Guest Post by Willis Eschenbach
Anthony put up a post titled “Why the new Otto et al climate sensitivity paper is important – it’s a sea change for some IPCC authors” The paper in question is “Energy budget constraints on climate response” (free registration required), supplementary online information (SOI) here, by Otto et alia, sixteen other alia to be precise. I agree that it’s an interesting and important paper, mostly because of who the authors are. However, I have to say there were some parts that I couldn’t fit together. Here’s their figure S2, showing the radiative forcing since 1850:
Figure 1. Forcings used in Otto 2013. Grey lines represent possible variations based on a monte carlo analysis of the errors in the parts that make up the total radiative forcing. They divide the total forcings into greenhouse gases (GHGs), volcanoes and solar, and a “residual” forcing which is assumed to be mostly aerosols. The estimated errors in these are used to generate a host of possible realizations, shown in gray above.
Now, when I saw that, I just rolled my eyes. Here we go again with the volcanoes, I thought.
See those big dips in the black line above? Those are reckoned to be the change in forcing due to volcanic eruptions. What happens is that the volcanoes spew light-colored aerosols into the stratosphere. This reflects more sunlight, and thus reduces the forcing in a measurable manner. As you can see, the larger volcanoes make a very significant change in the forcing. So I set out once again to see if the claimed temperature change due to the volcanic forcing held up in the real world.
But as often happens, before getting to the volcanoes I got sidetractored, this time by discovering that Otto et al. to the sixteenth power are not discussing eruptions from ordinary active volcanoes . Oh, no indeed.
Otto and his hexadecagonic cohort are discussing retroactive volcanoes.
Here’s why I say that. I digitized the Otto data. Figure 2 shows the results, including the dates of the larger eruptions which are responsible for the large dips in the amount of sunlight reaching the earth:
Figure 2. Forcings from the Otto 2013 paper, along with the volcanoes associated with each of the large dips in forcing. The earliest eruption is assumed to be Cotopaxi because of the very large dust veil index associated with that eruption.
Here’s the oddity I noticed. As you can see, not only are the volcanoes associated with the large drops in forcing. They also apparently are able to cause the temperatures to drop during the year before they occur … in other words, they cool retroactively. In each case, there’s a drop in forcing, not only in the year of the eruption, but in the previous year as well …
Here’s the likely reason why the retroactive drop in forcing occurs. It’s not a timing error in the data. Figure 3 shows the Otto forcing data compared to the GISS forcing data.
Figure 3. Forcings from the Otto paper compared with the GISS forcings.
Note that in both the GISS and the Otto forcings, the lowest points after the eruptions coincide perfectly, so it’s not from timing … but the years immediately before the eruptions are quite different. Rather than the forcing falling in the year prior to the eruption as the Otto data does, the GISS forcing remains high until the actual year of the eruption. Additionally, the size of the GISS volcanic forcings is about twice the size of the Otto volcanic forcings.
Now, the paper says that they are using the average model forcings from the Forster paper that I discussed recently. However, the Forster forcings look much like the GISS forcing shown above, with large volcanic excursions. In addition, the Forster results are not retroactive—as with the GISS data, the Forster forcing drops in the year of the volcano, and not the previous year as in the Otto forcings.
I suspect (and let me emphasize suspect) that what has happened is that either rashly or quite possibly inadvertently, someone has slightly smoothed the Forster forcing data. The difference is subtle, I didn’t notice myself until I looked at Figure 2 and went whaa?
I say it’s smoothed because if I use a simple 3-year centered moving average on the Forster data, I get something very near to the Otto forcing data. Such a smoothing makes the volcanic drops “retroactive”, since the centered moving average includes the following year’s data. Figure 4 shows those results.
Figure 4. The Forster (blue) and Otto (red) forcing data, along with a smoothed version of the Forster data. The smoothing is done using a simple centered 3-year moving average. The years prior to the eruptions of Krakatoa (orange diamond) and Pinatubo (red squares) are highlighted in both datasets to show the “retroactive” effect of the smoothing on the previous year’s data. The Forster data has a 0.3 W/m2 trend added to match the Otto data, as described in the Otto paper SOI.
Note how similar the simple smooth of the Forster data is to the Otto data. This is the only explanation I can think of for the retroactive nature of the Otto volcanoes.
If the Otto data is indeed incorrect, that could make a large difference in their results. It’s difficult to say, but since the size of the volcanic excursions in forcing have been cut in half in the Otto data, it seems like it might be important. In addition, when you are using a forcing time series dataset for predicting (hind casting or forecasting) results, it’s a lot easier to forecast next years temperature data when your forcing data for this year contains some information about next year … using a smoothed dataset as input to another calculation is almost always a huge mistake.
