Guest post by Alec Rawls
Solar physicist Sami Solanki and his colleagues at Germany’s Max Planck Institute for Solar System Research helped pioneer the use of cosmogenic isotopes from ice cores to create a proxy record for solar activity going back hundreds and thousands of years. Together with a group led by Ilya Usoskin at University of Oulu in Finland, Solanki describes “grand maximum” levels of solar activity from 1920 to 2000, with the sun being especially active since the 1940’s.
Comparing this solar record to temperature, these scientists find a strong correlation between solar activity and temperature persisting until quite recently. For example, over the period of the instrumental temperature record, a 2004 paper by Solanki and Krivova finds that the correlation is quite close, “however”:
However, it is also clear that since about 1980, while the total solar radiation, its ultraviolet component, and the cosmic ray intensity all exhibit the 11-year solar periodicity, there has otherwise been no significant increase in their values. In contrast, the Earth has warmed up considerably within this time period. This means that the Sun is not the cause of the present global warming.
But does this conclusion follow? Their own evidence says that until 1980 the dominant driver of climate was solar activity (and their longer-term temperature-proxy comparisons say the same thing). So how can they assert that two decades of the highest solar activity on record can’t be the cause of concurrent warming?
I suggested to Solanki and his colleagues that they must be implicitly assuming that by 1980 ocean temperatures had already equilibrated to whatever forcing effect the high level of solar activity was having. Otherwise warming would continue until equilibrium had been reached. Yet equilibration is never mentioned in any of their analyses.
Many thanks to Sami Solani and Manfred Schuessler for their important reply, finally making the implicit explicit. Here is the main part of their answer:
Dear Mr. Rawls,
You have raised an interesting question. Correlations between solar activity indices and climate assume that there is a constant lag between solar and climate variability (this is implicit in the nature of correlations). In some cases authors even implicitely or explicitely assume that this lag is zero, i.e. that the relationship is instantaneous. If we consider the period of time up to ca. 1970, then this lag lies roughly between 0 and 12 years (e.g., Solanki and Krivova 2003). Newer reconstructions, such as that of Krivova et al. (2007) tend to favour the lower lag. If we consider the period since 1970 alone, then the solar irradiance hasn’t shown an increasing trend, but rather a decreasing one, in contrast to global temperature, which has increased substantially. If this increase is due to the hypothetical influence of the oceans, as you suggest, then of course these short lag times would not be realistic. This, however, would mean that the relatively good correlation between solar and climate variability prior to 1970 would also have to be discarded as due to chance and would cease to be of relevance. Lags cannot be changed at will, certainly not without a good physical reason, i.e. one based on computations, that at least approximately model the Earth system’s behaviour.
To clarify, I did not quite suggest that post-1970 warming might be due to the influence of the oceans. I suggested that it could be due to the sun. The hypothesis isn’t that the oceans were giving up stored heat content but that they were continuing to absorb solar-driven heat. (Under the GCR-cloud theory, high solar wind blows the clouds away, increasing the amount of solar shortwave that pours into the oceans.)
Since Solanki and Schuessler see this slow-ocean-equilibration story as incompatible with short correlation lags, they are clearly identifying short lags with rapid equilibration. The question is whether this identification makes sense. If the equilibration process is not rapid, does it really mean that the short correlation lag between solar activity and temperature that these folks discovered must be mere chance? A simple counter-example shows the answer to be no.
Day vs. season
If you map the diurnal correlation between the strength of the sun’s rays on your back porch and temperature in the shade, you will find that the maximum correlation occurs with only a few hours lag. At noon, sun strength is no longer increasing, while the rate of temperature increase is near its maximum, with temperatures continuing to rise until sometime mid-afternoon.
So you find this very strong and rapid correlation between sunlight and backyard temperature. You’ve been plotting it for a few months, and now it’s June. There is no significant change day by day in the strength of the sun’s rays, or their duration, yet somehow peak backyard temperatures keep going up. The end of June is hotter than the beginning of June. Do you say that this can’t be explained by the sun because solar forcing has not been rising and you know that the temperature response to the sun is only a few hours?
This is exactly what Solanki et al. are doing. Instead of day vs. season they are finding temperature signals within the solar cycle and from one solar cycle to the next and assuming that these same response times apply to longer term changes in solar activity. But climate systems don’t just respond on one time scale.
This is what came out of the previous post, where Mike Lockwood cited the rapid response time that was estimated by Stephen Schwartz on the assumption that the planet can be represented by the simplest possible energy balance model with only one heat sink. Make the model one step more realistic by giving it two heat sinks, so that the sun and the atmosphere do not warm the entire ocean at once, but warm an upper layer which in turn, over time, transfers heat to a deeper ocean layer, and everything changes. Time to equilibrium from a step-up in forcing could be centuries, but as Daniel Kirk-Davidoff’s analysis of the two heat-sink model shows, a correlation study that does not span several times the period of any long term fluctuation in forcing will only pick up the relatively rapid response time of the upper ocean layer, revealing next to nothing about time-to-equilibrium for the full climate system.
