The UAH Satellite Temperature Record With Volcanic Noise Outliers Filtered Out
A guest post by Steven Goddard
I’ve often wondered what the UAH global temperature record would look like if the cooling effects of the eruptions of El Chichón in April, 1982 and Mount Pinatubo in June, 1991 were removed. Large volcanic eruptions shoot fine ash up to very high altitudes, which makes the upper atmosphere less transparent, allowing less sunlight (SW radiation) to reach the lower atmosphere. This has a noticeable cooling effect on the lower atmosphere and the earth’s surface which can last for years, as can be seen in the figures below. Note how the lower troposphere temperatures were depressed during periods when the atmospheric transmission was also depressed.
http://upload.wikimedia.org/wikipedia/commons/9/9c/Mauna_Loa_atmospheric_transmission.png
Next let’s look at the UAH satellite record:
http://www.woodfortrees.org/plot/uah/from:1978
Volcanic events are not related to man’s activities, and should not be included when calculating anthropogenic global warming trends.
My experiment was simple enough. I took the UAH monthly data and nulled out the periods of low atmospheric transmission (April 1982-December 1985) and (June 1991-December 1994.) In other words I set those months to zero anomaly. This is a reasonable approach, because zero anomaly is what UAH considers to be the mean temperature for the period. Using Google Spreadsheet’s linest() function, I then calculated the trend. With the volcanoes removed, the global warming trend dropped from 1.3 degrees per century to 1.0 degrees per century.
A far cry from the 6+ degrees at the high end of the IPCC scenarios.
What also becomes apparent from this graph is that recent lower troposphere temperatures have dropped back to near the 1978-1997 baseline. 2008 monthly temperatures averaged slightly lower than 1980 temperatures.
John Christy and I have written a paper that contains some of the answers raised in this thread. Go to
The name of that volcano is “El Chichón” and not “El Chicon”. Please change the title of the post.
REPLY: Fixed, thanks, Anthony
Very nice analysis and graphing. If I am not mistaken, the impact of removal of vulcanism would vary depending on what functions are used in curve fitting and how you pin endpoints. And while you are playing with outliers (my mother always warned me not to), what happens if you remove and patch over the 1998 Super-El Nino as well? Some in the climate change community would argue that events of this order of magnitude are “weather noise”, and if that is the case one might be completely justified in simply replacing them with the trend.
hswiseman,
Good question about the 1998 El Nino. I intentionally avoided that in the article because I didn’t want that to become a point of contention, but the answer to your question is that the trend drops to 0.87C/century if 1998 is removed.
I should defer to David Douglass here, but his link doesn’t seem to be present.
Great post Stephen.
You should try plotting the NIN3.4 SOI Index behind your UAH without volcanic outlyers to show the ENSO strength over the whole satellite record. As you are no doubt aware, both these volcanic periods included El-Ninos. As I recall, the 1982-83 El-Nino was very strong, bigger than that in 1997-98 in terms of its ENSO values and we certainly felt it in Australia with a severe drought. If we accept the proposition that El Ninos lead to globally-warmer temperatures, it seems reasonable to consider that the El Chichon volcanoe masked a temperature spike perhaps larger than that in 1997-98.
From my state of blissful ignorance of all things scientific, I see a logical problem in simply wiping-out the down-and-up temperature phases occurring after a volcanic eruption.
To do so presumes that our cars, farting cows and other modern wickednesses have had no effect on the extent of the down phase. If the down was less severe than it would have been had I not thrown an extra polar bear on the fire, my wicked activities must have had a continuing effect. If that is right, to draw a straight line between the start of the down and the corresponding point of the up would remove an upward force from the trend. Or so it seems to me.
Don’t worry, I’m still on your side, I just don’t find this particular analysis particularly compelling, sorry.
I look forward to having my idiocy exposed, but I don’t care because I voted for the winner.
I am of the view that volcanic eruptions are over rated when it comes to climate forcing. The majority of debris is washed out in the first year and any remaining SO2 doesnt hang around long (ice core records show only a 3 year record of SO2 for Tambora). The major impact on the Wiki chart above in 82 & 91 shows a 1 & 2 year disruption which is substantially less time than the blocked out null area’s on Steven’s chart. The UAH graph shows minor downward trend in 82 and perhaps nothing in 91. I know there is ENSO effects in the background, but how can we be sure exactly what drives minor ups and downs in the record with so many factors in play.
Here’s an interesting link on the subject:
http://www.cru.uea.ac.uk/cru/projects/soap/pubs/papers/wagner_ClimDyn2005.pdf
I don’t know if it’s accurate or not; it seems to want to sweep the entire Dalton Minimum temperature record under the vulcanism rug, but it’s an interesting paper.
I remember flying across from Taiwan to the U.S. not long after the eruption and the plane had to climb to maximum altitude to get over the layer from the eruption. The sky was noticeably brown all the way across the pacific from Taipei to San Francisco.
Here in Pendleton we get cloudless rain from topsoil dust blowing in from the high plains to the West of us. I assume the dust seeds water vapor into water droplets and falls as cloudless rain. Volcano ash would produce similar results but on a grander scale and it would last longer. It is possible that ash could stay in the atmosphere for many months and possibly a few years depending on the size of the eruption, continuing to seed water vapor and I suppose acting as a heat shield thus causing cooling. I would also assume that the affects would be regional, but maybe not global, since ash would not be well-mixed in the atmosphere. Mt St. Helen ash circled the globe more than once, riding on the jet stream. It washed out without much fanfare.
FatBigot — “From my state of blissful ignorance of all things scientific, I see a logical problem in simply wiping-out the down-and-up temperature phases occurring after a volcanic eruption.”
I think you may have missed the purpose of the exercise. Here’s a quick thought experiment: you have a sensor measuring something over time and there’s a glitch in the data at two points 30 minutes apart — a handful of points way up the first time, and a handful slightly down the second. You don’t need to throw out the data. Why? Because after experimenting a bit you realise that the glitches occured when a light switch was flipped.
So… what do you do? You remove the glitch points from the data to see if there’s some sort of trend in the data WITHOUT the glitches.
This is done all the time in real world data collection; sensors will often return data that needs to be averaged somewhat. And sometimes the readings are wierd enough that you declare data from point A to point B is simply an unusable outlier.
What I’m saying here is that there’s precedence for what Goddard did and that what he did is useful. He’s treating the volcanic data just as you would a glitch and then looking at what’s left to see what trend there may be without it.
Is this helpful? If not I’ll shut up.
I find it interesting that volcanoes preceded both warming steps.
Considering SO2 is a cloud nucleation compound is it possible that SO2 volcanoes could strip the Stratosphere of water vapor via precipitation, resulting in subsequent cooling of the stratosphere due to reduced greenhouse/shortwave absorption? (a boom and bust effect)
considering the obvious inverse correlation between stratospheric temp and tropospheric temp, it could it be possible that SO2 volcanoes have a long term warming effect. My guess is the stratosphere regulates convective precipitation, hence humidity and clouds. ie, the stratospheric temp sets the humidity thermostat, and enso forces under negative feedback against the buffering effect of evaporation/precipitation cycle.
By the same logic the climate change community will come back and justify the removal of the MWP and the LIA. If you can remove natural events, then so can they. Over geologic time periods and the natural cooling & warming natural cycles, those events are irrelevant and won’t change anything in the balance of things. One can’t just remove data because this exercise can always be justified… on both sides of the coin.
O.T. http://news.bbc.co.uk/2/hi/science/nature/7827040.stm
“The head of the World Meteorological Organisation has said that global warming does not mean the end of snow.
Secretary-General Michel Jarraud, stressed that Europe’s current harsh winter could not hide the fact of a rise in global temperatures.
He added that this would lead to snow and cold winters becoming more infrequent, but they would not disappear. “
Maybe some confusion could be caused here by Steven’s use of a warming figure in degrees per century. Removing the two volcanos wouldn’t make much difference to the trend since 1900, though it clearly affects the trend since 1979 when satellite records began. What it does do is ‘flatten the curve’ during the last decades of the C20th, and along with the dodgy postwar SST ‘bucket adjustment’ and the positive PDO, we can now understand the exaggerated trend which has led to the over-parameterisation of CO2 by the computer-scientist-turned-climatologist.
Even if MSU temps records seems more reliable than surface stations, there are still problems with temps mesurements :
Paris, last week : -9°C.
850 hpa temp above Paris : 0°C
In french this is called “inversion thermique”. Which was strenghtened with the albedo – snow on the ground.
Next winters could be very cold at the very surface on land, Low. Trop. MSU system would not always be able to “see” it.
Sorry for my awful english-writing.
So, while in the short term eliminating the temperature troughs introduced by volcanic eruptions, other natural drivers such as PDO/ENSO with their associated positive phase peaks remain. I would assume that in another thirty years or so, after these drivers run through their negative phase the result should be an even lower trend line of less than one degree per century.
Complicating all this will be what the long term impact of a quieter sun will be. We do live in interesting times.
“Volcanic events are not related to man’s activities, and should not be included when calculating anthropogenic global warming trends.”
Pardon, but volcanic events are clearly natural, occur on somewhat regular basis and form an integral part of the climate system. Hence any “global warming trend” must include volcanoes. The idea of, at this stage of knowledge, calculate the anthropogenic contribution of the trend is a deluge. At most we can frame it by noting that all major as of yet identified drivers have been positive during this period and hence climate sensitivity is on the low side. I do agree however that the absense of a major volcanoe eruption has contributed to a positive trend over the last 17 years.
RobJM (22:36:41) :
I find it interesting that volcanoes preceded both warming steps.
This statement caught my eye so I went back and read Steven Goddard’s assessment –
I took the UAH monthly data and nulled out the periods of low atmospheric transmission (April 1982-December 1985) and (June 1991-December 1994.) In other words I set those months to zero anomaly. This is a reasonable approach, because zero anomaly is what UAH considers to be the mean temperature for the period. Using Google Spreadsheet’s linest() function, I then calculated the trend.
