IPCC Projections Continue to Falsify
I promised I would check the status of the comparison between IPCC AR4 projection of 2C/century each month and report. The NOAA data came in last week, and I had a chance to update my spread sheet with all data series.
The main result is: Despite an uptick in the temperature, the IPCC projections or 2C/century still falsifies to p=95% (α=5%).
This result is illustrated in the figure below. The mean trend for the temperature calculated based on the average of all five data sets is show in orange. The uncertainty intervals are illustrated in fuzzy orange lines. The IPCC short term projection is shown in brown and lies outside the uncertainty intervals for the trends that are consistent with the data. Additional details are discussed later in this post.
Click for largerThe rest of this post shows:
- A table summarizing results of tests using individual instruments.
- A very brief discussion of Beta Error. The “Beta” or “Type 2″ error is important when interpreting the meaning of “failed to falsify results”
- Links to other bloggers discussing March temperatures.
Table of individual Results
This month, the IPCC 2C/century projection was falsified using the averaged data, and all main data reporting services except GISS. So, GISS failed to falsify. The results are summarized below. I have also added a column quantifying the “beta” (β) or “type 2″ error that would be associated with any fail to falsify result based on the average of all 5 instruments sets. (The beta is higher for individual instruments.)
| Best Fit Trend | Reject 2.0 C/century to confidence of p=95%. (α=5%) | β (beta error) relative to: |
||
| C/century <m> | Result of test. | Denialists Hypothesis 0 C/century |
TAR Hypothesis 1.5 C/century |
|
| Average all, fit T vs time: | -0.7 ± 2.0 | IPCC Projection Rejected | 49% | 95% |
| Average all, fit T vs (time, MEI): (See note 1:) |
0.1 ± 1.7 | IPCC Projection Rejected | Fit T vs time, then average: | -0.7 ± 2.1 | See note 2. |
| Individual Instruments | ||||
| GISS | 0.2 ± 2.1 | Fail to reject | ||
| HadCrut | -1.3 ± 1.8 | IPCC Projection Rejected | ||
| NOOA | 0.0 ± 1.6 | IPCC Projection Rejected | ||
| RSS | -1.5 ± 2.2 | IPCC Projection Rejected | ||
| UHA | -0.9 ± 2.8 | IPCC Projection Rejected | ||
| Note 1: There are known problems associated with using MEI in any correlation including lagged variables, because the MEI include time. However, this is included for now because people are interested in an estimate of the effect. I’m looking for better ways to do this, but have been swamped with real work over the past two weeks. | ||||
|
Note 2: Calculating the trend for the 5 individual instruments and averaging afterwards is shown for illustrative purposes. However, as I noted in an earlier post, this method is poor, as the uncertainty intervals only include the variation due to measurement uncertainty which is expected to be uncorrelated between instruments but also treats weather variability as uncorrelated. |
||||
| Note 3: “Beta” (β or ‘type 2′) error is the probability that a test will “fail to falsify” even though the null hypothesis is false. If we treat type 1 and type 2 error similarly, “failed falsify” means “confirmed” only when β is less than or equal to the chosen α, which is 5% for our tests. | ||||
Graphs of β error relative to alternatives.
What does the “Beta” (β) mean?
The “Beta” (β) error describes the probability that the result of a hypothesis test would be “failed to falsify the null” hypothesis when the null hypothesis is false.
Given the formalism of statistics, this type of error is very frequent when data contain noise or random components of any type and limited quantities of data are available. In fact, when one has not yet taken any data, the β error equals 100 %.
To a large extent, the idea that it takes years of data to formally test hypotheses about climate variables arises from the fact that many hypotheses in climate are proven using “failed to falsify” as a criterion. Failed to falsify only means “confirm”, when β error is low and it turns out that to get empirical confirmation of AGW in the first place too years. I discussed this generally here.
For now: Suffice it to note that the amount of data for my current test of 2C/century is such that:
- If the out and out denialists are correct, and warming is 0C/century is correct, we would expect our test of 2C/century to result in “failed to falsify” 49% of the time. (That is to say, we’d make the mistake of “failing to falsify” nearly 50% of the time, while incorrectly falsifying only 5% of the time.)
- If the IPCC TAR projection of 1.5 C/century is correct, we would expect the 2C/century result to “fail to falsify” 95% of the time. (We really need a lot of data to distinguish between these two values.)
Those who doubt the previous falsifications are now going to think “Hmmm… she wants to have her cake and eat it too!” After, all, I’m telling you fail to falsify means practically nothing, but falsification does mean something!
Well, … this is just the way it is.
The reason it is this way is that we initially gave the 2C/century preferred status. We structured the hypothesis test so its result is “fail to falsify” before we have even one iota of data. We also set bar high for “falsify” high: We must show that if 2C/century the data we get would happen only 1 time in 20 by pure random chance. So, we only say “falsify” when there is strong evidence that 2C/century must be wrong.
If the evidence 2C/century exists but is “medium” rather than “strong”, we say “fail to falsify”. It is the preference from saying 2C/century that results in ‘fail to falsify’ not actually meaning confirm. What “fail to falsify means is, “There is no strong evidence, and I refuse to believe it’s wrong unless the evidence is strong!”
