Guest Post by Willis Eschenbach
I’ve argued in a variety of posts that the usual canonical estimate of climate sensitivity, which is 3°C of warming for a doubling of CO2, is an order of magnitude too large. Today, at the urging of Steven Mosher in a thread on Lucia Liljegren’s excellent blog “The Blackboard”, I’ve taken a deeper look at the Berkeley Earth Surface Temperature (BEST) volcano forcings. It’s a curious tale, with an even more curious outcome. Here’s the graph in question:
Figure 1. BEST comparison of hindcast temperature changes due to CO2 plus volcanoes (heavy black line) with the BEST temperature data (light black lines). SOURCE
I asked Steven Mosher where the BEST folks got the data on the temperature change expected from volcanic forcing as shown in the heavy black line above … no reply. Setting that question aside, I decided to just use the data I had. So … I did what I usually do. I digitized their figure, since their underlying data wasn’t readily available. That allowed me to analyze their data, which revealed a very odd thing.
Their explanation of the black line in Figure 1 above (their Figure 5) is as follows:
A linear combination of volcanic sulfates and CO2 changes were fit to the land-surface temperature history to produce Figure 5. As we will describe in a moment, the addition of a solar activity proxy did not significantly improve the fit. The large negative excursions are associated with volcanic sulfate emissions, with the four largest eruptions having all occurred pre-1850; thus our extension to the pre-1850 data proved useful for the observation of these events. To perform the fit, we adjusted the sulfate record by applying an exponential decay with a two year half-life following emission. The choice of two-years was motivated by maximizing the fit, and is considerably longer than the 4-8 month half-life observed for sulfate total mass in the atmosphere (but plausible for reflectivity which depends on area not volume).
OK, that makes me nervous … they have used a linear regression fit to the temperature record of the lagged exponential decay, with a separately fitted time constant, of an estimate of volcanic sulfate emissions based on ice cores … OK, I’ll buy that, but at a discount. They are using the emissions from here, but although I can get close to the figure above, I cannot replicate it exactly.
I wanted to extract the volcanic data. My plan of attack was as follows. First, I would digitize the heavy black line from Figure 1 above. Then I’d match it up with the logarithm of the CO increase since 1750. Once I subtracted out the CO2 increase, the remainder would be the hindcast change in temperature resulting from the volcanic eruptions alone.
Figure 2 shows the first part of the calculation, the digitized black line from Figure 1 (CO2 + volcanoes) with the log CO2 overlaid on it in red.
Figure 2. The black line is the digitized black line from Figure 1. The red line is three times the log (base 2) of the change in CO2 plus an offset. CO2 data is from Law Dome ice cores 1750-1950, and from Mauna Loa thereafter.
I fit the CO2 curve to the data by hand and by eye, by manually adjusting the slope and the intercept of the regression, because standard regression methods don’t fit it to the top of the black line. A couple of things indicated to me that I was on the right track. First is the good fit of the log of the CO2 data to the BEST data. The second is that it turned out that the best fit is when using the standard climate sensitivity of 3°C for a doubling of CO2. Encouraged, I pressed on.
Subtracting the volcanic data from the CO2 data gives us the temperature change expected from volcanoes, as shown in Figure 3.
Figure 3. Volcanic temperature changes (cooling after eruptions) as hindcast by BEST (black line), and as fit from the lagged emissions as described in their citation above (red line).
Note that as I mentioned above, I can get close to the temperature changes they hindcast (black line) using a lagged version of their sulfate data as they described (red line), but the match is not exact. Since the black line is what they show in Figure 1 above, and the differences are minor, I’ll continue to use the heavy black line.
Now, let’s pause here for a moment and consider what they have done, and what they have not done. What they have done is converted changes in atmospheric CO2 forcing in watts per square metre (W/m2) to a hindcast temperature change (in degrees C). They did this conversion by using the standard climate sensitivity of 3°C of warming for each doubling of CO2 (doubling gives an additional 3.7 W/m2).
