Guest post by Alec Rawls
Technically Dr. Muscheler is asking me to retract the title of my post, “Raimund Muscheler says that a steady high level of forcing can’t cause warming“:
I am sure that you are aware of the fact that the title is wrong. I never said that steady high levels of forcing can’t cause warming.
He most certainly did. Here is the sentence of Muscheler’s that I was paraphrasing (with emphasis added):
Solar activity & cosmic rays were relatively constant (high solar activity, strong shielding and low cosmic rays) in the second part of the 20th century and, therefore, it is unlikely that solar activity (whatever process) was involved in causing the warming since 1970.
This is an unconditional statement: the high solar activity of the second half of the century can’t have caused warming because it was “relatively constant.” If Dr. Muscheler wants a retraction he’s going to have to issue it himself, and that actually seems to be what is going on here.
Raimund now rejects the claim that a steady high level of forcing can’t cause warming. Good. But then on what grounds can he dismiss a solar explanation for late 20th century warming?
His email offers a new rationale. Muscheler thinks the lack of warming from the 40s to the 70s vitiates the solar-warming hypothesis:
My point is rather nicely illustrated in the attached figure [at the top of the post]. It shows the sunspot data and temperature anomalies over the last 160 years (annual data and 11-yr average). It shows the high solar activity I was mentioning.
According to your reasoning one would expect a steady warming since 1950. However, the temperatures were rather constant from 1940 to 1970. Furthermore, the temperature and solar trends are opposite during the last 30 years. So I think one would have to invoke a very strange climate delay effect in order to explain the recent warming with solar forcing.
I would be happy if you could correct the title and add this clarification to your post.
Best wishes,
Raimund
There are a couple of points one can quibble with here:
1) Muscheler again invokes “opposite trends,” as if it is the trend in solar activity, not the level, that would be driving temperature.
2) Those trends have not been “opposite for 30 years.” Solar cycle 22, which ran from 1986-1996, had the same sunspot numbers as cycle 21 but was more intense by pretty much every other measure.
3) Muscheler seems to be asserting that temperature has been rising for the last 30 years when it has been roughly flat for the past 15 years (a fact that presents problems for Muscheler’s preferred CO2-warming theory, but is perfectly compatible with the solar-warming theory, after cycle 23 slowed down and dropped off a cliff).
But set those quibbles aside. What is interesting here is Muscheler’s new argument that if the sun had caused late 20th century warming then the planet should have warmed steadily since 1950.
My reply:
Actually, I would say that warming should have been steady since the 1920’s, but that is only if we are looking at the heat content of the oceans (where almost the entire heat content of the climatosphere resides). Unfortunately, we don’t have good ocean heat content data for this period, while the data we do have–global mean atmospheric surface temperature–is dominated by ocean oscillations.
You suggest that it would take some very strange lags for warming from the 40s to the 70s to not show up until later, but would this actually be strange? Doesn’t it fit with what we KNOW: that the cool 40s-70’s period coincided with a cool-phase of the Pacific Decadal Oscillation?
Ocean oscillations are widely acknowledged to be the dominant short term driver of global temperature
Just look at what the CO2 alarmists say as soon as their predicted warming fails to show up (April 2008):
Parts of North America and Europe may cool naturally over the next decade, as shifting ocean currents temporarily blunt the global-warming effect caused by mankind, Germany’s Leibniz Institute of Marine Sciences said. …
“Those natural climate variations could be stronger than the global-warming trend over the next 10-year period,” Wood said in an interview. “Without knowing that, you might erroneously think there’s no global warming going on.”
The Leibniz study, co-written by Noel Keenlyside, a research scientist at the institute, will be published in the May 1 issue of the journal Nature.
“If we don’t experience warming over the next 10 years, it doesn’t mean that greenhouse-gas warming is not with us,” Keenlyside said in an interview. “There can be natural fluctuations that may mask climate change in the short term.”
Wood and Keenlyside aren’t even talking about the PDO, just the measly AMO. For an historical example where natural fluctuations probably really did “mask climate change in the short term,” the PDO is the place to look.
Here is a comparison of JISAO’s PDO index (red) with the HadCRUT3 temperature record (black):
If ocean oscillations are as powerful a climate driver as the anti-CO2 alarmists claim then this graph suggests a simple story: that cold Pacific surface waters swallowed up a big gulp of warmth from 1940-1970, which the PDO then belched back up during its warm-phase in the 80s and 90s. Without the PDO there might well not have been a 40s-70s temperature dip, making warming over the 20th century much more even.