I am presuming your data are anomalies. If that is the case then the preceding data would have the lower ie ‘volcano’ effect, built in. Was the data after the volcanoes modified eg averaged without the V effect?
What would the picture look like without these extra anomalies?
Excuse my ignorance if this is BS 🙂
BTW congrats Anthony and all involved a wonderful forum/blog.
Why would the global warming trend dropped from 1.3 degrees per century to 1.0 degrees per century, when you REMOVED the effect of volcanoes, which by definition block sunlight (and reduce warming)?
The obvious answer is that your “set to zero anomaly approach” is wrong, because it is blocking out the warming that surrounds the (brief) cooling effect of the volcanoes. First you should only block out 1-2 years of data. Second you should draw a straight line between the start & end of your “block out” – perhaps using the average temperature a year before & a year after to reduce any “cherry picking” bias. Alternatively, it would make far more sense to estimate how much volcanoes reduced global temperure, and then add that on to the temperatures.
I’m afraid that this “article” is an embarrassment to Anthony Watt’s blog, and AGW sceptics in general.
Emmanuel ROBERT (00:15:10) :
Next winters could be very cold at the very surface on land, Low. Trop. MSU system would not always be able to “see” it.
Hmmm. Good points.
Sorry for my awful english-writing.
Your English is fine. I have relatives in Texas that have far worse English. (Ah say, thet thar is faa gooder English then Franky done spoke last yare …)
English is now an international language. No one owns it and no one controls it. It will continue to evolve toward a global patois. There is no equal of Le Academy Frances for the simple reason that no one would know what dialect to declare ‘approved’. How a Scottsman and a Texan communicate is beyond me!
So, IMHO, your English is no different from any other normal dialect of English (and much easier to understand than many.) No Worries, Mate! And no need for apologies. Tout va bien, n’est-ce pas?
(I never could get all the ending vowels right in French… so I’ll stop now.)
Ray (22:52:58) :
By the same logic the climate change community will come back and justify the removal of the MWP and the LIA.
What MWP & LIA?? The World has been uniformly cold for at least the last 1000 years!
Haven’t you people heard of the hockey stick? /sarc off
Dave.
“He’s treating the volcanic data just as you would a glitch and then looking at what’s left to see what trend there may be without it.”
Is this similar to 1960’s Olympic scoring when you throw out the high and low score and average the rest? For you yougins, this was because the judges from East Germany and Russia always scored American competitors low and their own countrymen high. The American judges would do the same to them.
Dave E and Ray
Of course they will come back and say that without the volcanos the temp rise would have been greater. I’m afraid I’m with Chris H on this one Steven.
Chris H.
“Why would the global warming trend dropped from 1.3 degrees per century to 1.0 degrees per century, when you REMOVED the effect of volcanoes, which by definition block sunlight (and reduce warming)?”
If you’ve followed the this website for any amount of time, you’ll remember an article about cooling the past to warm the present. By removing the past cooling, the past is warmer, there by flattening the trend to 1.0 degrees per century from the 1.3 degrees.
What’s more….if Steven Goddard had presumed a warming trend for 6 years (at say the rate of that decade) you’d probably see the trend drop to near 0 for the 30 year period.
I think the impact of Volcanoes has been considerably overstated.
I’ve looked into the temperature impact of each of the major ones in the temperature record and, although, there is certainly an impact, it is less than previously thought and it is certainly less than the global warming models have built in for them.
This is what GISS Model E has built in for volcanoes with as much as -0.4C impact for several years for the major volcanoes of Krakatoa and Mount Pinatubo for example.
http://img101.imageshack.us/img101/7802/modelevolcanoesmr4.png
Here is the Zoom-In for Krakatoa. While the models assumed a reduction in temperatures of about -0.4C for 5 years in this case, you can hardly see any net change in the monthly temperature trend of the time.
http://img297.imageshack.us/img297/16/krakatoata5.png
Here is the Zoom-In for El Chichon. Temps actually increased by +0.5C immediately after El Chichon (compared to the global warming models which included a -0.35C impact). Note there was a Super El Nino in 1982-83 which effectively overwhelmed the El Chichon volcano.
http://img232.imageshack.us/img232/760/elchichonks8.png
Here is Mount Pinatuba. It seems to have had the biggest impact on temperatures of all the volcanoes and the global warming models seem to have got this one closest (of all the volcanoes) but the modelled impact is still off by quite a bit in the long-term.
http://img55.imageshack.us/img55/2716/mountpinatubanb7.png
Note there is no longer any negative impact built into the warming models for volcanoes since it has been over 17 years since the last major one.
I got to experience volcanic effects first hand while living in Anchorage, Alaska from 1975-1978 (supporting missle systems for our uncle).
Woke up one winter morning and thought things looked a bit more “dingy” than usual outside, even though the sun was out and shining brightly.
I went outside, and there was a layer of volcanic ash covering everything. If you took a shovel and scooped off just the top inch or two, the “pristine” snow underneath almost glowed.
It was a strange experience, and it lasted for quite some time.
JimB
off topic… or complimentary topic… looks like he who shall not be named has a new paper out.. look at the summary, do I sense a bit of back peddling there? He actually mentions *shock* ocean currents.:) The rest is more of the same old crap. I still wonder why this guy has his job. http://www.columbia.edu/~jeh1/ See Jan 13th post. Got to love a guy who uses himself as three references.. hahahahaha!!!
Can someone share the link to the Douglas and Christy paper?
This might be of interest
http://landshape.org/enm/announce-new-fraud-detection-website/
“Detecting ‘massaging’ of data by human hands is an area of statistical analysis I have been working on for some time, and devoted one chapter of my book, Niche Modeling, to its application to environmental data sets.
The WikiChecks web site now incorporates a script for doing a Benford’s analysis of digit frequency, sometimes used in numerical analysis of tax and other financial data.
I have posted some initial tests on the site: random numbers and the like. I also ran each of the major monthly global temperature indices through the site: GISS, RSS, UAH and CRU. The results, listed from lowest deviation to highest are listed below.
RSS – Pr<1
GISS – Pr<0.05
etc etc
A few points.
This analysis does not remove statistical anomalies. It is removing two well defined non-climatological events, which have a well understood cooling effect. Even a 1% reduction in solar energy received at the surface, causes more than a 1C reduction in average surface temperature.
http://en.wikipedia.org/wiki/Black_body#Temperature_relation_between_a_planet_and_its_star
The arguments here that the null periods are too long, that this would somehow be analogous to removing climatological events, and that this is equivalent to removing statistical outliers – are simply not correct.
It does not remove “high and low” temperatures. It removes two time periods when there was a known non-climatological bias to the temperature.
The use of zero anomaly is the correct approach for those periods, because in the absence of other influences, the temperature should average to zero during those times.
The inclusion of ENSO data would be interesting as a more complex multi-variate analysis, but this analysis intentionally uses only one degree of freedom of a well understood non-climatological bias to the data set.
Shocking cold wave drops temps to 40 below zero
http://news.yahoo.com/s/ap/20090114/ap_on_re_us/snowstorm
volcanic eruptions do nothing, only man and his release of the evil CO2 will destroy the planet, it’s in Hansen’s bible of destruction.
I was going to say what Chris H said, only probably snarkier.
david douglass,
Do you agree with Steven’s analysis here?
Chris H,
As Steve M says, the cooling that is removed is near the beginning of data collection, thus reducing the trend. Not hard to follow……
Also, I must say I generally agree that natural events should not be removed from any data analysis or both sides will be doing it. All natural events, whether frequent or once in a lifetime are part of the game in a non-linear system.
Jan 14, 2009
NOAA: 2008 Temperature for U.S. Near Average, was Coldest Since 1997; Below Average for December
http://www.icecap.us/
More weather:
http://news.yahoo.com/s/ap/20090114/ap_on_re_us/snowstorm
I can’t remember many of these weather events in the last 20 years. The number of these has clearly increased in the last two years. Either more cold air is building up in the Arctic or something in the jet stream is now allowing this air to drive further south. Does anyone have an explanation?
The point about eliminating bias to find a valid trend is reasonable … if we can remove all biases. Not sure if this is possible in a chaotic system where so little is known.
@ Steve M. & Chris H:
“Why would the global warming trend dropped from 1.3 degrees per century to 1.0 degrees per century, when you REMOVED the effect of volcanoes, which by definition block sunlight (and reduce warming)?”
I had exactly this question in mind. The comment by Steve M. clarifies nicely. We are not dealing with an observed mechanism, but an artifact of statistical manipulation of data, correct?
Chris H.
Remember we are looking at total spread of signal variation, how much the temps have changed, and not actual temps.
Volcanic ash would have an affect wherever it happens to be in the atmosphere. Climate in that atmosphere would determine how long it stays afloat or gets washed out. I still think the premise to start with is that ash will not be well mixed globally so finding a global signal is probably the result of post raw data averaging by the folks that give us global temperature data. Because of adjustments that go both forward and backward in the anomaly (and don’t ya wish they’d stop doin that!?!?!?) data, one would be hard pressed to determine exactly when to start and end the filter. Still, I ask the question or pose the ponder that I wonder if ash from volcanoes in the Pacific Northwest behave differently in the atmosphere (washes out earlier) than ash in the Southern Hemisphere (lasts longer).
This got me too. I guess the way to think about it is that while removing cooling events should raise the overall average, the trend is a different matter. What’s interesting to me is that how quickly temperatures rebound to a more typical value after the volcano is over. I’m not sure what that tells us exactly but it seems interesting. I’ve been reading Svante Arhennius’s book “Worlds in the Making”. His take on global warming was a little different than the current hand wringing. He regarded it as a good thing that a future return of an ice age would be forestalled. He also stated that CO2 concentrations were lower over the oceans because the ocean absorbs so much of it. It seems that the wiggles in Keeling’s graph of CO2 concentrations at Mauna Loa tell us something similar – that there is a strong tendency to pull excess CO2 out of the air. Why else would its concentration be so low compared to Oxygen or Nitrogen? It tends to get pulled out, and I assume ends up in carbonate rocks.
