Claim: 'the pause' is caused by small volcanic eruptions

Small volcanic eruptions could be slowing global warming

From the AGU: WASHINGTON, DC— Small volcanic eruptions might eject more of an atmosphere-cooling gas into Earth’s upper atmosphere than previously thought, potentially contributing to the recent slowdown in global warming, according to a new study.

bg volcanoScientists have long known that volcanoes can cool the atmosphere, mainly by means of sulfur dioxide gas that eruptions expel. Droplets of sulfuric acid that form when the gas combines with oxygen in the upper atmosphere can remain for many months, reflecting sunlight away from Earth and lowering temperatures. However, previous research had suggested that relatively minor eruptions—those in the lower half of a scale used to rate volcano “explosivity”—do not contribute much to this cooling phenomenon.

Now, new ground-, air- and satellite measurements show that small volcanic eruptions that occurred between 2000 and 2013 have deflected almost double the amount of solar radiation previously estimated. By knocking incoming solar energy back out into space, sulfuric acid particles from these recent eruptions could be responsible for decreasing global temperatures by 0.05 to 0.12 degrees Celsius (0.09 to 0.22 degrees Fahrenheit) since 2000, according to the new study accepted to Geophysical Research Letters, a journal of the American Geophysical Union.

These new data could help to explain why increases in global temperatures have slowed over the past 15 years, a period dubbed the ‘global warming hiatus,’ according to the study’s authors.

The warmest year on record is 1998. After that, the steep climb in global temperatures observed over the 20th century appeared to level off. Scientists previously suggested that weak solar activity or heat uptake by the oceans could be responsible for this lull in temperature increases, but only recently have they thought minor volcanic eruptions might be a factor.

Climate projections typically don’t include the effect of volcanic eruptions, as these events are nearly impossible to predict, according to Alan Robock, a climatologist at Rutgers University in New Brunswick, N.J., who was not involved in the study. Only large eruptions on the scale of the cataclysmic 1991 Mount Pinatubo eruption in the Philippines, which ejected an estimated 20 million metric tons (44 billion pounds) of sulfur, were thought to impact global climate. But according to David Ridley, an atmospheric scientist at the Massachusetts Institute of Technology in Cambridge and lead author of the new study, classic climate models weren’t adding up.

“The prediction of global temperature from the [latest] models indicated continuing strong warming post-2000, when in reality the rate of warming has slowed,” said Ridley. That meant to him that a piece of the puzzle was missing, and he found it at the intersection of two atmospheric layers, the stratosphere and the troposphere– the lowest layer of the atmosphere, where all weather takes place. Those layers meet between 10 and 15 kilometers (six to nine miles) above the Earth.

Traditionally, scientists have used satellites to measure sulfuric acid droplets and other fine, suspended particles, or aerosols, that erupting volcanoes spew into the stratosphere. But ordinary water-vapor clouds in the troposphere can foil data collection below 15 km, Ridley said. “The satellite data does a great job of monitoring the particles above 15 km, which is fine in the tropics. However, towards the poles we are missing more and more of the particles residing in the lower stratosphere that can reach down to 10 km.”

To get around this, the new study combined observations from ground-, air- and space-based instruments to better observe aerosols in the lower portion of the stratosphere.

Four lidar systems measured laser light bouncing off aerosols to estimate the particles’ stratospheric concentrations, while a balloon-borne particle counter and satellite datasets provided cross-checks on the lidar measurements. A global network of ground-based sun-photometers, called AERONET, also detected aerosols by measuring the intensity of sunlight reaching the instruments. Together, these observing systems provided a more complete picture of the total amount of aerosols in the stratosphere, according to the study authors.

Including these new observations in a simple climate model, the researchers found that volcanic eruptions reduced the incoming solar power by -0.19 ± 0.09 watts of sunlight per square meter of the Earth’s surface during the ‘global warming hiatus’, enough to lower global surface temperatures by 0.05 to 0.12 degrees Celsius (0.09 to 0.22 degrees Fahrenheit).  By contrast, other studies have shown that the 1991 Mount Pinatubo eruption warded off about three to five watts per square meter at its peak, but tapered off to background levels in the years following the eruption. The shading from Pinatubo corresponded to a global temperature drop of 0.5 degrees Celsius (0.9 degrees Fahrenheit).

Robock said the new research provides evidence that there may be more aerosols in the atmosphere than previously thought. “This is part of the story about what has been driving climate change for the past 15 years,” he said. “It’s the best analysis we’ve had of the effects of a lot of small volcanic eruptions on climate.”

Ridley said he hopes the new data will make their way into climate models and help explain some of the inconsistencies that climate scientists have noted between the models and what is being observed.

Robock cautioned, however, that the ground-based AERONET instruments that the researchers used were developed to measure aerosols in the troposphere, not the stratosphere.  To build the best climate models, he said, a more robust monitoring system for stratospheric aerosols will need to be developed.


