argument is then: But we have had 5 year, 7 year and 8 year trends before without the longer warm trend has changed.

This is true, however, these dives in temperatures are almost always connected with the large volcanic eruptions as Lucia from the Blackboard here shows:

 

So, when we use 1998 or 2002 as start years, and only thereby can read the length of the present stagnating/falling temperature trend, we have to know: This time there are no volcano to blame.

And when the result – for example after the La Nina prognosis shown above – may give us 12-15-18 years of stagnating/falling trends – without the help of volcanoes – then this IS something significant against anything we have seen in the last decades of warming.

And without using start years 1998 or 2002 we cant tell how many years the falling trend this time is. Therefore its perfectly relevant to use 1998 or 2002 as start years.

And as fig 2 here indicates

http://bobtisdale.blogspot.com/2009/06/usgcrp-report-global-climate-change.html

the 1998 El Nino may have lifted the whole temperature level (perhaps by warming the Arctic) and in this context, it is definitely relevant to analyse using start point 1998.

There are many ways of defining how the temperature trend is best described, but the idea that we had a level shift in temperature 1998 too makes it relevant to checkout trends after 1998 red dotted line:

 

– more articles by Frank Lansner

http://hidethedecline.eu/pages/posts/a-brief-overview-of-chosen-frank-lansner-articles-in-english-208.php

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DirkH

Don’t worry. We have more CO2 in the air now, that’ll keep us warm. /sarc

ENSO makes havoc with short-term trends. When using northern extratropics as warming metrics, which somehow dictate the global trend, one can see the downturn has begun
http://climexp.knmi.nl/data/icrutem3_hadsst2_0-360E_30-90N_n_su_1990:2011.png
Oh, and since NH is back on the 1990 level, i declare all those “extreme weather events due to AGW” completely irrelevant.

Grumpy Old Man

Let’s hope Yellowstone doesn’t blow. Or we’re really in the deep mire. I don’t want cold, I want warm.

DD More

“In this view, we see 12 yeas of strongly falling temperature trends.
La Nina is upon us, and that it won’t help the global warming message.”
But Hansen was able to declare total run-away warming with just 10 years of change. From his graph, low point around 1978, to his famous 1988 Congressional meeting.
Forget about 30 years to see a climate shift.

SSam

You don’t need a Yellowstone. There are any number of volcanoes that are at or near the “pop the cork” stage. Grímsvötn, in Iceland tends to go off every 4 to 6 years and has inflated to the levels equal to or higher than it’s last eruptive event. A moment tensor plot for that one:
http://hraun.vedur.is/ja/vatnajokulsvoktun/grf_uppsafn.html
Grímsvötn along with Bárðarbunga, are the two dominant central vent volcanoes that sit under the Vatnajökull icecap with the five other volcanoes quietly biding their time.
Then there are the ever prolific Kamchatka peninsula volcanoes, they seem to erupt at the drop of a hat.
Add to that the rest of the ones around the world… well, there are enough out there to ruin your day if the timing gets bad.

Mike McMillan

We did have the Eyjafjallajökull eruption last year, so that may have some cooling influence, unless it was a local phenomenon like the MWP.
Dr Hansen’s GISS line on the charts is so, fer shure, like totally bogus.
It keeps leaping up, trying to set new records, then dropping back to gather strength for the next attempt. It’s like one of those spawning salmon trying to leap the falls.

Thanks for this. Bad news for those betting on yet a warmer decade befalling us.

Chris Smith

Trends which are so hard to detect are not trends – they are noise.
There may or may not be a trend, but if there is a trend, it is so small as to be undetectable.
You can choose endpoints to make it go up, or down or horizontal.
Why is anybody claiming that there is a dangerous trend here? It is a noisy signal that happens to be a bit higher at some recent points. It is not massively higher and if we look back even further, it has been higher without humans. What is all the fuss about?

George Tetley

How is it that politicians and greens both have the same problem, maybe its that there problem is a birth defect, or perhaps its those that have the ability to inquire and question the results that upset the green Utopia.

randyinsd

Very interesting data demo. Am currently reading Robert Bryce’s latest book “Power Hungry: The Myths of “Green Energy” and the Real Fuels of the Future.” Given the apparent lack of meaningful correlation between increasing carbon dioxide levels and global mean temperature one can only wonder what “angle” the “green” energy proponents will use to continue to sway political opinion in their favor.