The one thing we can say from the observed rapid temperature response to short term fluctuations in solar activity is that solar activity clearly does drive temperature. Add that the sun does not warm the ocean all at once—that the deeper ocean is warmed over time by the upper ocean as the two heat-sink model describes—and we can expect that the demonstrated warming effect of solar activity will cause long-period deeper ocean warming when there is a longer period rise in solar activity.
That is, the short time-lag correlation actually implies that longer period responses should also be taking place, once the most obvious steps to model realism are incorporated. Thus no, the finding of a short correlation lag does not contradict a solar explanation for late 20th century warming but supports it, just as the suns’ warming of the day supports a solar explanation for seasonal change.
This is why it is so important that widespread but unstated assumptions of rapid equilibration be made explicit. The assumption does not stand up to scrutiny, yet it has been allowed to escape scrutiny even as it does the heavy lifting in many scientists’ dismissal of a solar explanation for late 20th century warming. So again, many thanks to Doctors Solanki and Schuessler for making this assumption explicit.
GCM equilibration time
Here is the rest of the Solanki-Schuessler response:
You can rightly argue that a simple linear analysis, such as that carried out by Solanki and Krivova 2003, does not fully reflect the complex behaviour of the Earth system. Indeed, such an analysis does not replace introducing the solar irradiance record into a GCM (General Circulation Model), which includes the coupling between the oceans and the atmosphere, and computing the influence of the Sun’s behaviour. Such studies have not, to our knowledge, reached conclusions that differ significantly from those reached by the simple correlation analysis. If anything, they tend to indicate that the influence of the Sun is even smaller than the correlation studies suggest. The attached review paper gives a good and up-to-date overview of the state of research on Sun-climate relations. Figs. 27 and 28 (pp. 36 and 37) of this paper show that GCM models support the assumption of a short time lag, i.e., quasi-instantaneous reaction of the global temperatures on changes in forcing (as is well known to be the case for major volcanic eruptions, for instance). We think that this is due to the fact that only the mixed layer of the oceans is involved in climate variations due to short-term (decadal to centennial) variations of the forcing, so that the global equilibrium time of the oceans is irrelevant – but you may want to contact a climatologist if you wish to obtain more detailed information.
We hope to have been of help.
Sincerely yours,
Sami Solanki and Manfred Schuessler
What I have been able to glean about equilibration time in the IPCC GCMs is rather different from what Solanki and Schuessler assert. This came up in Part 2, where Schwartz’ short estimated time constant implied a low climate sensitivity, prompting a vigorous response from Gavin Schmidt and other “consensus” GCM compilers. Foster, Schmidt et al. said that in contrast to Schwartz’ 4-6 year time constant, the AR4 model “takes a number of decades to equilibrate after a change in external forcing.”
In a later RealClimate post, Schmidt suggests that:
Oceans have such a large heat capacity that it takes decades to hundreds of years for them to equilibrate to a new forcing.
The review paper that Solanki and Schuessler cite is Solar Influences on Climate, by Gray et al. 2010. S&S cite Gray’s Figures 27 and 28 as support for quasi-instantaneous temperature adjustment in response to a change in forcing, but it is hard to see the connection. The figures are from AR4 and just show the amount of recent warming that is attributed to CO2 in the AR4 models. That would be all of it, post 1955:
Figure 27 [Gray]. Global mean temperature anomalies, as observed (black line) and as modelled by thirteen climate models when the simulations include (a) both anthropogenic and natural forcings and (b) natural forcings only. The multi-model ensemble mean is shown in grey, and individual simulations are shown in colour, with curves of the same colour indicating different ensemble members for the same model.
Are S&S interpreting Figure 27a as showing a fit between forcings and temperature (in which case the close fit to observed temperatures would indeed indicate a rapid response to forcing)? But this isn’t what the graph shows at all. It compares observed temperatures to the temperatures that the AR4 model predicts in response to 20th century forcings. Equilibration speed (or lapse time) is one of the variables that modelers tweak to achieve a fit between predicted and actual temperatures.
It is not surprising that modelers manage to achieve a reasonably close fit over their calibration period (the 20th century). Every detail of their very complex model is tailored to achieve this. They presumably could achieve this level of fit in many ways. The fact that they do achieve it doesn’t say anything about how they achieve it. The equilibration speed could be anything.
Of course we do know a few fun facts about how the AR4 models are fit to the data. In particular, we know that the IPCC engages in blatant question begging by including only one solar variable in its AR4 models: Total Solar Irradiance, which is parameterized by the IPCC as having 1/14 the warming effect of CO2 (0.12 vs 1.66 W/m2).