Any attempt to ascribe any particular event with X-units-of-influence will always generate an uproar. If you state volcanoes cause X units of cooling you are bound to provoke a fascinating debate.
I feel this is great. Debate is good; what I dislike is the idea that “the debate is over.”
Beyond the initial cooling, I’ve read some ideas which suggest volcanoes may have a secondary effect, which warms the earth. Some suggest the cooling may instigate a rebound, a sort of slosh of the Pacific which manifests as a El Nino. Therefore volcanoes cause warming, as well as cooling.
The chemistry and photo-chemistry of the upper atmosphere is also involved. I can’t remember the exact steps, but either the SO2 attacks the Ozone, or the SO2 breaks down to something which attacks the Ozone. With less Ozone the UV radiation is effected, and you move on from there: One level of the atmosphere is warmed, which causes another to be cooler, and so on and so forth.
You can research a lot of this stuff if you Google “Ozone Hole” rather than “Global Warming.”
In any case, the more we learn the more we see how elaborate, intricate and wonderfully elegant the world we live in is. It becomes more and more obvious that Hansen’s and Mann’s models are way, way, way too simplistic.
Even something like plankton-rising-to-feed-at-nightfall can influence sea-surface temperatures, which influences the rainfall in the sub-Sahara, which influences the amount of dust in the atmosphere, which influences the amount of microscopic iron sifting down to the surface of the sea to feed plankton and algae and cause coral bleaching.
Debate is great. Study is wonderful. But for any one man to claim he understands all the nuances and interactions of our atmosphere indicates the man has achieved some sort of Cosmic Consciousness, or else is a fabulously arrogant nut.
Nice work but I think it can be improved by superimposing all three charts. Another thing to look at: the “UAH Without Volcanic Outliers” chart appears to have uniform spacing along the x-axis but some labels have been skipped. The x-axis is way too crowded and hard to read. A link to a larger image would have been nice.
What you’ve done is essentially the same thing as removing an object from a photograph. It becomes necessary to replace it with “what should be there” which is always open to interpretation. In this instance you’ve chosen to replace the cooling with zero anomaly. Some might argue that perhaps a linear trend exhibited connecting say, the before and after of the El Chichón period would have been more appropriate.
I think it’s already been mentioned that the attributed effects may be too long.
It may also occur to someone that Pinatubo seems to have had the same effect as El Chichón during an even warmer period despite different solar radiation transmission rates.
You need to add the reasoning behind your decisions.
E.M.Smith (01:37:38) :
This is not a climate issue so I will say this only once.
There is a “received dialect” in English. It is that given by the International Phonetic Alphabet (IPA) entries after main word entries in most dictionaries. See http://en.wikipedia.org/wiki/Help:IPA_for_English
That said all the English people I will admit to knowing rather like to hear it spoken in many different ways and would certainly encourage others to use it as best they can (generally) without criticism.
(Although it sometimes makes for a good chuckle – you shouldn’t “misunderestimate” our sense of humour)
Maybe we won’t have long to wait
http://www.iceagenow.com/Chait%C3%A9n_Volcano_a_Tambora-sized_Event.htm
Remember that around Maunder minimum, on 19 february 1600 the Huaynaputina erupted in the biggest eruption recorded in history:
http://en.wikipedia.org/wiki/Huaynaputina
This is interesting
“The rapid shrinking of glaciers in Greenland during recent years may stall, diminishing the Arctic island’s potential contribution to rising sea levels blamed on global warming, a U.K.-led research team found.”
http://www.bloomberg.com/apps/news?pid=20601100&sid=aXm16yRTS344&refer=germany
The more i learn the less i worry.
This issue takes us back to solar cycles.
See: http://petrology.oxfordjournals.org/cgi/content/full/46/4/783
“Estimates of the stratospheric loading of H2SO4 following the eruption of the Huaynaputina, Peru, in 1600 are consistent with this eruption causing the low temperatures for the summer of 1601, which were among the coldest in 1500 years in Fennoscandia (de Silva & Zielinski, 1998). A similar temporal link has been established between the low temperatures recorded in 1816 (‘the year without summer’) and the eruption of Tambora (Sumbawa island, Indonesia) in April 1815. This eruption produced an estimated stratospheric loading of 200 Mt H2SO4 and is considered the greatest S-producing eruption of the last 750 years (Stothers, 1984; de Silva & Zielinski, 1998; Palmer et al., 2001). If high-S volcanic eruptions are associated with, and perhaps triggered by, oxidized basaltic melts (as in Mt. Pinatubo), modeling of these processes needs to account for S being present as sulfate in the basalts.”
Lame-man question:
“Large volcanic eruptions shoot fine ash up to very high altitudes, which makes the upper atmosphere less transparent, allowing less sunlight (SW radiation) to reach the lower atmosphere.”
When the ash settles in the Arctic, could that have been part of the cause of the Sea Ice doing poorly?
Why are people still allowing this guy to make posts? He clearly has no knowledge of climate science.
Allen – Which guy are you referring to? Author or commenter?
There is something I don’t understand. That is probably due to my limited intellectual capacities. However I would like to share my problem with the other visitors.
– Vulcanic eruptions lead to lower global temperatures.
– So without these eruptions temperatures shoud have been higher ?
– What is then the reason that the global warming trend DROPPED by 0,3°C per century when one removes the influence of these events from the temperature data set ? I had expected that the removal of cooling (temperature depressing) events would have shown an increased temperature rise ?
James Chamberlain (06:24:28) :
“Chris H,
As Steve M says, the cooling that is removed is near the beginning of data collection, thus reducing the trend. Not hard to follow……
Also, I must say I generally agree that natural events should not be removed from any data analysis or both sides will be doing it. All natural events, whether frequent or once in a lifetime are part of the game in a non-linear system.”
I know I’m a bit thick, but unless you remove the natural from the trend how do you establish what isn’t natural?
I really can’t pretend that I know anything about climate, but it makes sense to me to start off by assuming that every trend – upwards or otherwise – is natural and then filter out the knowns to leave the unknowns THEN try to work out what the unknowns are and how they effect the trend.
Sorry if that sounds a bit Rumsfeldish – but I know what I mean 😉
Perhaps this will make it more clear to some readers.
The UAH data set is assumed to be golden. Indeed, it is probably the most accurate representation of global temperature data over the last 30 years.
The choice of null years was made entirely based on the Mauna Loa atmospheric transmission data. There was no statistical or climatological analysis involved in this choice.
Of course a reduction in sunlight reduces surface temperatures. If you look at the Mauna Loa graph, you can see that at the peak, atmospheric transmission was reduced by 15%. Indeed, a related effect is believed to have lead to the extinction of the dinosaurs and the idea of nuclear winter.
A larger graph can be seen here.
http://spreadsheets.google.com/pub?key=pj0h2MODqj3gZXr12j4HMUw&oid=1&output=image
DAV,
Your point about substituting a linear trend is well taken, but the trend was essentially zero from 1978-1997. Thus would produce the same results.
Reading now through comments that have been approved overnight, I’m guessing Allen is probably suggesting the author.
I’ll ask this question then: why do people “let” all Gore still talk about Hurricane frequency to Global Warming links when that has been disproven or Mount Kilimanjaro being a climate indicator when it clearly is an indicator of reduced evapotranspiration of the upwind deforested area?
Some folks think the analysis here is wrong, and an “embarrassment”, and I’m sure you’ll all rush right over to Tamino or Joe Romm etc, and say “Look WUWT has another analysis we think is stupid”, followed by the usual bashing routine, you know the drill.
You may not agree with the method, but looking at things differently, and yes even using alternate or non traditional methods, can lead to insight. Some of the same people that regularly criticize me, WUWT, and the content initially told me I was “stupid” for photographically documenting weather stations, lately I get criticized for not completing my work fast enough for some folks expectations.
This post was mostly a visual and thought exercise what happens to the trend when these events are removed.
Yes there are different and probably better ways it can be analyzed. Data analysis can be done ina multitude of ways, with widely varying results. Maybe Mr. Goddard will do some of the suggestions next. This blog is about provoking thought, even thoughts we may not agree with.
The idea here is to get input and exchange of ideas. Even mistakes are very useful, especially when accompanied with suggestions from others. I have made them, so have others posting here, and we”ll all build on them. In a university environment, mistakes or ideas that won’t fly get discussed, filtered, and honed prior to any publications through collaboration with staff and faculty.
That’s what we are doing here, in full view of everybody, and we do so with the courage to put our names to it, unlike some of the intellectual cowards that do drive by commentary, or run blogs under fictitious names.
If you have criticisms, that’s fine, point them out in a constructive way. if you want to engage in drive by snark with no risk to yourself, there are other blogs for that.
In the meantime I’ve sent off an email to Mr. Douglas to see if I can get him to return and provide the link, so that we can see what his peer reviewed paper has to say about the idea.
A number of David Douglass papers at this address
http://www.pas.rochester.edu/~douglass/recent-publications.html
Some of these co-written with Christy, some dealing with volcanic forcing, though not w/ Christy. One of these is:
“Climate forcing by the volcanic eruption of Mount Pinatubo”
Allen (07:31:56) :
“Why are people still allowing this guy to make posts? He clearly has no knowledge of climate science.”
Whomever was being referred to, I suspect that 30 years from now this statement will be true for all climate scientists of today. This has been true in many scientific fields as new discoveries dismantle old ideas.
What bothers me more is the climate scientists of today that think they know enough they can claim the debate is over.
Steven Goddard (06:04:22) : This analysis does not remove statistical anomalies. It is removing two well defined non-climatological events, which have a well understood cooling effect. … It does not remove “high and low” temperatures. It removes two time periods when there was a known non-climatological bias to the temperature
IOW: they are outliers. One is NOT allowed to remove data if they are not outliers. “Outlier” really means “anomalous.” It does NOT mean “appearing in the tails” except in the literal sense. Those are just easier to detect and how they got their name. Call them anomalies if you prefer.
