Guest Post by Willis Eschenbach
I see that Susan Solomon and her climate police have rounded up the usual suspects, which in this case are volcanic eruptions, in their desperation to explain the so-called “pause” in global warming that’s stretching towards two decades now. Their problem is that for a long while the climate alarmists have been shouting about about TWO DEGREES! PREPARE FOR TWO DEGREES OF DOOM BY 2100!! But to warm two degrees by 2100, you have to warm at 0.2°C per decade, or around 0.4°C during “the pause” … so they are now left trying to explain a missing warming that’s two-thirds of the 20th century warming of 0.6°C. One hates to confess to schadenfreude, but I’m sworn to honesty in these pages …
In any case, I got to thinking about their explanation that it wuz the volcanoes what done it, guv’nor, honest it wuz, and I did something I’d never thought to do. I calculated how much actual loss of solar energy occurs when there is a volcanic eruption. I did this by using the Mauna Loa atmospheric transmission data. These observations record what percentage of the solar energy is being absorbed by the atmosphere above the observatory. I multiplied this absorption percentage by the 24/7 average amount of solar energy (after albedo) which strikes Mauna Loa, which turns out to be 287 W/m2. (As you’d expect from their tropical location, this is larger than the global average of 240 W/m2 of sunlight after albedo). Figure 1 shows that result, which was a surprise to me:
Figure 1. Amount of solar energy absorbed by the atmosphere above Mauna Loa, Hawaii. Data Source
Now, before I discuss the surprising aspects of this graph, let me note that the Mauna Loa data very sensitively measures the effect of volcanic eruptions. Even small volcanoes show up in the record, and the big volcanoes are clearly visible. Given that … is there anyone out there foolish enough to buy the Susan Solomon explanation that the cause of the pause can be found in the volcanoes? I guess there must be people like that, the claim has been uncritically accepted in far too many circles, but really … who ya gonna trust? Susan Solomon, or your own lying eyes?
I’ll return to the question of the pause, but first let me talk of surprises. The thing that was surprising to me in this was the size of the loss of solar energy. The El Chichón and Pinatubo eruptions reduced the downwelling solar energy by maxima of forty and thirty watts per square metre at Mauna Loa. This is a huge reduction, much more than I would have guessed.
One measure of how much energy is lost is the total loss until such time as the absorption returns to its pre-eruption value. It turns out that in the case of both El Chichon and Pinatubo, the net loss of solar energy was about 450 watt-months per square metre. The loss was spread more widely (5 years) in the case of El Chichon than in the case of Pinatubo (3 years) before it returned to normal.
This means that for the period 1982-1987, Mauna Loa was running at 450 W-months/m2 divided by 60 months equals an average deficit of no less than 7.5 W/m2 of incoming energy over the five-year period … and it’s worse for Pinatubo, since that involved the same total energy but only lasted for three years. So for the three years from 1991-1994, Mauna Loa was running at a whacking great average solar energy deficit of 14 W/m2 …
Now, how much difference did this surprisingly large lack of incoming energy make? According to the IPCC, climate sensitivity is 3° per doubling of CO2, and a doubling of CO2 is a forcing increase of 3.7 W/m2 … and Mauna Loa was running at 14W/m2 shy of normal, that’s almost four doublings of CO2. So according to the IPCC, that kind of a decrease in forcing should have lead to a temperature drop of 11°C … so what actually happened?
Well, we’re in fantastic luck, because the temperature records at Mauna Loa are very good. Here’s what they say (study here):
Figure 2. Mauna Loa temperatures. Vertical red lines show the dates of the El Chichon (March 1982) and Pinatubo (June 1991) Graph from B. D. Malamud et al.: Temperature trends at the Mauna Loa observatory, Hawaii.
As you can see, despite the large decrease in incoming sunshine, there is absolutely no visible change in either the noon or the midnight temperatures … go figure. What happened from the volcano is nothing at all. No effect.
Now, y’all may recall that I have argued over and over against the concept of climate sensitivity. This is the widely-accepted hypothesis that the changes in temperature are determined by the changes in forcing. I’m a climate heretic—I don’t think climate works that way at all.
In particular, despite widespread skepticism, I have persisted in saying that volcanoes basically don’t do jack in the way of affecting the global temperature. I can finally demonstrate that unequivocally because I’ve stumbled across a very well-documented and precisely measured natural experiment.
At Mauna Loa we have a clear example of a measured decrease of 7 W/m2 in the average incoming solar energy for five years (1982-1987), and a decrease of 14 W/m2 for 3 years (1991-1994) … and there is absolutely no sign of either forcing decrease in the temperature record of the very place where the solar decrease was measured.
As I’ve said over and over, the emergent phenomena of the climate system respond instantly (hours or days, not months or years) to any change in the temperature. If it cools, we rapidly get a drop in albedo, which allows in more sun, and the balance is restored. If it warms, very soon thereafter albedo increases, we get less sun, and again the balance is restored. So while I was surprised by the size of the drop in downwelling solar energy, I was not surprised that we can’t find the signal of the solar drop in the temperature records.
