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
“what is the evidence for a large eruption at Cotopaxi in 1855?”
Here:
http://commons.wikimedia.org/wiki/File:Cotopaxi_(1855_with_house)_Frederic_Edwin_Church.jpg
It is smoking, so there!
As a matter of fact Cotopaxi was more or less continuously active 1850-1886, with major eruptions 1853, 1870, 1877 and 1886, but not in 1855. The 1877 eruption was one of the largest in historical times. There is no chance that a major eruption in 1855 would have gone unnoticed since Cotopaxi is less than 20 miles from Quito, the capitol of Ecuador.
Here is a chart showing how the Volcanoes impact temperatures in the Stratosphere and in the Troposphere from the UAH daily temperature dataset.
The impact from Pinatubo shows up as a sharp rise in the Stratosphere just 12 days after the eruption (and it peaks 110 days after the eruption 1.3C higher than the background temperature before the eruption). Temperatures in the Stratosphere then end up 0.5C to 1.0C lower than the background temperature was before the eruption due to the Ozone depletion caused by the volcanic sulfates and other chemicals. It might then take 20 years for the Ozone to rebuild. Technically, there is now less solar interception by Ozone in the stratosphere and more of it is getting to the surface.
I threw some lines on this chart for illustration but they are not scientific, just playing around.
Obviously, if you are going to model this, you should be modelling it with the very rapid / and longlasting impacts that they have, not smoothing the data before the event.
http://s15.postimg.org/z0ii1x56j/UAH_Strat_Trop_Volc_Lines_Apr2013.png
Bill Illis says:
May 23, 2013 at 7:37 am
I like this, but those weren’t the only 2 volcano’s the last 3 or so decades. If we have to have stratosphere data to tell, we can only guess which ones actually show up in past temperature record.
Would that be anything to do with solar cycle proxies?
Thanks Bill, so there is a very clear signal in stratosphere. A short pulse with fairly sharp termination plus a residual, opposite effect.
However , the lines you put on TLT plot have little to do with the data. There is absolutely nothing there other than the usual ups and downs that happen both before and after. There is actually a peak in the middle of El Chichon pulse.
I see nothing in TLT either on the scale of the pulse of longer residual that could be related to the two events.
So accepting that stratosphere data bears witness to a change in the TOA energy budget and there is not visible change in TLT, that tends to confirm what I said above about the model response to volcanism being the problem rather than the data.
BTW, I believe the modelling input (for recent events) is based on Mauna Loa optical density measurements.
Could this be the result of possibly using the volcano value as of the mid-point in the year, whereas the the temperature is the annual average? For example, if a volcano exploded on day 365/2 + 1, it would not show on that year’s figure. Then again, I’d guess they’d be consistent.
http://climategrog.wordpress.com/?attachment_id=260
Here is tropical SST for N. Pacific and N. Atlantic ( 0-20N) with annual cycle filtered out (not anomalies).
I can not see any sign of a volcano and nothing corresponding to the difference in energy budget suggested by the stratosphere data.
So if tropical stratospheric eruptions don’t show up in TLT and don’t affect tropical SST where is the permanent offset in temperature predicted by these models to be witnessed in climate DATA?
Just looking back at the model output Willis posted yesterday, there’s a good 0.3 K drop after Mt Pinatubo, that should be visible somewhere !
http://wattsupwiththat.files.wordpress.com/2013/05/cmip5-model-temperature-and-forcing-change.jpg?w=640
Shouldn’t it ??
Reich.Eschhaus says:
“Why don’t you ask Nic?”
I can confirm that the forcing data from Forster et al (2013) used in Otto et al (2013) had a 3-year centered running mean smooth applied.
Because the estimates in the study are based on averages over periods of 10 years or more, the smooth will have had little effect on the results.