Is the PDO really this influential, or is it largely coincidence that the PDO was in a cool phase when GMAST dipped a couple of tenths between 1940 and 1970? Without good heat content data it is very hard to gauge but logically there is no upper bound on how powerful an effect ocean oscillations can have. As Jo Nova describes meteorologist William Kininmonth’s “deep cold abyss,” the ocean depths form a great pool of “stored coldness” which is “periodically unleashed on the surface temperatures,” a slumbering dragon that with a flick of its tail can grab away large amounts of surface warmth. Thus we certainly can’t rule out that on time scales of up to decades GMAST really is dominated by ocean oscillations.
The CO2-warming theory needs to invoke ocean oscillations more than the solar theory does
Both have the same difficulty with the 40s-70s dip in temperature. For either theory to work the mid-20th century cooling pretty much has to be explained by ocean oscillations, but the CO2 theory now has to rely on the short-term dominance of ocean oscillations to explain the lack of recent warming as well.
That’s the point of Trenberth’s “missing heat,” right? By his calculations there must be lots of CO2-driven heat accumulating in the oceans. Set aside whether the real problem is with Trenberth’s measurements and calculations, the solar theory has no difficulty explaining why temperatures would be leveling off. With the sun having gone quiet this is the maximum likelihood solar projection (with cooling predicted to follow). It is the special case where GMAST actually tracks ocean heat content. Differences between GMAST and ocean heat are to be expected, but it is the CO2 theory that now needs to invoke that likely divergence from maximum liklihood.
Obviously it is not tenable to reject the ocean oscillation argument when applied to the solar theory but accept in when applied to CO2, but this is what the consensus scientists are effectively doing.
Gavin Schmidt on the asymptotic approach to equilibrium
Dr. Muscheler and I almost got to the ocean oscillations question way back in 2005, but Gavin Schmidt grabbed the hand-off. Raimund had claimed in a RealClimate post that a steady high level of forcing can’t cause warming:
Regardless of any discussion about solar irradiance in past centuries, the sunspot record and neutron monitor data (which can be compared with radionuclide records) show that solar activity has not increased since the 1950s and is therefore unlikely to be able to explain the recent warming.
I objected in the comments that:
What matters is not the trend in solar activity but the level. It does not have to KEEP going up to be a possible cause of warming. It just has to be high, and it has been since the forties.
Presumably you are looking at the modest drop in temperature in the fifties and sixties as inconsistent with a simple solar warming explanation, but it doesn’t have to be simple. Earth has heat sinks that could lead to measured effects being delayed.
Gavin Schmidt’s response was similar to Muscheler’s today, but Schmidt was explicit about what the process of equilibration should look like:
Response: You are correct in that you would expect a lag, however, the response to an increase to a steady level of forcing is a lagged increase in temperature and then a asymptotic relaxation to the eventual equilibrium. This is not what is seen. In fact, the rate of temperature increase is rising, and that is only compatible with a continuing increase in the forcing, i.e. from greenhouse gases. – gavin
Like Muscheler, Schmidt ignores the PDO. It is ocean heat content that should undergo an “asymptotic relaxation to the eventual equilibrium,” but all Schneider has to go by is GMAST, so he is implicity assuming that ocean heat content is faithfully tracked by GMAST, regardless of the fact that this relationship can be profoundly obscured by ocean oscillations.
We know that GMAST underwent a substantial mid-century gyration where 20th century warming actually reversed for a couple of decades before accelerated upwards again but we do NOT know that ocean heat content underwent any such gyration. Schmidt assumes it did but the PDO record suggests that it likely did not, in which case Schmidt’s argument that late-century warming must have been caused by CO2 collapses.
The problem is the hidden nature of these ocean-equilibration assumptions
If Schmidt and Muscheler want to dismiss a solar explanation for late 20th century warming by invoking the highly speculative assumption that GMAST is a good proxy for ocean heat content over with the 20th century, that fine. As long as this assumption is made explicit then others can evaluate it and toss any following conclusions in the trash. The problem is that the consensus scientists are not telling the public their real grounds for dismissing a solar explanation.
