New solar reconstruction paper suggests 6x greater solar forcing change than cited by the IPCC

This is interesting. This recent paper published in the journal Astronomy & Astrophysics here has done a reconstruction of TSI using Beryllium 10 isotope records combined with sunspot records. The paper suggests that the Total Solar Irradiance (TSI) has increased since the end of the Little Ice Age (around 1850) by up to 6 x more than cited by the IPCC.

Modulation potential (lower panel) and TSI reconstructions (upper panel) for the last 2500 years. Data prior to 1600 AD are based on the modulation potential derived from 10Be records from the Greenland Ice core Project (red curves). Data since 1600 AD are based on the two composites shown in Fig. 1 (red and cyan curves). The grey-shaded area indicates the intrinsic uncertainty.

Here is how they did it:

For the reconstruction to the past this amplitude is scaled with proxies for solar activity. Two proxies are available for the reconstruction: Group sunspot number, which is available from the present to 1610 AD, and the solar modulation potential extending back to circa 7300 BC. The latter is a measure of the heliospheric shielding from cosmic rays derived from the analysis of cosmogenic isotope abundances in tree rings or ice

cores, and is available with a time resolution of 2-3 solar cycles (Steinhilber et al. 2008). Although sunspot number dropped to zero for a long time during the Maunder minimum, the solar cycle was uninterrupted (Beer et al. 1998; Usoskin et al. 2001) and the modulation potential did not fall to zero. Hence, a reconstruction based solely on sunspot number may underestimate the solar activity during theMaunderminimum. Therefore in our reconstruction we used the solar modulation potential to calculate the long-term variations and sunspot number to superpose them with the 11-year cycle variations (see the Online Section 6.2).

The modulation potential used in the calculations is based on the composite of data determined from the cosmogenic isotope records of 10Be and neutronmonitor. 10Be data are available up to about 1970 (McCracken et al. 2004) and neutron monitor data, which are used to calculate the current solar modulation potential, are available since the 1950s.

A new approach to the long-term reconstruction of the solar irradiance leads to large historical solar forcing

A. I. Shapiro, W. Schmutz1, E. Rozanov, M. Schoell, M. Haberreiter1, A. V. Shapiro and S. Nyeki

1 Physikalisch-Meteorologishes Observatorium Davos, World Radiation Center, 7260 Davos Dorf, Switzerland

2 Institute for Atmospheric and Climate science ETH, Zurich, Switzerland

3 Institute for Astronomy ETH, Zurich, Switzerland

Abstract 

Context. The variable Sun is the most likely candidate for the natural forcing of past climate changes on time scales of 50 to 1000 years. Evidence for this understanding is that the terrestrial climate correlates positively with the solar activity. During the past 10 000 years, the Sun has experienced the substantial variations in activity and there have been numerous attempts to reconstruct solar irradiance. While there is general agreement on how solar forcing varied during the last several hundred years – all reconstructions are proportional to the solar activity – there is scientific controversy on the magnitude of solar forcing. Aims. We present a reconstruction of the total and spectral solar irradiance covering 130 nm–10 μm from 1610 to the present with an annual resolution and for the Holocene with a 22-year resolution. Methods. We assume that the minimum state of the quiet Sun in time corresponds to the observed quietest area on the present Sun. Then we use available long-term proxies of the solar activity, which are 10Be isotope concentrations in ice cores and 22-year smoothed neutron monitor data, to interpolate between the present quiet Sun and the minimum state of the quiet Sun. This determines the long-term trend in the solar variability, which is then superposed with the 11-year activity cycle calculated from the sunspot number. The time-dependent solar spectral irradiance from about 7000 BC to the present is then derived using a state-of-the-art radiation code.

Conclusions

We present a new technique to reconstruct total and spectral solar irradiance over the Holocene. We obtained a large historical solar forcing between the Maunder minimum and the present, as well as a significant increase in solar irradiance in the first half of the twentieth-century. Our value of the historical solar forcing is remarkably larger than other estimations published in the recent literature.