Pamela Gray says:
May 22, 2013 at 6:15 pm
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 was close enough to hear the explosion. The weather was regionally overcast, mod clouds. The plume moved fast, outside of the local weather zone within hours. Ash fall shut down the E-W highway though southern British Columbia along the US border in the late afternoon, shortly after I passed through. Cloud masses had descended on the peaks when I was through. Ash was very light up in Calgary, but the skys were hazy. There was a touch of ash all across western Canada, and some said that the rains we got the eruption were unusual, but June is the second rainy period of Calgary area (February is the largest, but for snow), so the effect is probably just a Baxter correlation-causation.
The local effect in Calgary of Mt. St. Helen was slight, and I doubt that there was enough to show up planetwide. Note that you DON”T see on the graphs is all the other big volcanic eruptions that have occurred. Just some, and not just the big ones: it appears that you need to also go high AND be located in a (possibly) low latitude area to get planetary coverage.
Sort of like coronal mass ejections, come to think about it: they happen many more times than we experience, as they have to be in the right place at the right time or they make no impression on us.
Retroactive volcanoes! Nothing is beyond the powers of CO2 to produce extraordinary things, as long as it is the sort of CO2 produced by Man!
I began measuring sunlight, UV-B, total ozone, total water vapor and aerosol optical thickness on 04 Feb 1990. The major eruption of Mount Pinatubo occurred on 15 June 1991. Beginning a month or so thereafter, I photographed and measured high altitude residues from the eruption and astonishingly brilliant twilight displays. The initial debris cloud evolved into a global sulfate cloud. Optical depth at various wavelengths from the UV to 1000 nm increased sharply and the output from a solar cell fell up to 20 percent. Both local temperature and column water vapor dropped. These parameters exhibited an exponential recovery over about 3 years. In short, this major eruption had a distinct but temporary impact on the atmosphere, sunlight and temperature at my site in South Central Texas.
Excellent. Fortuitous time to start your record.
Is that data you are willing to make available ?
Of course, I was only looking at SST. Land would not have the same capacity to adjust and is more sensitive , having a lesser heat capacity.
What latitude is your station at?
@Nic Lewis
“I can confirm that the forcing data from Forster et al (2013) used in Otto et al (2013) had a 3-year centered running mean smooth applied.”
Thanks Nic! Was this information in the article?
@Willis
I think that explains it all, doesn’t it? (Couldn’t you just have asked Nic or any of the other authors so you would not waste valuable time to write a blog post on it?)
Greg Goodman: Is that data you are willing to make available ?
+++++++++++++++++++++++++++++++++++++++++++++++
See http://www.forrestmims.org. I wrote a lengthy article on Pinatubo measurements for Science Probe magazine. I’ll discuss the Pinatubo effect in detail in a new paper when my time series reaches 25 years (it’s now 23 years).
Reich.Eschhaus
“Was this information in the article?”
I don’t think so. But I can’t see that it is a material point, for the reason I gave before.
@Nic Lewis
“But I can’t see that it is a material point, for the reason I gave before.”
I didn’t think it was, Willis brought it up. As you said:
“Because the estimates in the study are based on averages over periods of 10 years or more, the smooth will have had little effect on the results.”
Quite.
(congrats on the article btw)
As Greg Goodman noted, both Eyjafjallajökull and Grímsvötn were on the low end of the scale as for what volcanoes can do. Eyjafjallajökull wan’t that energetic, so not much of it had a chance to reach the stratosphere (even for that latitude), Grímsvötn nailed it hard, but the odd thing was that the SO2 signature did not really show up until about a week after the eruption was over. The SO2 plume drifted north east up into the polar cell and that was about it.
Forrest M. Mims III says:
Greg Goodman: Is that data you are willing to make available ?
+++++++++++++++++++++++++++++++++++++++++++++++
See http://www.forrestmims.org. I wrote a lengthy article on Pinatubo measurements for Science Probe magazine. I’ll discuss the Pinatubo effect in detail in a new paper when my time series reaches 25 years (it’s now 23 years).
Thanks. Lots of cool graphs but I can’t find any numerical data.
could you post a specific link to where I can download the data ?