The consensus position, re-iterated over and over again, is a simple unqualified statement that because solar activity was not going up over the second half of the 20th century it cannot have caused warming over this period (or is unlikely to have caused warming over this period). I have collected a dozen such statements from scientific papers, news articles, and most recently from the First Order Draft of AR5.
Only when I have pressed these scientists on the irrationality of their claim that a steady high level of forcing can’t cause warming do they start hinting towards the highly speculative arguments about ocean equilibration that are the actual basis for their dismissal of the solar hypothesis. Reliance on such hidden assumptions is not science, so job one is to get these unstated assumptions out in the open where they can properly evaluated. Not surprisingly, unscrutinized assumptions do not stand up well to scrutiny, so job two is knocking ’em down.
The rapid equilibrium assumptions of Lockwood and Solanki, knocked down. The implicit assumption by Muscheler and Schmidt that GMAST should track ocean heat content with no major divergence now knocked down as well. It is a weak argument at best, requiring strong claims about matters of vast uncertainty, wrecking any pretension to have ruled out a solar driver for late 20th century warming.
Until these hidden assumptions are stated I suggest that we all take at face value the positions that these scientists actually assert. When they say that because a high level of forcing was relatively constant it is unlikely to have caused warming, we should say that they think you can’t heat a pot of water by turning the flame to maximum and leaving it there, because that is exactly what they are saying.
Then when they come back with their “what I really meant was,” we can expose their real thinking for the unexamined nonsense it is.
I have read over and over again that the Sun can’t be affecting the overall temperature of the Earth, since the TSI is “relatively constant”. After the orbiting satellites were able to measure TSI directly [above the atmosphere], we found out that the Ultraviolet energy reaching the upper atmosphere varied greatly.
Temperature is related to pressure in a gas. The faster the atoms/molecules move, and bump into each other, the higher the pressure/temperature. I would propose that the low frequency energy transfer [infrared energy] is much less efficient at altering temperature verses high frequency energy transfer [ultraviolet]. The experiment would have the same amount of energy in each case; but how efficient each frequency energy would alter the temperature of, say, ozone.
Before everyone jumps on me, note the laser. The input energy [frequency is related to energy] must exceed the threshold level of the quantum energy states of the electrons position before the electron will accept energy and change state. I would propose that the same action is having the same type of affect on the ozone molecules; therefore, the energy absorption would occur more efficiently at certain frequencies.
If the above is true, then the Sun’s ultraviolet energy would have a much greater effect on the Ozone layer than previously assumed.
Can anyone answer this question? Has a definitive experiment been completed with oxygen/ozone at rarefied pressures? Note that the typical difference between a Sunspot minimum and a Sunspot maximum is about 0.1C on overall Earth’s temperature.
I would rather have new experiments and concepts to promote scientific understanding than bickering!!
Dr. Lurtz says:
October 20, 2012 at 8:00 am
Can anyone answer this question? Has a definitive experiment been completed with oxygen/ozone at rarefied pressures? Note that the typical difference between a Sunspot minimum and a Sunspot maximum is about 0.1C on overall Earth’s temperature.
The action of UV on ozone is know to vary at different altitudes/pressures, though it’s all poorly understood as ye,t so far as I know.
Although the effect of the solar cycle appears to be around 0.1C when you smooth the temperature record at an appropriate period (37 months) to reveal it, this is misleading. That’s because big El Nino’s tend to start at solar minimum, and are often followed by a La Nina rebound near solar maximum. This anti-phase relation with the solar cycle flattens the apparent climate response in smoothed plots. Also consider that a lot of the energy pushed into the ocean when the Sun is active gets stored in the Pacific Warm Pool where it is hidden from the surface record, before it re=appears in the El Nino which depletes the OHC for a while.
In defense of Muscheler, you first quote him correctly:
“therefore, it is unlikely that solar activity (whatever process) was involved in causing the warming since 1970.”
then insist that “Raimund Muscheler says that a steady high level of forcing can’t cause warming“.
He correctly denies saying this…as he did not say so. At least not in sentence you quote. He said what he said-> “it is unlikely that solar activity was involved in causing the warming since 1970”.
I’m sure he would be satisfied if you changed your title to say:
Raimund Muscheler says that it is unlikely that solar activity was involved in causing the warming since 1970.
