Guest Post by Willis Eschenbach
The claim is often made that volcanoes support the theory that forcing rules temperature. The aerosols from the eruptions are injected into the stratosphere. This reflects additional sunlight, and cuts the amount of sunshine that strikes the surface. As a result of this reduction in forcing, the biggest volcanic eruptions are said to depress global temperatures, sometimes for years.
The idea that large volcanoes significantly cool the planet is widely accepted. This effect is built into the climate models, for example. It is a reflection of the dominant climate paradigm, which is that surface temperature is a linear function of forcing. Since it can be measured observationally that the volcanoes greatly reduce the global solar forcing, it follows that they must significantly affect the global temperature.
However, I hold that the climate system is not an inert slave of changes in forcing. I hold that the climate system immediately and actively responds to changes in forcing by adjusting things like albedo, cloud type, cloud formation times and locations, timing of Nino/Nina alterations, and the like, to quickly counteract any forcing changes.
Which means, of course, that according to my hypothesis, even very large volcanoes should a have very small effect on the global temperature. To see which hypothesis is true, mine or the standard AGW hypothesis, I devised a little game I call “Spot the Volcanoes”. Two of the largest volcanoes of the century occurred within a twenty year time span. See if you can tell where they occurred.
Figure 1. First difference (month-to-month change) in global surface air temperature. Timespan shown is twenty years. Two of the largest volcanoes of the 20th century are shown in this record. The volcano in the picture is Mt. Redoubt, Alaska, one of my favorite mountains.
In Figure 1, to make things a bit difficult, I show the month-by-month CHANGE in temperature. This is not the temperature itself, but the month-by-month change in temperature, called “delta T” (∆T). If the temperature is a function of the forcing, the eruptions should be making the temperatures drop for a while. So the game is, where in Figure 1 are the two eruptions? Make your choice before you take the jump …
The answer is shown in Figure 2 below. It contains the record of the atmospheric transmission over Mauna Loa. The two eruptions, of El Chichon and Mt. Pinatubo, are very apparent in the Mauna Loa (MLO) record. I have scaled the Mauna Loa record to the corresponding GISS estimate for the forcing from Pinatubo (in W/m2), in order to show the generally accepted size of the volcanic forcing.
Figure 2. As in Figure 1, plus Mauna Loa atmospheric transmittance observations. These observations are of the total amount of clear-sky sunlight making it through the atmosphere.
Now, I can already hear folks grumbling, that this was not a fair game, that it was rigged because it was the first differences and not the actual temperature itself. And besides, most people don’t spend much time looking at first differences, so it was too hard. And perhaps those folks are 100% correct.
So let’s play a bonus round of “Spot the Volcanoes”, this time using the real temperature data. Figure 3 shows a stretch of the HadCRUT3 global surface air temperature record. This time it includes one smaller and two larger volcanoes. See if you can spot where the big ones erupted:
Figure 3. A stretch of the HadCRUT3 temperature record containing one small and two large eruptions. Don’t bother trying to find the small one.
So once again, the game is to spot two volcanoes.
Now at this time,
.
We’ve got to play the game show music,
.
. dee
. dee
. da dee dee dum
.
So as to hide the answer,
.
Until you make your choice, of the exact location of the two eruptions in Figure 3.
.
So here it is.
Figure 4. As in Figure 2, showing the eruptions of El Chichon (1982) and Pinatubo (1993). The small eruption is Mt. Agung (1963).
I’m sure you understand my point. There is nothing to see. The kinds of temperature excursions we see after the volcanoes are not different from the temperature excursions before the volcanoes.
How big an effect should we have seen, given the IPCC assumptions about climate sensitivity? Well, the average change in forcing over the three years following the Pinatubo eruption is ~ -1.7 W/m2. Now, that’s about half the forcing change expected from a doubling of CO2, maintained for three entire years … and where’s the response? Using the IPCC numbers, we should have seen a temperature drop of 1.4°C at equilibrium, and three years after the step change we should have seen at least a full degree of that …
Instead of a full degree of cooling after Pinatubo, or even half a degree, we see maybe a tenth of a degree of cooling.