Even a 1% reduction in solar energy received at the surface, causes more than a 1C reduction in average surface temperature.
http://en.wikipedia.org/wiki/Black_body#Temperature_relation_between_a_planet_and_its_star
So then Pinatubo should not have had the same effect as El Chichón? Your chart implies Pinatubo had a larger effect than El Chichón which, according to the first chart, reduced solar transmission by another 3%. Why?
The arguments here that the null periods are too long, that this would somehow be analogous to removing climatological events, and that this is equivalent to removing statistical outliers – are simply not correct.
Why would the outlier status of the data have anything to do with the length of the null periods? How DID you choose the length?
The use of zero anomaly is the correct approach for those periods, because in the absence of other influences, the temperature should average to zero during those times.
You need to support this statement. The periods before and after El Chichón show a temperature rise. Why would it stop if there were no volcano?
—
I should really give you time to answer my previous criticisms. But I must ask: Is the original post irrevocably cast? Instead of replying in the comments, why don’t you place your reasoning as addenda? Not doing so has been a criticism levelled at AGW sites in the past (though not necessarily here). My criticisms may seem harsh but the AGW fold won’t be kinder.
I am happy to debate the scientific merit of this exercise, which is robust. However, it is impossible to debate ad hominem attacks.
Obviously, low numbers occurring on the left side of a graph with a positive linear trend, will reduce the magnitude of that trend. I am frankly surprised that anyone who believes that they understand science or math would object to that idea.
It is also obvious that reduced sunlight at the surface will reduce temperatures. This should be considered a simple, non-controversial exercise.
In my last post
Obviously, low numbers
should read
Obviously, removal of low numbers
DAV,
Again, I am not removing “outliers.”
I am removing time periods where the temperature record was strongly influenced by one time, short-lived, well defined, well understood, external phenomenon. This is not a statistical analysis, no matter how many times you repeat that idea.
Volcanoes have nothing to do with anthropogenic global warming.
Steven Goddard (08:08:46) : Your point about substituting a linear trend is well taken, but the trend was essentially zero from 1978-1997. Thus would produce the same results
Well, OK, but your likely to get disagreement on that. It certainly looks like the period following El Chichón is higher than the one preceding it and simply saying otherwise sounds strange.
Steve,
I think it would be useful if you updated this post, and got all data plotted on the same graph scales. Visual comparisons are difficult given these three different presentations.
I think that would make the presentation more understandable. As it stands now, it requires a lot of visual interpolation.
Applying physics and paleoclimatology to the Algore/UN/IPCC/Pachauri myth of man-made, and animal-made, global warming/climate change.
To paraphrase Alexander Graham Bell: What has the mutitude of UN/IPCC computer models and politicians wrought?
————————————————————-
Comment
http://www.klimamanifest-von-heiligenroth.de/manifest-bgr-e.htm
“Today UN Intergovernmental Panel on Climate Change (IPCC) develops scenarios on climate change in the future. The governments of the world have signed actions against man made climate change since Rio 1992. All activities are based on the thesis that additional CO2 in the atmosphere since the beginning of industrial revolution in the 19th century has led to warming in the 20 th century. As a background they use amongst others few measured temperature data since the end of the 19th century, CO2 data since mid of the 20 th century and results of computer models.”
“All laws of nature however prove the reverse connection i.e. that the temperature is the cause for a release of CO2. The diurnal variation of the CO2, the seasonal fluctuation and the proven time delay of the CO2-deagassing show that these processes are clearly controlled by temperature.”
“Because of this we cannot find any evidence of a warming caused by CO2 in 600 million years of climate history. The average concentration of CO2 in air is currently 380 ppm (parts per million). This is so minimal that a dominant influence on warming is excluded. Man made produced CO2 is about 3% of the whole emissions, that means 11.4 ppm (or 0.00114%) can contribute to warming by greenhouse effect. This is impossible due to laws of physics.”
“Today weather forecasts are valid for hardly more than three days and do not result on calculation of radiation conditions but exclusive on weather influencing parameters as pressure, temperature, humidity, windspeed in air and further data. 71% of the surface of earth is covered by oceans which establish the most effective control of heat and CO2. Human impact on cities and land use are neclectable compared to this. Because climate is weather statistics and in fact climate is influenced by asctrophysical processes, mankind do not change global climate.”
The Heiligenroth Climate Manifesto (15 September 2007)
There is no proven influence on the climate by man-made emissions of CO2.
Scenarios for future climate change derived from computer models are speculative and contradicted by climate history.
There has been climate change at all times of Earth history, with alternating cold and warm phases.
The trace gas CO2 does not pollute the atmosphere. CO2 is an essential resource for plant growth and therefore a precondition for life on Earth.
We commit ourselves to the effective preservation of our environment and support arrangements to prevent unnecessary stress to ecosystems.
We strongly warn against taking action under the assumption of an imminent climate catastrophe which will not be beneficial for our environment and will cause economic damage.
@ wattsupwiththat (08:13:37) :
“…lately I get criticized for not completing my work fast enough for some folks expectations.”
I confess to having that thought cross my mind at times until I remember all that you have accomplished in such a short time. Not only is there the surfacestations project but just look at how vigourously this little blog of yours has grown. Frankly, I don’t know how you do it. Perhaps after tomorrow we’ll see a new element at the top of the sidebar.
As for this particular post, it took me a moment to grasp what Mr. Goddard was getting at. I think it is an interesting “what if” exercise. If the climate begins to cool over the next few decades and a number of volcanic eruptions occur, I have no doubt that AGW proponents will claim that those eruptions are masking the warming. Here we have a tool that can take out such effects, both at the early part of the trendline as well as later. With the data from Mauna Loa, the period to be set at zero anomaly can easily be determined and it can be shown if all other factors are still resulting in warming or if cooling is really happening.
While the ash may reflect sunlight and cool the earth while it is airborne, what effect does the ash have on the earths albedo when it settles on ice and snow?
Would it not make the ice and snow dingier and lower the albedo, thereby increasing warming?
This is not an attack on this article or on the exercise but a critique of the basics of doing such exercise. If you can’t take critiques then don’t publish.
“Volcanoes have nothing to do with anthropogenic global warming.”
If we remove everything that has nothing to do with antropogenic global warming, you are eventually left with ONLY antropogenic global warming.
In the same line of logic, then you could remove every natural occuring cooling and warming phenomenon that influence the climate. Then what you are looking at has nothing to do with climate. You end up with man made climate inductions – if there is such a thing and it could be just noise which could show that we have nothing to do with climate – which is not a bad thing to help proving our role in global climate change.
“I am removing time periods where the temperature record was strongly influenced by one time, short-lived, well defined, well understood, external phenomenon. ”
I question that it is so well defined and well understood. It is not an external phenomenon since volanic erruptions are part of the earth and have and important role in global climate regulation. It is more than just ashes in the atmosphere, the repercusions are manyfolds.
REPLY: Criticisms on exercise are welcome, it is only ad homs and snark that we object to. – Anthony
“Here is the Zoom-In for Krakatoa. While the models assumed a reduction in temperatures of about -0.4C for 5 years in this case, you can hardly see any net change in the monthly temperature trend of the time.”
Is it my imagination, or is there a five month lag from almost every volcanic forcing peak to a temperature anomaly peak? I’d be interested in seeing the chart with that red line shifted right about 4 to 6 months.
Yes, ash will temporarily lower the albedo of ice and snow, and will also affect (lower) oceanic albedo, also temporarily, though not necessarily for the same duration.
How much CO² does a volcano belch, anyway?
o/t
Looks to me a strange thing. When we have low solar activity looks that we have great vulcanoes iruptions, in the past. Is that correct or am I wrong? Is possible to have a great connection between the Sun and the vulcanoes? Perhaps magnetism? Thanks in advance.
Steven Goddard (08:36:25) : Again, I am not removing “outliers.” I am removing time periods where the temperature record was strongly influenced by one time, short-lived, well defined, well understood, external phenomenon. This is not a statistical analysis, no matter how many times you repeat that idea.
Just FYI: It’s hard to do any analysis without involving statistics. E.g., you can’t do a regression without using statistics. You have used the word “trend” when describing the temperatures between years XXX and YYY. How did you arrive at that “trend” without statistical analysis or does “statistical analysis” have some particularly restricted meaning to you?
Outliers are removed because of their strong and unfair influence (“bias”) on the analysis. The word actually DOES mean not normal, though. You can’t call them anomalies either because anomalies ALSO means not normal. So what should one call data that biases but is otherwise normal in appearance? I don’t know so I call them “outliers” because they have the same effect regardless of name.
Volcanoes have nothing to do with anthropogenic global warming.
Who said they do? Outside of the context of the AGW debate, what were you hoping to accomplish? Is your work the equivalent of tossing paint on the wall just to see what it would look like?
—-
I don’t want to get int a flame war over this. I think it needs improvement and, in particular, it lacks the reasoning behind your decisions. Whether you change it or not is of course up to you but I suggest you view your post in less adoring eyes than those of a loving parent.
possibly more significantly, ash, soot and other small particles aggressively increase the melting of ice and snow.
Bill P
Thank you, the link to Douglas’ publications (http://www.pas.rochester.edu/~douglass/recent-publications.html
) is very are helpful.
Ray (09:15:52) :I question that it is so well defined and well understood. It is not an external phenomenon since volcanic eruptions are part of the earth and have and important role in global climate regulation. It is more than just ashes in the atmosphere, the repercussions are manyfolds.
It’s valid because they are events that are random and otherwise independent of the temperature record. It’s fair to ask: what would the record look like if this event had not occurred? But that’s the rub. Any invalidity arises from the very real problem of choosing a replacement which amounts to a guess. It’s the biggest hole in Steve’s presentation. He needs to plug it by documenting his choices.