We note that our conclusions can not be tested on the basis of the last 30 years of solar observations because, according to the proxy data, the Sun was in a maximumplato state in its longterm evolution.All recently published reconstructions agree well during the satellite observational period and diverge only in the past. This implies that observational data do not allow to select and favor one of the proposed reconstructions. Therefore, until new evidence become available we are in a situation that different approaches and hypothesis yield different solar forcing values. Our result allows the climate community to evaluate the full range of present uncertainty in solar forcing.

The full dataset of the solar spectral irradiance back to 7000

BC is available upon request.

Here is the paper, available online in entirety here (PDF) h/t to The Hockey Schtick

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Claude Harvey

“This implies that observational data do not allow to select and favor one of the proposed reconstructions. Therefore, until new evidence become available we are in a situation that different approaches and hypothesis yield different solar forcing values. Our result allows the climate community to evaluate the full range of present uncertainty in solar forcing.”
My! My! What an ingenious escape clause! We don’t claim our results are true because that would undermine the foundations of AGW theory. We merely did all this work to expand the band of uncertainty! We can still maintain that AGW theory is sound, but with the caveat that “the band of uncertainty” is merely expanded.
That kind of equivocation, boys and girls, is what it takes to get such a paper published these days. The fact that such a paper can see the light of day, even with said equivocation, is progress over where things stood only a couple of years ago.

Konrad

Good to see this paper up at WUWT. I find this an interesting paper in that the authors make no claim that their method is superior or “robust” Rather they highlight the difficulties inherent in all TSI reconstruction attempts, including those that seek to stamp the TSI record flat.
It will be interesting to compare the authors proposed reconstruction to the solar forcing that Willis discovers in his GCM forcing adventure.

Sean Houlihane

Interesting. How do they justify extending the proxy for TSI into a region beyond the level which has been proposed as a stable background level on top of which the solar cycle adds modulation? I think I’m right in saying that there is no evidence yet to directly link the LIA with reduced TSI?

Breaking news on BBC Today
0719: It has emerged that the coalition cabinet is reportedly spit over the government’s policy on climate change. Environment correspondent Roger Harrabin reports.
This marks quite a dramatic shift, because so far the UK politicians have all been on one “consensus” (publicly) and one cannot forget that the Tories were elected by a leader who said they were going to be the “greenest government ever”.

Adam

Claude Harvey,
I have to disagree with you. That quote was my favorite part. It means the people who put together this paper are actual scientists. Scientists who recognize the limits of their research and the possibility they can be wrong. As oppose to “scientists” who try to hide their data, or don’t want people to admit the limits of science in public as it could give those “deniers” ammunition.

John Finn

The main argument against solar forcing being responsible for post 1970-warming still seems valid, i.e. the TSI trend since ~1950 is approximately zero. Also (from the TSI reconstruction since 1600) would we not expect temperatures during the 18th century to be comparable to those in the late 20th century.

David Schofield

Scottish Sceptic says:
May 10, 2011 at 1:12 am
Breaking news on BBC Today
0719: It has emerged that the coalition cabinet is reportedly spit over the government’s policy on climate change. Environment correspondent Roger Harrabin reports.
I think you’ll find that the dissenters want to go further.

David Schofield

What would the models produce if that solar forcing variable was multiplied 6 times?

Joe Lalonde

Anthony,
Is it me or strictly using the Greenland ice core as proxy is a little ridiculous as to the proximity it is away from the rest of the planet for measuring the sun spots using a proxy?
A massive amount of atmosphere and weather conditions to be able to reach that point compared to the equatorial region.

David Schofield

Scottish Sceptic says:
May 10, 2011 at 1:12 am
Breaking news on BBC Today
0719: It has emerged that the coalition cabinet is reportedly spit over the government’s policy on climate change. Environment correspondent Roger Harrabin reports.
It is on Radio 4 listen again;
http://www.bbc.co.uk/programmes/b010xzxh

John Finn says, May 10, 2011 at 1:40 am
the TSI trend since ~1950 is approximately zero
Indeed, but one may not forget that it costs a lot of years to warm the oceans up. Even with a constant high level of TSI, it takes about 30 years (or more) to reach a new high in seawater temperature. The fact that since about 2000 there is no increase in temperature anymore (besides ENSO variability), shows that the new equilibrium is more or less reached. The next decade will show the real impact of the sun, as we currently have a less active sun, which should translate in lower temperatures (or not)…