Gray’s Figure 27 makes the impact of this assumption graphic. When total solar effects are fixed on the input side of the model to have 1/14th the warming power of CO2, the model output “shows” CO2 to be the dominant climate driver. It’s called “garbage in, garbage out.”
Data vs. assumption
The question is why Solanki and Schuessler are satisfied with the IPCC’s TSI-only characterization of solar effects when their own data screams out so strongly against it. They look at how little solar effect on climate is built into the AR4 model and say:
If anything [these models] tend to indicate that the influence of the Sun is even smaller than the correlation studies suggest.
The discrepancy between their correlation studies and the AR4 model can be seen in the glaring difference between 1955-1980 in Figure 27 above and in Figure 2b from Solanki and Krivova:
The black line is instrumental temperature. Dotted lines are inverted GCR (reconstructed, and as measured in Climax Colorado since 1953). Close correlation between solar activity and temperature continues to 1980.
Henrik Svensmark finds a still longer correlation. After controlling for PDO, he finds that the short term correlation between solar activity and temperature continues to the present day:
FIG. 2 [Svensmark]: … The upper panel shows observations of temperatures (blue) and cosmic rays (red). The lower panel shows the match achieved by removing El Nino, the North Atlantic Oscillation, volcanic aerosols, and also a linear trend (0.14 ± 0.4 K/Decade).
There is no way that the high degree of short term correlation between solar activity and temperature observed by Solanki and Schuessler pre-1980 can be explained by the tiny variations in Total Solar Insolation (about a tenth of a percent over the solar cycle). Yet when they see how the IPCC’s TSI-only model under-predicts their own observations, they don’t question the IPCC’s fixing of total solar effects at 1/14th the strength of CO2, but count this garbage-in model as evidence against their own data. That’s not right guys. Data is supposed to trump theory/assumption. That’s the definition of the scientific method.
Solanki, Schuessler and their colleagues have done some of the most important climate research of the last decade, creating several of the paleo-reconstructions of solar activity that make extended solar-climate studies possible. Unfortunately, they are misinterpreting the correlation between solar activity and temperature. Short correlation lags do not imply rapid equilibration. They just reflect the rapid temperature response of the upper ocean layer, leaving the equilibration speed of deeper ocean layers an open question. Thus short correlation lags provide no grounds for dismissing a solar explanation for late 20th century warming. Scientists who have been presuming otherwise should be willing to reconsider.
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Leif Svalgaard says:
April 7, 2011 at 5:42 pm
If every upturn of solar activity is followed by an equal downturn, one would expect temps to do the same.
Only if:
1) solar activity is the only driver of temperature. It isn’t. We have orbital irregularities which for 90% of the past million years covered much of the world with ice. We are in one of the 10% times where this is not the case, howerver we still have huge accumulation of ice at the poles as well as very cold deep oceans.
2)each upturn is followed by an equal downturn. The sun is not well enough understood to say if this is true or. It seems unlikely that the length of upturn and downturn would be exactly equal, except perhaps over very long timescales of many thousands of years.
ferd berple says:
April 7, 2011 at 8:04 pm
Solar activity doesn’t determine the absolute temperature of the atmosphere, it determines the rate of change of temperature.
If the climate heats up when solar activity increases, it cools down just the same when solar activity is decreasing.
Leif Svalgaard says:
Say SSN mean over cycle goes up from 40 to 150 over several cycles, you assume a warming, let’s say for the sake of the argument 1 degree. Then I would expect a cooling of 1 degree if the SSN in the following same number of cycles goes down from 150 to 40. Agree? If so, your argument fails, because the climate would then just revert to what it was.
Leif your argument assumes that the oceans will equally absorb or release heat, and that is far from the case. Ocean warm pools plateau at about 32 C due to the Clausius–Clapeyron relation. After that temperature additional input is more likely returned to space via evaporation and convection. In La Nina periods, the Walker circulation is enhanced and more cold water is brought to the surface in the eastern and central Pacific. (The thermocline is very shallow at the equator) while the warm pool is more concentrated and restricted in the western Pacific as is the cloud cover which reflects insolation. Likewise transport of warm waters to the subtropical gyres is enhanced along the western boundary currents. Under those conditions the ocean is has maximum potential to both absorb heat and store heat.
During El Nino phases the warm pool is extended eastwards as is the cloud cover reflecting heat. The warm water layer is extended thus deepening the thermocline so less cold water is brought to the surface to be heated. This in turn also lessens the Bjerknes feedback and slows the Walker circulation as well. These conditions minimize heat absorption of insolation and enhance venting the warm pool as well as slowing down transport and storage of warm waters to the subtropical gyres.
The PDO is some what of an extension of the El Nino phenomenon but also acts to enhance or disrupt the Walker circulation with help from its impact on circulation and monsoons and thus impacts El Nino/La Ninas. Winds in positive PDO favors more El Ninos fewer La Ninas. While negative PDOs favor La Ninas and fewer El Ninos. For that reason I suggest changes in the PDO are a good proxy for periods of maximum heat absorption versus ventilation.