The paper:

Total volcanic stratospheric aerosol optical depths and implications for global climate change


Understanding the cooling effect of recent volcanoes is of particular interest in the context of the post-2000 slowing of the rate of global warming. Satellite observations of aerosol optical depth (AOD) above 15 km have demonstrated that small-magnitude volcanic eruptions substantially perturb incoming solar radiation. Here we use lidar, AERONET and balloon-borne observations to provide evidence that currently available satellite databases neglect substantial amounts of volcanic aerosol between the tropopause and 15 km at mid to high latitudes, and therefore underestimate total radiative forcing resulting from the recent eruptions. Incorporating these estimates into a simple climate model, we determine the global volcanic aerosol forcing since 2000 to be −0.19 ± 0.09 Wm−2. This translates into an estimated global cooling of 0.05 to 0.12 °C. We conclude that recent volcanic events are responsible for more post-2000 cooling than is implied by satellite databases that neglect volcanic aerosol effects below 15 km.


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What excuse number are we up to now? Anyone keeping track?
Trade winds
No trade winds
Deep ocean heat
El Niño
Upper atmosphere


Oh boy! Let’s add this to the list. The fact that there are over 55 excuses now just shows you they don’t really ‘understand’ or want to understand the main cause of the recent rise in global temperatures post late 70s. NOTE: They don’t blame co2 for the 1910 to 1940 warming.
“New excuse for the “pause” of global warming #58:”
Wednesday, 5 November, 2014


May i have the other excuses please ? (serious : to a french journalist)

Greg Goodman

No, this counter-intuitive volcano argument has already been tried. Excuse no. 8 IIRC 😉
I already commented on this today in Willis’ thread.
The haitus is caused by the LACK of volcanoes because it was the volcanoes that caused the late 20th warming in the first place.
Stratospheric cooling :
Surface warming:
The sulphuric acid reacts not just “oxygen” O2 but ozone : O3. Ozone blocks UV , so less UV is one cause of warming. Sorry UN, none of this has to do with CFCs the Montreal protocol as can be seem from first plot. CFCs have not been bouncing up and down in time with major volacanic eruptions.
There’s more than just the ozone, but if they want to talk about ozone it’s in the stratosphere where it counts, not at 15km.
At least they working with real data but the claimed excuse for the pause is just more maybe, could-be pseudo-science.


My favorite remains the china burned to much coal explanation.

Did anybody note the range of precision ? To get a perspective multiply a 100 ! Maybe we should have more coal fired plants to cool the climate ?

Richard G

As soon as I saw the word “robust” I stopped reading.

Otter (ClimateOtter on Twitter)

Ok. ‘Hiding in the deep oceans’ has been debunked by recent research. They continue to insist that THE SUN has no or minimal impact on climate. And Chinese aerosols are out…? So, once again, a NATURAL cause makes its’ presence felt (IF, IF, mind you).
I believe it to be a combination of influences- solar, volcanoes, (what else?)- and apparently, NOT MAN.

Maybe it is the La Nina el Nino dance…


Volcanoes tend to be big and when they erupt people for miles around know about it and report it.
The earth tremors they produce can be picked up by seismographs located around the world.
On average, between 50-70 volcanoes erupt each year and at any given time there are about 20 erupting.
If we have more volcanic activity then I would expect to see:
1. Papers by vulcanologists discussing the increased activity.
2. Papers by seismologists discussing the increasing seismic activity caused by the increased volcanic activity.
3. Documentarys telling us we are all going to die due to increased volcanic activity.
4. Somebody to name the 71 or more volcanoes that erupted each year that we have had increased activity.
5. Climatologist’s blaming it on CO2*


Yes but vulcanologists are not climate ‘scientists ‘ so despite being experts in their area , they have no value in this area because the ‘models ‘ have said its true and the lack of reality to support it means nothing .

Eustace Cranch

Hey, the warmists just launched a bright, shiny new excuse. You don’t really think they’d hand you the ammunition to shoot it down, do you?


6. Someone figure out just how mankind and our wicked ways are to blame for said increase


Please stop giving volcanologists, climatologists and seismologists, tips for grant applications.


Heads I win tails you lose , while I thought we had be told time and again the ‘wonderful’ models already allowed for volcanic eruptions and that is why they ‘knew’ they played no part in warming .
Climate ‘science’ has more excuses for its failure than TV evangelist explaining why once again they caught with their pants down.


How on earth are they using LiDAR to analyse atmospheric aerosol concentration? LiDAR is an aerial survey technique for generating digital topography files.


Phew, thank the good Lord for that, so we ARE going to fry after all…
I was becoming distinctly uncomfortable with a wobbly belief-system there….

Ursus Augustus

“small” eruptions “might” eject etc
Code for look for some minute phenomenon that has likely never been examined regarding its quantitative effect on the global climate but which obviously makes a contribution visisble to the naked eye, the more visible the better, then speculate that it “might be” the explanation for why the whole AGW thing seems to be falling apart.
Pro’s:- Plausible case for further funding and puts doubt on the “Deniers” case plus good copy to supportive media
Cons:_ Well, yeah – so its a con but it’ll all be forgotten by the time we publish the results that show it was a complete red herring ( if we can even be bothered.