If the ratio of El-Nino to La-Nina changed recently from the positive side towards the negative side.Then Global warming is indeed going to stop.
But Global Warming has never been global for at least the last 32 years anyway.
It has been mostly confined to the Northern Hemisphere since the 1970’s.

Mohatdebos

Forget the volcanos, it is much more interesting to speculate on the explanations the warmistas will come up with to explain the coming cooling (that has already started). This year they came up with warmcool — Europe is cold because the Hudson Bay did not freeze. What will it be next year!

This time there are no volcanoes to blame? Hah! Look see…
http://www.poetpatriot.com/timeline/tmlndisvolcanos.htm
What about cumulative effects? Or northern transport theory?

ShrNfr

There is a good chance of a nor’easter coming up the Atlantic coast and throwing more snow at all the folks on the east coast. This is starting to feel link 1978. For those who have forgotten, there were a couple of big snows that did not melt in 1978 before the blizzard hit. The blizzard would have been just your average severe storm except for the fact that the earlier ones left no place to put the snow.

Peter Miller

Just some more relevant stuff you won’t see in the next fantasy report from the IPCC.
Alarmists revel in El Ninos, as it supposedly proves their point, while La Ninas are either ignored or dismissed as irrelevant aberrations.
This post should generate more than the normal amount of rants from the AGW faithful.

Frank Lansner wrote, “And the La Nina – allthough predticed to weaken during spring time – is by many predicted to match the 1999-2001 La Nina.”
Please provide links to the web pages of the official government forecast models that predict a repeat of the 1998/99/00/01 La Niña.
Also how did you “simulate” the effects of a new multiyear La Niña? Splicing some new wiggles onto the spreadsheet is meaningless without an explanation. Please explain using one dataset.

SSam

Re: Mike McMillan says:
“…We did have the Eyjafjallajökull eruption last year…”
Funny that. On at least three occasions, Eyjafjallajökull has gone off pretty much in conjunction with it’s neighbor, Katla. The idea being that one triggers the other. This lead to a lot of press screaming about a looming catastrophe. Sure, it was bad enough to the air travel industry, but the tie in with Katla deserves a closer look.
In the geologic record, Eyjafjallajökull has erupted four times… add the most recent and that makes it five. In the same period, Katla has erupted 131 times. On average, about every 64 years. Eyjafjallajökull’s average is 423 years. So, it’s pretty hard not to have an eruption of Eyjafjallajökull that is not closely spaced in time to a Katla event. I think the largest offset is 10 years, and in that case Katla preceded Eyjafjallajökull. (Katla again erupted 40 years later.)
Humor is where you find it.

Carl Chapman

If the sun’s magnetic field continues to weaken, and we’re entering a repeat of the Maunder Minimum, then another trend would need to be imposed on top of the El Nino/La Nina. It could be much more significant. Hansen would need to make Herculean efforts to “adjust” that sort of cooling away.

David L

Doesn’t matter. Hansen and others, the keepers of the sacred data, fiddle with the numbers. So regardless of what nature is doing, they’ll keep fiddling to their benefit. All the global warming is “happening” where nobody lives (like the arctic) so it’s impossible for the average person to know for sure.

I hope the drop from now is only to -0.3 before the bounce. It all depends what that big deep mysterious ocean does. I calculate it will bottom out at around -0.32 +/-0.05C towards the end of 2011 according to Roy Spencers metric/ I think it may fall further than that, but it’s only a hunch.

Carl Chapman

When the sun’s activity is low, as in the Maunder Minimum and the Dalton Minimum, does that change the SOI to more of the cool La Nina and less of the warm El Nino? Are there records of El Nino/La Nina going back that far?

richard verney

Interesting post. Although, I like the warm and would not be troubled of the world were to warm, I am looking forward to seeing the extent to which 2011 will cool and what bounce back there will be following La Nina. I think that this will tell us quite a bit, and it is the best prospect of some reality filtering into this debate.
One thing is sure, we do not want a volcano eruption since that will confuse the issue. The warmist will argue that the eruption caused the cooling (assuming that 2011 and 2012 will show some cooling) and we will never know to what extent that claim may be correct. We want to be able to witness a natural cycle without some further forcing.