For me, the best thing about the Otto paper was that via the Forster paper, it provided the data and the impetus to write my last post on climate sensitivity. It also provided an insight into how to analyze the effects of the volcanoes on the historical data versus the claims of the models regarding the volcanic effects … stay tuned, my new findings in that regard are the subject of my next post, interesting stuff.
Best wishes to all,
w.
DATA
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Oops, they’ll take care of that. Just a shift here and a shift there and voila!
Too many cooks…
This is why looking really hard at the data, all the data, is so important.
Thanks Willis.
Greg Goodman will come by to explain how Willis got the volcano forcings all screwed up in 4… 3… 2….
I haven’t read the paper. Did they estimate the magnitude of each eruption and use those values in their model or did they adjust the values to fit the Hadcrut data? Is the Hadcrut data a running average?
Why don’t you ask Nic?
A drop in temperature and forcing is an indication a large volcanic eruption is underway. Is the current temperature drop in the northern hemisphere a warning of a impending large volcanic eruption? Yellowstone national park ?
Nice find, Willis. The forcings are anticipating the volcano–a pre-active forcing.
Here is a study of how the weather was affected in the area right after Mount Saint Helens blew up in 1980. “Interestingly, this eruption had virtually no climatic effects.”
http://cliffmass.blogspot.com/2013/05/weather-impacts-of-mount-saint-helens.html
Weather Impacts of the Mount Saint Helens Eruption
They show that the eruption caused cooling during the day and warming during the night for a brief time period.
The full paper is here:
http://journals.ametsoc.org/doi/pdf/10.1175/1520-0493%281982%29110%3C0614%3ATSTIOT%3E2.0.CO%3B2
Hey…animals can detect an earthquake before humans can. So it could happen. In this “Gaia smokes pot” age, Maria is sentient!
The Willamette Valley can rain the feathers off a duck. So I would hazard a guess that whatever Mt. St. Helens coughed up ended up in the water treatment facilities PDQ.
I’ve often thought there must be a case where a trailing smoothing is better than one that’s symmetric about the point being smoothed. I seems like this a case where that might be valid. At least you wouldn’t get the event starting before it happened (you would delay it I guess which might be just as bad), but then is smoothing even appropriate for something like this?
There is no reason why….seven volcanoes would lie….
maybe….they just wanted to put some warts on Mann’s hockey stick.
Oh come on, Willis… you’re completely ignoring the possibility of time-traveling volcanic ash!
Seriously though, great sleuthing!
If I might interject a note of further caution; it seems that they have cherry-picked their eruption list. For example, no sign of Askja, a VE5 in 1875, and most glaringly, the VE5+ of Cerro Azul of April 1932, followed a few months later in January of ’33 by Kharimkotan’s VE5. There is no indication of any effects from this on the graph… well, assuming, that is, that we exclude the downward blip in 1920 through 1921. (Retrovolcanos in action?)
willis
there was a big fuss about the real effects of a massive eruption in 1258AD
“Reconstructions of past climate on the basis of tree rings may miss the short-lived cooling events caused by volcanic eruptions, reports a paper published online this week in Nature Geoscience. The work suggests that, in particular, the tree-ring-based reconstructions may be missing cooling linked to the ad 1258-1259 eruption of an unidentified volcano. Tree-ring chronologies are often collected from regions that are at or near the minimum temperature for tree growth. Michael Mann and colleagues used numerical simulations of climate and tree growth to show that when temperatures fall abruptly for one or two growing seasons, trees in these regions undergo little or no growth. The resultant lack of a tree ring corresponding to the period of cooling thus masks the climate event in subsequent reconstructions. These results show that a 2 °C cooling associated with the ad 1258-1259 eruption (as indicated by climate models) cannot be excluded by existing tree-ring data.
http://www.natureasia.com/en/research/highlight/1558
It would be very interesting if you could digitise the Mann hockey stick to see if there is a retroactive effect in the 1258 incident. It was so large it probably had an effect two years before it blew
tonyb
We should be worried by this paper. It looks to me as if the data has been cherry picked.There were at least fifty significant eruptions during this period, many with a volcanic explosive index greater than the volcanoes included in the analysis. Their effect on climate is determined by a number of factors: how much SO2 is emitted, how high it is emitted, how long the eruption lasted, the latitude of the volcano (because the higher the latitude the closer the stratosphere is to ground level), the height of the volcano (where it erupts if the new eruption is lower than the peak), etc.