John Marshall

Solar driven climate? Whatever next?
The evidence is mounting against CO2 as the culprit.
Inability to find the troposphere hot spot.
Ice core data placing temperature rise before CO2 rise.
Now solar variability.
The IPCC will hate this because they refuse to accept any solar variation at all.
Keep the evidence rolling in.

lateintheday

. . .comparable to late 20th Century
yes, if you prefer to ignore sensitivity to initial conditions or assume a straightforward, contemporaneous, purely linear climate response. Doubt it works that way.
Interesting post though. Whilst welcome, I can’t get too carried away, since reading this blog has taught me to treat proxy reconstructions with a pinch of salt.

John Davis

The TSI trend since 1950 might be close to zero, but the level is high. Bear in mind that no less an authority then James Hansen has pointed out that present levels of CO2 forcing, even if they stayed constant, will have stored up temperature increases for the next 50 years or so. It’s a very big bucket of water, and it’s going to take a long time to warm – or cool.

Edim

“The main argument against solar forcing being responsible for post 1970-warming still seems valid, i.e. the TSI trend since ~1950 is approximately zero. Also (from the TSI reconstruction since 1600) would we not expect temperatures during the 18th century to be comparable to those in the late 20th century.”
It is very likely that post 1970 warming is overestimated (anthropogenic local warming).
Even if the solar forcing during the 18th century was comparable to the late 20th century, that still does not mean that the temperatures should be comparable as well. Durin the LIA we had a lot of ice buildup and when the solar forcing increased again, there was a lot of thermal inertia. A lot of heat is needed to melt the ice.
But I still think that the temperatures during ~40s were comparable to the ~80s/90s.

rbateman

John Finn says:
May 10, 2011 at 1:40 am
Try reading the paper.
It’s the UV range (175-242 nm) of the Solar Spectra that comprises most of the change in TSI and SSI.

I would not put too much money on it. Beryllium records from Greenland ice cores, are highly unreliable, I would say border on useless.
Antarctic records I am not familiar with, I would think that they should be far more reliable.
Why do I question Greenland’s 10Be?
See here: http://www.vukcevic.talktalk.net/CET&10Be.htm

Christopher Hanley

Can someone answer: how is past TSI estimated and how it is now measured, at the surface or by satellite?

David Schofield

Should point out the item is 1 hour 20mins 30 secs.

There are two or three factors involved during solar max and minimums – one is the TSI, the others are cloud cover and UV displacement effects on the jetstream (which also affects cloud cover) – these lead to ‘pulsed’ warmings of the ocean surface waters to 200m and time lags that redistribute that heat to land – these latter are complex teleconnections from ocean basin to basin – and this determines the global average temperature. From 1980-2001 low level reflective cloud cover decreased by 4-5% – quite enough to account for ‘global warming’. After 2001 it came back by about 2% and the oceans soon afterwards stopped accumulating heat.
If we focus on one factor alone, we get a distorted picture.

Alistair McKechnie

Interesting study but although I scoured it most carefully to see if their findings could correlate with the warming over the last ten years, it actually seemed to have a negative correlation – quieter sun, more warming. So when they use the word ‘historical’ in the title of the report, they obviously do mean ‘historical’.
So as a scientifically robust counter to the IPCC argument, this is very far from doing the job.

thingadonta

Yeah ,but the AGW crowd have a get out of jail free card. They say that if the climate is very sensitive with regards to the sun, it must be very sensitive for everything else as well, so the C02 greenhouse effect increases even more if the sun’s effects are larger. This is a false equivalence, or rather, a tendancy to lump all climate effects together, rather than to recognise that nature genearlly doesnt follow patterns in a linear or predictable form, which I hesitate to say, tends to be a socialist assumption (.i.e evenness and equivalence).

StuartMcL

Alistair McKechnie says:
May 10, 2011 at 3:24 am
Interesting study but although I scoured it most carefully to see if their findings could correlate with the warming over the last ten years,

What warming over the last 10 years?