Setting that question aside, let me return to the “pause”. Solomon et al. used the Vernier aerosol optical depth (AOD) dataset, which is available here. It is a calculated global dataset based on various observations. The explanation of the calculations is here. If anything, there is less recent variation in that dataset than in the Mauna Loa dataset. Figure 3 compares the two over the period of the satellite temperature observations.
Figure 3. Compares the negative of the aerosol optical depth with the Mauna Loa transmissivity data. Mauna Loa data rescaled to match AOD data for comparison purposes only.
So it doesn’t much matter which one we use to compare to the temperature data. Let me use the Mauna Loa transmissivity data, since the native units are in the same range as the temperature anomaly. Figure 4 shows the comparison of the Mauna Loa transmission data with the UAH MSU satellite-based lower troposphere temperature data:
Figure 4. Satellite lower tropospheric temperatures (blue) and Mauna Loa solar transmission (black line). Note that while Pinatubo happened at the start of a temperature drop, El Chichon happened at the start of a temperature rise. In addition, in neither case are the rise or the drop notable—the drop 1988-1989 or 2007-2009 is indistinguishable from the post-Pinatubo drop.
Finally, lest some folks claim that because Mauna Loa is in the northern hemisphere we can’t compare it to the global temperature changes, Figure 5 shows the comparison of the Mauna Loa with the northern hemisphere temperatures:
Like I said … I know there must be folks out there that can be convinced that the changes in the black line, the known effects of the volcanoes, are the reason that there is a “pause” in the global temperatures … I’m not one of them.
CONCLUSIONS:
• I may never find better evidence of the lack of connection between changes in forcing and changes in temperature than the measured large drop in solar forcing and the total lack of corresponding temperature change at Mauna Loa. It is a superb natural experiment, and has been very precisely measured for over half a century. It provides strong evidence in favor of my hypothesis that the temperature is controlled by emergent phenomena, and has very little to do with forcing.
• The change in forcing from the 21st century volcanoes is trivially small in both the Vernier AOD dataset and the Mauna Loa dataset. It is far too small to have the effect that they are claiming. I don’t care what the climate models told Solomon et al., the post-2000 changes in volcanic forcing are meaningless.
• My oft-repeated claims about the lack of effect of volcanoes on the global temperature are completely borne out by these results.
My regards to all,
w.
AS ALWAYS: If you disagree with me or anyone, please quote the words you disagree with. That way we can all know exactly what it is you have a problem with. Vague handwaving claims go nowhere.
MAUNA LOA TRANSMISSION DATA: From their website
The “apparent” transmission, or transmission ratio (Ellis & Pueschel, Science, 1971), is derived from broadband (0.3 to 2.8um) direct solar irradiance observations at the Mauna Loa Observatory (19.533 ° N, 155.578 ° W, elev. 3.4 km) in Hawaii. Data are for clear-sky mornings between solar elevations of 11.3 and 30 degrees.
OK excellent work so why did we get ice ages then if everything is so in balance?
Clearly sometimes everything is within a reasonable balance now but at times in the past everything has been reasonably out of balance but no one appears capable of determining exactly why sometimes there is balance and sometimes there is not. It does occur to me very often that all of these conversations are only possible because right now there is enough fuel, enough stability, enough technology and enough people to comment on the now and very carefully avoiding in specific instances the past like ice ages. This question has to be answered otherwise everything else is complete nonsense.
Where on earth did you get that average 240W/m2 for insolation? The earth receives 1370w/m2 at TOA. Correct for albedo and adsorption and the total becomes 960W/m2 over the earth’s discal area. This translates as an average 480W/m2 over a hemisphere. Remember the day/night process. Total radiation is 240W/m2 FROM THE WHOLE PLANET. (two hemispheres).
The SB formulae gives a temperature of +33C for 480W/m2, reasonable given that te water cycle has to work. Your 240W/m2 gives -18C which means that the water cycle would NOT work.
Get Real.
This is an excellent post as usual.
I wonder if there are any data sets showing the atmospheric pressure around Mauna Loa for the same time period?
I’d suspect we would see high [er than normal] pressure at about the time of the eruptions and back to normal after 3 years (Pinatubo) and 5 years (El Chichon).
“to warm two degrees by 2100, you have to warm at 0.2°C per decade”.
According to the NASA GISS, temperature anomaly in 1993 was +0.2°C, in 2013 was +0.6°C. That’s, um, 0.4°C in 20 years. Which is two decades.
If a large stratospheric eruption has no temperature impact …
How can no volcanoes have a large temperature impact?
In climate science, this actually makes sense to them.
Pamela Gray says: February 24, 2014 at 9:32 pm
Thank you Willis for the interesting work and thank you Pamela for the great video animation.
I agree with much of this. The decrease in atmospheric transmission is mostly due to reflection, though, not absorption. One interesting aspect of the major eruptions is the increased greenhouse effect of the aerosol layer…there is a rather large warming in the lower stratosphere, as seen in the satellite LS (lower stratosphere) temperatures.