For example: Cotopaxi erupted at least once each year for the whole of the 1850’s decade. So why was only the 1855 eruption shown?.
Probably the most important volcanic eruption for the Northern Hemisphere in the 1750-1850 period was the Laki fissure of Grimsvotn in 1783/84. It was only a VE4 eruption but it lasted 8 months and put much more SO2 into the stratosphere than Tambora in 1815, which was a VE7 but only lasted about 10 days. However Tambora is in the tropics and so affected the climate in both hemispheres.
Finally don’t forget volcanoes generally emit huge quantities of CO2. Surely volcanic emissions of CO2 must have the same effect as CO2 emissions from burning coal.
Retroactive volcanoes?
We’re doomed!
Smoothing.
The volcano takes heat out of the atmosphere in order to build up a bigger burst. /sarc.
For those interested, there is a book called Melting the Earth which looks at historical explanations for volcanism going back thousands of years. It’s an interesting look at human psychology and the development of scientific ideas-it was a VERY long time before humans got anywhere near right about what causes volcanos in the first place. The same goes for mountain ranges, earthquakes, and most other things in the earth sciences. Humans just don’t seem very good at picking the right ideas about how the earth operates, and it doesn’t help that the earth is very complex in the first place. ‘Trust us’ climate scientists should take notice, the earth sciences have a very long history of premature, ill-conceived, model-based, politically compromised and plain wrong ideas, which are very often overturned by empirical data, which only becomes available later. History seems to be repeating itself with the modern AGW movement.
Willis, if you go back and look at the simulations that start in 850, you’ll find other interesting things WRT volcanoes.
“Note that in both the GISS and the Otto forcings, the lowest points after the eruptions coincide perfectly, so it’s not from timing”
Oh yes. They (the models, HADCUT GISS el al. ) are ‘adjusted’ at least monthly to agree. Yes the ‘Hand Of Mann’ is quite apparent.
A ‘Sea Change’ to the ‘IPCC’ ? No ! The real sea change will occur on the death of Hansen, Jones, Schmidt and Trendberth and a few other misanthropes like the Emperor of the IPCC.
I left out Mann ! Yes ! I want Mann to stay alive well into 104 at least and by electrical-mechanical methods (I’ll buy those for him).
No holding breath till blue from me, this is a battle of attrition and time is not on the side of Hansen, Jones, Schmidt (multiple physiological afflictions and addictions) and Trendberth.
Lovely graves all.
Willis, You say,”…since the size of the volcanic excursions in forcing have been cut in half in the Otto data…”
That being the case, what would you estimate the effect to be on Otto, et al’s climate sensitivity estimates? JP
So we can now credit Otto with discovering a volcano predictor ?
Never underestimate the power of the great god Vulcan; for lo! His retroactive volcanoes spew aerosols across the very fabric of Time!
I have to echo Arizona CJ sentiment about the missing eruptions. Another item that is sort of a burr in my saddle is Carbonyl Sulfide (OCS). It’s long lived in the atmosphere (I’ve read up to 9 year life span) until it gets up into 200nm – 270nm light where it dissociates. Once it does that, it can become a sulfate and participate in the aerosol layer screening games. I don’t have anything to back it up, but I think that this could be a mechanism where the more sedate flood basalt events (Eldga, Laki, Tolbachik, etc.) could provide an influence on the aerosol index. With it’s long stay time, it can be wafted up the edge of the troposphere between the large scale circulation cells. If it crosses the tropopause, there is plenty of hard UV there to dissociate the molecule. And, as you probably know, the latitudes of the general upward circulation are 0°, and 60°. Within a few hundred miles of 60°N are the Kamchatka volcanoes and Icelandic volcanoes. I have no idea of what percentage of the sulfur budget for a volcano is in the form of OCS. Usually you only find data on H2S and SO2.
Just a thought. Your mileage may vary.
Obviously, one should not be using any kind of multi-year smoothing functions for the volcano forcing.
It is just a matter of a few weeks before the stratosphere responds to the volcanoes, maybe another few weeks before the surface temperatures start falling (less than would be expected I might add).
With all these lags and delayed forcing/temperature responses, climate science needs to quit smoothing the factors beyond the timelines which they actually operate on.
GHGs operate on the order of hours, water vapor feedback has to be on the order of days, cloud optical depth feedback is also on the order of days, volcanoes are weeks (extending out to 3 years before the aerosols dissapate), albedo changes from ice melt might be decades to 1000s of years but all these impacts must have the time resolution that they operate on.