But, once a falsification is logged we really can’t just forget the evidence existed (and materialized rather quickly in this particular case.)
What are we likely to see going forward?
Even though 2C/century has been shown likely false, and it is likely falls, we will probably see some ‘fail to falsifies’ to ‘falsify’ transitions for quite some time. I think this because
- I think it’s nearly impossible that the climate trend is 0C/century (or below). The only way we’d get a permanent string of “falsify” this soon after decreeing the “start” data of 2001 is if the trend were much lower than 0C/century. So, that won’t happen.
- We got a falsify the first time I ran the test. (I was expecting to get “failed to falsify”, but… well.. number are numbers.)
- We know we are in the region where β error is high for all underlying trends I think remotely possible. This means we should get “fail to falsify” quite often, even though the 2C/century is probably false.
So, how will readers know if the “falsification” we are currently getting are incorrect? One way is if we see “fail to falsify” with β<5%. The other way is if we get a result, starting with data from 2001 that falsifies 2 C/century, but on the high side.
In the meantime, “failing to falsify” means rather little, as we expect that result rather often even if 2C/century is flat out wrong.
Other People Discussing March Data
Since this is just the regularly scheduled comparison, I thought I’d bring readers links to what other people are saying about the recent temperature fluctuations:
- David Stockwell Compares Norhtern and Southern Hemisphere temperatures.
- Anthony Watts discusses a German who claimsHadCrut data converging to GISS data, but Anthony finds that claim suspect.
- Chris Colose note GISS Temps are up in March.
- Roger Pielke Sr. discusses some reasons why Northern and Southern Hemisphere temperatures may diverge.
- Craig James compares this March to previous Marches on record.
- Hall of Record talks about recent “coolth”.
- Redstate.com discusses why 10 years is not long enough to be a trend.
- Yid with a Lid also discusses the temperatures.
As a closing note, I observe that most the bloggers talking about the recent temperatures are on the AGW-skeptic end. For the most part, I found these links on Technorati, so presumably I would have found AGW-believers blogs discussing the temperatures if they were discussing the temperatures.
I’ll try to remember to repeat this in a few months when El Nino returns just to see the results. 
Comments
lucia (Comment#2029) April 21st, 2008 at 4:45 pm
Raven,
That depends.
Look down 3 rows, and find the analysis with note “See note 2.”. That analysis involves assuming the 5 data sets are independent- and that applies both the the weather and uncertainty noise.. It’s done by first fitting Temp vs. Time and then calculating the slope, and then averaging. Then, I calculate the uncertainty based on the standard deviation around that mean slope, divide by the square root of (N-1) and apply the t-test for 4 degrees of freedom.
In that analysis, the assumption the uncertainties are indepenednet is clearly false, and that’s why I don’t show any conclusion based on that. However, I post the answer, just so people can see. (It also lets me explain that that is not what I do for my main method should they ask. )
In contrast, the “main” method, which is listed in the top result row doesn’t really assume anything about the dependence of independence. The calculation is done in this order:
The average temperature for the month is the simple average of the five sets. This calculation involves no computation of uncertainty, because a) we don’t know the uncertainty for any individual temperature and b) we don’t need that information at this point.
Had we needed it, then I would have had to make an assumption about independence. But I don’t need to make any assumption, so I don’t.
After averaging, I apply the linear regression to that set. The uncertainty is whatever it is. (If they were truly independent, we would have certain expectations about how that dropped.)
Then, I compute the uncertainty in the fit according to the standard method for uncertainties in fits. That also makes no assumption about dependence of independence.
So, the only case that makes an assumption is listed in row three. That’s noted in “note 2″, and I don’t use it!
The place dependence of independece does come in is indirectly. If the uncertainties due to measurement in the five sets were independent, we’d see the uncertainty obtained by averaging be lower than the those obtained with each instrument. In contrast, if they were all totally dependent with each other, we’d see no reduction by averaging.
But whatever happened, it would fall out naturally– making no assumption.
I hope this answers without being too confusing.
James A. Donald (Comment#2030) April 21st, 2008 at 10:15 pm
Every so often, the IPCC issues a graph showing the doom that will come upon us if we do not repent of our sinful ways, but they all seem to have vanished, which leads me to suspect it would be interesting to dig out one of these graphs issued around 2001, and plot the recent satellite data on top of it. Can anyone point me to one such graph of doom, or recollect a website that carried them back in 2001?
lucia (Comment#2037) April 22nd, 2008 at 3:39 am
James,
The Third Assessment Report (TAR) was issued in 2001. You can flip through the pages here:
http://www.ipcc.ch/ipccreports.....sh/080.htm
Boris (Comment#2040) April 22nd, 2008 at 4:23 am
Political blogs should not write about global warming. Yikes.
terry (Comment#2043) April 22nd, 2008 at 5:46 am
I agree Boris, they shouldn’t but they do, myself included.