If we stick to a very simplistic (conseptual) model, Is not the figure 2b an interesting “indicator” of the “CO2-effect”? Would not night temperature be the most effective measure of the “insulating” properties of CO2? (Less signal to noise ratio) The simplyfying assumption then being that temperature have remained “unaffected” by eventual changes in water vapor, clouds, etc.
Incidentally (or perhaps not :-)) the night temperature increase os some 0.5 deg/ 30 years , which corresponds to some 1.5 deg by an extrapolation.
Cassanders
In Cod we trust
Data again Mr Eschenbach, didn’t we talk about this before. There are some perfectly acceptable models over on aisle 6 in between the bent hockey sticks and the UK’s drier winters…..
…which corresponds to 1.5 deg. C per century by simple linear extrapolation.
Cassanders
Here are two links to animations provided by NOAA:
http://www.youtube.com/watch?v=9OBCXWAHo5I&feature=player_embedded
Personally, as a volcanologist, I’m not sure volcanoes can be held responsible for a “pause” in global warming. There have been too few large-scale eruptions in the past decades to make such a statement. Meantime, having observed the glaciers in Alaska during the last decade, I can say they are receding faster and faster. It’s just the same in the French Alps. Global warming is on the way. there might be some fluctuations here and there, but the global trend is worrying.
More on volcanoes on my bilingual blog:
http://volcans.blogs-de-voyage.fr
Reblogged this on gottadobetterthanthis and commented:
Willis provides direct observational evidenced that large volcano eruptions do not affect temperature in Hawaii despite the fact the decrease in solar energy there is obvious.
We live on a water planet. Seems obvious to me.
Your chart of Mona Loa temperature at noon and midnight shows that midnight temperature has increased at a rate of about 0.04C/yr although the words at the bottom state it has decreased at the same rate. A typo no doubt. But isn’t higher nighttime temperature but not daytime temperature one of the claimed hallmarks of AGW theory?
Clear air, but do clouds follow aerosols. I would think so.
There is a claim that low level and non-eruptive activity has increased this decade. How likely is it that this would show up in Manuan Loa clear air?
http://www.colorado.edu/news/releases/2013/03/01/volcanic-aerosols-not-pollutants-tamped-down-recent-earth-warming-says-cu
El – Chichon exstinguished possibly one of the largest El-Nino’s and cooled the climate for years, and Pinatubo cooled the climate during a period of what should have been much warmer years. Redoubt was not enough to do anything, but it does not appear to have put enough SO2 into the stratosphere to show up on the stratospheric temperature satellite data. The climate aboslutely responded to millions of pounds of SO2 in the Stratosphere, through the 80’s and 90’s, I lived it.
The trouble with the IPCC’s ‘volcanos ate my warming’ excuse is that they don’t have a volcano at their house at the moment to eat it.
but the Solomon paper was peer reviewed
sorry, attempt to use font, peer reviewed
Willis, how much of the Mauna Loa temperature is under local influence and how much under the influence of the north Pacific ocean? Could it be that the vast oceanic heat sink is buffering the thermometer response to the insolation decrease?
If we look at the collective ejecta from all major eruptions since 2000 it does not add up to the volume ejected in the single 1991 eruption of Pinatubo. Assigning a generous estimate of the volume of each of the 19 recent major eruptions since 2000 there have been approximately 8 to 9 cubic kilometers of ejecta, whereas there were greater than 10 cubic kilometers ejected from Pinatubo in that single 1991 eruption.
Also, we just had a significant eruption two weeks ago of Mt Kelud, Indonesia. In fact, that single eruption has been the largest of the 21st century, so we should watch the temperatures to see if there is a difference. Although it is the largest in the 21st century, it is still an order of magnitude less than Pinatubo.
One quibble. The 2009 Eruption that caused the opacity blip was VEI4 Surychev in the Kurile Island, and not Redoubt. Otherwise, spot on. Santer and Solomon’s new paper is the third of its kind. Solomon had one in 2011, and Neely of CU wrote one in 2013 that got quite a lot of media hype.
Logic is simple. Models say pause says missing heat. It cannot be found anywhere in the oceans. So it isn’t there. IPCC says aerosols are the only Cooling radiative forcing. So it mustnbenin the aerosol fudge factors. Volcanoes spew aerosols. Voila. Except these wash out quickly unless they reach above the tropopause. Aging, Chichon, Pinatube, and Surychev did. As a counter example, Mt St Helen’s didn’t there have been 9 VEI 4 eruptions since 2000, and only Suyrchev temporarily affected atmospheric opacity and albedo. An essay from my draft next book.
Thanks Willis. Very interesting.
I would guess that surface pressure increases, winds slow, and, most importatly, evaporation would decrease, leading to less IR cooling.
I would guess that surface pressure increases, winds slow, and, most importatly, evaporation would decrease, leading to less IR cooling.
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Temperatures dropping mean increases in wind speed.
Look at the planets. The farther out you go, the higher the wind speeds.
On earth, look at the temperatures night and day, and wind speeds night and day. Night time wind speeds are higher, and less variable compared to the day. The reason is that during the day over land, thermals rise. These are columns of rising air. That acts like trunks of trees in a forest, and the wind has to weave its way through. The result is slower wind speeds, but more variability.
And cloud increase.