When you use the word “says” you are implying that you are quoting someone. But in this case, you are not, you are drawing an inference. You might get away with “Raimund Muscheler implies that a steady high level of forcing can’t cause warming“, or “suggests” , or “in effect says”….
Proper use of language is important –> improper use, particularly when there arises an appearance of misquoting another colleague, leads to bickering.
Leif Svalgaard, thanks for the document.
Most of the above bickering is way over my head.But the mark of a true expert is the ability to explain to a 12 year old the essence of their expertise, what I got from the bickering was 1 Time to read Bob Tisdales book again,2 Alex Rawls is onto something,a provocative argument at least.Which has inflamed some egos.The key is unstated assumptions, climate science is being greeted with derision by the public, maybe its time for a few, we do not knows and its possible we are wrong, because the arrogance and authority memes are not working.I look forward to more rational debate on the state of our knowledge, our assumptions and natures cycles.
“I am saying it is totally inadequate to do much else the speculate and overly generalize.”
Precisely seems we humans are only able to understand an issue with 2,3,4 max inputs and need to have a main culpable. Worse we try to reduce everything to it.
Maybe it has to do with religion, sacrifices to gods …
Leif Svalgaard:
begin quote
Alec Rawls says:
October 19, 2012 at 4:35 pm
But he did not want to walk back his dismissal of the solar explanation. He wanted to re-argue it and re-affirm it.
and he did with verve and strength.
end quote
Let me add my opinion to those who agree that Rawls interpreted Muscheler correctly. Aside from the fact that words aren’t perfect, Muscheler strongly asserts that a steady solar insolation can’t produce a rising temperature.
Leif Svalgaard’s argument, as I understand it, is that with the most recent and reliable reconstructions of the history of solar activity, temperature change and solar activity are almost perfectly uncorrelated over a time span of 300 years, and the association apparent in Alec Rawls’ graph only appears in the 20th century. That is, a claim of a causal relationship is disconfirmed by the complete data.
tallbloke: “Each of us must decide on the right balance between honesty and effectiveness”
-Stephen H Schneider-
He was wrong. You should never sacrifice honesty. Pragmatically, if it becomes known that you have sacrificed honesty, or even are willing to, then you lose effectiveness.
Richard M on how the mostly high levels of solar activity since the Maunder minimum could have successively warmed each succeeding century:
Unfortunately, Leif does not actually seem to believe that continued high levels of forcing can cause continued warming, since he rejects a solar explanation for late 20th century warming on the grounds that:
I find this very strange, since at my strenuous urging I finally got him to agree that one can indeed heat a pot of water by turning the flame to maximum and leaving it there. Leif, showing his scientific mettle, even calls this the “best” way to heat water, and I agree with you Leif, I AGREE.
But when the “pot of water” is the earth Leif backtracks. I put his inconsistency to him directly. If he acknowledges that the water in the pot on his stove is hotter after it has been sitting over the high flame for a couple of minutes than when he first put it on, then:
His answer: “simply because like effects come from like causes.” If the high sun caused it to be warm in the late 20th century, he is saying, then the planet would have been warm when the sun was high earlier. Or equivalently, if it was the high flame that caused his pot of water to be hot after a couple of minutes, then it would have caused his water to be hot when he first put it on.
The element he fails to take into account in the case of the planet is of course HISTORY, as recorded in the state of the ocean heat sink. I have been urging Leif for a couple of years now that he needs to account for the hysteresis of the oceans but Leif has a strict policy of never learning anything from anybody so here we are. Leif is the jolly bad Santa, with a lump of coal for everybody. Like Richard, I too don’t think that Leif and I actually have much to disagree about, but his fantastic obstreperousness will never let him admit it. Kind of grows on you after a while.
Have a good trip to Oslo Leif!
Alec Rawls: The element he fails to take into account in the case of the planet is of course HISTORY, as recorded in the state of the ocean heat sink.
This sounds like special pleading. Do you have (does anyone have), time series of the state of the ocean heat sink, global mean temperature, and solar activity, over a span of 3 centuries?
Matthew R Marler says: October 20, 2012 at 10:34 am
That is, a claim of a causal relationship is disconfirmed by the complete data.
Not entirely.
The North hemisphere temperature record since 1880 is accepted as a relatively reliable. It can be split into two simple components made of an inclining linear trend and the residual which could be associated with natural variability from one or more sources.