Be fair, guys,
This new study uses actual real measurements and finds that the effects of small volcanoes may have been underestimated in the climate models.
So far so good.
But is there any evidence that this effect was not also present between 1980 and 2000?


Their logic is flawed.
They are using AERONET to infer how much SO2 is between the tropopause and 15km. From this they infer volcanic activity.
So far so good.
AERONET only started in about 1998 so they have no figures before that so now they take a leap of faith and fail with their logic.
They infer that because there is a pause and because their levels of SO2 are more than they expected there must be more SO2 now than before they started measuring it with AERONET. Therefore there is more volcanic activity now.
In other words they use the fact that there is a pause to deduce that volcanic activity has increased. They do not use observations to deduce that volcanic activity has increased.

Karl Compton

Kinda reminds me of the Ozone Hole. It was there when we first had the tools to see it, so it must be our fault, or some kind of flawed logic like that. Blame America first. Then the West. Then technology. Then humanity in general.


Now, new ground-, air- and satellite measurements show that small volcanic eruptions that occurred between 2000 and 2013 have deflected almost double the amount of solar radiation previously estimated.

That is 13 years. Now, how about applying this thinking to any 13 year period? What about the period from 1910 to 1923 when it warmed? These researchers might be the victims of current research, observations, assumptions and their models.

Are volcanic eruptions on the rise?
Not according to Lee Siebert
, director of the Smithsonian Global Volcanism Program (GVP).
Charged with documenting, analyzing and disseminating information about Earth’s active volcanoes, the GVP boasts 40 years of data to indicate it’s business as usual under the crust…..
“If you plot data from the last 200 years, there’s a clear increase in the number of eruptions over time,” Siebert said, “but that’s not a function of the actual number of eruptions but rather due to reporting effects.”

you have hit the nail on the head. A study that starts in 2000 can’t differentiate between post-2000 and pre-2000, so it can’t provide the answer. The best it can do is to suggest something to be looked at further. But no, that’s not good enough for our brilliant post-modern scientists, they have to plunge straight into the usual circular logic: things changed in 2000, we’ve looked at the post-2000 period and found something, this something must have been different before 2000, this something is therefore what caused the change. I am getting tired of the tunnel vision and rank stupidity.


Another “we can’t think of any other reason” so….


From the abstract:
” Incorporating these estimates into a simple climate model..”
“Estimates” into a climate model= GIGO

Richard G

Along that same line–when they began to measure they found more then they had estimated. So their estimates were shown to be wrong by the data, but they put those estimates into their models anyway.


So what were these little volcanoes doing before the hiatus?


They were dormant, the extra heat in the atmosphere caused minute cracks in the surface allowing magma to flow into them, enlarging to the point where the volcano could form and erupt. None of these deadly volcanoes would have seen the light of day had it not been for climate change.


Pure speculation. Not a whit of data.



M Courtney

So they find that volcanoes emit more sulphates than thought. – OK, that’s measured.
But before they measured the volcanoes, did the volcanoes not emit the sulphates?
Are these quantum volcanoes that collapse into a sulphate emitting volcano on observation?
Or do we now have more volcanoes – after 1998 volcanoes have become more subtle and so no-one has noticed them going off, but they are there – natural selection at work – yet what are these volcanoes predators?
Or is this just a case of the models were wrong (GIGO) and we have to spin to make it worse than we thought?


There are more volcanoes under the sea than on land. All produce CO2, SO2, HCl, etc.


Isn’t this one excuse number 53?
I may have to re-write my musical contribution:


Nice…I always have liked that song.


Volcanogenic CO2 contributes over 60% of the CO2 in the atmosphere. We contribute 3%


Yes, but that 3% matters!


Actually those numbers are completely false — human activity emits more CO2 than volcanoes:
Nice try.


If “.gov” is in a supporting link, I am instantly suspicious…..especially with respect to any climate-related research.


The latest (2014) info is my information. The USGS paper was to help Obama.
There are more volcanoes under tha sea than on land. 53000miles of ocean ridge system and every mile with volcanogenic CO2 bubbling out mixing with sea water and being emitted when that water reaches the warmer surface. There are between 1m and 3m volcanoes on the planet ALL CO2 producers which makes my 60% look a bit slim. Our 3% is not only not important but ignorable. (especially since CO2 does not drive climate)

Non Nomen

When will we shut off these volcanoes???


I keep reading sceptics making the claim that volcanoes emit more co2 than man. Maybe in the past, but not now. People should stop repeating this claim UNLESS you can show me the information. Always back such assertions with references. I would love to be shown to be wrong as it would allow me to point to volcanoes! If the facts change, I will change my mind.