Barry Day

Why is it ” Hydrothermal Vent Complexes Causing Global Warming”is ignored or seldom entered into the equation??
http://tinyurl.com/3gowq2j

Peter Taylor
hi Peter
I am somewhat ambivalent about the notion that there is a wholseale transfer of heat from Ocean to land which sems to be the generally agreed maxim.
i live 100 yards from the South coast of England. The warming effect of the gulf stream is easily overcome by the wind direction and the nature of the weather fronts they bring. For example we would normally reckon that in a ‘normal’ year (which rarely seems to happen) the warmth of the gulf stream will just about keep frosts away from our garden until February. 2 miles inland the warming effect has been lost all through the winter. Cloud cover will have a considerable effect on keeping the sea warm, especially at night.
During the last few winters, when we had strong easterlies and high pressure, the intense cold and lack of cloud they brought meant we had frosts even in November and the gulf stream had a marginal effect.
Whether the warming effect of the oceans can therfore be said to affect the whole of the UK or by inference entire continental land masses i would be dubious. Wind direction and the effects of weather systems are to my mind every bit as important.
tonyb

Since TSI is how the warmists try to discredit Milankovitch I remain skeptical. While total TSI might matter somewhat, it matters more where that energy is striking the Earth. That is why the Earth is colder in January when the Earth is closest to the sun and warmist in July when it is farthest from the sun.
The annual TSI variation is enough to show that location matter more than very small variations in the total amount of energy.

lateintheday

Alistair McKechnie
I suggest you don’t use the word ‘robust’ on this site if you want to avoid ridicule.
However, judging by the rest of your comment that aim does not appear to be high on your list of priorities.
It never ceases to amaze me that CO2 is given every possible route and timeframe by which warming could show itself. Solar influence on the other hand . . . apparently that has to be both immediate and without any complexity attached.

Great that this is beginning to make it into the literature, after we’ve been saying it for several years.
The way Nir Shaviv’s findings have been ignored since 2005 by mainstream climate science is nothing short of shameful.
http://sciencebits.com/calorimeter

Martin Lewitt

John Finn,
“The main argument against solar forcing being responsible for post 1970-warming still seems valid, i.e. the TSI trend since ~1950 is approximately zero. ”
Keep in mind that solar activity was still at this unusually high plateau for the latter half of the century, and there is a mid-century cooling that is a problem for the CO2 hypothesis as well. Model diagnostics show that models disagreeing with each other on sensititivity ranging from 2C to 6C can all “match” the observed 20th century climate, because of the uncertainty in aerosols, that same uncertainty in aerosols can aid solar forcing in explaining the mid-century cooling and rapid temperature increases in the 1980s and 90s.

Garacka

I second Adam at 1:34 am. The conclusion is refreshing.

Martin Lewitt

thingadonta,
“Yeah ,but the AGW crowd have a get out of jail free card. They say that if the climate is very sensitive with regards to the sun, it must be very sensitive for everything else as well, so the C02 greenhouse effect increases even more if the sun’s effects are larger”
On the contrary, this result works against that “get out of jail free card. We have no model independent estimates of climate sensitivity to CO2 forcing in the current climate regime, so the best model independent attempts have used estimates of the sensitivity to variation in solar and aerosol forcing. Because the estimates of solar variability were low, the required sensitivities solar forcing to explain the medieval warm period and the little ice age had to be correspondingly higher, and based on an invalid assumption of equivilence justified higher sensitivities to CO2. Sensitivity to solar was often in the 2 to 3 degrees C range. A result of higher solar variability like this report, removes one of the model independent justifications for a higher sensitivity, because it is no longer needed for solar. The geographical, vertical and chemical couplings to the climate (including the oceans of course) are quite different for solar and CO2, and the assumption of equivalence in a nonlinear dynamic system was never justified.