They have also converted stratospheric injections of volcanic sulfates (in Teragrams) to a hindcast temperature change (in degrees C). They have done this by brute force, using a lagged model of the results of the stratospheric sulfate injections which is fit to the temperature.
But what they haven’t done, as far as I could find, is to calculate the forcing due to the volcanic eruptions (in W/m2). They just fitted the sulfate data directly to the temperature data and skipped the intermediate step. Without knowing the forcing due to the eruptions, I couldn’t estimate what climate sensitivity they had used to calculate the temperature response to the volcanic eruptions.
However, there’s more than one way to skin a cat. The NASA GISS folks have an estimate of the volcanic forcing (in W/m2, column headed “StratAer” for stratospheric aerosols from volcanoes). So to investigate BEST’s climate sensitivity, I used the GISS volcanic forcings. They only cover the period 1880—2000, but I could still use them to estimate the climate sensitivity that BEST had used for the volcanic forcings. And that’s where I found the curious part. Figure 4 shows the volcanic forcing in W/m2 from NASA GISS, along with the BEST hindcast temperature response from that forcing.
Figure 4. Black line shows the BEST hindcast temperature anomaly (cooling) from the eruptions. Red line is the change in forcing, in watts per square metre (W/m2), from the eruptions. Green line shows the best fit theoretical cooling resulting from the GISS forcing. Note the different time period from the preceding figures.
As you can see, the regression (green line) of the GISS forcing gives a reasonable approximation of the BEST temperature anomaly, so again we’re on the right track. The curious part is the relative sizes. The change in temperature is just under a tenth of the change in forcing (0.08°C per W/m2).
This equates to a climate sensitivity of about 0.3°C per doubling of CO2 (0.08°C/W/m2 times 3.7 W/m2/doubling = 0.3°C/doubling)… which is a tenth of the canonical figure of three degrees per doubling of CO2.
So in their graph, in the heavy black line they have combined a climate sensitivity of 3°C per doubling for the CO2 portion, with a climate sensitivity of only 0.3°C per doubling for the volcanic portion …
Now this is indeed an odd result. There are several possible ways to explain this finding of a climate sensitivity of 0.3°C per doubling. Here are the possibilities
1. The NASA GISS folks have overestimated the forcing due to volcanoes by a factor of ten, a full order of magnitude. Possible, but very doubtful. The reduction in clear-sky sunlight following volcanic eruptions has been studied at length. We have a pretty good idea of the loss in incoming energy. We might be wrong by a factor of two, but not by a factor of ten.
2. The BEST temperature data underestimates the variation in temperature following volcanic eruptions by a full order of magnitude. Even more doubtful. The BEST temperature data is not perfect, but it is arguably the best we got.
3. The BEST data and the NASA data are both wrong, but providentially they are each wrong in the right direction to cancel each other out and give a sensitivity of three degrees per doubling. Odds are thin on that happening by chance, plus the reasons above still apply.
4. Both the NASA and BEST data are roughly correct, and the climate sensitivity actually is on the order of a tenth of what is claimed.
Me, I go for door number four, small climate sensitivity. I say the climate is buffered by a variety of homeostatic mechanisms that tend to minimize the temperature effects of changes in the forcing, as I have discussed at length in a variety of posts.
However, as always, alternative hypotheses are welcome.
Regards to everyone,
w.
DATA: I did this on an excel spreadsheet, which is here. While it is not user-friendly, I don’t think it is actively user-aggressive … the BEST temperature data on that spreadsheet is from here. Note that curiously, the BEST folks have not removed all of the annual cycle from their temperature data, there remains about a full degree of annual swing … go figure.
[UPDATE] Richard Telford in the comments points out that what I have calculated is the instantaneous sensitivity, and he is correct.