Nic Lewis
“I can confirm that the forcing data from Forster et al (2013) used in Otto et al (2013) had a 3-year centered running mean smooth applied.”
Like I said above, the filter’s unnecessary and detrimental but probably down at the knit pick level of significance.
Just out of curiosity , are you sure it wasn’t a 5 year RM filter? Both attenuation and shape of defects suggests 5y to me.
Once again, thanks for you efforts on this analysis. Things are slowly getting more realistic but it takes time to slow a juggernaut.
http://www.forrestmims.org/
“My review mainly concerns the role of water vapor, a key component of global climate models. A special concern is that a new paper on a major global water vapor study (NVAP-M) needs to be cited in the final draft of AR5. This study shows no up or down trend in global water vapor, a finding of major significance that differs with studies cited in AR5. Climate modelers assume that water vapor, the principle greenhouse gas, will increase with carbon dioxide, but the NVAP-M study holds that has not occurred. Carbon dioxide has continued to increase, but global water vapor has not.”
Good luck with that endeavour.
That is key point that I’m trying it make here. I was unaware of that paper, Thanks.
With the level of volcanic forcing shown here there would be a net imbalance if the hypothesises water vapour feedback ‘evaporates’. My contention is that it is the climate response more that the forcing which is wrong.
A preliminary scan of various temperature records show topics have no visibly obvious volcanic signal. Land outside the tropics, in particular temperate NH, are the only regions where that is something clearly attributable. I will be taking a closer look at that to quantify it.
This would appear to vindicate Willis’ TS “governor” hypothesis.
Since land is much more responsive to changes in forcing due to its lower specific heat capacity (as I demonstrated in one of Willis’ earlier threads) and is only 30% of global surface, it appears that GCM are badly failing to reproduce the actual climate response volcanic events.
As I have said on many occasions now, the two errors go hand in hand. It is the failure to model a correct response to volcanism that leads to the water vapour feedback hypothesis.
Your graphics indicate that your careful monitoring has produced a high quality regional record that would help establish a number of parameters. I would encourage you to publish that now, rather than to wait for a round number.
BTW , you may wish to correct the phase shift in your running means They don’t line up with the data and give a spurious delay in relation to Pinatubo.
It also appears that some of the smaller detail in some plots is being bend sideways by the phase distortion implicit in the simple running mean. You may find it useful to adopt a less distorting filter.
http://climategrog.wordpress.com/2013/05/19/triple-running-mean-filters/
Good luck with the review process.
Greg Goodman (May 23, 2013 at 6:15 am) wrote:
“[BTW , I would like to ask you about a comment you made on persistence of 9y cycles and your wavelet analysis, that you made recently if you would contact me http://climategrog.wordpress.com ]”
Let’s discuss this in public. Tallbloke’s Talkshop is the best place for that.
http://judithcurry.com/2013/05/21/how-to-humble-a-wing-nut/#comment-324234
I sincerely look forward to future discussions with you when the time & circumstances are right.
One often finds that when a major earthquake hits, there are many aftershocks. So is it possible that huge volcanoes in the oceans occurred which were not detected, but which spewed huge amounts of SO2 into the air to cause a lowering of temperature? And later one on land occurred as an aftereffect of the one in the ocean and which was plainly visible and caused a further reduction in temperature?
Is “forcing” a physical quantity, measurable more or less directly? Or is it a mythical quantity used to cover our lack of understanding how the climate works?
Nic has provided the data used in Otta et al on his new discussion of the paper so I’ve plotted it up to see how it compares to the temperature record.
http://climategrog.wordpress.com/?attachment_id=273
As I said above this will thus create a spurious correlation giving the impression that the model is capturing this key feature of the temperature record in its hindcasts.
I don’t see this as making a material difference to the Otto paper but it will make a visible and false improvement to hindcasts, one of the primary metrics of the quality of the models.
Well spotted Willis.