I really wish Gavin would put as much effort into getting the oddities with the GISTEMP dataset fixed rather than writing coffee table books and trying new models to show the sun has little impact.
This paper gets extra points for using the word “robust”. – Anthony
Solar trends and global warming (PDF here)
R. E. Benestad
Climate Division, Norwegian Meteorological Institute, Oslo, Norway
G. A. Schmidt
NASA Goddard Institute for Space Studies, New York, New York, USA
We use a suite of global climate model simulations for the 20th century to assess the contribution of solar forcing to the past trends in the global mean temperature. In particular, we examine how robust different published methodologies are at detecting and attributing solar-related climate change in the presence of intrinsic climate variability and multiple forcings.
We demonstrate that naive application of linear analytical methods such as regression gives nonrobust results. We also demonstrate that the methodologies used by Scafetta and West (2005, 2006a, 2006b, 2007, 2008) are not robust to
these same factors and that their error bars are significantly larger than reported. Our analysis shows that the most likely contribution from solar forcing a global warming is 7 ± 1% for the 20th century and is negligible for warming since 1980.
Received 17 December 2008; accepted 13 May 2009; published 21 July 2009.
Citation: Benestad, R. E., and G. A. Schmidt (2009), Solar trends and
global warming, J. Geophys. Res., 114, D14101,
doi:10.1029/2008JD011639.
hat tip to Leif Svalgaard
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Allan M R MacRae (15:31:09) : I agree totally
Mike Lorrey says:
And, what makes you believe that the models use a significantly different sensitivity for a given W/m^2 of solar forcing as they do for a given W/m^2 forcing of CO2? I don’t believe that they do.
Steven Hill says:
I am sure that we could find substances that would kill you at far lower concentrations. However, more to the point in this particular case: When ~99% of the atmosphere consists of diatomic molecules that are essentially transparent to infrared radiation, the remaining ~1% can have a disproportionate effect on the climate. Furthermore, the fact that the warming effect of various greenhouse gases is approximately logarithmic over a large range of concentrations also means that relatively small concentrations can have a disproportionate effect.
It is also worth noting that the difference between the global temperature at the Last Glacial Maximum (when the place where I am sitting was covered in a couple miles thickness of ice) and now is only about a 2% change on an absolute temperature scale. So, on such an absolute scale, the kind of temperature changes that can have a significant impact are rather small.
One has to wonder why the observations (red line) on the graph stop at the year 2000. More recent data are certainly available. Why weren’t they used? Perhaps they would not support the conclusions?
Also, only the blue line (reconstructions, all) and solar continue passed the year 2000. The blue line goes up precipitously, with what appears to be only solar to account for this rise. This part of the graph appears to fly in the face of the robust conclusions.
Oh boy – that is embarrassing to see. What did the author expect? The error prone GCMs don’t account for any solar forcing, so he runs them and sees there is no solar forcing in the GCMs. Well Duh!
Did he prove there was no solar forcing in reality? Yeah, actually he sort of did. Solar intensity seems to be rising (whatever that ‘solar’ line is in the chart) and so is the temperature in the models. Seems to be to be quite clear that small increases in “solar’ drive large increases in their simulated climate!
Was he expect to see the ‘solar’ map directly one to one? Has he ever heard of a little thing called a ‘multiplier’?
Has the math and interpretation skills of this nation really degraded this far?
I skimmed it and saved it to my hard drive. Because I only skimmed it, my following comments may not be entirely accurate.
Seems like their climate models make unsubstantiated assumptions about the equilibrium absolute global temperature associated with a given level of solar forcing — and about the time delay to reach equilibrium. Moreover, some potential mechanisms were ignored.
I’m not sure that this paper provides any significant new information regarding the subject. Mainly its an effort to debunk contrary viewpoints. But, we already know that IPCC models downplay solar forcing (by any mechanism). Hence, using the models as a touchstone to ascertain the import of solar forcing must give the result they got.
So lets get this right…
Step 1: construct naive models to simulate climate over the past century which contain a) no solar forcing, b) crude cloud physics, c) incorrect feedback processes and d) no evidence of internal dynamics such as NAO, PNA, PDO, El Nino etc.
Step 2: when these simplistic models initially show a terrible fit to real climate (what a surprise), tweak the sensitivity of 1 parameter (CO2) until it “fits”
Step 3: conclude that because the (models of) climate appears to be so sensitive to CO2 that a doubling in the actual climate will lead to catastrophic runaway warming
Step 4: use said simplistic and hyersensitve models to test whether the Suns variability contributes to the (model) climate
Step 5: act genuinely surprised when solar variability doesn’t change the (model) climate that much
What a cartload of horse excrement….
As I read this the EDS commercial of the cowboys herding cats comes to mind. Using color, digital graphics, and misdirection the EDS-cowboys show how to get the cats to swarm like iron filings toward a magnet.