DAV I agree, and I’ve been in contact with Steve by email and he says he’ll post an update, but will not be able to do so until tomorrow. The gap could be replaced with a coupe of choices, yielding different outcomes.
I look at this as the ulterior motive of Global Warming, and that is as an excuse to play Frankenstein Monster experiments on our climate and attempt to control it.
When the Hurricanes were seeded and it all backfired in their faces, they withdrew to thier corners to nurse thier wounds. Now the climate control freaks are back, and they have a new box of matches to play with.
Volcanos, the Sun, and Climate.
Solar activity and climate link has been proven, and accepted by many pro AGW folks to be a strong correlation up to approx 1985. After 1985 there seems to be a disconnect between the relations. Or is there:
Volcanic activity and solar influence:
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?2003ESASP.535..393S&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf
One can gather from the article above 2 points:
1. it is likely that the recent solar maximum resulted in lower volcanic activity. resulting in increased temperatures
2. it is likely that the current solar activity (minimum) will result in increased volcanic activity. take your guess at what would happen…. my guess is we are due for another large eruption.
This following report is somewhat comical. I think the volcano’s had less effect, because there were less eruptions??? hmmm
Quote:
The authors say that, overall, eruptions in the 20th century have exerted fewer obvious effects in the tropics. They said this could be because there were fewer major events in that century–but they noted it could also be “because of the damping effect of large-scale 20th-century warming.”
http://www.terradaily.com/reports/Volcanoes_Cool_The_Tropics_999.html
Knowing why you are wrong is just as important as knowing if you are correct.
First let me say that this is a great blog and I have enjoyed all of the post over the last year or so when I first came across the site.
It would seem to me that what we are talking about is common cause vs special cause. You have removed the special cause (volcanoes) leaving the common causes (AGW/sun cycles/ocean phases) and plotted that trend line. This would show us the overall temp. trend without the special causes that are not “normal” within the system. Shewhart originally referred to special cause as assignable-cause, clearly you can assign a cause to these periods of cooling. The rest of warming 1C is still unknown unless you believe in the current consensus.
The argument to remove other natural events only holds water if they can be demonstred to be inherently unpredictable.
I am wondering about the effects of the precipiated ash, similarly to Bruce (09:12:47), but further, what happens when it falls onto the ground and water,
temporarily lowering the albedo. This might explain the rapid return to ‘normal’ or the previous temperature. Thanks for this piece Steve Goddard.
A possibly obvious comment regarding the potentially over-emphasis of the volcanic effect on global temps.
The ocean integrates the incoming solar, largely visible light, over many years, call a decade significant with respect to its release. Huge volcanic eruptions decrease the incoming solar for a year, at most two.
The immediate effect on global temps of tropical eruptions then is at least an order of magnitude greater than its long term effect.
Bruce said
“While the ash may reflect sunlight and cool the earth while it is airborne, what effect does the ash have on the earths albedo when it settles on ice and snow? Would it not make the ice and snow dingier and lower the albedo, thereby increasing warming?”
Back in the 1850’s there was a report written on the effects of soot in the Arctic as this had been noticed. As I understand it soot- whether from a volcano or from a big enough cloud of it as pollution coming from say China- initially causes cooling of the atmosphere. It can then setlle on the arctic changing the colour of the ice/snow from white to blackish and thereby lowering the albedo thereby increasing warming and creating break up of ice. This in itself crerates more open water which in itself further increases warming.
However, at some point when it cools again, that means that pristine white ice and snow will reform, thereby reflecting sunlight again. However….snow is a good insulator in the winter thereby making it difficult for thick ice to form under it. In summer however snow reflects sun and protects the ice underneath.
Now whether that all means that volcanoes or soot eventually has a negative, positive, or neutral effect I dont know, but I am sure others on this thread will have an opinion.
TonyB
Regarding the question of whether it is legitimate to remove the effects of volcanic actions from global temperatures: I think the matter is clear. There are two assertions in question. First, it is asserted that global temperatures have increased in recent years (define “recent” as you like). Second, it is asserted that the increase in global temperatures has been caused in part by man-made causes. The graph above concerns the first assertion only. The question is, how relevant are volcanic eruptions to underlying global temperature trends? As volcanic eruptions are clearly transient phenomena, they can hardly be said to be contributing one way or another to any possible underlying trend. Let me be clear: if the effects of volcanos are left in the graph, then they affect any trend computed from the data. They do not, however, have any effect on atmospheric trends, up or down. They are an independent, transient forcing. As such, I see no reason not to eliminate their effect from any other possible effect. This is standard procedure in any kind of statistical analysis – account for what you are not interested in, and focus on what you are interested in. Analysis of variance consists entirely of doing just that.
No one suggests that volcanos are part of “global warming,” so no one should be concerned about removing their effects from global temperature records. Volcanos on the scale we have seen in recent decades play no part in any proposed long-term change in climate, and their effect should, in fact, be removed from the data before looking at the underlying trends. Whether this particular analysis deals with volcanic effects properly is another matter, and open to debate by reasonable people.
For what it’s worth, I, as a non-scientist, appreciate what the OP was trying to do, i.e., ask a “what if …” question, which is something that AGW enthusiasts seem to wish to avoid.
This is only my second post here, although I have been lurking for a while, and all I can say is please keep up this kind of stuff as it’s only by being exposed to arguments on both sides without the extreme abuse that does appear in other places that is helping me to understand the subject somewhat better as time goes by.
Two points:
1. I notice that many of us use “climate” and “weather” interchangeably. i.e. volcanic eruptions are climate forcing”. I believe that eruptions force weather directly and climate indirectly.
From my simplistic lay point of view, global climate is a mathematical construct of compiled regional weather data over three decades or longer. Weather is what happens day by day usually expressed in terms of surface and atmospheric temperatures, winds, humidity, barometric pressures. For more effective communication, casual use of these terms should be avoided in favor of precision.
The AGW theory is premised upon what is assumed will occur in the atmosphere due solely to the influence of man-caused trace greenhouse gases over many decades. AGWers know they cannot predict weather with any precision for more than a few days. So they deliberately confuse the differences between weather and climate in order to advance their theory about the causes of climate change.
We skeptics add to the confusion by using current weather events to refute the AGWers misrepresentations and lies. The challenge is to reduce the dialog about climate change into simple, understandable terms. To date, the AGWers, with an assist from the true believing useful idiots in the MSM, have the upper hand. We need to adjust and improve.
2. Steve Goddard’s study removes the volcanic eruption data from climate data because they are natural events and outliers. I am curious to know what the data would show if ENSO and LNSO data was also removed as outliers. The remaining climate forcings, including AGW, could be better approximated. Am I wrong? Why?
Steven
I was interested in the same thing a few months back and did a bit of work using the RSS TLS data and trying to compensate for the volcanoes. The trend changed from 0.0013 to 0.0012. I didn’t think it significant and thought my method was a bit “dorky”. Would you be interested in the spreadsheet just to see my method, which you may be able to develop with more sophistication?
G Alston (22:25:50) :
This is done all the time in real world data collection; sensors will often return data that needs to be averaged somewhat. And sometimes the readings are wierd enough that you declare data from point A to point B is simply an unusable outlier.
I agree, but with the caveat that first the experimental setup is examined to find the “light switch,” that the raw data is maintained, there’s transparency in the smoothing, etc. i.e. First you have to establish that the data in question is, in fact, an outlier and not something new and unexpected. (I’ve several times identified new things because I didn’t assume odd looking data was an artifact of the experimental setup.)
With regard to volcanic ash, one of the useful outcomes of the TTAPS Nuclear Winter scare was the increased research (primarily, as I recall, by the old Defense Nuclear Agency) into the behavior of particulate ejecta in the stratosphere. If memory serves:
Unsurprisingly, the heavier it is, the quicker it washes or falls out. Persistence is on the order of days for the heavier/larger particles (~10 micron) to months for the lightest. It takes up to a few years for the (finest/smallest) ejecta to completely wash out. The climate effects correlated well with size and quantity of particulates.
If there’s any interest, I’ll try to dig out some of the reports.
Would it not have been better to have used RSS MSU land data to plot the effect of any signal from the two events? I’m of the mind that any drop in Solar radiation would show up there first. The use of the words cooling effect on the lower atmosphere and the earth’s surface which can last for years,is ambiguous.
Wow, you really twisted that one around. You took the statement:
“Volcanoes have nothing to do with anthropogenic global warming.”
And turned it into:
“In the same line of logic, then you could remove every natural occuring cooling and warming phenomenon that influence the climate. Then what you are looking at has nothing to do with climate.”
Nice spin.
All this makes me remember the Willie Soon and Steven H.Yaskell´s article:
http://www.cfa.harvard.edu/~wsoon/1816-Mercury03-d/Summer_of_1816.pdf
Steven Goddard:
I only skimmed over the responses, so if I am repeating someone else, my apologies.
Would it not be better to remove the volcano events altogether, both the year and the anomaly, rather then setting them to zero?
If I use Excel, and calculate the slope, and I get a slope of 1.275 deg/century from 12/1978 to present, using all data.
If I delete the time periods in question (4/1982-12/1985 and 6/1991-12/1994), the slope is 1.0203 deg century.
If I input zero into the time periods in question, I get a slope of 1.0365 deg/century.
My feeling, even though the results are similar, is that you need to remove the year and the anomaly both. If you don’t know exactly what the value should be, all you are doing setting an arbitrary value. The base period should probably be recalculated too, by deleting the data.
I get an average anomaly of -0.02909 for the full reference period, using all data. With the deleted time period, I get a value of plus 0.025674. While this does not affect the slope, it reduces the amplitude of the positive anomalies, and increases the amplitude of the negative, when the difference of the average anomaly is subtracted from remaining data.
I used 12/1978 to 12/1997 as the reference period. I used a straight average to calculate the anomaly with out the volcano months.
Steve,
What you have basically shown is that if you eliminate two periods in the satellite record where the temperatures were below average then, because these periods occur in the early and mid part of the satellite temperature records, that tends to lower the trend over the whole satellite temperature record.