However, as I showed in “Time Lags in the Climate System“, in a system that is driven cyclically and that picks up and loses heat via exponential gain and decay, the instantaneous sensitivity is related to the longer-term sensitivity by the relationship
where t1 is the lag, t is the length of the cycle, and s2/s1 is the size of the reduction in amplitude. Since in this case we are dealing with the BEST land-only temperatures, where the lag is short (less than a month on average) that means that the short-term sensitivity is about 64% of the longer-term sensitivity. This would make the longer-term sensitivity about 0.46°C per doubling of CO2. This is still far, far below the usual estimate of 3°C per doubling.
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Jose says:
August 13, 2012 at 7:20 am
Depends among other things on the type and size of the aerosol, whether it is water-soluble, and whether it is injected into the stratosphere or not.
No exact answer can be given, since it will approach equilibrium gradually, and it never “arrives”.
It doesn’t take that long for land to respond to increased forcing. The thermal lag in the annual cycle (the time between the summer solstice and the warmest time of the year) is under a month for the earth’s land surface.
Finally, since the warming to equilibrium is exponential, we see the largest effect of the warming right away, and it then warms at a slower and slower rate into the future. This means that it gets near to equilibrium quickly.
I have 700 papers that mention the term here on my computer. I can’t say I’ve pored over them all, but I have scanned them all, read most of them, and pored over and revisited many of them.
And you? Roughly how many scientific papers which make estimates of the climate sensitivity have you read?
Here’s the thing, Jose. It doesn’t matter how many I’ve read. All that matters is whether my ideas are true and valid. That’s all that counts. And yes … in addition to having interesting and perhaps valid ideas, I have also done my homework.
All the best,
w.
Bob Tisdale says:
August 13, 2012 at 7:24 am
Willis: In your past posts about volcanoes, have you looked at the response of Land+Sea Surface Temperature data, like GISS LOTI, to the Mount Pinatubo eruption? If so, what was the maximum initial temperature drop that you found for it?
Thanks, Bob. See my posts “Prediction is hard, especially of the future“, and “Pinatubo and the Albedo Thermostat“.
w.
Some updated data showing Berkeley versus Total Solar Irradiance back to 1753.
Not a close link but I note that Berkeley’s algorithm probably overstates the real warming trend by about 35% (based on numerous comparisons with other known temperature datasets which indicates that Berkeley’s record splitting algorithm probably favors breakpoints that go down versus breakpoints that go up).
http://s10.postimage.org/f2qsk2nqx/Berkeley_TSI_1753.png
Mr. Eschenbach’s assertion that the climate sensitivity is “a tenth of the canonical figure of three degrees per doubling of CO2” runs a foul of the scientific illegitimacy of the contention that the climate system has a “climate sensitivity” as a property.
By definition, the “climate sensitivity” is the ratio of the change in the spatially averaged equilibrium surface air temperature to the change in the logarithm to the base 2 of the CO2 concentration. The equilibrium temperature is not an observable and it follows that when folks, including Mr. Eschenbach, speculate about the numerical value of the climate sensitivity, these speculations are insusceptible to being refuted by reference to measurements of the (unobservable) equilibrium surface air temperature.
willis the data is cited in the paper with a url as many people explained to you
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/climate_forcing/volcanic_aerosols/gao2008ivi2/ivi2totalloading501-2000.txt
And the other dataset used per Gao’s instructions is here
http://data.giss.nasa.gov/modelforce/strataer/
“I have 700 papers that mention the term here on my computer.”
Willis, that argument appears to be the key one in this post-normal science. Academics no longer argue from the evidence, instead they argue from the count of papers as if it had any meaning at all in science.
In other words, it’s a lemming approach … all the other idiots believe the way forward is over the cliff so …. they too must be stupid and jump over the cliff.
Philip Bradley says:
“And I am sceptical of the effects of the Laki eruption. Laki was an effusive eruption and unlike Plinian eruptions didn’t inject sulphates into the stratosphere.”
The Laki eruption in 1783 is the only large scale fissure eruption that has occurred on Earth in historical times. That means that we have no data to compare it with so as to how effective such eruptions are in injecting materials into the stratosphere. However to call it “effusive” is perhaps a bit tame. Icelandic sources describe lava fountains reaching a height of a kilometer or more, and the extreme rate of lava discharge would have caused convection more than sufficient to carry part of the SO2 into the lower stratosphere (even thunderstorms can do that).