Bill Illis

This reconstruction is more like the solar variation which would be required to cause the Little Ice Age and some of the other climate cycles we have experienced. I note they have TSI about 8 watts/m2 lower in the late 1400s, 6 w/m2 lower in the late 1600s and 4 watts/m2 lower in 1900.
————–
David Schofield says:
May 10, 2011 at 2:04 am
What would the models produce if that solar forcing variable was multiplied 6 times?
———-
The majority of the warming since 1900 could then be explained by the Sun (in the climate models). They might then better match the 1910 to 1944 warm cycle (which the models cannot do), the 1946 to 1975 down cycle and the 1976 to 2002 up cycle.
(Note the 10be numbers do not match the sunspot cycles exactly in the 20th century. Sunspot levels peaked around 1950, just as temperatures were falling, but the 10be levels seem to peak earlier closer to the 1946 down-step in temperatures).

kim

The sun has risen and the British policy cock crows.
=============

Alan D McIntire

Another reply to John Finn:
I put a pot on the stove, pour soup in the pot, turn the stove burner up to warm and leave it there- there’s no change in burner level over a period of time, yet my soup still warms. Evedently you’ve never warmed soup in a pot.

Maybe I’m misunderstanding something (yet again!) but it seems to me that they are making a massive mistake. Unfortunately I’m not an expert in this area, and I didn’t even fully understand what they were saying (my excuse is that it’s late at night in this part of the globe and I can’t spend any longer on it right now), but this is what I interpreted from it:
They assume that the solar activity indicated by the 10Be records, and which relates to temperature changes, can be interpreted and evaluated as TSI. ie, the assumption is that the temperature changes were caused by direct solar forcing. Hence the TSI variations must have been x times greater than previously thought.
To my simple mind, this is very poor logic indeed. The possibility of indirect effects need to be considered.
Again, the different treatment accorded CO2 and the Sun is striking.

MarkW

The full dataset of the solar spectral irradiance back to 7000
BC is available upon request.
—-
Now that’s how you do science.

Stephen Wilde

Peter Taylor says:
May 10, 2011 at 3:20 am
I agree.
The main residual factor to be resolved is the correct mechanism for the cloudcover changes.
Svensmark’s cosmic ray effect is certainly a possibility and well thought of by many but I find it implausible for various reasons.
I prefer the idea that more clouds globally result primarily from more air mass mixing from longer air mass boundaries when the jets shift equatorward or become more meridional.
If the solar variations can drive that (and as explained elsewhere I think they can) then we have a suitable amplification mechanism explaining the large energy budget effect from small solar changes.
The cosmic ray changes could just be a coincidental separate effect from reduced solar activity.

kim

The sun has risen.
British policy cock crows.
Cabinet ar’t work.
==========

Pamela Gray

In the face of the tremendous energy available in Earth’s coupled oceanic/atmospheric natural oscillating variations, as it spins and tilts on its axis, I am unimpressed with the Sun’s relatively tiny changes in available energy to out perform our own Earth. IMHO, the Sun, and dare I say anthropogenic CO2, remain distant cousins in the major Earthly drivers of temperature change.

NikFromNYC

“I WANT TO BELIEVE”, said the climatologist.
http://oi55.tinypic.com/21lll04.jpg
“How might I explain this article to my young boy?”, he asked himself.
“The sun did it, before, but oh no no not now!”, he said to himself.
“Daddy, what *is* the sun? Why is the sky blue but the sun yellow?”, Xavier asked.
“Well, X, it’s got to do with particles that come in and out of our great universe from nowhere and go back there too, to nowhere.”
“That creates inertia, a sort of soup that other pairs of not-yet-mutually-annihilated particles must always swim in, except in liquid helium.”
“Like balloons?”, X asked.
“Xavier, you will be a lawyer. I’ll pay for that. Science doesn’t fit you. You ask too may questions.”, the climatologist said.

Stephen Wilde

Mike Jonas says:
May 10, 2011 at 6:20 am
“They assume that the solar activity indicated by the 10Be records, and which relates to temperature changes, can be interpreted and evaluated as TSI. ie, the assumption is that the temperature changes were caused by direct solar forcing. Hence the TSI variations must have been x times greater than previously thought.”
I don’t think they have been as simplistic as that:
“Fig. 4 presents a reconstruction of the integrated
flux for several, selected spectral regions. The contrast between
different brightness components of the quiet Sun is especially
high in the UV, which results in a large historical variability of
the UV spectral irradiance. The irradiance in the Schumann-
Runge bands and Herzberg continuum increases from the
Maunder minimum to the present by about 26.6% and 10.9%
respectively, which is much larger than 0.4% for TSI and the
visible region. The variability is also relatively high around the
CN violet system whose strength is very sensitive to even small
temperature differences due to the high value of the dissociation
potential. The large UV variability reported here is especially
of importance to the climate community because it influences
climate via an indirect, non-linearly amplified forcing.”
Thus they seem to be recognising the wavelength variations as a greater contributor to climate forcing than the absolute level of TSI.
My judgement is that those variations alter the vertical temperature profile of the atmosphere to alter surface pressure distribution and cloudiness.
Thus when the sun was more active during the late 20th century the entire atmosphere did not respond in the same way to the solar forcing.
Instead the thermosphere and troposphere warmed but the stratosphere and mesosphere cooled.
Now with a quieter sun the thermosphere has cooled, the troposphere has stopped warming and the stratosphere and mesosphere appear to have stopped cooling.