This is not surprising but:
(1) If you were able to look at the trend over a longer term (which you aren’t with the satellite data but could with the surface data), then you would find that eliminating these data would tend to increase the trend over earlier periods (say, 1970 to 1985) and would probably not make much difference to the trend over a longer period (say, 1970 to 2008).
(2) To the extent that the volcanic eruptions do have a long term effect on global temperatures (and they certainly ought to have some even if the short term effects are most dramatic), eliminating them would tend to increase the temperature trend. I.e., if there hadn’t been any volcanic eruptions, we presumably would have had somewhat more warming.
Hence overall, it seems to me that your approach here seems to pull out the result that you want when a more realistic approach to the question “How did the El Chichón and Pinatubo volcanic eruptions affect global temperature records?” would likely conclude that they caused the warming to be somewhat greater overall than it would otherwise have been without them.
Steve Hempell (10:11:06) :
Steven
I was interested in the same thing a few months back and did a bit of work using the RSS TLS data and trying to compensate for the volcanoes. The trend changed from 0.0013 to 0.0012. I didn’t think it significant and thought my method was a bit “dorky”. Would you be interested in the spreadsheet just to see my method, which you may be able to develop with more sophistication?
If I can use this as a springboard to jump in between SG and DAV, I’m not sure I follow DAV’s criticism that Steven didn’t supply a reasoning for the choice he made about where to “zero” the data to remove the effect of volcanic eruptions on the period data. I would have expected more questions about how Steven did it. A common technique in situations like this is to use a “dummy variable.” This is a variable that is set to “0” for periods where something is presumed to have no effect, and “1” where it is presumed to have some effect. Now in the ordinary case, this results in quantifying a shift in the constant term, something like what many here would probably refer to as a “step function.” But since our interest is in what effect it might have on the trend, then the appropriate thing to do is to use a “cross-dummy variable” in which we multiply the dummy variable times the trend variable.
I took a quick stab at this this morning, using UAH data through October, and doing it the way I just described, the result was more in line with what Steve Hempell suggests: it is there, but maybe not as great as what SG is saying. I’m going to put together a UAH dataset through December, and give this another whirl.
Meanwhile, I look forward to a fixed link/reference to the study David Douglass was intending to refer to.
I assume the comments in post Chris H (01:28:43) : have been
responded to .
A couple of other quick comments:
As someone has already mentioned, there was major el nino in 1982/83, but there were also moderate el ninos in 1991/92 and 1993. It’s reasonable to assume, therefore, that both volcano-affected periods would have been warmer than the periods immediately before and after. This would further flatten the trend – and, in the case of 1992(3), may have even pushed the “warmest year of the millenium” back a few years.
On the issue of “what ifs”. What if El Chicon and Pinatubo had not erupted in 1982 and 1991 respectively, but in 1995 (as per Hansen’s 1988 model) and 2004? Would we now be looking at significant global cooling?
Finally, and I’ve said this before, the reason Hansen’s scenario B trend ran so close to the actual observed trend for so long was down to the modelled volcano eruption (in 1995) compared to the actual eruption(s) in 1991 and, to a lesser extent, in 1983. Remember, although his projections go from 1988, the trends cited begin in 1984. There is a reason for the 1984 start date but I can never remember what it is.
Anyway – a good post which demonstrates just how sensitive temperature trends are to disturbances by all sorts of random factors.
Two correctioms necessary to my previous post:
1. “Chicon” should be “Chichon”
2. Apparently the Hansen projections began in 1984. The point remains, though, temperatures were at a local min in 1984.
Make that: “The weather effects correlated well with size and quantity of particulates.”
Sheesh I give up
A correction to my previous correction:-
“correctiom” should read “correction”
Ray @19:15 said:
“If we remove everything that has nothing to do with antropogenic global warming, you are eventually left with ONLY antropogenic global warming.”
That’s the goal.
If we back up to 1980 for a moment.
The best available historical temperature proxies had us coming out of the Little Ice Age with a pace of about 1C/century from 1700-1900. Entirely non-anthropomorphic. What the climatologists now recognize as oceanic effects (at least partially) gets added to this. Then add the effect of carbon dioxide. And now vulcanism.
That’s four things: Long term (non-human) trends, Oceanic effects, AGW, and volcanoes.
In 1998, Mann’s paper used a novel treatment to weight a very small set of trees quite heavily for determining a longer term temperature reconstruction. These trees didn’t see much of a Little Ice Age. So his temperature reconstruction effectively eliminated it from discussion. Set “Long term climactic trends” to near zero.
The effect of the oceanic effects was also thought to be more ‘weather’ than ‘climate’, and thus assumed to average out over longer time scales. (Which it should, it just happens that our best data starts at an extreme.) So oceanic effect was assumed to be near zero.
Volcanic effects were likewise deemed transient.
So the IPCC’s predictions essentially attribute the bulk of the warming to humans. So, something like 2.0C/c of anthropomorphic global warming is the result and prediction of the first couple reports using Mann’s reconstruction.
But this year, leading climatologists have admitted (paraphrased) “Well, the period 2000-2008 has had the underlying temperature trend suppressed by oceanic effects.” That implies to me that oceanic effects can be (at least) a full ±1C/c trend. And also that we were basically seeing the positive impact of this same cycle for the period 1980-2000.
If we can correctly remove the vulcanism, the long-term non-anthropomorphic trend, and the oceanic effects, we’re left with the human impact.
Even if you don’t use non-Mannian temperature reconstructions, that comes out a closer to zero than to 2.0C/c. If you think the historians are correct in reporting a widespread and strong MWP and LIA, then you end up extremely close to zero.
OT
http://news.yahoo.com/s/afp/20090112/sc_afp/denmarkresearchclimategeology_newsmlmmd
COPENHAGEN (AFP) – The earth’s climate has been significantly affected by the planet’s magnetic field, according to a Danish study published Monday that could challenge the notion that human emissions are responsible for global warming.
“Our results show a strong correlation between the strength of the earth’s magnetic field and the amount of precipitation in the tropics,” one of the two Danish geophysicists behind the study, Mads Faurschou Knudsen of the geology department at Aarhus University in western Denmark, told the Videnskab journal.
He and his colleague Peter Riisager, of the Geological Survey of Denmark and Greenland (GEUS), compared a reconstruction of the prehistoric magnetic field 5,000 years ago based on data drawn from stalagmites and stalactites found in China and Oman.
The results of the study, which has also been published in US scientific journal Geology, lend support to a controversial theory published a decade ago by Danish astrophysicist Henrik Svensmark, who claimed the climate was highly influenced by galactic cosmic ray (GCR) particles penetrating the earth’s atmosphere.
In other words I set those months to zero anomaly. This is a reasonable approach, because zero anomaly is what UAH considers to be the mean temperature for the period….The use of zero anomaly is the correct approach for those periods, because in the absence of other influences, the temperature should average to zero during those times
I think this is wrong for a couple of reasons, firstly the ‘zero anomaly’ in no way implies a ‘normal’ temperature. It is no more or less than the average reading from Jan 1979 – Dec 1998, you have to set a baseline somewhere and this is what UAH chose,. But by using this as your zero for infilling, and then recalculating (I presume, it is not clear) the trend to the present day your averaging period and your trend period do not align – you have a decade of trend that is not included in the averaging. If the average after Dec 1998 is higher than zero then your zero anomaly will be too low.
Secondly, the UAH zero anomaly was obviously calculated with the volcanic biases in place, so you are attempting to calculate a reasonable substitution value for the temperature without the volcanoes from data that includes the volcanoes!
I think an interesting exercise would be to calculate the average of all the data and substitute that as your infill value, then recalculate the average and use that as your infill and see how that affects the outcome, if at all.
PS Congratulations to AW on the Science Blog poll win.
Fascinating. Is it safe to say volcanic eruptions can counteract the (supposed) effects of global warming?
my famous take on global warming:
http://smellytourist.wordpress.com/2009/01/12/hunt-polar-bear/
from
http://www.smellytourist.wordpress.com
I just got back from the other side of the planet. This is my first chance to see WUWT in a week and a half, I tried dozens of times from four different servers – no luck for what seems to be at the top of the list for the best science blog of 2008.
On topic, I just completed a very long piece of work related to the satellite trend data. I used GISS data to remove a discontinuity between RSS and UAH and got a near perfect match of the two datasets.
http://noconsensus.wordpress.com/2009/01/14/give-a-kid-a-toy/
The discontinuity between RSS and UAH happened at around 1992, I have been unable to figure out why the problem exists there but perhaps the eruption created some problem in satellite data interpretation. Before and after 1992 the satellites match within the margin of error for the instrument data (the same margin of error tamino said was stupidly small).
The GISS correction to the section of the satellite trends which had a difference resulted in a reduction of the long term trend in both metrics. I found it pretty interesting.
I do have a question. I was looking at http://www.volcano.si.edu/world/largeeruptions.cfm?sortorder=desc
its a list of Large Holocene Eruptions, why did you pick the eruptions you did to take out and ignore the others? I realize they were larger than the others but there are blocks of years without and the occasional ‘big one’.. interestingly enough there was a 6 year “break” between 1994 and 2000.. It would be interesting to see if blocks of years without eruptions sported higher temps then the surrounding time lines or if the carry over effects from El C. were enough to keep temps down. It would also be interesting to see how specific volcanos effect different parts of the world climate wise..
I do applaude you’re efforts though. Its nice to see a scientist thinking outside the GW box:)
What folly this has become. If we humans are responsible for only about 12 parts per million of the CO2 in the atmosphere, how then are we to reduce our emissions to get less CO2 by more than 25 parts per million (required by the Kyoto Treaty)?
If I use 40 gallons of gasoline per month, can I then reduce my use of gasoline by 100 gallons per month? If I consume 2 pounds of food per day, can I reduce my food consumption by 5 pounds of food per day?
