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:
“How do you explain that it clearly suggests that CO2 lags temperature?”
What’s to explain? This is not anything new. Without human activity, how would CO2 increase of its own accord? It wouldn’t, clearly. Warming, due for example to solar or orbital variations, would cause outgassing from the oceans.
You have yet to explain why “CO2 levels pre-1958 are highly questionable, imo.”
“Please explain how the future causes the past.”
Perhaps you need to rephrase this question so it makes sense.
“As regards the UAH temperature data, when you fit a straight line through the warming portion of a sine curve, this will give you a misleading warming trend. The cooling portion preceded 1979, having occurred from about 1945 to 1975.”
There is no UAH data from before 1979. Datasets that extend further back cannot even remotely be fitted by a sine curve so it’s not clear why you mention one.
“My bet is when the surface temperature data is analyzed and the warming bias removed, there will be no net warming from ~1940 to 2008.”
You’ve lost that one already.
“As regards cooling predictions, there are countless more since 2008, including a recent one (”no warming for 20 years”) from the warmist camp”
Using terminology like “warmist camp” is a little bit immature, don’t you think? You have misunderstood this one, anyway. No-one claims that the climate will do anything other than warm in response to more CO2, in the long term. In the short term, internal variations can temporarily offset the CO2-induced warming.
“but those are the easy ones, since Earth has been cooling for almost a decade.”
Not even wrong. Over pretty much any 10 year period in the instrumental record, there is no trend that is statistically different from zero. This is because climate is not a phenomenon that can be measured over a decade. If you want to understand your error here, what you need to do is this: calculate trends from x-present, starting from x=2007, say, and working backwards. At each stage, use a realistic model of the noise characteristics to calculate the error on the trend. Find the first value of x for which the trend is statistically significant. Tell us whether the trend is positive or negative. See if you can find any value of x for which there exists a statistically significant negative trend.
“The paradox is that you predict global warming , and I hope you are right – because humanity does much better during warm periods.”
“does better”? Without further definition this is basically meaningless. Tell us, though, considering the cold period known as the little ice age – why did world GDP per capital not drop during this time? Why, if warm times makes humans “do better”, are the most prosperous countries currently predominantly at mid-northern latitudes? Why is Scandinavia, for example, far more developed than equatorial Africa?
“In any case, I am convinced that the body of evidence suggests that the sensitivity of Earth’s climate to a doubling of CO2 is much less than 1 degree C, and your side of this debate is promoting needless hysteria at great cost to society.”
I do not have a “side”. There isn’t really a “debate”. If the sensitivity were even as low as 1°C/2xCO2, then the paleoclimate record becomes impossible to explain.
“”” Vincent (08:41:58) :
Jimmy Haigh and jmc,
the GHG hypothesis does NOT violate the second law of thermodynamics. I have read this paper, initially with great expectation, but was disappointed. Mostly it is a textbook on various physical processes including irrelevances like Freznels law. When you finally get to the analysis of the supposed violation of the second law of thermodynamics, there are serious flaws.
The second law states that heat cannot of its own accord travel from a cold place to a warm place. If it did so, the cold place would become yet colder whilst the warm place gets hotter. Yet GHG works on the principal that outgoing LR radiation is absorbed and re-emitted by the GHG and some of this re-emitted radiation will come back down to the ground and have a warming effect. Since the region where the GHG does this is cooler than the ground, this is supposed to violate the second law of thermodynamics. “””
The earth’s surface is known to emit long wave IR radiation corresponding roughly to a black body spectrum at a temperature around 288 K; and some of that radiation escapes into space. Some of that may land on the dark side of the moon; particularly near new moon times; and in principle, we could measure the total radiation that hits the moon’s cold side.
Well the angular subtense of the sun is pretty much the same as the moon, so the same amount of radiation that hits the moon, also travels to the sun and lands there, even though the surface temperature is around 6000 K
Somehow I don’t think there is a Maxwell’s Demon out there on the sun, telling earth sourced IR photons; No, you can’t come in here.
Clausius stated the second law as follows; ‘No cyclic machine can have no other effect, than to transport heat from a source at one temperature, to a sink at a higher temperature. ‘
Note the word “cyclic”.