Contemporary sources makes it very clear that the eruption had extreme atmospheric effects both in the near and far field. I tend to believe those sources more than current speculation.
Terry Oldberg:
At August 13, 2012 at 8:34 pm you say
Please explain why you think the “equilibrium surface temperature” needs to be known – or is relevant – to refutation of an estimate or a speculation of climate sensitivity.
Richard
richardscourtney:
Thank you for giving me the opportunity to clarify. The climate sensitivity (aka equilibrium climate sensitivity) is the proportionality constant in an equation that maps the change in the atmospheric CO2 concentration to the change in the logarithm to the base 2 of the spatially averaged equilibrium surface air temperature. When it is asserted that the climate sensitivity has a particular numerical value (e.g. 3 Celsius per doubling of the CO2 concentration), this assertion is insusceptible to refutation because the equilibrium temperature (aka steady-state temperature) is not an observable feature of the real world.
As assertions of numerical values for the climate sensitivity are insusceptible to refutation, a science of climate change cannot be built around them. On the other hand, spatially averaged surface air temperatures are an observable feature of the real world and thus a science of climate change could be built around them. This science would have as components: 1) a theory 2) conditional predictions by this theory of the spatially averaged surface air temperatures in the events forming a specified statistical population and 3) validation of this theory in a sampling of events drawn from this population and observed. A consequence from methodological blunders on the part of professional climatologists is for none of these components to currently exist. After decades of work and the expenditure of more than 100 billion US$ on research, we have no science of climate change and this is true even though many professional climatologists insist that one exists.
Willis Eschenbach: “in a system that is driven cyclically, the instantaneous sensitivity is related to the longer-term sensitivity by . . . ”
Could you expand on how you apply to the problem at hand the equation you thereupon set forth? More specifically:
Willis Eschenbach: “Since in this case we are dealing with the BEST land-only temperatures, where the lag is short (less than a month on average) that means that the short-term sensitivity is about 64% of the final sensitivity.”
Could you explain how you plug “short (less than a month on average)” into that equation? The equation you’re applying deals with diffusion phenomena, and it relates the time lags between sinusoidal variations at different diffusion depths to those variations’ amplitudes (and the variations’ periods). My difficulty is identifying the cyclical signal. In infer from your “64%” that you observe a phase lag that is -0.159 log(0.64) = 7.1% of the cyclical signal’s period. It would be helpful if you could identify the cyclical signal, period, and lag you used. If you could be explicit about where you see an analog to diffusion depth, that, too, would be helpful.
Mosh, still doesn’t mean squat if the model isn’t tested. Calibration and training periods? Ever heard of them? I know you have, since you discussed them at length on Steve MacIntyre’s blog years ago.
Highflight56433 asks about atmospheric density and composition. Atmospheric density increase will result in an increase in temperature, as per the combined gas laws, regardless of composition. As to the greenhouse experiment with differing concentrations of CO2, I have not seen the results of any experiment along this track but would bet on no temperature difference assuming the same inputs. Anthony Watts experiment was similar, but the CO2 concentrations were not accurately known, but showed no temperature difference to a lower temperature in the vessel with the higher CO2 concentration. To my knowledge he has not repeated this with higher accuracy but time will tell.
Again, I don’t get the point of this article…the climate sensitivity is quite different whether the external forcing is a doubling of co2 or volcanic aerosols, so the comparison cannot be done like this…
JJ:
At August 14, 2012 at 2:29 am
the climate sensitivity is quite different whether the external forcing is a doubling of co2 or volcanic aerosols,
Richard
IS THE NON-FEEDBACK CLIMATE SENSITIVITY 1.2 OR 0.6 DEG C?