It is indeed a pity that our public school system stopped teaching simple arithmetic so many years ago. All of these grand theories (actually, not even decent hypotheses, at best, wild eyed speculations) and it is clear that these “scientists” can’t comprehend simple arithmetic.
These natural events have been going on throughout history. There is no way that humans can in any way exert control over them. What CO2 we humans produce is no more than a fart in a windstorm relative to what nature produces.
Oh, I get it. These PhDs have no useful work they can be employed at. So then what? I guess that huge research funding needs to be provided so that studies can be made as to how to cap these erupting volcanoes and sequester the CO2 they produce. Madness indeed.
‘I am wondering about the effects of the precipiated ash, similarly to Bruce (09:12:47), but further, what happens when it falls onto the ground and water,…’
A long this line of questioning
This well is a very general question. Ash, like any organic solid particle, will absorb short wave radiation, block short wave radiation reaching the surface which cools the surface. If that layer the ash was in the upper atmosphere, would that show up as a “hot spot”? And, as that layer of ash descended toward the surface (assuming convection was shut off) wouldn’t that “hot spot”, at some point in time, be picked up by the surface weather stations?
No they don’t assume changes solely due to human influence, but they believe that human influence is overwhelming the natural variation.
LarryOldTimer says:
And, if pigs had wings then they could fly. However, in the real world, we are currently responsible for about 100 ppm of excess CO2 in the atmosphere above pre-industrial levels. And, in fact, we have emitted enough CO2 through the burning of fossil fuels to raise the concentration in the atmosphere by 200 ppm; fortunately, natural processes (mainly uptake by the oceans and plants) have absorbed about half of it.
Also, I am not sure how you calculated what the Kyoto treaty requires in terms of a reduction in CO2 levels. All that Kyoto requires is a certain reduction in emissions for the 2008-2012 timeframe relative to the 1990 timeframe. It will not reduce the amount of CO2 in the atmosphere but will, at best, slow the rate of increase (or maybe the rate of the rate of increase…depending on what the nations that don’t have limits under Kyoto do).
If you are coming to conclusions such as this, perhaps it should be a hint that the problem may lie more with your misunderstanding than with some inability of scientists to do arithmetic!
That graph clearly shows that the last 5 years have been much hotter than any other 5 year period in the record and it also shows that the most recent temperature are a long way above those at the start of the series (despite “la Nina” and a cold sun ATM). It is also evident that a trend line shows a very strong warming trend.
This post has succeeded in showing that the UAH data shows a warming planet.
Here’s how I would have done it:
http://i44.tinypic.com/fvlocm.jpg
But it looks like the results are the same as what Steven Goddard came up with, as far as overall effect on the trend is concerned.
My Dear Larry,
By the reasoning of the European Union here, and what seems to be the emerging Obama establishment, you do indeed have to reduce your present consumption of 40 gallons of petrol a month by 100 gallons. At least. Ah, the blessings of scientific government.
On topic, if a decent bang from a volcano produces enough ash high in the atmosphere to reduce the effect of sunlight, does that blanket of ash add, if only a little, to the so-called greenhouse effect?
It takes time for the ash ejected into the stratosphere to propagate across the entire hemisphere, and even longer for it to propagate across the equator.
Couldn’t you examine the temperature profiles for the hemisphere opposite the eruption and use that to establish an interpolation rule?
John Phillip is close to what I would (have) done. It is iterative. You set the slope for the excised data to equal the slope computed. I am assuming you are using OLS. Set the del to be 0.0001and reiterate until met or less than. Keep in mind that an assumption is that it is linear, etc.
However, I think that in and of itself, it is interesting that it should remind posters of certain attributes of trends. We have heard from several about “cherry picking” start and end dates. I agree. However, a more subtle point is what happens when the cooling occurs near the beginning and/or warming at the end of a time series by data manipulation, or vice versa. You can also, for example, say that natural forcings were according to a certain period and use that as a baseline, in which case the difference of assumed natural versus what is attributed to man also suffers from the same problems.
However, as posted above, the elimination or quantification of the natural signal such that the antropogenic signal can be determined is what the IPCC is allegedly doing.
Joel Shore (13:29:00)
‘…..concentration in the atmosphere by 200 ppm; fortunately, natural processes (mainly uptake by the oceans and plants) have absorbed about half of it.’
Good. More plant food. Less fertilizer needed by farmers.
Joel Shore (13:29:00)
None of that matters. Why? Because carbon dioxide is not harmful, it is beneficial. CO2 has been much higher in the past. The current extremely low levels are not a problem. At all.
Jeff Id says:
I do find it strange that a correction to resolve a discrepancy between the two satellite datasets lowers the trend in both. I suppose this is because you really resolved the discrepancy by relying on a 3rd data set (the surface temperatures), but color me skeptical of this result.
You may find it of interest to lookat this paper by Spencer and Christy: http://www.devilskitchen.net/dk_blog/2007_christy_tropics.pdf, who compared the RSS and UAH data sets for the tropics specifically (where the trend disagrees most dramatically). They also note that most of the difference in the trends can be accounted for by a shift between them that seems to be “broadly occurring in 1992”. (They then go on, not surprisingly, to make arguments as to why they believe that this shift is due to a problem in the RSS dataset and that their UAH dataset is more correct.)
Smokey says:
And, sea levels have been tens of meters higher too, which is also not any sort of problem…unless you are one of the hundreds of millions of people who live this close to see level. And, for that matter, there have been supervolcanoes and major asteroid impacts and all sorts of things…so apparently these aren’t anything to worry about either!
Basil (13:37:34) :
Here’s how I would have done it:
http://i44.tinypic.com/fvlocm.jpg
But it looks like the results are the same as what Steven Goddard came up with, as far as overall effect on the trend is concerned.
Removing the volcanoes changed the linear trend from 12.7C/decade to 9.9C/decade. Wow ! Get a cork (a big one).
This topic brings up (yet again) the problems associated with any warming or cooling effect. If volcanoes have a net cooling effect then over the centuries the earth would become a giant ice globe. Since this has not happened then one of two things is most likely true. 1) Volcanoes have any identical warming effect (what is the probability of this?). Or, 2) the earth’s climate has a thermostat (chaotic attractor).
I think 2) is far more likely because it also handles all the other potential warming and cooling effects. In other words, nature has built in feedbacks that prevent the earth from cooling too much or warming too much from this attractor state.
If this is true the concept of positive feedbacks to AGW is extremely unlikely. I would think climate scientists would start from this likely situation and try to determine exactly what these effects are. Outside of a few who have publicly disagreed with CAGW it appears few of the others are up to the task.
As for GCMs … they should also be built with this as a point of validity. Without it there is a distinct probability they are wrong and these developers are pretty much wasting their time.
Mike McMillan (14:55:43) :
Removing the volcanoes changed the linear trend from 12.7C/decade to 9.9C/decade. Wow ! Get a cork (a big one).
Yeah, she’s gonna blow.
Okay, let’s divide those numbers by 10.
Feel safer now?
No, divide by 100.
What time is it? I need some sleep.
Here’s my try at time aligning the charts –
http://i40.tinypic.com/2629x0x.jpg
Off topic but,
Science is clear and technology available,
The loss of 20-30% of ‘original’ forest cover by 1990 is responsible for nearly 45% of the increase in atmospheric CO2 observed since 1850 (Malhi et al., 2002).
http://www.globalcanopy.org/main.php?m=5&sm=24&ssm=68&artid=38
Let’s be clear about the timelines if there is any adjustments to be made.
If Mount Pinatuba erupted in June, 1991, there is no need to apply an adjustment to May 1991.
Here is the timeline of the major eruptions.
Krakatoa – August 1883
Santa Maria – October 1902
Novarupta – June 1912
Agung – two eruptions in March 1963 and May 1963 and smaller ones after
El Chichon – two eruptions in March 1982 and April 1982
Mount Pinatuba – June 1991
“And, for that matter, there have been supervolcanoes and major asteroid impacts and all sorts of things…so apparently these aren’t anything to worry about either!”
You better relax man, you’re gonna get ulcers worrying about all that stuff…
I guess we’re gonna have to raise alot more taxes!!
People, let’s get back to 5th grade science textbooks. All else being relatively the same (as in the Sun is still in the heavens) plate tectonics and axis tilt, combined with oceanic circulation, determines climate. It will warm a bit there. It will cool a bit here. But the overall climate will be about the same. Until the geography changes and the ocean circulation adjust to new locations of continents and subduction zones.
So let’s get real. Greenhouse gases cannot wipe out climate. Example: The Pacific Northwest will be relatively wet. The Inland Empire will be relatively dry. Land situated near a large body of salt water with an on-shore air flow and a subduction zone will always have the same climate relatively speaking. You will get clouds building up next to the mountain range and dry land beyond that. However, tilt and orbit wobble can turn your backyard climate into a very large BBQ or a deep freeze, depending on the wobble. If your backyard decides to move to a new latitude location, you will either have bananas or polar bears in your backyard. But greenhouse gases will not change climate, they will affect weather, just like volcanic ash does. Let me say it again: GHG cannot change climate.
People always talk about what climate was like bizillions of years ago and that GHG’s are such a powerful before- or after-effect (take your pick as to which side you are on). This is nonsense. Oceanic circulation and plate tectonics determine climate, just like your 5th grade science book explained quite clearly. All the rest is weather (which I love). End of lesson. Test Friday.
So if you are an AGW proponent, please tell me what mountain range grew overnight? If you are an ice-age proponent, when did we wobble and what continent moved?
Bill Illis (17:44:32) :
Bill, did I miss something…did someone “apply an adjustment to May 1991?”
Steven pegged the Pinatubo period as beginning at June 1991, and that’s where I peg the beginning for my second dummy variable.
Basil
Basil and Bill, my question to you has to do with the data you used. Isn’t it adjusted historically (both before and after) by the providers of such data for things like volcano effects (or other effects for that matter)? I know we have had posts here about how past data gets adjusted as time goes by. Is it possible to get the unadjusted anomaly data and then run your volcano filter?