The English usage is a trifle arcane; the expected “other” effect, is of course an input of energy or work done from some other origin.
Your ordinary household refrigerator transports “heat” from the cold inside to the warm outside, leaving the inside colder, and the outside warmer.
Unplug it, to disconnect an “other” effects, and it ceases to function.
George
Lief I am not convinced. If a body loses more energy at a given time then the body as a whole will lose energy. Whatever you measure at the surface is not necessarily indicative of the surface plasma as a whole. Does this make sense?
Leif (08:30:26) asks “what magnetic impact?”
As Leif well knows, studies of the physical record have consistently found a .6 to .8 correlation between GCR proxies and temperature proxies. Usoskin et al. 2005, for instance, “Solar activity over the last 1150 yrs: does it correlate with climate?” found: “a correlation coefficient of about .7 – .8 at a 94% – 98% confidence level.”
Because GCR and TSI both vary with solar activity, high decadal and centennial scale correlations between GCR and temperature do not by themselves rule out that the GCR-correlated temperature changes are actually being caused by variations in TSI. Because TSI variations are so miniscule, this would require a very high climate sensitivity, which seems to be contradicted by all the direct evidence about climate sensitivity, but set that aside.
While the decadal and centennial GCR-temperature correlations do not contradict the TSI explanation, this explanation IS contradicted by the .75 correlation between GCR and temperature that Shaviv and Veiser found on million year time scales. Their 550 million year study looked at climate correlations across transit through the Milky Way’s spiral arms, where the GCR flux impacting the solar system becomes more intense. On this time scale, variations in solar activity are not visible except for secular trends, effectively controlling for TSI, yet the same correlation between GCR and temperature is seen, providing good evidence that it is the GCR that is driving climate, not TSI.
Add this to the direct evidence that climate sensitivity is low, and may actually dampen down forcings instead of amplify them, and the case for a magnetic impact becomes very strong. A better question would be “what TSI impact”? We KNOW that TSI variations are very small, and our best direct evidence about climate sensitivity says that this too is small. Multiply the two together and the result is small.
Leif reserves his skepticism for the effect that according to the physical evidence is doing most of the work. Seems to me he is pretty much in the same boat as Schmidt on this one. My comment on Schmidt at 23:43:55.
RW:
Huh?? Does that mean orbital/solar variations are due to human activity? And without human activity, CO2 can not increase ‘of its own accord’? Whiskey Tango Foxtrot??
And there are plenty of other wacky statements in that polemic besides that confused contradiction. Time to get off the meds.
Score one for Allan M R MacRae.
“However, it will correctly tend to predict the climatic consequences of the seasonal forcing, e.g., it will show that here in Rochester the climate in July is much warmer than in January.”
Thus, climate models are based on the assumption (and hope) that climate trends over hundred year time frames are predictable in the same way that summer and winter are predictable.
Given that we don’t even know what (if anything) caused the Little Ice Age, such an assumption seems unjustified, to put it mildly.
Molon Labe says:
It is true that their model assumes just the solar effects due to the direct variation in TSI. However, this assumption does not go unchecked. They note:
Patagon has very incorrectly summarized this as saying: “It’s not in the model therefore it does not matter.” What it actually says is something like, “If this assumption were wrong, we would expect to find the forcing coefficient determined by regression for solar in the real data to be much larger than that for the forcing coefficient for GHGs. However, in actual fact, the regression coefficients for solar and GHGs forcings were similar to each other in both the ‘model data’ and the real data. This suggests that the real world is behaving like the model world…i.e., that there doesn’t appear to be any mysterious mechanism in the real world that is amplifying the effect of TSI variations (or depends on some other aspect of the solar irradiance such as just the UV component).”
RW (10:21:34) : “I do not have a “side”. There isn’t really a “debate”. If the sensitivity were even as low as 1°C/2xCO2, then the paleoclimate record becomes impossible to explain.”
Unless you have some bullet-proof proxy for the Sun’s output, you can’t be sure it is more of a variable star than we know.
One way you recognize a good scientist is how hard he tries to prove himself wrong and explains all the ways he has tried in published papers. One doesn’t see much of that in many of the climate papers. You guys need to try harder.