Which produces more CO2, volcanic or human activity?
….. Our studies show that globally, volcanoes on land and under the sea release a total of about 200 million tonnes of CO2 annually. …..
Because while 200 million tonnes of CO2 is large, the global fossil fuel CO2 emissions for 2003 tipped the scales at 26.8 billion tonnes. Thus, not only does volcanic CO2 not dwarf that of human activity, it actually comprises less than 1 percent of that value.

Jimbo, I have to do a better job of copying things I see, but I read something in the last six months that said the number of volcanoes measured to get what we attribute to volcano emissions is under 10. The article said that 3,000 active volcanoes have not been measured. Do you know anything about this?

Uhh…I just remembered. The article discussed underwater volcanoes.

Danny Thomas

Can you assist me with this: “Robock said the new research provides evidence that there may be more aerosols in the atmosphere than previously thought. “This is part of the story about what has been driving climate change for the past 15 years,” he said. “It’s the best analysis we’ve had of the effects of a lot of small volcanic eruptions on climate.”
Is there reliable backtesting available over time? Asking because they seem to be relating this to a specific time window (the last 15 years) so would we not need to compare temps to SO2 over a longer time span relative to CO2?
Second. If we’re just discovering more SO2 (or aerosols) are there other sources for them in substantial enough quantities to measure? In other words, are these aerosols only natural (and only volcanic?) or partially anthropogenic.
Speak slowly please. I can’t do the chemistry.


Another government paper written to sway the gullable. Government papers are good at cherry picking but little else.
See my reply to a comment above.

Vince Causey

I’d like to see a graph of the number of excuses superimposed on the one above.

Tim Hammond

So something they didn’t know about can be responsible for the Pause but they know everything about the time before the Pause so it must be CO2?
Either they know everything so it’s CO2, or they don’t, in which case may be it is, maybe it isn’t. The more they come up with stuff they didn’t know, the weaker their argument is – do they not see that?


See Willis in previous paper.
So who is right?
I know who I believe ….. .

Small volcanic eruptions are almost continuous, and always were. Logically, they cannot be used even as a partial explanation for any recent changes of temperatures (or lack thereof).


well what about Bardarbunga volcano? nobody seems interested in this volcano which if it went into a full eruption it could could send us into a mini ice age. at the moment it is putting out between 30000 to 40000 tons of SO2 gas every day for the last 3 months. can anybody answer this ?


I think the SO2 doesn’t count as a coolant unless it gets blasted into the stratosphere.


I have read somewhere recently (don’t remember where) that SO2 gets into the upper atmosphere much easier at higher latitudes.


I keep asking Anthony to do a diary on Bardarbunga just to get viewpoints. Recently there was an Icelandic website saying Bardarbunga was now possibly putting out 60,000 tons of SO2 per day.
Dr. Spencer on his monthly temperature charts always points out the Mt. Pinatubo cooling and the super-El Nino heating. Dr. Spencer sees a correlation between some volcanoes and cooling.
Today I see the Laki diary which claims no correlation between volcanoes and temperature.
I would like to see an educated (real volcanologist) attempt at explaining volcanoes/climate.


Awesome video of the Bardarbunga volcano:


davidgmills: And me with no marshmallows. Drat!

Next on the excuse list – how CO2 causes smaller volcanic eruptions.


May you live long enough to read the claim of the alarmists that the “pause” is due to the ice that’s crushing all their roofs as the next glaciation takes hold.

They’re getting desperate aren’t they? The real cause of the pause, I fear, is that I am taking a second ice-cube in my gin-and-tonic each evening, but don’t tell them. … Let them find out.

old construction worker

Lets see,
The sun has a better correlation to temp than CO2
The moon’s orbit has a better correlation to temp than CO2
Small Volcanoes has a better correlation to temp than CO2
PDO has a better correlation to temp than CO2
La Nina, El Nino has a better correlation to temp than CO2
AMO has a better correlation to temp than CO2
How many scientist have sold their souls for a piece of silver.

The Ghost Of Big Jim Cooley

…and science suffers, and will be knocked back. It’s like we’re entering a new Dark Age.


Over what time frame? Please show me the correlations for the last 150 years.