The rise in temperatures in the 30’s and 40’s coincided with a positive PDO. temperature in the Arctic were higher than they are now. When the PDO went negative in the 1940’s it had a cooling effect and dampened the effects of the remaining increases in solar activity peaking in the 50’s as measured by surface temperatures, but it was maximizing absorption of that peak insolation and raised ocean temperatures. When The PDO went positive in the late 70’s it generated more El Ninos raising temperatures, it altered wind patters that have been demonstrated by many to be the major cause of loss of Arctic ice (not temperature) which then also vented more ocean heat so higher temperatures were measured . At the same time solar activity rebounded higher in the 80’s and 90’s but not as high as the late 50’s. However the stored ocean heat, the positive PDO and high solar activity of the 80’s and 90’s conspired to make warmer global surface temperatures. But because the PDO was venting and not absorbing at the time the ocean warming ‘stalled” as evidenced in Argo data. The 90’s was a period of no a Ninas or some say perpetual El Ninos
If this scenario holds true, then the current negative trend for the PDO not only suggests more La Ninas and near term cooling but because oceans are also in the maximum heat absorbing condition, but the solar activity has plummeted, it suggests the oceans will not warm further and likely cool. Unless the solar activity increase then I think we will be on a bigger cooling trend with only a minimum bump in temperatures when the PDO goes positive again.
And just I looked at a paper from D’Arrigo on PDO and Asian monsoons where the PDO is extrapolated back to the 1740-60’s glacial advance and there is a strong suggestion of a negative PDO or NPI that could have dampened the increased solar activity during that time.
Leif Svalgaard says:
If the climate heats up when solar activity increases, it cools down just the same when solar activity is decreasing.
Over millions of years this may well be statistically true, but not on shorter time scales, say 100k years.
Heating and cooling is not symetric over timescales less than thousands (millions) of years, as it influences other factors such as the turnover rate in the deep oceans.
A pan of ice water put on a stove does not heat up or cool off symetrically when you turn the heat up and down. Planet earth has huge quantities of ice floating in the oceans, as well as large amounts of cold water in the deep oceans, and a fantastically large block of ice at the south pole, quite possibly a remnant of the past ice ages.
ferd berple says:
April 7, 2011 at 8:11 pm
1) solar activity is the only driver of temperature.
Exactly, the Sun is but a minor player.
2)each upturn is followed by an equal downturn. The sun is not well enough understood to say if this is true or.
We have direct observations over 400 years and indirect data for the past 11,000 years and the Sun does return to near zero at each solar minimum.
Jim Steele says:
April 7, 2011 at 8:40 pm
Leif Svalgaard says:
The rise in temperatures in the 30′s and 40′s coincided with a positive PDO.
Now you invoke the oceans and not the Sun.
Both of you are grasping for straws, and invoking second order effects. The issue is if the Sun is the MAJOR driver of climate and it seems clear from your convoluted arguments that it is not.
I’ve said it before, but it bears repeating.
Anyone my age or older who grew up in Europe (and its true to a lesser extent of Australia and perhaps N America) will remember the reason why winter minimum temperatures have risen since the 1960s. Which is most of the anomaly referred to.
It was a morning ritual to light a coal fire in winter. And for anyone who has not seen this, it is an incredibly smoky operation. A large amount of smoke was generated for 5 to 15 minutes until the coal lit.
Daily minimum temperatures occur a short while after dawn at the point solar heating exceeds radiant cooling. The smoke from millions of coal fires created a near horizon smoke haze and reduced the amount of sunlight reaching the ground early in the day.
Remove the coal fire smoke = remove the haze = earlier and higher minimum temperatures especially in winter
I doubt there is a climate scientist working today who has ever seen a coal fire being lit.
Leif Svalgaard says:
April 7, 2011 at 10:48 pm
Both of you are grasping for straws, and invoking second order effects. The issue is if the Sun is the MAJOR driver of climate and it seems clear from your convoluted arguments that it is not.
It’s quite straightforward realy. There is a clear and undeniable relationship between solar activity and climate – except when there’s not. In these cases there are all sots of complicated lags and effects. The current favourite lag time is ~20 years. This has increased from the 4-8 years proposed by Theodor Landscheidt in ~2000. No doubt it will increase further as the expected cooling fails to materialise.
Leif Svalgaard says:
April 7, 2011 at 10:48 pm
Exactly, the Sun is but a minor player.
That explains why the heating we observe on earth is also observed on other planets. The sun is a minor player and the CO2 heating of the earth is radiating out, warming the other planets as well. Not.
The problem comes from a mathematical mistake. Trying to correlate solar activity with average temperature, rather than the rate of change in temperature. Some planets are hotter than earth, some are cooler. This tells us very little about solar activity. What is important is the observed rate of warming on earth and the other planets.