But wait, as they say on TV … it’s even worse than that. The drop after Pinatubo may be just by chance, because after the earlier El Chichon eruption we see maybe a tenth of a degree of warming … and the average three year change in forcing for El Chichon is only trivially smaller than Pinatubo, at ~ -1.6 W/m.
So this is a great natural experiment regarding changes in forcing. From these observations, as near as we can tell, half the forcing change expected from a doubling of CO2 was applied for three full years, at two different times, and it resulted in … well, pretty much nothing.
So I’d say that the volcanic eruption data strongly supports my thermostat hypothesis, which says that changes in forcing are almost immediately and nearly completely offset by opposing changes in other aspects of the climate system.
w.
PS—Here’s the double bonus question … the UAH lower temperature record:
Figure 5. UAH MSU satellite based global lower tropospheric temperature record.
This time the game is a bit different. Are there one or two volcanoes in the record, and where is it / are they?.
Now at this time,
.
We’ve got to play the game show music like last time,
.
. dee
. dee
. da dee dee dum
.
So as to hide the answer,
.
Until you make your choice, of the exact location of the two eruptions in Figure 5.
.
So here it is.
Figure 6. As Figure 5 plus transmittance information.
Note that as with the surface temperature record, the globe cooled slightly after Pinatubo … and that as with the surface temperature record, the globe warmed slightly after El Chichon. And since the post-Pinatubo drop is indistinguishable from the post-1983 and the post-1988 drops, there is no reason to assume that the post-1991 drop is due solely to Pinatubo.
Which in my opinion is why all of the analyses focus on Pinatubo, while poor El Chichon is roundly ignored because it didn’t get the memo about causing a temperature drop.
PS—Does this mean volcanoes have no effect on the climate? No, it just means that because of the immediate and basically “equal but opposite” response of the climate system to forcing changes, the effect is much more local, much shorter lived, and much smaller than would be expected if the IPCC estimates of climate sensitivity were correct.
FURTHER READING: Climate forcing by the volcanic eruption of Mount Pinatubo
[UPDATE] People have asked for more information about how the climate responds to counteract the cooling action of the volcano. Figure 7 shows the response of the albedo to the Pinatubo eruption. The albedo immediately began to drop, allowing more and more sunlight to warm the surface.
Figure 7. Anomaly in post-albedo solar isolation for the period 1984-1998. The transmittance change due to the volcano is shown in red. Albedo data from Hatzianastassiou et al.
You can see that it’s not too hard to spot the volcano in this graph … which is exactly the reason why it’s so hard to spot in the other graphs.
w.
…I like this game 🙂
The impact of volcanoes is interesting, because it forces the oceans to “divert from statistical means”. Twenty years ago I did some research concerning the reaction of the ocean; details here http://www.whatisclimate.com/conditions-for-the-protection-of-the-global-climate.html#_aa14 concluding –inter alias- :
“The fact that the air circulation did not reach its minimum until 1888 is not surprising. From the middle of the 1880s on, a “weakening” of the oceans in the higher latitudes must have become noticeable. The less heat energy the ocean feeds into the atmosphere, the weaker become the dynamics in the atmosphere. This also becomes clear when it is seen that three years after Krakatoa the temperatures above land rose more sharply than above the oceans.”
Or…those temperatures´anomalies, being really a straight line, is meaningless.
That’s interesting, but what does it really mean? We’ve seen other data where volcanic eruptions apparently have more obvious effects. You show a small sample, pick some graphs that are not necessarily random or representative of temperature data generally available. I’m not buying it yet.
You left out a few details that would have helped.
The strong 1982 El-Nino that can blunt the effect of a large volcanic eruption.Which is an atmospheric effect.
You also did not tell us what the level of dust and other particles were from Mt. Pinatubo and El Chichon.Were they that insignificant?
Generally the higher the dust and other “cooling” materials can go up into the upper atmosphere the greater the short term cooling effect.Since very few volcanoes in past push them high enough to do much of anything.That is why many eruption effects do not show up in the temperature record.