Caleb

The GFS 2m chart already supposes an anomaly of under -.24, with an anomaly in the 18 hour forecast of nearly -.30, before it bounces back up towards normal. (And I think the bounce-back is partly due to the fact the long-term modeling is based on “norms.”) (You can’t really trust the GFS, in the long term.)
The Global anomaly is shown in small red writing just above the right side of the map at:
http://www.coaps.fsu.edu/~maue/extreme/gfs/current/raw_temp_c.html#picture
This is a neat map to check out on a regular basis, just to see what the GFS computer is up to. Also the “current” map gives you a rough idea of what the global temeperatures are up to. They have really been plunging the past couple of months.

Cold is hot, warming causes freezing, freedom is slavery, ignorance is strength, …

Murray Duffin

I havbe been trying for about 3 weeks to find a way to submit this: http://agwnot.blogspot.com/2011/01/chaotic-climate-and-next-ice-age-four_23.html
as a guest post. It follows logically several items that have been posted recently, and might stumilate some interesting discussion.
[Reply: Submit it to Tips & Notes. ~dbs, mod.]

And for those interested, the post Frank was attempting to link does work.
http://bobtisdale.blogspot.com/2009/06/usgcrp-report-global-climate-change.html
And the illustration he referred to was this one:
http://i44.tinypic.com/16leq39.jpg
It’s from my post “RSS MSU TLT Time-Latitude Plots…Show Climate Responses That Cannot Be Easily Illustrated With Time-Series Graphs Alone.”
http://bobtisdale.blogspot.com/2009/06/rss-msu-tlt-time-latitude-plots.html

La Nina with the low solar activity will make the next decade interesting to watch. I think there will be some strong cooling for the next ten years.
John Kehr

Werner Brozek

“Mike McMillan says:
January 23, 2011 at 11:30 am
Dr Hansen’s GISS line on the charts is so, fer shure, like totally bogus.”
I would find that hard to argue with. I did some number crunching and came up with this:
I have read that GISS is the only record that is accurate since it adequately considers what happens in the polar regions, unlike other data sets. I have done some “back of the envelope calculations” to see if this is a valid assumption. I challenge any GISS supporter to challenge my assumptions and/or calculations and show that I am way out to lunch. If you cannot do this, I will assume it is the GISS calculations that are out to lunch.
Here are my assumptions and/or calculations: (I will generally work to 2 significant digits.)
1. The surface area of Earth is 5.1 x 10^8 km squared.
2. The RSS data is only good to 82.5 degrees.
3. It is almost exclusively the northern Arctic that is presumably way warmer and not Antarctica. For example, we always read about the northern ice melting and not what the southern areas are gaining in ice.
4. The circumference of Earth is 40,000 km.
5. I will assume the area between 82.5 degrees and 90 degrees can be assumed to be a flat circle so spherical trigonometry is not needed.
6. The area of a circle is pi r squared.
7. The distance between 82.5 degrees and 90.0 degrees is 40,000 x 7.5/360 = 830 km
8. The area in the north polar region above 82.5 degrees is 2.2 x 10^6 km squared.
9. The ratio of the area between the whole earth and the north polar region above 82.5 degrees is 5.1 x 10^8 km squared/2.2 x 10^6 km squared = 230.
10. People wondered if the satellite record for 2010 would be higher than for 1998. Let us compare these two between RSS and GISS.
11. According to GISS, the difference in anomaly was 0.07 degrees C higher for 2010 versus 1998.
12. According to RSS, it was 0.04 degrees C higher for 1998 versus 2010.
13. The net difference between 1998 and 2010 between RSS and GISS is 0.11 degrees C.
14. If we are to assume the only difference between these is due to GISS accurately accounting for what happens above 82.5 degrees, then this area had to be 230 x 0.11 = 25 degrees warmer in 2010 than 1998.
15. If we assume the site at http://ocean.dmi.dk/arctic/meant80n.uk.php can be trusted for temperatures above 80 degrees north, we see very little difference between 1998 and 2010. The 2010 seems slightly warmer, but nothing remotely close to 25 degrees warmer as an average for the whole year.
Readers may disagree with some assumptions I used, but whatever issue anyone may have, does it affect the final conclusion about the lack of superiority of GISS data to any real extent?