Using the Stefan-Boltzmann equation
Q = kT^4 (Equation 1)
Where Q is the radiation energy emitted by the surface of the earth and k = 5.67 x 10^(-8) W/(m^2 K^4)
Differentiating Equation 1 with respect to T gives:
dQ/dT = 4kT^3 = 4*(kT^4)/T = 4Q/T (Equation 2)
Taking the reciprocal of the above equation gives:
dT/dQ = T/(4Q) (Equation 3)
From the above equation, the small change in global mean temperature dT as a result of change in the emitted radiation energy dQ by the globe may be calculated using the equation:
dT = T*dQ/(4Q) (Equation 4)
At equilibrium condition, the radiation energy Q emitted by the earth is assumed to be equal to the solar energy absorbed at the earth’s surface:
Q = (1-a)Sp/2 (Equation 5)
In this equation, Sp is the solar constant of 1370 W/m^2 at the mean distance of the earth from the sun distributed on its projected area Ap = Pi*r^2. Instead of the projected area, the solar energy from the sun is actually distribute around half of the spherical surface area As = 2*Pi*r^2. As a result, the solar energy distributed around half of the spherical surface area is given by Ss = Sp* Pi*r^2/(2*Pi*r^2) = Sp/2. The solar energy Ss does not reach the surface of the earth because part of it given by a*Ss is reflected by the atmosphere, where “a” is the albedo of the atmosphere. Therefore, the solar energy that reaches the surface of the earth is Ss-a*Ss = (1-a)Ss = (1-a)Sp/2.
Equation 5 could also be written as:
4Q = 2*(1-a)Sp (Equation 6)
Substituting Equation 6 into 4 gives:
dT = T*dQ/(2*(1-a)*Sp) (Equation 7)
The increase in forcing for doubling of CO2 is estimated to be dQ = 4 W/m^2. The global mean temperature is T = 288 K, the earth’s albedo is a = 0.3 and the solar constant Sp = 1370 W/m^2. Substituting these values into Equation 7 gives an estimate for the non-feed back climate sensitivity:
dT = 288*4/(2*(1-0.3)*1370) = 288*4/(2*0.7*1370) = 0.6
This means that the non-feed back climate sensitivity of the earth is 0.6 deg C for doubling of CO2.
Do you agree?
JJ: the climate sensitivity is quite different whether the external forcing is a doubling of co2 or volcanic aerosols,
richardscourtney says:
Really?! Please explain why.
Come now Richard, isn’t it obvious? The noxious gases, particulates, etc. from volcanoes are natural and therefore good, whereas CO2-plant food is man-made and therefore bad.
Let’s not forget that there are volcanoes… and there are volcanoes… There are many different types of eruptions depending on the volcano’s geology. They’re all different. And then there are all of the undersea volcanoes – who knows how many there are of those? Volcanoes are erupting somewhere all the time.
Why does volcanic forcing in W/m2 have such a small impact compared to GHG forcing in the same W/m2.
Willis notes that the climate adjusts to offset some/most of the forcing. The climate models also had built in some of this dampening effect initially and then they lowered it even further through an “efficiency factor” when it was realized the impact was even less than dampened impact.
Okay, so volcanoes have less impact than one would initially assume given the reduction in solar energy reaching the Earth’s surface in W/m2. The climate models have been downscaled to simulate the actual impact versus the theoritical impact. Berkeley changed it to 1.5C per Tg of Sulfate emission (and this is still too high given the sulfate dataset they used is poor and they did compare it to the high resolution temperature data but rather eye-balled it, it seems).
So, what faith do we then place in the temperature impact per W/m2 of GHG forcing. Why are we still stuck at 0.8C/W/m2 when it is starting to look every day like this is off by a factor of at least 2 (just like the volcanic forcing was off by a factor of 7 to 10).
Willis:
I don’t think you have showed anything new here from what you did with the seasonal cycle stuff you were looking at. What you are showing is that if you assume the climate system is well-modeled as having a single time constant and that said time constant is short then you indeed get very low estimates for the climate sensitivity.