But a few that did such as Tambora,Krakatoa,Laki among others huge eruptions.They ALWAYS caused a big cool down for a short time after wards that clearly stood out.Some caused a lot suffering.
Tambora is a good case for significant climatic disruption that cause the famous phrase “the year without summer”
Year Without Summer: Effects Of Tambora Volcanic Eruption On Iberian Peninsula Studied For First Time
http://www.sciencedaily.com/releases/2009/02/090225161422.htm
Mike Baillie has been sparing with the volcanoes-do-it-all crowd for years. He thinks the older climate excursions result from extraterrestrial inputs: http://cosmictusk.com/?s=mike+baillie
I know he was controversial with skeptics when he claimed his data was proprietary, but he is a good egg and has been unfairly squelched by his critics (many of your same).
Good observations, good game. Your initial statement is a bit contentious though – i.e. that the climate always responds through a series of negative feedbacks. It’s a complex system with both positive and negative feedbacks. Other well-characterised systems with a mixture of postive and negative feedbacks (e.g. electrical circuits) tend to lurch between metastable states – a bit like moving a ping-pong ball around in an eggbox. Give it a little push and it will roll back to where it came from, push it hard enough and it will abruptly go somewhere else. Anyway, you’ve convinced me that recent volcanoes haven’t really done enough to push the ball out its current place, but not that the climate is immune to stronger forcings.
Have you read the book “Volcano Weather” and what do you have on Tambora? If the global records are correct, Tambora had a huge effect and crops in the US failed due to mid-summer frosts. Unless I am missing something, your general hypothesis about forcing is vulnerable to a single, well-documented countervailing example.
It just takes a sufficiently large volcano to have an effect on the climate. Consider Krakatoa for instance. http://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa
It seems likely that the ensuing temperature drop was not just a coincidence.
The last super volcano, 600,000 years ago, nearly led to the extinction of the human race. http://lennyp.hubpages.com/hub/Supervolcanoes
Willis
As an unapologetic simpleton, may I say how much I enjoyed this article. Indeed, I greatly enjoy most of them–at least those that I can partially understand!
Thank you for all your hard work. (But there can be no doubt you must take great pleasure from putting them all together.)
Geoff Alder
So Gia works, balancing out the hiccoughs along the way as was originally proposed. Sad even Gia’s wondrous working have to be ignored for the sake of power and money.
It seems we have more than a few “Playas”.
For those who’ve forgotten about Pinatubo, we had an ozone hole at the North Pole following the eruption.
For those who flipped up Krakatoa, even Gaia takes time when she has a rant to restabilize. Nonetheless, Willis’ point still holds, with the ueber tonnage of dust, ash, SO2, etc thrown into the atmosphere, the world still recovered within a short (geologically speaking) time period. In my mind, 5 years isn’t forever – Wikipedia, 1883 eruption of Krakatoa. It would take strong persistent negative feedback to fix something of that scale that fast.
I got the second volcano exactly right in the first graph. I got the timing first volcano right if you spot me much larger margin of error on the second graph. On the last graph I got both volcanos right, the second spot on, and the first with a wider margin of error.
Had you not said how many volcanos I would have guessed that there were a whole lot more than I was guessing.
The Eschenbach Thermostat Theory suggests that after a major eruption, with insolation at the surface reduced, ITCZ Cu-nims should start later in the day.
Could this be measured??
It’s always worth noting that there isn’t just one forcing in effect – we have solar, ENSO, volcanic, anthropogenic GHG’s, etc. When you add _all_ of the forcing changes together it is rather more clear – instead of trying to spot changes from volcanic forcing when, for example, ENSO and solar changes are occurring at the same time.