Solar activity is like the gas pedal on your car. When you press the gas pedal down, the car will tend to speed up. When you let the pedal back up, the car will tend to slow down.
However, you cannot tell by looking at just the speed of the car how hard you are pressing on the pedal. You need to look at the acceleration. In climate science, average temperature is the speed of the car; a misleading value. The rate of change in temperature is the acceleration; the correct indicator.
A secondary problem comes in assuming that the car is traveling on level ground. That 1 unit of acceleration or deceleration will always result in the exact same change in speed. The earth is not a simple homogeneous structure that heats and cools evenly. Nor is the energy from the sun a simple gas pedal. It is a spectrum with a significant frequency shift, which requires one to consider the photoelectric effect.
http://en.wikipedia.org/wiki/Photoelectric_effect
By 1905 it was known that the energy of photoelectrons increases with increasing frequency of incident light and is independent of the intensity of the light. However, the manner of the increase was not experimentally determined until 1915 when Robert Andrews Millikan showed that Einstein’s prediction was correct.
“Anyone my age or older who grew up in Europe (and its true to a lesser extent of Australia and perhaps N America) will remember the reason why winter minimum temperatures have risen since the 1960s. Which is most of the anomaly referred to.”
North American used coal widely for household heating as well. Our house had a coal chute and bin in the basement, but the furnace was eventually converted to oil. Listen to “The Shadow”, the old radio plays. They advertised the advantages of “Blue Coal” for heating your house. Given current prices, it might be time to convert back.
Leif Svalgaard says:
April 7, 2011 at 10:48 pm
ferd berple says:
April 7, 2011 at 8:11 pm
1) solar activity is the only driver of temperature.
Exactly, the Sun is but a minor player.
2)each upturn is followed by an equal downturn. The sun is not well enough understood to say if this is true or.
We have direct observations over 400 years and indirect data for the past 11,000 years and the Sun does return to near zero at each solar minimum.
Jim Steele says:
April 7, 2011 at 8:40 pm
Leif Svalgaard says:
The rise in temperatures in the 30′s and 40′s coincided with a positive PDO.
Now you invoke the oceans and not the Sun.
Both of you are grasping for straws, and invoking second order effects. The issue is if the Sun is the MAJOR driver of climate and it seems clear from your convoluted arguments that it is not.
———————————–
I think that Ferd and Jim have put forward good arguments most of which you have chosen to ignore. Your main argument seems to be that if the sun was the main driver the surface temperature should correlate with it. Not only do Jim and Ferd give good reasons why this is not true but anyone who has ever tried to control a complex thermal load would know it is not true; the load temperature rarely correlates with the power. If it did proportional control is all that would be needed and not PID.
You say that the sun is not the major determinant of climate. However the sun is the only source of energy. We also know that there have been huge fluctuations in the earth’s climate that are correlated to the effective irradiance at the earth’s surface (Milankovitch cycles). These changes in climate are larger than one would expect from a simple energy balance equation so the reason for the quasi harmonic fluctuations are not clear except that huge energy reservoirs are likely to be involved. Ice build clearly prevents excessive surface cooling (by releasing latent heat and possibly reducing radiation )and Jim, Ferd, I and others believe that the oceans prevent excessive warming at the surface by melting ice and building warm pools at lower depths. The fact that large volumes of energy might move between these energy sources/sinks with only a small solar trigger would not be a surprise to anyone who is used to resonant systems. In this context the related tiny change in atmospheric energy is not a surprise either. What exactly is your alternative explanation of the Milankovitch cycles?
The fact is that the energy stored in the climate sphere including the oceans the icecaps and all the atmosphere below the tropopause is about the same as would be contained in the mass of the oceans at 3C and this is probably now at the maximum it will ever be, having had 14000 years of interglacial warming. The long term average must be below this. I for one find that a very worrying thought. Looking at the evidence from previous epochs we can be reasonably sure that there are negative feedback mechanisms that prevent overheating but the feedbacks to prevent cooling are not so powerful. We are always on a knifes edge; that is why ice ages are triggered so easily. It is not warming that we should be worried about.
Can we stop with the metaphors? As written here, they smack of dodges, not solar science.
ferd berple says:
April 8, 2011 at 5:47 am
That explains why the heating we observe on earth is also observed on other planets.
This is an oft repeated myth. There is no evidence for this.
Nor is the energy from the sun a simple gas pedal. It is a spectrum with a significant frequency shift, which requires one to consider the photoelectric effect.
Has nothing to do with anything.
Jim Steele says:
April 7, 2011 at 8:40 pm
I think that Ferd and Jim have put forward good arguments most of which you have chosen to ignore.
No, I have carefully explained why they fail.