Frank Lansner: You introduced your final graph with, “There are many ways of defining how the temperature trend is best described…” And you used what appear to be 3rd, 4th, and 5th order polynomial trend lines on the graph. Polynomial trends are always a mistake when attempting to imply future changes in temperature. I’ve duplicated your graph with the poly trends, but using HADCRUT global temperature anomalies:
http://i51.tinypic.com/2khgf7.jpg
The poly trends all appear to have peaked around 2005, especially when they’re all grouped together.
But the problem with poly trends is they can be extended back in time to show that their use as a predictive tool is poor, to say the least:
http://i55.tinypic.com/9lifqh.jpg
And if they can’t hindcast, what good are they for implying a forecast? None:
http://i52.tinypic.com/10wuyb7.jpg
I would strongly suggest that you stop using poly trends to imply future changes in temperature.

Claude Harvey

How many times could a local prophet be wrong before the townsfolk took him off the payroll? Ma and Pa Kettle can read a thermometer and they can see the ocean. I cannot imagine they much appreciate an army of government funded “scientists”, being paid for with their tax dollars, telling them they’re about to burn up and die if they don’t drown first.

Caleb

Bob Tisdale,
Actually I think your poly trends for the future are spot on.
Red = inflation rate
Purple = WUWT readership
Green = Confidence in GISS
Blue = Number of hairs remaining on my head
By the way, thanks for all your solid work.

Jay

Bob Tisdale wrote:
“Also how did you “simulate” the effects of a new multiyear La Niña? Splicing some new wiggles onto the spreadsheet is meaningless without an explanation. Please explain using one dataset.”
The graphs are interesting, but like the AGW proponents, it is too much reliant on simulations. Interesting speculation, but not data.
-J

Cam (Melbourne, Australia)

La Nina is natural variability – El Nino is climate change.
Above-average rainfall is natural variability – below-average rainfall is climate change.
Cold extremes is natural variability – heat extremes is climate change.
Deadly wildfires are climate change – deadly floods are climate change…..? what – woops, hang on I’ve got myself confused now!!
Oh heck – let’s just say every weather event is our fault and be done with it.

Dear Bob..
There has been many suggestions of a strong La Nina now, one of the latest here from NASA:
http://www.ouramazingplanet.com/current-la-nina-could-be-strongest-ever-recorded-0987/
“current la nina could be strongest ever recorded” Jan 2011
or
http://www.bom.gov.au/climate/enso/
“One of the strongest La Niña events on record ” 19 Jan 2011.
Etcetc.
Bob, this article is not a debate exactly of how strong the coming Nina will be of what type etcetc.
The 1999-2001 La Nina was not one of the strongest La Nina on record but in stead it was a longer duration. I coud have chosen the 1988-89 in stead. The point is that a strong La Nina now certainly prolongs the period of missing heat in the temperature trends for years. This to say: The type and strength of the coming La Nina is a serious challenge to the AGW.
Then you write:

And if they can’t hindcast, what good are they for implying a forecast? None:
http://i52.tinypic.com/10wuyb7.jpg

I did not forecast temperatures using Hadcrut temperature history or similar.
K.R. Frank

Cam (Melbourne, Australia) says: January 23, 2011 at 3:32 pm
“La Nina is natural variability – El Nino is climate change.”
This is VERY true 😉
K.R. Frank

Theo Goodwin

I thought this little graph project was very interesting. What the author did is start with Warmista graphs and construct his own graphs. What the author is doing is projecting new graphs from old graphs and his conjectures. That’s better than the Warmista. Because Warmista do no more than project new graphs from old graphs and they manufacture their own data. None of it is prediction. No one has a set of physical hypotheses describing all the relevant features of Earth’s atmosphere, ocean, and land that would permit the needed predictions.

David A. Evans

Cam (Melbourne, Australia) says:
January 23, 2011 at 3:32 pm

Oh heck – let’s just say every weather event is our fault and be done with it.

NOW you’re getting it! 😉
DaveE.

Hi Theo!
You write: “None of it is prediction.”
True, I predict nothing, I show how trends will react to a La Nina impact like 1999-2001.
And obviously the odds that the coming La Nina will be exactly the same type and duration as the 1999-2001 La Nina is zero.
Therefore the message here is neither quantitative precise nor a prediction. I simply show that a strong La Nina will give AGW agenda real problems. And this I find relevant.
K.R. Frank

Joe Lalonde

Frank,
This may be beyond any La Nina you have ever seen due to the vast amount of water vapour being produced from the warm waters in the Arctic.
Currently, almost of of the land mass in the northen hemisphere is in cloud cover.
Really impressive to see!