“Because we keep getting posters making ‘inane, fatuous, irrelevent’ statements about the concentration of CO2 based apparently on their personal incredulity and lack of knowledge of the physics and chemistry”
Your lack of knowledge is showing. Even if a CO2 molecule got ‘hot’ from radiated heat it would either lose the energy to the surrounding air by collision and at 400 ppm would have NO thermal effect (drowned in thermal noise). The idea that a CO2 molecule radiates back down to a warmer Earth and warms it is playing fast and loose with basic thermodynamics.
So does CO2 keep the Earth or is it H2O which is the primary infra-red blanket?
Well desert air is bone dry so try spending a night in the middle of the Sahara in shorts and T-shirt, see just what the min to max temperature swings are when you only have 400ppm of a GHG that only covers 6% of the relevant I-R range. If the day-time temps can drop that far that fast overnight then CO2 must be assumed to have no discernible effect.
RW (10:21:34) :
Maybe you can tell me why the calculated climate sensitivity of .75C would be the same today as it was during the last glacial max. Basically, the question is why would the climate today respond the same way as the climate at the peak of an ice age?
press (10:36:05) :
Lief I am not convinced. If a body loses more energy at a given time then the body as a whole will lose energy. Whatever you measure at the surface is not necessarily indicative of the surface plasma as a whole. Does this make sense?
No, it does not make a lot of sense [nor a little bit]. By your logic: If a body gains more energy at a given time then the body as a whole will gain energy. During the solar cycle, the body loses some and gains some. At the end of the day it is even.
Alec Rawls (10:40:04) :
“Solar activity over the last 1150 yrs: does it correlate with climate?” found: “a correlation coefficient of about .7 – .8 at a 94% – 98% confidence level.”
And how well do we know the record of both? The record has very high autocorrelation and contains only a handful of independent points.
Their 550 million year study looked at climate correlations
And how well do we know that record?
Leif reserves his skepticism for the effect that according to the physical evidence is doing most of the work.
The evidence is very poor and doesn’t hold up very well when looked at in detail. Cosmic ray intensity returns to the same level at each solar minimum, while temps do not. The solar cycle is clear in GCRs [although only a few percent] but very weak in temps [0.1C], so the few percent variation of GCRs cause a tenth of a degree of [cyclical] temperature variation. Hardly something to write home about.
My question is, why would anyone assume that a single calculation by a single office is the final word? Doesn’t science require replication of findings and observation confirming theory?? Or have I stumbled back to reality.
Joel:
Like cyanide or botulinus toxin, for example? Whereas most other substances are not harmful at far higher concentrations. You do not prove your point by using outliers.
Phil:
Apart from shifting the spectral bands slightly, what effect do these trace impurities have on the physical properties of corundum? And, besides chromium or iron, how many other substances would have no noticeable effect whatsoever? And how many substances besides corundum would show no noticeable change by having equivalent amounts of those impurities added?
How much more cherry-picking are we going to see?
Sandy:
Not quite. The re-radiation by CO2 molecules doesn’t warm the surface, but rather slows the rate at which heat is lost from the surface through radiation.
But it’s (almost) irrelevant anyway, as almost all the heat loss from the surface is through convection and evaporation, with only a tiny amount being lost through radiation, and even that tiny amount being slowed far more by water vapor re-radiation than that of CO2.
Wow that graph looks dramatic! Shooting up like a rocket! At least maybe we can only really blame human activity after 1980 on this apocalyptic result…
Speaking of Solar… A beautiful little solar cycle *23*! magnetic signature is stirring… It might produce a spot…
This may sound Hollywood-ish but this very strange minimum and the refusal of cycle 23 to die just keeps reminding me of the number 23 enigma… coincidence or not it’s pretty cool if you ask me 🙂
Indiana Bones (11:27:06) :
“My question is, why would anyone assume that a single calculation by a single office is the final word? Doesn’t science require replication of findings and observation confirming theory?? Or have I stumbled back to reality.”
I think you have hit upon one problem: No one can do a controlled experiment on the Earth. Sucks, they can’t even measure its surface temperature!
Kevin Cave 22:38:16) :
So the sun is irrelevent in the context of AGW is it? Here’s a very simple, but I believe effective, thought experiment… the sun’s been switched off.