However, you haven’t provided any evidence that the climate system is in fact well-modeled by having a single time constant and that said time constant is short and, in fact, this contradicts a lot of what is currently understood about the climate system.
Girma says:
You have two major errors here:
(1) The average intensity of solar radiation to use is not Sp/2; it is Sp/4. This is because the sun intercepts an amount of power equal to Sp*(Pi*r^2) but radiates at the rate given by the Stefan-Boltzmann Equation over the entire 4*Pi*r^2 area of its surface. There is a factor of 4 difference between Pi*r^2 and 4*pi*r^2.
(2) The correct temperature to use for the Earth is the effective radiating temperature of 255 K.
If you correct these two errors, you get about 1.06 C, which is basically the accepted value. (There is a slight correction for the fact that the warming is non-uniform, which raises the best estimate of the no-feedback sensitivity to about 1.2 C.)
Steven Mosher says:
August 13, 2012 at 8:48 pm
Steven Mosher says:
August 13, 2012 at 8:53 pm (Edit)
I cited and talked about both of those datasets above in the head post and in the comments. Do try to keep up with the discussion.
w.
Joe Born says:
August 14, 2012 at 1:42 am
Thanks as always for your questions, Joe. We have a system where the earth both absorbs and loses energy on a cyclical basis. The result of this is that the peak temperature lags the peak insolation. In such a system, the longer the lag, the less the system heats up or cools down. This makes intuitive sense, as something that warms and cools faster will get hotter (and colder) when driven cyclically than something that warms and cools more slowly.
As you point out, volcanoes are not a cyclical phenomenon … but they are an approximately half-wave driving cycle, so we can use the same relationship. The question then becomes, how long is the cycle? I have made the most conservative estimate, that the cycle is a year and the half-cycle is six months, based on the observations of volcanic dust. As the BEST folks say, they discuss the “4-8 month half-life observed for sulfate total mass in the atmosphere”, so six months for the half-cycle is a reasonable estimate.
So what I have done is an estimate based on the known response time of the land to an approximately one-year cycle. I’ve done those calculations on a 1°x1° gridcell basis for a paper that I’m writing up for the journals. Although there are variations, the land of the planet has about a 0.8 – 0.9 month lag time with respect to the driving solar forcing, with the peak at 0.86.
As you have pointed out, this is all in the nature of an estimate … but that’s all we have. For example, the BEST forcing is an estimate as well, where they use a 2-year half-life for the stratospheric particles. Since my final climate sensitivity would be less if I assumed a two-year effective cycle for the volcanic forcing, I have made the conservative choice of one year.
All the best,
w.
Terry Oldberg:
Sincere thanks for your answer to my request for clarification which you provide at August 14, 2012 at 8:42 am.
Firstly, I say that I strongly agree with you when you say
Indeed, I go further in that I say a science of climate change will not be evinced until climate science stops the pseudoscientific search for confirmation of AGW and returns to scientific study of climate mechanisms.
That said, I return to the subject of climate sensitivity.
It is quite possible that the hypothesis of radiative forcing driving climate change(s) is plain wrong: I have explained this repeatedly including on WUWT. However, in the context of this thread, that radiative forcing hypothesis is taken as a given. Therefore, I am assuming it is true for the purpose of this discussion.
An observation of a change of known magnitude to radiative forcing can be compared to subsequent change to global temperature. This shows the ‘climate sensitivity’ of the cause of the change to radiative forcing. Indeed, Willis explains how he did this in the estimate he reports in his above article. He says:
etc.
The estimate will a variety of sources of error (any estimate of anything does). In this case, a major potential source of error is the time period chosen for completion of the effect of the change to radiative forcing. In reality the effect will never complete because it will continue to reduce at decaying rate of reduction towards equilibrium. And circumstances will change with time (to create a different equilibrium) so the effect will not achieve true equilibrium.
However, when the effect has reduced to a sufficiently small value (relative to errors in the estimate) then the effect can be assumed to have completed for practical purposes. Hence, the need to choose an appropriate time period for assumed effective completion (Willis says – and explains why – he chose a period of 6 months in his analysis).