Frank Lansner replied, “There has been many suggestions of a strong La Nina now, one of the latest here from NASA…. And you quote from the NASA page on Sea Level, “‘current la nina could be strongest ever recorded. Jan 2011′”
I did not ask you about the strength of this La Niña or about “suggestions”. I asked you justify the statement you made in your post. It was, “And the La Nina – allthough predticed to weaken during spring time – is by many predicted to match the 1999-2001 La Nina.”
Let me rephrase my question: Who are the “many” who predicted the current La Nina will become a multiyear La Nina that lasts as long as and is as strong as the 1998/99/00/01 La Nina? Your “Simulated 1999-01 La Nina” graph depends on the “many” who made that prediction. Again, who are the “many”, Frank? And please provide links to the predictions of the “many”.
You replied, “I did not forecast temperatures using Hadcrut temperature history or similar.”
You used polynomial trends in your last graph, Frank. The polynomial trends you used give the impression that the rise in global temperatures peaked about 2005. And my point was, polynomial trends are misleading, because once you extend them forward or back in time, they fail. Here’s the same graph with RSS TLT anomalies, which is the dataset you used in your graph, with the poly trends extended forward and back in time:
http://i51.tinypic.com/akeltu.jpg
Also, you failed to reply to my other question: Also how did you “simulate” the effects of a new multiyear La Niña?

Frank Lansner replied, “The type and strength of the coming La Nina is a serious challenge to the AGW.”
What “coming La Nina,” Frank? NOAA predicts the La Nina will only last through spring. And if it’s only going to last until spring, that means it is at or near its peak. Refer to the following NOAA ENSO update:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf
They write on page 30, “La Niña is expected to last well into the Northern Hemisphere spring 2011.” That’s as far as they are projecting.

Rick Bradford

To expect the Warmists to abandon their theory of catastrophic warming simply because the data says there is cooling, would be to completely misunderstand the mindset of these people.

Jay says: “The graphs are interesting, but like the AGW proponents, it is too much reliant on simulations.”
What simulations? Frank Lansner appears to have spliced the effects of a former multiyear La Nina onto the current one. He claims there are “many” who predict a multiyear La Nina, but so far he’s provided no documentation of the “many”.

Ben H

While I have not yet heard claims that La Nina is caused by Global Warming, I did hear just last Friday on ABC-TV News that this cold winter was caused by Global Warming and that we should expect to see similar winters in the future because of Global Warming. My opinion is that no matter how cold the weather becomes, it will be claimed by “Climate Experts” that it is caused by Global Warming. They have NO SHAME!

richcar 1225

NIWA in their state of the climate report refers to the IPO (interdecadal pacific oscillation) that when negative is dominated by LA Ninas in frequency and strength. They claim it turned negative in 2000 and if similar to the 1947-1977 negative IPO should run for another twenty years.
http://lch.web.psi.ch/files/Publikationen/analytic/Eichleretal_GRL2009.pdf
They also point that this is the opposite of what climate modelers predicted.
This with twenty more years of negative NAO in the northern hemisphere, negative PDO, declining AMO and a sun that has been declining since 1990 and we should have some significant global cooling.

Baa Humbug

From the Australian BoM site ENSO Wrap up

La Niña continues to dominate in the Pacific
Issued on Wednesday 19 January 2011 | Product Code IDCKGEWWOO
One of the strongest La Niña events on record continues to influence the climate of the Pacific Basin.

Climate indicators of ENSO, including tropical cloud amount, the Southern Oscillation Index (SOI), trade winds and Pacific sea surface and sub-surface temperatures, all remain well in excess of La Niña thresholds. Most have exceeded these thresholds since the middle of 2010. The average August to December SOI (+21.1) has only been exceeded by the La Niña of 1917-18 (+24.4), with the 1975-76 La Niña value (+18.8) ranked third. Several other indices also suggest the La Niña events of 2010-11, 1975-76, 1917-18, 1955-56 and possibly 1988-89, rank closely in terms of the strongest events on record.