I wonder how long it would take for the Earth to start getting intolerably cold, and whether the fraction of a percent of human-introduced carbon dioxide would make a blind bit of difference.
The temperature drops on average by 10C in the 12 hours after the Sun sets. So, on average, the Earth’s temperature drops by 0.83C each hour after the Sun is no longer beating down on the Earth each day.
By the middle of day 3, temps will have fallen by 40C and every river on the planet will be frozen right to the bottom (followed soon after by every lake and then the oceans). Land near the ocean at the equator will be moderated somewhat but everything else will already be frozen solid by day 3.
This example also provides a good explanation for the timelines of the greenhouse effect. Before the end of day 2, all of the 33 degree greenhouse effect has already been lost to space. There is no 30 year lag in the greenhouse effect – it is only a delay (or accumulation) of 36 hours in how long it takes for the Sun’s energy to escape into space. The energy random walks around the molecules in the ground and then in the atmosphere for an average of 18 hours before it escapes into space. (oceans and icesheets can also accumulate that energy so this where the lags come from but this accumulation will be much less than 10% of the total).
RW:
You’re right. How else would you explain the paleoclimate record unless the sensitivity is so high that it responds to CO2 increases 800 years in the future?
Sandy (10:53:27) :Obviously your name tell us you know a lot of deserts :-).
It is outrageously absurd that nonsense of CO2 warming. That is why I have always joked about GWrs. saying that when going to bed they warm their feet with a bottle filled with hot air.
Bill Illis (11:49:05) :
Following that logic, shouldn’t CO2 peak its trapping capacity two days after release also? How could that lead to a catastrophic tipping point?
Leif Svalgaard (19:53:27) :
The trend in solar TSI is much smaller than B&S [perhaps remove the ‘&’ 🙂 ] assume [and even smaller than Bob T’s], so their solar input variation is much smaller than what they worked with. That may mean that their ‘7%’ might similarly be a lot less than 7%.
Well to me this implies then that Schmidt has too much weight on TSI variations in his early climate recontructions – which means they must be wrong in terms of how they modelled the temperature variations at the start of the 20th century.
Either the Earth’s climate is very sensitive to solar variation (through some yet to be proved mechanism), or some other factor, which is not modelled (or modelled incorrectly) drove climate during the first half of the 20th century.
Furthermore, it’s logical to think that this factor hasn’t simply gone away, which means any modelling for the second half of the 20th century and beyond will be erroneous since the models are missing this variable.
Sandy:
I can vouch for that. I once spent a night on the fringes of an African desert in midsummer. I’ve never been so cold in all my life.
Ben G (12:07:15) :
Well to me this implies then that Schmidt has too much weight on TSI variations in his early climate recontructions – which means they must be wrong in terms of how they modelled the temperature variations at the start of the 20th century.
He very likely was and they very likely are.
Either the Earth’s climate is very sensitive to solar variation (through some yet to be proved mechanism), or some other factor, which is not modelled (or modelled incorrectly) drove climate during the first half of the 20th century.
I don’t think the climate is hypersensitive to solar variations, because we would likely have had a run-away situation somewhere along the 4 billion years climate history. It seems to me that on the contrary, the climate is very ‘robust’ [Anthony – do I get points for using that word, like Gavin did?] against perturbations [internal and external] to have maintained a livable temperature over all that time.
The sun is a variable star. It sometimes produces 200 sunspots a month, other times, none at all for years on end. The number of spots does correlate with temperature. Not perfectly, but better than those who would smooth the sun into homogeneity or perfect regularity would have us believe.
Download and hang onto the original data before it gets ‘adjusted’ to fit someones idea of how things were, are, and should be.
David: How could that lead to a catastrophic tipping point?
That is the scary part: The CO2 political and sociological issue will have catastrophic consequences for the world…
In my country, a few weeks ago, 24 policemen were assasinated because some NGO’ s told native amazon indians that a new issued bill, intended for the rational exploitation of the forests, was going to deprive them of their land, which was not true at all. Those NGO’s guys are most probably trying not to allow any investments in the area, in order to be only ones who through giving to the indians carbon credits at US$3. per forest hectare they would profit. (we can only guess the amount they will graciously and enforcedly sell those carbon shares to the “polluters” of the first world)