We know it can’t happen but it is fun to watch. Start with the bright red, white, and blue graph — you are unpatriotic if you disagree with this; then set TSI = S — because?, because it includes “spectral changes”, and then account for the Earth’s “geometry” — meaning, I think, it is spherical; add in a term for CO2 — while “ignoring all other factors”, and include a term ‘n’ for variability thought to be “noise.” That’s only part way through page 2. Many pages later we learn “. . .solar-related trends over the last
century are unlikely to have been bigger than 0.1 to 0.2 oC.”
We don’t understand what is going on with the Sun nor with the interactions between Sun and Earth. This research and report does not investigate these issues. Therefore, we have learned nothing.
Andrew W wrote: “Such a pity that denialists are only about to get their papers published in E&E.”
I sincerely hope you are not Andrew Weaver. If so, it confirms my suspicion that “real” climatologists are delighted to block papers that do not conform with your scientific and political agendas.
So, since the sun seems to have little effect, how did those models reproduce the Medieval Warming Period and the Little Ice Age? I’m curious to know what forcings caused those events in the models. I hope they are not still generating Mann’s discredited hockey stick. Now, Gavin cannot use the Maunder minimum to explain the little ice age so how is he going to model it?
“”” RW (16:34:16) :
“I am curious what caused so rapid increase of global temperatures between 1905-1940, when the gas-which-must-not-be-named was almost constant.”
Between 1905 and 1940, CO2 concentrations rose from about 297ppm to about 311ppm. It would be perverse to call a 5% rise “almost constant”. “””
Well given that the effect of CO2 increase is only linked to the temperature via a log function (base 2 presumably) and log 1.05 is about 0.07 to base 2, that would say about 7% of the “climate sensitivity factor” would be accounted for by such a rise, which is only 0.07 deg C if the CSF is 1 deg operdoubling. I’d say that’s almost constant.
Then there are those who say the CSF is way less than 1 deg C; which would mean that the CO2 really is even more constant than was thought; not that I believe in the CSF at all, but the modellers do.
Steven Hill (17:02:17) :
Well, it appears that the arctic is not melting as much as 2008, this trend could change, however it appears it won’t. Let’s face it, the climate is cooler and it’s kind of hard to not think it’s the sun to me.
Actually it’s already passed 2008 so your assertion is incorrect.
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
CO2 may be a factor, a very slim one if you ask me. How can 330ppm affect anything? It’s like a few grains of sand hidden in a gallon bucket of sand.
Nonsense, try reading up on the physics.
Add 330ppm of chromium to corundum (colorless) and you’ve got a ruby add iron instead and you’ve got a sapphire. Still think that a low concentration of an absorber can’t have a noticeable effect? Without that 330ppm of CO2 this planet would be a ball of ice.
I see some serious flaws here. Comparing observation to an unproven model full of assumptions is simply a waste of his any every one elses time.
1. Only HadCRUT and GISSTEMP was used to assess the solar influence post 1980 when UAH data is available. The trend shown by eyeballing the graph is about 0.5 degrees or more from 1980. The UAH trend is smaller than this and would automatically increase the solar forcing so a 1% error margin is not reflecting the true uncertainty. Multiple data sets should be analysed.
2. The models fail to replicate natural climatic variation such as ENSO and PDO cycles. If the model cannot replicate these patterns, how you seperate the various forcings correctly?
3. The models are forced to fit HadCRUT or GISSTEMP data, this on its own causes potential issues, but secondly, a large climate sensitivity is assumed with little support, and then aerosol forcings and concentrations are assumed to suppress the over exagerated warming predicted in order for the model to hindcast. Just because a model hind casts known data by adjusting unkown data means nothing. The models have no proven forecasting skill. Hence they can not be used for assess forcings.
4. The models do not account for the solar signals observed throughout the climate, from river baseflows, rainfall, extreme flood frequency to sea level rise, hence they can’t fully replicate the suns role on climate.
5. The models only hind cast back over a short period of time. Run them back further and they can not account for anything natural.
6. You could just as easily build a model with positive climate feedbacks due to solar forcing with a high climate sensitivty and then supress it with aerosols and make the same assumption that co2 has had no role. This doesnt make it right. Its circular reasoning! The model assumes the sun only effects the climate in a small way, so thats the answer you will get out the model. The model is not some kind of inteligent system that works out for itself the suns influence. Unless the sun is programmed to have an influence it wont.
Is Journal Geophys. Res. on the take for AGWers just like Nature? How many others are there?
Actually, this seems to be a decent paper on TSI, which has been calculated in terms of its variation and ability to heat Earth. The TSI calculation combined with known Earth atmospheric deflection, absorption, and LWR has a fair chance of being modeled and compared with temperature series accurately enough that I give this paper a passing grade. Any temp variation produced by TSI changes is buried in the noise of all the other parameters, both known and modeled, known and modeled poorly, and unknown.