Franks little essay is a conjecture OF INTEREST. He made no claims of predictive ability. Franks only claim is that if this La Nina continues, it will be interesting to see how warmists will spin the falling temperatures.
To see WHAT MAY HAPPEN TO TEMPERATURE ANOMALIES if this La Nina continued, Frank simply and reasonably assumed a similar impact on Ts from this La Nina as from previous La Nina. (the impact may possibly be stronger due to the strength of this La Nina)
This is an essay of interesting conjecture only, not meant for journal publication. No need to get picky about fine details.
Serious scientists need not comment. The rest of us will have fun discussing this WHAT IF conjecture.
Well done Frank.

R. Gates

Your analysis is interesting, but we’ll certainly have to wait for the full decade of 2010-2019 to see what how the true longer term trend is affected. We have a combination of events that must all be factored into the equation, not just the ENSO cycle. The long and deep solar minimum must also be factored in. So it will be interesting to see how the next few years shape up. How strong will the next El Nino be and how will it line-up with Solar Max 24 (no matter how weak)? Also needed to be factored in here will be the alignment and effects of the PDO and the AMO in particular. If they both turn cool as well, it would add another layer of cooling.
Let’s assume then, even though the decade of 2000-2009 was the warmest on instrument record, that somehow the decade of 2010-2019 shows no warming and AS A DECADE is cooler than 2000-2009, but warmer than 1990-1999. What would this tell us? What if, on the other hand, with all the short term effects mentioned, ENSO, solar, PDO, AMO, etc. that somehow the decade of 2010-2019 turns out to be warmer than the decade of 2000-2009? This would certainly be a tell us a lot about the power of the longer term CO2 forcing.
Really, we’ll just have to wait until 2019 is over to draw any conclusions. As it stands right now, 2000-2009 is the warmest decade on record, despite a long and deep solar minimum during the 2007-2009 period on top of a nice La Nina during that same period.

John Andrews

Lets loosen up on these graphs. They make us all liars. Lets use a constant range for the anomaly of +- 2 deg C so that we can see a meaningful statistically significant change bumping into the upper or lower bounds. All the rest of this is just graphing the noise in the signal.

There is always the possibility that this could be a 2 yr long la nina – and we do have previous ones that long that wernt as strong as this one

Snowguy716

I’m actually a little surprised at the intensity of this La Niña. But at the same time, I’m also surprised by the the high latitude blocking in the NH.
I think La Niña is actually a product of a warmer world driven by a stronger sun. A stronger sun means less clouds anyway… that extra solar energy reaches the tropical Pacific and enhances the walker circulation, thus increasing trade winds. Cold water pools up from below.
Some reconstructions of Pacific Decadal Oscillation data (I think the PDO is poorly defined… I do not believe there are regular 20-30 year PDO cycles) show the index being very very low around the time of the MWP. This would be consistent with the strong sun/strong and frequent La Niña regime.
Remember… the desert southwest and Mexico would have dried out significantly (which led to the downfall of the great civilizations there). I have no doubt that the persistent strong La Niñas were interrupted by great El Niño events that wreaked havoc across the globe… but these were probably relatively few and far between.
From the records we have… the weather wasn’t so much warmer in the MWP as much as it was more consistent. England tended to have warmer, if drier summers… but the weather tended to cooperate while the winters were mild and wet. This indicates a La Niña (-ENSO) +NAO/+AO regime… not unlike the super Niña of 1988/89.
When the Little Ice Age began, it wasn’t like weather got consistently colder. It was colder on average, but it was also much more inconsistent. Some summers were warm with plentiful rain in England while others were cold and miserable with frosts that caused famine. El Niños, though weaker, would become more common as less solar radiation increased cloudiness. This would slow the trade winds and you’d get El Niño conditions.
Remember that often times after major tropical volcanic eruptions where solar radiation is reduced around the tropics, El Niños tend to form. Look at 1963/64, 1982/83, 1991/92… even as the globe is cooling, many traditionally cold areas see a mild winter. Other than the famous Halloween storm in October/November of 1991, that winter was mild here in northern Minnesota. The summer of 1992, however, was the coldest ever recorded (until 2004).
So, I think atmospherically speaking.. I’m perplexed by this incredibly strong La Niña with low solar activity. I guess the only partial comparison is the 1973-1976 event that occurred during a period of lowish solar activity. That wreaked havoc on Australia like we’re seeing now… but we didn’t have nearly the atmospheric blocking and the eastern U.S. was very mild. I think we’re in a period of unprecedented weather… at least what we have recorded.