Simple calculation shows that this residual oscillating component (it very closely matches the AMO with amplitude excursion of ~0.6C) is directly related to the sunspot cycles for the period:
http://www.vukcevic.talktalk.net/GSC1.htm
On the other hand there is close correlation between the N.A. SST (AMO) and global temperatures for period 1880-2010, with a single exception at 1969-70 when there is an inexplicable drop in the AMO of 0.325C, and than trends continue on a parallel up-slope.
Se top graph in :
http://www.vukcevic.talktalk.net/NAP-SST.htm
Why this difference it is not clear, it could be due to global data ‘homogenization’, on the other hand geological data from the N. Atlantic show close correlation to average movement of the N.A. SST (see second graph in the above link).
Now it can be also shown that there is also reasonable correlation between the sunspot records and the N.A. geological data going back to 1650
http://www.vukcevic.talktalk.net/SSN-NAP.htm
Therefore one could be led to conclude that the N.A. SST (and the global temperatures before 1969) are correlated to the solar activity.
There is no absolute certainty in the climate science, but having above in mind balance of probability is that the global temperature variability to the great extent is caused by the solar activity.
You may not accept any of the above, if you think you know better, I bring it to the inquisitive readers’ attention to consider at least as a thought provoking, which is only first step in a aspiration to find out more.
Among some (not all) AGW devotees it has been notable absence of any aspiration to find out more.
Matthew R Marler
How about 8 centuries?
http://virakkraft.com/Steinhilber-TSI-%20Mann08-temp.png
Because of the heat capacity you have to use integrals, as Alec has explained a dozen times.
On a decadal scale the Pacific oscillation is stronger, and again of course you have to think integrals. http://virakkraft.com/PDO-integral-Hadcrut4.png
Don’t bother Alec. Certain people have decided not to understand this because they can’t find it in their centuries old text books.
lgl says:
October 20, 2012 at 12:42 pm
How about 8 centuries?
http://virakkraft.com/Steinhilber-TSI-%20Mann08-temp.png
Love it. Stitch that Michael.
Very interesting integration of Steinhilber’s TSI reconstuction linked by lgl. Any info on where this comes from and how it was calculated? In addition to the scaling it seems that the fit would have to have been optimized by the choice of a zero point, above which solar activity is modeled as adding heat to the oceans and below which the oceans are seen as cooling. I’d be interested to see the details.
Marler asks:
Just because we don’t have any direct measurements of ocean heat content over this period doesn’t mean we can ignore the hysteresis of the oceans, as Leif does. Is Marler with Leif on that? Does he think that if the sun was responsible for late 20th century warming then the planet would have been the same temperature when the sun was previously at similar levels, regardless of the state of the ocean heat sink? Pretty wacky.
Alec Rawls says:
October 20, 2012 at 1:46 pm
In addition to the scaling it seems that the fit would have to have been optimized by the choice of a zero point, above which solar activity is modeled as adding heat to the oceans and below which the oceans are seen as cooling. I’d be interested to see the details.
Hi Alec. Did you see the comment i addressed to you at
tallbloke says:
October 19, 2012 at 11:39 pm
I’d appreciate you input.
Thanks
TB
From vukcevic on October 20, 2012 at 6:23 am:
Which leads to a graph of sunspot number and something called “North Atlantic Precursor”.
Tracking that down lead to your page:
http://www.vukcevic.talktalk.net/NAO-.htm
So your “strong correlation” is between SSN and some dataset of your own creation of unknown derivation that is somehow related to the North Atlantic Oscillation but preceding it by about 9 years.
Okay. I grabbed the International SSN (monthly plot data) and the NAO Index (Historical Index, monthly), crammed them in a spreadsheet. The NAO data only goes from 1950 so the Leif et al pre-1946 SSN correction didn’t apply.
As recommended for solar research, I used the 12-month moving average smoothing of the SSN.
Time passed, numbers were played with as years were shifted. Finally to make sense of the graph with the noisy NAO data, I applied a matching 12-month smoothing to the monthly NAO data.
And saw how the NAO varies many times during a solar cycle, with no discernible pattern.
I have no idea how you cook up your “secret recipe” NAP. But I can tell the SSN and the NAO are not related. You are claiming your NAP and SSN are strongly correlated, while hinting your NAP and the NAO are somehow related.