This makes good sense to me….
Why would somebody publish a report on somthing they have already written off as not the cause of global warming?
The thought that he could be wrong is eating away at him, day by day, and he has to morraly adress the situation.
This is how most people deal with denial. They position their mentality towards an opinion, and then provide supporting deranged arguements to build their confidence.
In this case Mr Schmidtt has created his own supporting deranged arguement, to disprove the solar link, and within this piece, we will find the faults that could provide evidence that shows the sun has had an even greater influence.
Perhaps, he is hoping that somebody finds somthing, so he can plead innocent when the errors are found.
And this is what the experts are for, not myself. Good luck
Find the errors and use the same report to show a higher solar influence.
I was looking here Phil, your correct on that other one.
http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
As for your theory on CO2, you can’t prove that the addition of man adding to the 330 ppm means anything…so kaput to that as well. CO2 is a meaningless gas when compared to H20 and other gases.
All this crap about life on Mars and it’s CO2 levels is all fiction
Let’s recalculate gavin’s number (using his own assumptions) since he has to use a climate model to do his simple calculations.
Total solar irradiance change from 1900 to 2000 according to Lean 2004 – 2.0 watts/m^2.
Divide by 4 and the albedo = 2 watts/m^2 * 0.7/4 = 0.35 watts/m^2.
Use gavin’s 0.45C per watt/m^2 temp impact = 0.35 * 0.45 = +0.158C from 1900 to 2000. (add another 0.05C going back to 1610).
Thus, the solar change accounts for 25% of the change in temperatures (using gavin’s own assumptions).
Which is very similar to what he writes on page 8 of the Results section (before he summarily dismisses them and then just starts over) –
“Thus the solar forcing contributed with 12.61 ± 9.31% of the forcing compared to greenhouse gases, but could account of 24.63 ± 10.7% of
the change in ‘‘all”, ….”
Phil. (18:12:45) :
Maybe you can answer, why would the sensitivity figure be constant at .75C? That is where Hansen calculated it to be during the last glacial maximum. Why would it be the same now?
We’re not interested in forcing a warming. We’re interested in this warming.
Benestad and Schmidt are still using Lean et al 1995 and 2000 data, though they do acknowledge that the newer datasets [Foukal et al., 2006; Wang et al., 2005] have a smaller long-term trends. Benestad and Schmidt state, “the use of the older forcing would tend to increase the attribution to solar in our analyses. The impact of different estimates is addressed in later sensitivity tests.” Yet I do not find Foukal et al mentioned again in the paper, other than in the references. And, outside of the references, the only other time Wang et al is mentioned is the a discussion of how Scafetta and West spliced TSI datasets.
Also note the “smaller long-term trends” of Wang et al is still greater than the Svalgaard and Preminger trends:
http://s5.tinypic.com/mmuclk.jpg
I discussed this tendency of climate modelers “to increase the attribution to solar” in the post “IPCC 20th Century Simulations Get a Boost from Outdated Solar Forcings”. My version with the larger graphs is here:
http://bobtisdale.blogspot.com/2009/03/ipcc-20th-century-simulations-get-boost.html
The WUWT version with 88 comments is here:
http://wattsupwiththat.com/2009/03/05/ipcc-20th-century-simulations-get-a-boost-from-outdated-solar-forcings/
Regards
So the solar parameter/proxy he used peaked at 1940, rather than 1960? Not that I can see it really. It should have continued rising until 1960 which wouldn’t correlate well with the halting of warming that started in 1945.
It sure helps hide the ocean modulation…the cooling starting at 1945, and then the warming starting 1980ish which correlates with PDO/AMO doesn’t show up. You can’t get good correlation without both solar and ocean cycles. Seems like he knows what he’s doing…
Is there any way to reprint the graph? With the TSI scaled properly?
The TSI only covers a tiny fraction of the graph………
This is another publicity front, as there will soon be evidence released proving solar forcing……. who thinks the senate got a copy of this graph. ha ha.
The solar influence should be the most noticable line on the graph, not the least.
He’s fired in my books
“Phil. (18:12:45) :
Without that 330ppm of CO2 this planet would be a ball of ice.”
So, by your logic, it was colder during the Medievil Warm and Roman Warm periods becuase there was less (Apparently) CO2 in the air than today? It seems history does not agree with your logic.
Wow!…browsing the pdf he certainly has reasonable data for the solar proxy…Page12 illustrates nicely the lack of correlation if using solar only. You have to add ocean modulations to achieve the majority of the remaining error.
Not sure how he morphed the solar data from Lean to the forcing he shows.
How de do dat?
Really?
Why would solar forcing be pertinent before1980, but not after? Did someone unplug the sun while I wasn’t looking? You mean the lack of sun can cool, but an active sun cannot warm? Huh? Forgive my lack of logical understanding here, but this makes absolutely no sense to me.