DJ wrote:
That graph clearly shows that the last 5 years have been much hotter than any other 5 year period in the record and it also shows that the most recent temperature are a long way above those at the start of the series (despite “la Nina” and a cold sun ATM). It is also evident that a trend line shows a very strong warming trend.
This post has succeeded in showing that the UAH data shows a warming planet.
But it doesn’t show that the warming is man-made.
For example:
Fast Melting Glaciers Expose 7,000 Years Old Fossil Forest
Melting ice has ‘provided’ us with frozen mammoths and even frozen people, like the famous Oetzi from the Alps, as if they were kept in a fridge. No wonder that melting glaciers in Western Canada, which recently reached a historic minimum, have unveiled 7,000-year-old tree stumps.
Wood fossil a glimpse of Northern Canada’s forested past
Another remnant of Nunavut’s warmer past, of a time when forests covered the Far North, has been uncovered on Bylot Island near Pond Inlet…. Despite the potentially catastrophic nature of climate change, global warming may bring back productive forests — the lungs of a healthy planet — to the high latitudes.
Clearly, the planet has been warmer for forests to have existed in those much colder locations in the past. If the warming now is man-made, how did man warm the planet back then that enabled the growth of those forests?
Joel Shore (14:32:09) :
Smokey says:
None of that matters. Why? Because carbon dioxide is not harmful, it is beneficial. CO2 has been much higher in the past. The current extremely low levels are not a problem. At all.
And, sea levels have been tens of meters higher too, which is also not any sort of problem…unless you areone of the hundreds of millions of people who live this close to see level. And, for that matter, there have been supervolcanoes and major asteroid impacts and all sorts of things…so apparently these aren’t anything to worry about either!
Alright….We’ve been here before. Please quantify the see {sea} level rise that will displace millions of people.
Pamela Gray,
Interesting argument, the geography did not change, so what did? I like it.
But, my question has been (but not expressed), how much do undersea volcanoes and thermal vents affect the ocean currents? Or undersea earthquakes that move the sea floor up or down? I have no expertise or much knowledge in this area, but I do know a lot about fluid dynamics as a chemical engineer. It does not take much disturbance to impact the flow.
Anyone who has ever built a rock dam in a small stream will know what I mean. A small pebble has little effect. But, a rock of sufficient size will certainly affect the flow.
Is there any literature on this?
Roger E. Sowell
Marina del Rey, California
Pamela,
I used the UAH dataset here:
http://vortex.nsstc.uah.edu/data/msu/t2lt/tltglhmam_5.2
If it has been adjusted for the effect of volcanic eruptions, I was unaware of that. I don’t think it has, and would need some proof of that.
Worry about them all you like. But the solution is to adapt, not attempt to control the global climate, because it can’t be done. The oceans will rise and fall in spite of CO2 levels.
Oh. My bad. You used satellite. Adjusted for orbit drift but I think that is about it. My fav report on UAH is here
http://icecap.us/images/uploads/DOUGLASPAPER.pdf
And I still say we are talking about weather. Yes, long term weather, but weather nonetheless.
“Joel Shore (14:32:09) :
And, sea levels have been tens of meters higher too, which is also not any sort of problem…unless you are one of the hundreds of millions of people who live this close to see level. And, for that matter, there have been supervolcanoes and major asteroid impacts and all sorts of things…so apparently these aren’t anything to worry about either!”
(I can just hear this coming from the lips of Marjoe Gortner, Just add “Brothers and sisters”, to the beginning of the paragraph)
Meanwhile prices of seaside property are skyrocketing, even Al is buying seaside property… it seems like he would think it a poor investment. Do all the political and scientific elite think the common man is THAT stupid? Just wondering…
Sorry, Joel, but your rhetoric does not sound like the dispassionate observations of a man of science. Perhaps you need to get out of the lab and take a vacation… the beach, maybe?
Cold Thailand?
http://www.terradaily.com/reports/Tropical_Thailand_declares_emergency_as_cold_hits_999.html
A semiformed thought… Couldn’t you think of this temperature series as being rather like a complex sound. Some frequencies are very high (the spike from the volcano) and some are very low frequencies (the AGW component, slowly increasing over a long time – in theory). If that is a reasonable analog, then a short time Fourier transform ought to show the distribution. See:
http://en.wikipedia.org/wiki/Short-time_Fourier_transform
At the bottom is an example of a sound analysis. Imagine it with a big spike at the high frequency end (the volcano) and some low signal in the low end (AGW or other long term natural warming trend).
That ought to let you see the relative sizes of the different time series oscillations too (*NSOs)…
Or maybe I need to think about it some more…
Looks like Germany is closing rivers due to ice and having folks freeze to death (cold is bad, warm is good…)
http://www.terradaily.com/reports/Ice_closes_German_rivers_to_shipping_authorities_999.html
Slovakia, freezing and short of natural gas due to Russia / Ukraine ping pong, restarts a nuclear reactor (it was supposed to be shut down as terms for joining the EU. Austria not happy.)
http://www.nuclearpowerdaily.com/reports/Bratislava_restarts_nuclear_reactor_to_avoid_blackout_999.html
Gee. I think I see a pattern developing.
a) It’s cold. Very cold.
b) When it’s cold, people do what they need to do to stay warm.
c) They will get back to you on ‘agreements’ and ‘saving the world’ later.
d) Nuclear works in any weather. Wind, solar, and (in this case) gas; not so much…
Alan S. Blue (12:05:45)
That’s an extremely important point you make in that coherent analysis. This stuff is useful for pinpointing the true effect of CO2, which, of course, we don’t know yet. Nor, may I not be the last to point out, do we know the magnitude of water vapor feedback, nor truly even its sign. So, look again Joel; your mind may have deceived you.
==============================================
Steve: Great Patience
I do not agree with the ideas of Dr. Grinsted
The naked eye I have the impression that your article agrees with this:
http://www.glaciology.net/Home/PDFs/Announcements/Volcanic-impact-on-sea-level-and-the-global-water-cycle
I agree with Steve.
The Chaiten volcano continues to grow, similar to an eruption of Tambora is not fully discarded
While Volcanoes do not have as much of an impact on surface temperatures, they are certainly the main driver of Stratosphere temperatures.
Volcanoes cause a temporary +1.0C to +1.5C increase in Stratosphere temperatures and then temps seem to drop 18 months later to a new lower level; about -0.5C lower than where they were before. They might slowly build back up to normal until a new volcano occurs.
Stratosphere cooling is a key fingerprint of global warming.
But if you look at this chart, it is more Volcanoes that are the main driver of Stratosphere cooling not GHGs. (This same up and down swing occurs with the radiosonde data for the Agung volcano in 1963 before the satellite data became available).
http://img258.imageshack.us/img258/235/uahstratvolcanoesyb5.png
I believe this is the papar David Douglass was referring to in the first comment.
If you have a little bit of statistics it is well worth the read. In summary, they treat predicting 20th century temperature as a time-series regression problem with a model of the form:
T(t) = k1S(t) + k 2V(t) + k3 I(t) + k 4 L(t) + b
where T(t) is the temperature at time t, S represents el-nino effects, V volcanic effects, I is solar irradiance, L is a linear term and b is a constant (k1, k2, k3, k4, and b are to be estimated from the data).
They find a very good fit with:
k1 = 0.129 +/- 0.008 K/K
k2 = -2.9 +/- 0.2 K/um
k3 = 0.103 +/- 0.017 K/(W/m2)
k4 = 76.8 +/- 10.0 mK/decade
b = -140 +/- 23 K
Units for the el-nino coefficient k1 are degrees K of warming per degree K of SST 3.4 anomaly. For the Volcano coefficient k2: degrees K of warming per micrometer of atmospheric optical density. For the solar irradiance k3: degrees K of warming per W/m2 of solar forcing.
k4 is most related to the subject matter of this post. It is the linear trend in the data after all the other effects have been removed: 0.77 degrees K per century.
Angus Reid Global Monitor reports that – While still high, the proportion of people in the United States who are concerned about climate change has dropped this year, according to a poll by Rasmussen Reports. 65 per cent of respondents believe global warming is a very or somewhat serious problem, down eight points since April. In addition, 43 per cent of respondents believe global warming is primarily caused by human activity, while 43 per cent blame long term planetary trends.
The latter [those who believe in the long term planetary cycles cause] is up 9% since the last report. So it would appear by this survey that the skeptics are no longer a fringe group but an equal majority and growing fast in numbers.
http://www.angus-reid.com/polls/view/fewer_americans_worried_about_climate_change/
David Douglas emailed me back with a link to the paper that was missing in the first comment of this thread:
Anthony;
The link to the paper “Limits on CO2 Climate Forcing from Recent Temperature Data of Earth” is
http://arxiv.org/abs/0809.0581
Also a copy is attached.
Regards;
David Douglass
Funny, I lived in La Crosse, WI summer of ’83 the hottest summer other than ’88 (outside Milwaukee by then) in my feeble memory. Entire month of July had highs in the 90s except a day or two around 100. El Chichon wasn’t much around here.
All these place experiencing record/bitter cold, somebody has to eat the high pressure system from hell. That would be my neck of the woods, No. Calif., where we hit the upper 70’s and broke records. We would gladly trade for some rain/cold to help defray the misery pumping up over into British Columbia and blizzarding down on the MidWest.
But, unfortunately, someone is running cloud-seeding experiments in NE Calif, and ever since they started doing it, the storms have parted over that area, sending torrential rain & snow into Washington & Oregon, and the rest south. The middle is bone dry.
I believe this effect is well-known, not an oops.
I was wondering.. When it comes to atmospheric CO2, has anyone read Ernst-Georg Beck’s paper on the last 180 years and how the processes for measuring CO2 have changed, and varied?
http://www.biomind.de/nogreenhouse/daten/EE%2018-2_Beck.pdf
Pretty interesting read. If he is right, it would sure change things.