Actually, this is categorically untrue. CO2 has a truly excellent correlation to global temperatures from 1850 through the present. Not only excellent, but almost exactly what is predicted by only its direct action as a greenhouse gas. Over that time, HadCRUT4 can be amazingly well fit by:
T_h = -0.11 + 2.62*\ln(C/311.8)
where C is the concentration of CO2 in parts per million and T_h is the HadCRUT4 global temperature anomaly. This fit implies a total climate sensitivity per doubling of CO_2 of 1.82 K, quite reasonably close to the ~1 K predicted by line by line software using the actual spectrum of CO_2.
This fit is a two parameter fit! And one of those basically fits the zero of the absolutely arbitrary scale of the Hadley anomaly. The 2.62 is the only meaningful number present.
That doesn’t prove that CO_2 is solely responsible for the warming, because this curve does not extrapolate backwards into the arbitrary past. Things are more complex than this. What it means is that over the thermometric era, CO_2 is a possible explanation for some or all of the observed warming.
Incidentally, the PDO has absolutely terrible correlation to observed temperature. I can’t even use it to modulate the CO_2 based component and get a better fit than CO_2 alone. Nor do any of the other oscillations have a good correlation. They have a good correlation with this feature, or that feature, sometimes — like volcanoes. But they are not well correlated with anything I can see in the data to the point where I can even think about putting together a plausible model using them — so far. I’m currently looking at Mauna Loa top of troposphere insolation, or some function of “Volcanic Explosivity Index” (VEI) as discrete temperature changes linked to named eruption events with some trailing decay time, but I’m guessing that volcanic explosions have a highly variable chemistry and that they certainly have different latitudes and different cone heights and hence kick things into the atmospheric circulation differently, so I’m not very optimistic.
Besides, one can just look at HadCRUT4 and see that even VEI 5 events like Mt St. Helens or El Chichon (Pinatubo was a 6) have almost no attributable effect on the climate, and we could simply be mistaken in attributing the behavior of global temperature variation from 1992 to 1995 to Pinatubo — it is of the same order as the clearly visible natural variation of the climate over all of HadCRUT4, so how can we be certain in any quantitative attribution of it as a cause? Noise is known to be at least as large as its “signal”.

Catherine Ronconi

HadCRUT4 is garbage. It can’t be relied for any purpose except to show that CO2 obviously hasn’t had a measurable impact on global temperature, since models assuming that it does have failed so miserably to predict GASTA.
Nor should it come as a surprise that it and all other surface station temperature recreations are garbage when you know how they were compiled and computed.


That’s even more sceptical than me.
HadCRUT 4 is weak but its the best we’ve got.
Julie Andrews would like to sing in the Austrian Alps. But if she had to use a slag heap I’m sure she would.
So must we.
HadCRUT seems to be less politically corrupted than GISS. It’s main weaknesses are inherent to all blending of different weather stations and it’s calibration against GISS.
But it isn’t just a fantasy – like the computer models. (In my opinion).

Catherine Ronconi

It’s more insidious than a fantasy. It’s adjusted, interpolated, folded, bent, spindled & mutilated.
Granted that if anything GISS is even smellier garbage, but just. Is it better than BEST? Possibly.
If they’re all the best that “climate science” has to offer, then IMO better not to use any global reconstruction at all. Compare to best stations for regions, such as (admittedly adjusted, too) CET or the US or well maintained oceanic island stations, without trying to create a global average sure to be execrable at best and more likely worse than worthless, except, as I say and others have said, to demonstrate how miserably the CO2-based models fail.
IMO a truly valid GASTA, if such a creature be possible, should and would show at most the ECS found in the lab, although feedbacks are probably net negative, so no enhanced GHG effect would be at least as likely.


I get where you’re coming from but we are talking about GASTA here. What is GASTA for? It is just a measure of a net change to the planet… no cause or reality involved.
It’s like a Global weather forecast – were all sunny with a chance of showers (from drought to monsoon).
Or Global height above sea level.
Or Global freedom.
It’s politically determined to be important and actually meaningful absolutely nowhere.
HadCRUT seems to be the best Global measurement of change to the weather from all the surface measurements. In my judgement.
Does such a measure matter? Yes (politically).
Does such a measurement have physical reality? Meh (it won’t kill you).
So I’m not so sceptical as to throw out the whole effort.

Catherine Ronconi

I would throw out all efforts to date as hopelessly flawed, including intentionally so.
HadCRU has “lost” the Met Office “data” upon which they purportedly built their original pile of rotten garbage, made only stinkier with time.
A panel with no oxen to be Gored or sacred cows to protect needs to start over, assuming a global average is even theoretically possible. Its methodology needs to be complete transparent and repeatable.

Catherine Ronconi



It’s a good point you make. Losing the original data is a faux pas.
But Exeter does hold good records; the CET is as good as it gets.
Starting again is very appealing, it sounds like the BEST thing to do. But politics will still intervene.
I prefer to plough the slough and get muddy rather than returf the bog and pretend its not floating on the mire.
But I do concede that that may be too pessimistic.

Catherine Ronconi

That CET is good, though adjusted to show more warming in the past 50 years, I’ve already mentioned. There are other regional data sets that aren’t too bad or could be readily fixed.
Your pessimism may well be justified, but there will be a push for GISS garbage to be dumped and a new, clean attempt to be made, less tendentious than BEST. Probably won’t happen in the US until there is a President Paul or equivalent, however.


Very interesting… Now show me where in history CO2 has not lagged temperature. Cause and effect. The truth is that at no time in the record has Co2 lead, and temp followed. Show me in the record where I am wrong!

Catherine Ronconi

GISS may well make some phony adjustments, infills, zombie station fictions, raising instead of lowering temperature for UHIs, etc, that HadCRU doesn’t, but I wonder if Hansen and Schmidt also do as Jones does, ie raising ocean temperatures to fall in line with the already bogus land “data”.
So I really don’t know which gatekeepers are more corrupt, on this side of the cooling Atlantic or the other.