Michael Ozanne

“John Finn says:
The main argument against solar forcing being responsible for post 1970-warming still seems valid, i.e. the TSI trend since ~1950 is approximately zero. Also (from the TSI reconstruction since 1600) would we not expect temperatures during the 18th century to be comparable to those in the late 20th century.”
Well firstly, there is no increasing trend from the higher level plateau reached in 1950 would be a better way of describing it. Your question presupposes that we know how long it takes the Earth to reach an equilibrium temperature following an increase in received solar energy, presupposes that the 17th century temperature measurements are accurate, and reliable, presupposes that the current temperature measurements are accurate and reliable. Lets just say that not all parties are in agreement with those suppositions……:-)

The main problem with the paper is visible in the upper right hand plot of the Figure. It shows a large change in [assumed] TSI from 1900 to 1950 and no change thereafter. All evidence we have from solar indicators is that the sun the last few years have returned to conditions of a century ago. This would seem to include TSI as well, unless they can give a reason for why not [and the paper doesn’t do that]. Since the large increase in their TSI drives the reconstruction back in time, the whole thing becomes dubious. You could contrast this with the conclusion of Schrijver et al.
http://wattsupwiththat.com/2011/03/19/the-minimal-solar-activity-in-2008%e2%80%932009-and-its-implications-for-long%e2%80%90term-climate-modeling/
My money is on Schrijver, but there is a lot of room for confirmation bias with two such disparate papers: you get to choose which ones fits your agenda.

kwik

Good grief! I am sure some medieval-declined “scientist” is sneaking out to his climate-Den right now, adding these people to the dreaded BLACKLIST !
And it is all too late anyway;
http://thescotsman.scotsman.com/latestnews/Brown-Fifty-days–to.5747301.jp

Pamela Gray says: May 10, 2011 at 6:49 am
IMHO, the Sun, and dare I say anthropogenic CO2, remain distant cousins in the major Earthly drivers of temperature change.
Agree. Sun provides all the energy but no variability. Oceans and atmosphere are more like two naughty children, while CO2 is a pretentious little upstart; all ‘smoke’ no fire.

References are made to ‘Earth’s thermal equilibrium’. I doubt that such state is ever established. For Earth to do that, first the oceans would have to be in equilibrium; that is highly unlikely since the oceans are continuously perturbed by multiplicity of currents. Among number of other reasons currents are promoted by the lack of equilibrium. Nature’s circular causation.

Patrick M.

Is it just my eyes or do the cyan lines end at 1970? Is this “Hide the decline – Part II”?

Patrick M. says:
May 10, 2011 at 10:08 am
Is it just my eyes or do the cyan lines end at 1970? Is this “Hide the decline – Part II”?
No, it is just that the ice core data is not well measured in the upper 30-50 years of the record, because the snow hasn’t yet turned into firm ice.

Leif, it looks like they used data sources from before the decline. Papers cited are from 2004 and 2008, I didn’t read the paper to know if they got updated data.
To the left, resolution in only 22years.

Anything is possible

Leif Svalgaard says:
May 10, 2011 at 8:53 am
“My money is on Schrijver, but there is a lot of room for confirmation bias with two such disparate papers: you get to choose which ones fits your agenda”.
____________________________________________________________
21st. Century climate “science” in a nutshell :
Very long on agendas and confirmation biases. Very short on definitive facts.
As compelling a reason as there is for NOT allowing it to drive political policy.