Your main argument seems to be that if the sun was the main driver the surface temperature should correlate with it. Not only do Jim and Ferd give good reasons why this is not true
No, they claim that heating accumulated during high solar activity is not lost during low solar activity. E.g. that the period after the Maunder Minimum started out with low temperatures and that high solar activity is struggling to overcome that deficit, but they forget that before the Maunder Minimum solar activity was high, so the low activity during the MM would have to overcome the precondition of the previous high in order to cool down as much. This does not make sense. But, people are, of course, entitled to believe what does not make sense. Many do.
What exactly is your alternative explanation of the Milankovitch cycles?
As Milankovitch himself pointed out the solar insolation [not irradiance, which has not changed] at high Northern latitudes [where the land masses are] varies with the tilt of the Earth’s axis and changes in orbital parameters. So from simple energy balance arguments the variations follow.
We are always on a knifes edge; that is why ice ages are triggered so easily
No, the END of glaciations are sudden. The decent into a glaciation is, well, glacial and takes tens of thousands of year.
Leif Svalgaard says:
April 8, 2011 at 7:58 am
Jim Steele says:
April 7, 2011 at 8:40 pm
In reply to my statement that “your main argument seems to be that if the sun was the main driver the surface temperature should correlate with it. Not only do Jim and Ferd give good reasons why this is not true…
No, they claim that heating accumulated during high solar activity is not lost during low solar activity. E.g. that the period after the Maunder Minimum started out with low temperatures and that high solar activity is struggling to overcome that deficit, but they forget that before the Maunder Minimum solar activity was high, so the low activity during the MM would have to overcome the precondition of the previous high in order to cool down as much. This does not make sense. But, people are, of course, entitled to believe what does not make sense. Many do.
I do read them as saying this. What I hear is that the temperature per se is not enough to define the forcing. Their belief is that the rate of temperature increase is a better measure. I personally happen to believe that the truth is somewhere in between since heat losses are temperature dependent. But if temperature rise is the better variable then for a given forcing change the end temperature is dependent on the start temperature. You may not agree but I can’t see why it “does not make sense”. They clearly accept that the heat gained during warm periods is lost during cold ones otherwise the the world would gradually warm or cool. The argument is over what timescales that equilibrium is reached.
What exactly is your alternative explanation of the Milankovitch cycles?
As Milankovitch himself pointed out the solar insolation [not irradiance, which has not changed] at high Northern latitudes [where the land masses are] varies with the tilt of the Earth’s axis and changes in orbital parameters. So from simple energy balance arguments the variations follow.
My point was that the simple energy balance calculations do not give this result. The change in insolation is not enough to cause the sudden warming associated with the interglacial. In my mind there has to be some slow accumulation of energy which takes place without surface warming such that the small input energy increase is not balanced by increased radiation to space.
Incidentally irradiance when applied to the sun is called insolation so I do not know what your comment above was supposed to mean. If you mean the sun’s output did not change then I might agree with you. If you are saying that the spectral irradiance did not change then I might agree with you. However in both cases I do not know.
We are always on a knifes edge; that is why ice ages are triggered so easily
No, the END of glaciations are sudden. The decent into a glaciation is, well, glacial and takes tens of thousands of year.
Here again you are denying something I did not say. I did not say the ice ages were sudden I said the ice ages were triggered easily. By that I mean that the huge input of energy capable of melting millions of cubic kilometres of ice and balancing the radiation losses associated with 10C higher surface temperatures has to be on full power to stop the world slipping back into the freezer. It is not a quick decline but it is difficult to stop it. The world’s normal state is unacceptably cold.
Sorry in the above post first line of comment I meant to say I do not read them saying this.
Leif Svalgaard says:
The rise in temperatures in the 30′s and 40′s coincided with a positive PDO.
Now you invoke the oceans and not the Sun.
Leif please. I have argued all along that the sun is the driver but oceans hold a memory of that input and determines where and how the heat is redistributed. And it becomes a ridiculous argument to analyze climate without taking that interaction into account. And it has been one of the major flaws in most studies that examine solar effects on climate. Milankovitch cycles by themselves can not explain the rapid changes in temperatures during the ice age where average temperatures fluctuate by 5-10C in 5-100 year periods – Dansgaard Oeschger events. Some oceanographers argue the ice ages’ closing of the Bering Strait generated deeper stratification of cold and warm layers that when finally vented due to increasing instabilities then generated these sudden temperature changes. Wunsch has suggested those cycles are not that statistically significant. And the glacial-interglacial cycles have changed from periodicities of 40,000 years to 100, 000 years. Clearly there is room for discussion, without insulting dismissal of vewpoints you fail or are unwilling to grasp.