So why does the ice core data show the exact opposite? That data shows that temperature drives CO2 levels not as you claim.


Did they make sure that 97% of scientists agree with their “explanation”?


“Incorporating these estimates into a simple climate model…”
Estimates incorporated into a simplified depiction of what we want to say.
Pity the earth doesn’t work like that.


And yet the volcanic activity that cools Earth is responsible for warming Mars?
“The study, by scientists from Brown University and Israel’s Weizmann Institute of Science, suggests that warmth and water flow on ancient Mars were probably episodic, related to brief periods of volcanic activity that spewed tons of greenhouse-inducing sulfur dioxide gas into the atmosphere.
Read more at:

Danny Thomas

Isn’t “all other things being equal” missing from this?


But SO2 reflects radiation??

M Courtney

It’s a completely different case. Sulphates on Mars are adding atmosphere where there was virtually none. And if the theory is correct, adding water vapour where there was none too.
It’s not an apples to apples comparison.


SO2 is supposed to cool due to increasing the albedo.
Any claim about Mars’ historic temperatures is conjecture nothing else.


well the models, made various assumptions with respect to positive reinforcement in order to get such high temperature sensitivity. Most of these have been shown to be false and therefore we are left with the basic response to carbon dioxide, which is pretty much nothing on its own. So perhaps that the reason for the “pause”.

Non Nomen

I do not quite understand how volcanoes behaved in the past. Did they remain stock-still until some 18 years ago they decided to blow their acids into the atmosphere to influence it and to fool mankind? How about the influence of volcanoes in these many billions of years B.C.?


You can look up plots of known volcanic activity over various spans. The best records realistically only go back a few years in a remotely trustworthy manner. We know about major eruptions earlier, but, they were major and easily observed. So, prior to satellite based observation there are numerous eruptions on dry land that were never recorded and at sea … no way to really know. Undersea eruptions would probably not affect the albedo much, though warm plumes of water could potentially affect the formation of low level clouds locally. If you read Willis Eschenbach’s analyses of volcanic events vs temperature data, there really is not much, if any, evidence for global effects.
Even major eruptions become problematic when you deal with records from the deeper past (say around the time of the fall of the Roman Empire). There are mentions in Chinese of historical texts of something big that happened, probably in Indonesia around 400 – 500 CE, but the Chinese were too far away to know what actually happened, and closer to the event either no records survived later historical events, like wars and fires and mildew, or no one literate survived to write a record. The best guess is that Krakatoa erupted on roughly the same scale as the known 19th C event, but that’s is just an educated guess at best.
When you come down to it, we know some about how the planet works, but really only just “some.” There is a huge reserve of historical documentation for rare events for which we have no direct empirical explanation, just guesses.


Is The Pause caused by an increase in small volcanos? Or was the warming period caused by a temporary decrease in small volcanos?

Jeff L

As far as I can tell from the abstract & press release, I can’t see any “control” case – ie the same data set prior to “the pause” showing substantially less aerosols to come to the conclusion they did. As far as I can tell, they assumed that was the case & used a “climate model” to get the answer. But of course it is all just to get funding : ” To build the best climate models, he said, a more robust monitoring system for stratospheric aerosols will need to be developed “.
This doesn’t appear to prove anything. It is either a shameless ploy for funding or they are doing really poor science.

The science is “settled”, but it seems every year there are dozens of stories like this about “underestimating” this or that feature of the climate. It implies they may need to rethink the basic theory, but they never do. Yet each time some minor little natural thing turns out to have a bigger affect on climate than they thought it only goes to show to skeptics how much more effect natural variation has than AGW proponents allow for.

James Bull

So add this to the study
If 97% of Scientists Say Global Warming is Real, 100% Say It Has Nearly Stopped
Does that make it 101% saying there is a pause….(sarc)
James Bull

If AGW is a serious problem and if vulcanologists concur with this new theory for the “hiatus,” then a solution has been identified. Hallelujah! Now all we need to do is get working on producing aerosol producing machines that pump pollution into the atmosphere. I hope environmentalists will welcome this planet saving pollution.

DD More

From a June 14 WUWT posting – Study: Climate engineering can’t erase climate change
Other climate engineering strategies are less appealing, such as fertilizing the ocean with iron to absorb carbon dioxide or reducing global warming by injecting particles into the atmosphere to block sunlight.

“Take the example of solar radiation management, which is the idea of putting aerosols into the stratosphere, kind of like what happens when a large volcano erupts,” Axsen explains.
“This is asurprisingly cheap way to reduce global temperatures, and we have the technology to do it. But our study asked other important questions. What are the environmental risks? Will global citizens accept this? What country would manage this? Is that fair? Suddenly, this strategy does not look so attractive.”