The important point is that the true equilibrium is not relevant: only selection of the appropriate time period for effective equilibrium is need. There is a caveat to this in that more than one equilibrium condition may exist (e.g. an equilibrium over land and a different equilibrium over oceans). Indeed, in this thread Joel Shore has asserted that two time constants are needed because of this caveat. However, this is not true if an appropriate time period for all the equilibria is used.
So, when you said at August 13, 2012 at 8:34 pm
I asked August 14, 2012 at 1:16 am
I am grateful for your reply to that question at August 14, 2012 at 8:42 am and which I am now answering. However, it does not resolve my failure to understand your point.
Your reply says
As I have said, I agree we need a science of climate change, but I fail to see how that is relevant to your point which I queried.
In this response I have tried to explain why I have difficulty understanding why knowing climate equilibrium state is relevant to the validity of climate sensitivity issues. And I regret that your answer to my question has not reduced my difficulty.
Richard
richardscourtney:
Ambiguity of reference by the term “climate sensitivity” (CS) to the associated ideas may be muddying the waters. I’ve used the term in reference to the change in the global equilibrium temperature from a specified change in the logarithm to the base 2 of the CO2 concentration (e.g., 3 Celsius per CO2 doubling). My conclusion of an insusceptibility to refutation seems to me to follow from this definition of the CS, for the magnitude of the CS is a function of the equilibrium temperature and this quantity is not observable. Do we agree on this?
‘Not concluded reading the post yet Willis but looking forward to it as i do with many of your posts. The early thing that struck me was Mosher not forthcoming with information? That seems odd given his proclivity for hounding others for data.
( as usual my full name available privately if required by anyone, I prefer a nickname, it’s been with me a looong time.)”
That would be for a couple reasons.
1. The core data is clearly linked to in the paper with the URL. read the footnotes.
2. we had to supplement that data with data from Sato as we discussed previously on Lucia’s
so I am bring it up at todays meeting to see if I can get a consolidated final file for folks.
I volunteer one day a week, so today is my day to go make my requests.
3. We are in the process of bringing up a public SVN so folks can get access that way since the code will have dependencies that can only be resolved if you have access to everything. That takes time and testing. 95% of the code is available via ftp, some of the code for doing figures may wait until actual publication as we are actively responding to reviewers. At the end branches would get gathered into the trunk. So today a branch may have tons of code and figures that never get published. Creating a package that has code to support all the published work in its final form while protecting work in progress ( like studies on heat waves, the SST work, work on satellites, diurnal trend work ) isnt an overnite gig.
phlogiston says:
August 13, 2012 at 4:35 pm
Richard Telford
“Equilibrium”? What are you talking about? Equilibrium is practically never reached in the climate system – if it were then winds and ocean currents would cease, a nightmare scenario.
——————————-
You are completely correct that the climate system never reaches equilibrium – the deep ocean and other slowly responding elements of the system do not have time to adjust before the climate forcing have changed. But your concept of what an equilibrium climate would look like is completely wrong. An climate that is in equilibrium still has weather, currents and waves, but there is no trend in the type of weather, strength of currents or size of waves. So, on average, the distribution of weather, currents and waves in each 30 year period would resemble that in all other 30 year periods under an equilibrium climate.
Just because the climate never reaches equilibrium does not mean that equilibrium climates are not a useful concept in the same way that an asymptote is a useful concept. Eschenbach is attempting to calculate a value for a concept known as equilibrium climate sensitivity, the amount of warming expected at equilibrium from a doubling of CO2. This cannot be done without reference to equilibrium climates.
tty says:
August 14, 2012 at 12:22 am
I agree there is a great deal we don’t know about the Laki eruption. One thing of note is that the peak of the Laki eruption, July 1783, was the hottest month ever recorded in the Central England Temperature record. Which is somewhat problematic for the volcanic cooling thesis.
http://cadair.aber.ac.uk/dspace/bitstream/handle/2160/230/Laki?sequence=3