The poles are in heat deficit fluxing more heat to the atmosphere than they absorb. The tropics absorb more heat than they release. This is simple basic science. Changes in the Arctic are greatly effected by oceanic and atmospheric heat distribution. Warm Gulf Stream waters sit below colder Arctic surface waters, and even below warm Pacific waters because of differences in salinity. Due to heavy evaporation warm water becomes more saline and dense sinking below colder less saline water. Oceanographers note the great salinity anomaly during the 70’s and others lesser events where fresher colder arctic water moved south ad circulated on the surface of the north Atlantic for a decade bringing colder surface temperatures. Several studies by very respected researchers like Hurrell have demonstrated how changes in sea level pressure in part due to changes in ocean heat content redirect winds such as the North Atlantic Oscillation, and he maintains that almost all of Europe’s recent warming can be accounted for by changes in the NAO and its effect on winds and ocean heat distribution. At the same latitude of the Antarctic peninsula, the western half is about 10 degrees warmer lacking ice while the eastern side houses the densest most persistent ice pack in the Antarctic. And I am only touching the tip of the ocean’s climate iceberg.
As you requested I laid out a case for the solar ocean interaction causing asymmetries in heat storage and distribution. In return you dismiss it, not with scientific arguments specific to what was stated, but again with insulting remarks.
You obviously have your head only in holes of the sunspots, and lack any understanding of oceanographic mechanisms. Inspite of much evidence you, you cling to the simplistic and completely unsupported notion that the ocean heat absorption and release simply parallels changes in solar input. To do so requires that you demonstrate that there are no periodic changes in ocean heat content, but even models designed before the PDO was ever named and that strictly look at natural variation demonstrated that global heat can fluctuate by .5 C over 50 years time. I demonstrated how changes in frequency of El Ninos and La Ninas can impact absorption and release of solar input. You failed to show why those arguments were not valid. So instead of arguing the science once again you resort to arrogant dismal of well documented science with comments like “people are entitled to believe the wrong thing they do it all the time”. Perhaps a mirror would be useful. You repeated use of insulting arrogance has lost all my respect for your ability to discuss issues in an objective manner.
The hypothesis that some are putting forward is that some special set of initial conditions has resulted in sea surface temperatures to continue to rise for several decades AFTER solar activity has peaked.
This means the oceans had not yet reach equilibrium, the same (or slightly falling) amount of incoming energy was still causing the oceans to warm. The problem this raises is what IS the new equilibrium temperature for this level of solar irradience ?
The fact that sea temperatures continued to rise in the 90s after falling briefly when major volcanic eruptions dimmed the solar input shows that they had not reached a new equilibrium temperature despite no further increase in the solar maximum or change in GCR flux.
If you assume that 2010 was the year the system did reach equilibrium with the past 3 decades of solar activity then the present equilibrium temperature must be higher than in the past for the same solar input.
Otherwise sea temperatures, sea level and ice mass would show similar exceptional levels when the solar output was similar in the past.
Add a small refinement, Dave, and the parallels get more exact and complex:
The flame is ABOVE the pot, directing its heat onto the surface of the water (unevenly across the diameter(s) of the pot). Various slow and quick circulation currents are induced in the pot, which is, btw, hanging off a hook and swinging gently back and forth.
There is a lot of ‘threshing of empty straw’ in the above posts.
Sun provides energy for but doesn’t modulate climate. That is done by the Earth’s rotation, revolution and anything beyond that by the heat capacity of the oceans deeper layers. Long term oceanic indices like PDO, ENSO, AMO, etc. are major climatic factors and have no solar cycle component. They are indicators to what climate is doing, so to understand what drives climate it is essential to know what drives PDO, ENSO and AMO.
The answer is in data, and the data is here:
http://www.vukcevic.talktalk.net/PDO-ENSO-AMO.htm
izen says:
Actually, one of the main pieces of evidence that the oceans never did reach equilibrium in response to high 20th century solar activity is that temperatures seem to have been signficantly warmer during the Medieval Warm Period, when solar activity did not reach as high a level. Unless someone can come up with some other MWP cause than the sun, it seems that continued high solar activity would have driven current temperatures higher still, if history is our guide.
Jim Steele says: “The rise in temperatures in the 30′s and 40′s coincided with a positive PDO. ”
The PDO is an abstract form of the Sea Surface Temperatures of the North Pacific north of 20N. The SST anomalies for that area of the North Pacific are actually inversely related to the PDO.
(Sorry for the delay in responding to your comment.)
Alec Rawls says: April 8, 2011 at 1:50 pm
Unless someone can come up with some other MWP cause than the sun, it seems that continued high solar activity would have driven current temperatures higher still, if history is our guide.
Yes there is, North Atlantic Precursor (NAP), which is nothing to do with sun and in no way related to solar activity. Data pre 1650 are sparse but for post 1650 there are accurate records.
Here is NAP 1650- 2010
http://www.vukcevic.talktalk.net/CET-NAP.htm
and NAP 1100-1600
http://www.vukcevic.talktalk.net/NAP11-16.htm
compared to tree ring data from California, not exact match but close enough (CA is long way of N. Atlantic after all)
@- Alec Rawls says:
April 8, 2011 at 1:50 pm
“Actually, one of the main pieces of evidence that the oceans never did reach equilibrium in response to high 20th century solar activity is that temperatures seem to have been signficantly warmer during the Medieval Warm Period, when solar activity did not reach as high a level.”