Mount Pinatubo Facts
• 15-20 million tons of sulfur dioxide were discharged in the atmosphere following the eruption which caused a global cooling among others.
• Mount Pinatubo’s eruption caused the ejection of 10 cubic kilometers of magma
The Pinatubo eruption delayed temperatures for about 3 years, so this would require 5 to 7 millions tons of SO2 per year and 3 KM^3 of dust per year. All injected up around 50,000 ft.
In what world besides an ‘Ivory Tower’ is this cheap and easy?


The Pinatubo eruption delayed temperatures for about 3 years,

Maybe. This is certainly the oft-quoted assertion. But if so, why didn’t the double-whammy of Mt. St. Helens and El Chichon in 1980 and 1982, respectively, which very definitely affected the stratosphere (El Chichon dumped 7 million tons) have no discernible effect on global temperatures? See the graphics I included or linked in another reply, or Willis’ other thread on this general subject.
It is by no means clear that even large volcanic explosions like Mt. Pinatubo have an effect on the climate that is distinguishable from natural variation. Note well I’m not saying no effect, I’m saying that that effect is within the range of natural noise and is rapidly erased because the climate is almost completely insensitive to even 1 to 10% variations in the amount of sunlight being received at the top of the troposphere.
But we know that already! The top of atmosphere insolation varies by 7% maximum to minimum every year (by over 90 watts/meter^2) as the Earth undergoes its elliptical orbit. I’m assuming that the Mauna Loa apparent transmission is relative to this much larger baseline, although I’ll have to read the referenced papers to see if in fact they cancel it out (and if so, how). If they don’t, I have a pretty serious problem with what they are publishing, as I’m a pretty firm believer in P_s/4\pi r^2 variation of solar intensity for a nearly constant power output by the sun. Yet we see the annual peak in global average temperature in the northern hemisphere summer when the Earth is farthest from the sun and the minimum in its winter when it is closest to the sun.
Insolation per se is not the determining factor in global average temperature! It is much more complex than that.
Given this, why in the world would we expect some immediate, significant, year spanning response even to large volcanic perturbations that are only transiently larger than the annual fluctuation and are not similarly sustained? They are lost in the noise. Not as an assertion, as a simple matter of observational fact. Nobody, and I do mean nobody, can look at the temperature data and guess where volcanoes happened. One can barely look at where volcanoes happened and interpret some variation in the temperature as the response.

Steve Reddish

RGB, you noted that:
“we see the annual peak in global average temperature in the northern hemisphere summer when the Earth is farthest from the sun and the minimum in its winter when it is closest to the sun.” despite top of atmosphere insolation varying by 7%, with max at time of NH winter.
Perhaps the Earth warms the most during NH summer because the NH has 68% of the total land area, while the the SH has only 32%. Thus 7% weaker sunlight is falling on approximately twice the land area during peak of NH summer compared to peak of NH winter when 7% stronger sunlight is falling on approximately half the land area. The change in land area exposed to the sun is far greater than the change in strength of sunlight due to the change in Earth-Sun distance.
Since land is warmed by sunlight (temperature rises) more readily than ocean, the peak warming would be during the time of year when the most land is receiving sunlight.


NH winter receives less radiation despite being closer to the sun because the angle of incidence reduces and the days are shorter.

Ulric Lyons

RGB ” Nobody, and I do mean nobody, can look at the temperature data and guess where volcanoes happened.”
You’ll stand a better chance of finding them by looking at temperature deviations before the events.


Didn’t these guys spend over a decade telling us how little affect any amount volcanic activity had?


Yes. And, they’re the same ones who’ve been saying that changes in solar activity have no effect on climate.

Offhand I would observe that the aerosol rich eruptions of Agung 1963, El Chichón 1982 and Pinatubo 1991 caused clearly visible warming of the upper atmosphere due to the particles heating up in the sun.
So where is the stratospheric warming now from those aerosols? Instead it appears that the stratospheric temperatures are having the same pause as the surface records.

Robert W Turner

This is empirical evidence disproving their hypothesis. Next.

OK – can someone remind me about the claim that efforts to reduce pollution in the 60’s and 70’s were successful and changed the radiation balance? So SO2 from volcanoes caused the pause. What about the SO2 we used to throw into the atmosphere. Did humans cause some warming by cleaning up our emissions? If not A then not B?

Chris Schoneveld

Excuse no. 53

Danny Thomas

Do you have the list compiled? I’d love a copy if you don’t mind sharing.

Chris Schoneveld

See on WUWT (at the top) Climate Fail Files

Danny Thomas

Thank you. I’d gone there but only saw the 3, but after clicking on the list of excuses there it is.


“To build the best climate models, he said, a more robust monitoring system for stratospheric aerosols will need to be developed.”
OH, Goodie! More Grant money!

Dave O.

It’s pretty clear that the warmists have staked out some ideological turf and are going to defend it no matter what. This isn’t science.