I’ll also point out that looking at the changes in temperatures relative to forcing changes supports the climate sensitivity estimates – if you actually run the numbers…
Foster and Rahmstorf 2011 – forcing attribution over the last 30 years (http://iopscience.iop.org/1748-9326/6/4/044022)
Lean and Rind 2008 – forcing attribution 1896 to 2006 (http://content.imamu.edu.sa/Scholars/it/net/lean2008gl034864-marked-attached.pdf)
“PS—Does this mean volcanoes have no effect on the climate? No, it just means that because of the immediate and basically “equal but opposite” response of the climate system to forcing changes, the effect is much more local, much shorter lived”
I disagree; I see it like this: All of the time, that oscillator that quasiperiodically creates La Niña / El Niño events, is charged by UV penetrating the oceans down to the boundary layer. The forcing modulation influences how fast this “heat capacitor” is charged. The timing and direction of the next event is influenced by that; but as it can take quite a while for it to occur, consequences of the volcanic eruption can be hidden for an unpredictable amount of time.
With regards to the immediate reaction of the atmosphere, though, Willis seems to be right.
In the cases of Tambora and Krakatoa, can we see how long it took for the temperature to come back? Would the apparently short time mean mean response is pretty quick, and that therefore heat in the pipeline or long approaches to ‘equiliibrium’ are nonsense?
Amazing. Even being roughly familiar with the changes in temps over the last decades, I still got it wrong! What this tells me is that even MASSIVE events by themselves don’t drive climate but rather a million factors affect what happens. Great demonstration.
Thanks for the discussion. Most of what people call large eruptions are in geological terms a quite small to minor. Fortunately the truly big ones are very infrequent.
Willis, good article.
In this quote:
“I hold that the climate system immediately and actively responds to changes in forcing by adjusting things like albedo, cloud type, cloud formation times and locations, timing of Nino/Nina alterations, and the like, to quickly counteract any forcing changes.”
Are you suggesting that there is a natural “balance” of/on/by/for the planet?
The other possibility is that you have demonstrated that the temperature anomaly record and global average temperature information is useless for climate study as it cannot even find evidence of major forcings.
The apocryphal evidence was that winters were noticeably more severe following the El Chichon eruption. The effect did not show up until the following winter. In Colorado we had the longest period of continuous snow cover on the ground in the Denver metro area on record (63 days) stretching from the Thanksgiving day blizzard of 1983 (21.5 inches snow fall over 37 hours ) with high winds. The snow cover persisted until January 27 of 1984.
Granted this is only one local weather anomaly but the public perception at the time following these major volcanic eruptions was that the following winters 6 – 18 months after the event were noticeably harsher than usual.
Many of us question the validity and usefulness of the temperature records and the use of global average temperatures and temperature anomalies for climate study. In view of that fact, it is just as likely that your demonstration shows the lack of validity of those temperature records, as it does demonstrate your hypothesis that the world climate actively resists forcing by compensation.
Although I generally agree that thermal convection and the other related consequences of strong thunderstorm development is a powerful component of the “heat engine” we call weather, we can’t have it both ways and say the temperature records are worthless when arguing one hypothesis and then on another day use those same records to falsify a different hypothesis.
Larry
Sandy says:
March 16, 2012 at 9:03 am
Thanks, Sandy. I’ve been wondering about that myself. Unfortunately, the datasets that might be of use (TAO buoys, Argo floats, etc.) generally don’t start until after Pinatubo.
w.
Good hypothesis, not sure its spot on but is looking likely. I love the real world versus models, real wins every time.
Marvellous.
The climate models use of forcings which are derived from Pinatubo seems to be blown out of the sky.
However, just because the models are wrong it doesn’t mean that all volcanoes will be of localised impact. There could be a scale of explosion (bigger then these two) which breaks out of the lower atmosphere and into the jet stream. If the volume of dust was big enough that could cause a global impact.
Science fiction, I know, but mega-volcanoes (steam explosions) are supposedly on a different scale.
The post high powered volcano drops are obvious in the anomaly record but temporary (2 or 3 years). the IPCC assumes they know and understand all climate forces, which is where the wheels fall of their wagon – it tends to make them artificially increase the sensitvity to the forces that they do consider because they cannot attribute any force to the variables they do not consider (clouds, GCR aerosols etc).