I don’t think that any paleoclimate reconstruction is sufficiently certain to establish with certainty that the MWP was globally warmer in terms of ocean temperatures than the present.
This link –
http://pages.science-skeptical.de/MWP/MedievalWarmPeriod.html
Has a rather neat collection of the various data for the climate over that period in map form showing the independent measurements using differing methods all over the globe. It is certainly possible to find a peak in the medieval period. Much more difficult to show it was synchronous between the northern and southern hemispheres. A case can be made that it was a north-south antiphase cycle where one hemisphere warms, then the other. Try it on the link, its like a tile matching game trying to find two peaks that match, especially between the N/S polar regions.
” Unless someone can come up with some other MWP cause than the sun, it seems that continued high solar activity would have driven current temperatures higher still, if history is our guide.”
If your assumption is correct that ocean temperatures were higher with a lower solar input during a global MWP it seems that continued high solar activity WILL drive current temperatures higher still, if history is our guide.
Then any fall in solar activity at present will have little effect just as the last few decades of stasis/reduction has still seen temperatures rising. The equilibrium temperature will be even higher than 2010. Because it was higher with lower TSI in the MWP.
Unless there was some other MWP cause than the sun we are going to get a lot hotter because there must be much more warming in the pipeline given the greater energy input in the present.
Or there is some other cause for the warming observed at present than the sun.
Consider this thought experiment. Take any temperature forcing, call it F. Don’t worry if is the sun, CO2, or the man in the moon.
Now turn the forcing on and off in a regular interval, so that you get a square wave:
_|¯|_|¯|_|¯|_|¯|_|¯|_|¯|_
Now, assuming all things remain equal, the acceleration (rate of increase) in temperature (in a simple object) will show the following behavior.
_|¯|_|¯|_|¯|_|¯|_|¯|_|¯|_
But average temperature itself will show the following behavior:
_ / \ / \ / \ / \ / \ / \
Forgive the crude graphics. What I’m trying to show is that while forcings and acceleration are a square wave, temperature is a saw tooth pattern.
This is the problem in using average temperature when looking for a correlation with solar activity. It is the wrong “grain” in information processing / data warehousing terminology. As soon as you add noise and complex graphs, the difference in grain will mask the correlation.
This is a classic data mining mistake when looking for correlations in data. In the simplest terms, that is what climate models are. They are time series data mining models that seek to correlate forcings with temperature, to predict future behavior. Data mining 101. We do it all the time in marketing to predict customer behavior.
Before you rule out correlations, you need to make sure the data you are correlating is at the same grain. Solar activity needs to be correlated with the rate of change of temperature before any reliable conclusions can be drawn.
izen says:
Warmth in the deeper oceans is not necessarily “in the pipeline” in the sense you are using it here. It need not cause ANY surface warming. Remember that the upper ocean layer responds quickly to any change in forcing. With the sun having gone quiet, this means, under the solar warming hypothesis, that the upper ocean layer should be cooling, and this is what drives surface temperatures, or GMAST. The effect of the stored heat in the deeper ocean would be to slow down this cooling. So there is “heat in the pipeline,” but it shows up not as rising surface temperatures, but as slowed down cooling.
One of the issues to sort out here is the difference between a long period response and a lag. There is no obvious reason why there should be any lag at all between the end of grand maximum levels of solar activity and the beginning of global cooling. That doesn’t mean there aren’t lags, but lags and equilibration time are very different things.
@- Alec Rawls says:
April 8, 2011 at 8:30 pm
“Warmth in the deeper oceans is not necessarily “in the pipeline” in the sense you are using it here. It need not cause ANY surface warming. Remember that the upper ocean layer responds quickly to any change in forcing. With the sun having gone quiet, this means, under the solar warming hypothesis, that the upper ocean layer should be cooling,…”
But it is not sufficient to sustain cooling unless you have a new ‘Maunder minimum’. After each solar minimum in the previous cycles since the 60s – cycle 19 – the oceans have continued to warm despite the reduction in solar activity since cycle 19. The temperature averaged over a solar cycle has been increasing with each cycle while the solar activity has shown a small reduction.
This would indicate that the system is still well below the equilibrium temperature as any increase of the solar output above the zero sunspot baseline has driven cumulative warming.
“One of the issues to sort out here is the difference between a long period response and a lag. There is no obvious reason why there should be any lag at all between the end of grand maximum levels of solar activity and the beginning of global cooling. That doesn’t mean there aren’t lags, but lags and equilibration time are very different things.”
No, lags and equilibrium time are the SAME thing.
Otherwise you would be breaking the 1LoT.
And you can’t break that, its the LAW! (J.D)