Therefore I must conclude it is most likely your “strong correlation” comes from incorporating something else you find “strongly correlated” to SSN into your NAP, that does not show up in the NAO. It’s the only logical conclusion I can draw at this point.
kadaka (KD Knoebel) says:
October 20, 2012 at 1:54 pm
……..
Hi,
I do appreciate you taking some interest, it is far more than many do, and it is usual grief from Dr. LS. that discourages all but the bravest.
NAP; data was offered to Dr. Svalgaard to forward to the Stamford’s geological department with a view of some cooperation for a finalization. He declined. Data is related to geological records of the part of Greenland –Scotland ridge, which is controlling the Atlantic inflow and Arctic outflow. Data is available, but dispersed in numerous sources, took some time to assembly and see no reason why should be given away to just anyone.
NAO as the air pressure index is highly volatile, so you need to take longer average, in the article http://www.vukcevic.talktalk.net/NAOn.htm (one but last illustration) it is clearly marked as 11 year average.
Why 9 year advance? not entirely clear, but since it is the north leg of the NAO (Icelandic pressure) that is determinant, it presumably takes some years for the warm atlantic currents to reach the Arctic and return as cold currents via Denmark Strait (Icelandic pressure) and few more years to loop into the subpolar gyre to initiate AMO oscillation
http://www.divediscover.whoi.edu/arctic/images/ArcticCurrents-labels.jpg
Hence in order of occurrence NAP>NAO>AMO (refer to http://www.vukcevic.talktalk.net/NAOn.htm one but last illustration)
Just as a reminder compare NAP waveform with the CET spectrum components (1660-2021) http://www.vukcevic.talktalk.net/CET-NV.htm
I hope some of the above helps, but if not than your ‘how you cook up your “secret recipe” NAP misgiving is by far safer than accepting ‘blanco’ assurance.
correction :CET spectrum components (1660-2011)
Alec
There’s a Steinhilber.xls at http://www.leif.org/research/files.htm
“optimized ” – well, I like “using pre-industrial time as the verification period” better, and then you have to set the long term HMF average to around 5.
There’s a serious misunderstanding &/or misinterpretation of Jean Dickey (NASA JPL) above.
Clarification:
A 3-century-old modeling assumption which is supported by not so much as a single observation has been overthrown:
http://i46.tinypic.com/303ipeo.png
+
http://i49.tinypic.com/wwdwy8.png
=
http://i48.tinypic.com/2v14sc5.gif
(slow animation of preceding pair)
–
lgl: Thanks for stopping by.
Alec Rawls: Just because we don’t have any direct measurements of ocean heat content over this period doesn’t mean we can ignore the hysteresis of the oceans, as Leif does.
It means that we can not say anything in particular about the ocean heat content. Using the late 20th century solar activity/earth temp time series, we can estimate a relationship between solar activity and temperature change; using that and past records, we can infer/impute a time series of ohc values. Such a procedure might yield testable hypotheses of what sorts of past ocean temperature series would result if we figured out ways to estimate them — and those might agree with the computed estimates. That it could be done does not prove that Leif is wrong, only that it’s non-parsimonious to conclude that he’s wrong. That it could be done does not establish that Alex is correct, though he could be — but the unknown history of ohc has to be just right.
Alec quotes
I am sure that you are aware of the fact that the title is wrong. I never said that steady high levels of forcing can’t cause warming.
———–
Alec is ignoring what someone says, makes up a non equivalent statement he calls a paraphrase, and claims this is what the other person means, even after the other person makes it very, very clear they didn’t say or mean that. Great one Alec.
Alec just makes up to much stuff. He does a lot of hand waving about the dynamics of heat transfer in the ocean. Has he actually done any calculations himself? Personally I don’t understand something properly until i have done the sums or written a computer program to do the sums for me.
Hi Tallbloke: Thanks for pointing out your earlier comment. Interesting AMO findings, and I like the ssn integration as a way of including solar effects. Allows you to keep track of impact on ocean heat content.
When I saw the STI integration graph I was wondering if it might have come from you. I thought I remembered you having done something like that before. It’s a useful exercise. Ideally the zero point would be modulated by ocean heat content and/or ssts, since it is the comparison between energy into the oceans vs. energy radiated back out that determines warming or cooling, but we don’t have much historical ohc or sst data so a fixed zero point would seem to be the best that can be done.