The Iconoclast

Certainly it could be possible possible that scientists have miscalculated the impact of volcanoes on global temperatures. But if using that to even partially explain the pause wouldn’t you have to also make a claim that there has been an increase in eruptive output since some time before the pause started? Have they made that claim? Without that then the miscalculation cannot explain the pause, although if they’re correct then it’s another source of error in the models.
Oh I get it, when they crank up aerosols the models don’t run as hot. The modeling community can say my bad and use this to justify changing their aerosol numbers to to generate numbers closer to what’s actually happened and then claiming the models are much improved while still making sure the algorithms show dangerous warming in the longer term future.

Dodgy Geezer

@Non Nomen
…When will we shut off these volcanoes???
I propose that we should institute Carbon Trading to suppress them. Basically, if you are a country with a volcano in it and it erupts, you should pay $1 per estimated tonne of CO2 released to the Volcanic Emissions Climate Foundation. Just let me set it up…

When will we shut off post-modern science???


This is one of many cases where new measurement technologies have been used, and the papers assume that the effect they are claiming only began when they could measure it. As noted above, there doesn’t seem to be a trend in volcanic activity, just new measurements.

Vince Causey

The negative forcing they are quoting is tiny, not much different from TSI that has been derided as too small to account for climate change. If their conjecture is right then the divergence currently occurring between observation and models couldn’t possibly grow any larger.
But if the divergence continues to increase . ..

Mike the Morlock

Hi Vince, the number they use for blocked TSI is .05 too .120 C are they trying to steal the TSI change from there being a lower solar cycle? Off the top of my head the numbers look disconcerting. Also the time frame. The pause has only been openly admitted to for two or so years, has there been time to think up a study, submit grants obtain equipment take measurements etc. Or did they just grab existing sat data and wing it.
Sorry something seems off with all this.

Bruce Cobb

The phrase “grasping at straws” springs to mind.

Don Easterbrook

First the Alarmists tell us that volcanic eruptions cause global warming because of the CO2 they emit–now they are telling us that volcanic eruptions cause global cooling! These are the same people that claim the global cooling of 1945-1977 (when CO2 emissions were soaring) was caused by burning higher-sulfur coal (which somehow must have mysteriously ended abruptly in 1978 despite the fact that much more coal is being burned now than in the 1960’s and 70’s).
Volcanic eruptions have been going on for many hundreds of millions of years. To blame recent cooling on eruptions, you would need to prove abrupt changes in eruptive activity (that’s how climate changes have typically occurred throughout geologic history) and explain why climate shows no correlation with volcanic eruptions. As Willis and I have both argued, the influence of volcanic eruptions on climate is insignificant. Read Willis’s post of a few days ago about the Icelandic eruption of 1783, which didn’t have any unusual effect on Europe’s climate.

Keith Willshaw

I suppose the pause might be caused by the Cold Fairy waving her magic wand. This is a about as likely as most of the other excuses given so far.

I also conclude that these small volcanic eruptions are having NO cooling effect as evidenced by looking at the stratospheric temperature profile which shows no warming in response to all these small volcanic eruptions.
Look at the chart Leftturnandre sent a few post back.
Nevertheless I would like to know what is the residence time in the atmosphere for all the SO2 BARDARBUNGA volcano in Iceland is putting out? It is putting out vast amounts of SO2 but at very low altitudes.
I think a great indicator of what effect volcanic activity is having on the climate is the Volcanic Aerosol Optical Thickness Chart which shows very low levels since the turn of the century.

Brock Way

“The prediction of global temperature from the [latest] models indicated continuing strong warming post-2000, when in reality the rate of warming has slowed,” said Ridley. That meant to him that a piece of the puzzle was missing
Yeah, but when you correct it for time of observation it fits perfectly.
In other news…b.b.b.b.but Pinatubo!
As one can see volcanic aerosol optical thickness has been low this century.


I don’t know which causes the alarm bells to go off first, the AGU or the words “small” and “excuse.”

There have been no more small eruptions since 2000 than were from 1985 to 1999.
Total garbage and lame excuse making.
Also, it’s not a slow down in warming, but in unadjusted data, a cooling since the late 1990s.

Doug Proctor

“Slowing” is not the same as “hiatus”.
The reviewer shows his warmist position by using “slowing” while the authors use”hiatus”.


I suspect glaciers would have to be bearing down on Toronto before the global warming enthusiasts will admit that maybe, just maybe, they don’t know all the factors that cause climate change.

Marilynn in NorCal

Nah, they would just claim that unseasonably high temperatures had caused the glacier to slip its moorings.

M Courtney

For evidence that they can’t be dissuaded, see the comments on the Guardian reporting of the snow in the USA.


‘Hiatus’ from google:- a pause or break in continuity in a sequence or activity.
“there was a brief hiatus in the war with France”
synonyms: pause, break, interval, interruption, suspension, intermission, interlude, gap, lacuna, lull, rest, respite, breathing space, time out
I think youre being harsh Doug – slowing down of a rate could still just about be called Hiatus. And as an admission from a warmist I’ll take that any day. Still splitting hairs really