This would include all sides of the political spectrum.
terry (Comment#2044) April 22nd, 2008 at 5:52 am
Lucia I got a little bit lost trying to understand beta. is there a formula you used to run the test? I think I can get it if I can have something to plug numbers into and then chug away. (that’s how I learned calculus…plug and chug.)
lucia (Comment#2045) April 22nd, 2008 at 6:14 am
Terry,
There isn’t a formula so much as a procedure. I describe it here:
http://rankexploits.com/musing...../#comments
What you need to do is:
Figure out how to do the hypothesis test for 2C/century.
In the process, figure out the values of the slope that would “falsify” 2C/century. For the period of time since 2001, these happen to be a bit below 0 on the low side and a bit above 4 c/century on this high side for our current tests. The calculation of these values uses the standard error for the slope, which is calculated based on the magnitude of the “weather noise” we have actually experienced. Lets’ call these “Low bound” = 0C/century; “high bound” = 4C/century. (I’m rounding to make the explanation easier to type– but the real values aren’t 0 or 4).
So, you know you would falsify 2C/century if the trend “m”<0 C/century=mlow or if 4 C/century < mhigh.
So, given you will say falsify for these cases, here is how you figure out the likelyhood you would falsify if the trend were really 0C/century.
For the purpose of calculation, assume the trend is 0C/century.
2) Assume that the weather variability is still what we have experienced. So, you can just take the standard errors on the slope you got from the previous calculation.
Recall you will falsify 2C/century if m<mlow=0C/century or if 4C/century=mhigh<m.
Calculate two things, but assuming the true mean is 0C/century.
a) Probability you will falsify, because m is less than the lower bound for 2C/century.
The probability that the weather would exhibit a slope less than mlow (0C/century). You use the gaussian distribution for this. (It’s programed in Excel). Note that in this example, 0C/century happens to equal the mean, so if the true mean were 0C/century, we would determine there is a 50% chance that the weather would have a trend with a slope less than 0C/century. (The other 1/2 the time, the slope would be greater than 0C/century. )
This image may help (Though it’s backwards for the current discussion):
b) Probability you will falsify, because m is greater than the lower bound for 2C/century. The probability the weather would exhibit a slope greater than 4 C/century. (This ends up being really, really small for our case.)
Add the probabilities from (a) and (b). You’ll get something just above 50%. That’s the total probability you will falsify 2 C/century when the real value is 0 C/century. This is called “The Power”.
So, the probability you fail to falsify is 1-Power= β. This is “beta” error contingent on m=0C/century, because in this hypothetical, we assumed m is really 0C/century.
Obviously, this can all be repeated for any alternate hypothesis. In the table, I used 0C/century and 1.5C/century, because those seemed like reasonable ones. The first value is the one the denialists insist on. The second one would be the TAR; so that would interest us if we wanted to figure out if the AR4 values are any better than the TAR values.
John V (Comment#2046) April 22nd, 2008 at 7:28 am
lucia,
I put together my own spreadsheet of temperature trends, and I’m happy to say that our results agree (within 0.1K/century) on all trends. The small differences are probably due to different values of rho in the Cochrane-Orcutt regression. It’s pretty sensitive.
The C-O trends are still more negative than the OLS trends, but the gap is closing. I looked at different time periods and the C-O trends are at times more positive than the OLS trends. That gives me confidence that C-O is not inherently biased towards negative trends. (I couldn’t see how it would be, but it never hurts to check). In fact, C-O seems like a sensible technique IMHO.
Basically, I agree that the 7-year trend from Jan2001 to Mar2008 is not consistent with a century-long average trend of 2.0K/century.
So, why is the current short-term trend different than the longer-term trend? Why is it basically flat since 2001? You have discussed ENSO, and your correlation with MEI makes sense to me. As you’ve shown, it’s not enough to explain the trend.
You have hypothesized that a PDO switch in 2001 would explain the change. In comments, you have also expressed some interest in the solar cycle vs temperature correlations from WattsUpWithThat.com. I’m surprised you haven’t yet looked at the influence of the current solar cycle on the short-term temperature trend.
The correlation between solar cycle and temperature is not well defined. At the low end, Tamino has shown that the correlation is weak if it exists at all. At the high end, Camp and Tung 2007 show an effect of ~0.16K between solar min and solar max. In the middle, other empircal analyses have found ~0.1K and model simulations have predicted ~0.06K.
In Jan2001 we were near solar maximum. In early 2008 we are at solar minimum. If we assume a short lag time between solar cycle and temperature (consistent with the 2 month lag between MEI and temperature), then we can expect the temperature signal to be near full amplitude.
Using rough numbers, the trend from the solar cycle over the last 7 years is between 0.06K/7years (0.9K/century) and 0.16K/7years (2.4K/century). It could actually be 50% higher or it could be zero using the published 95% confidence limits.
Adding the range of solar cycle trends to your MEI-adjusted trend:
MEI-Adjusted + Small Solar Trend: 1.0 +- 1.7 K/century
MEI-Adjusted + Large Solar Trend: 2.4 +- 1.7 K/century
These trends definitely fail to falsify 2.0K/century. The same is true of the average trends that are not MEI-adjusted. Have I missed something obvious?
lucia (Comment#2048) April 22nd, 2008 at 8:47 am
Hi JohnV,
I think it’s worth while for everyone to look at various possible reasons. But, I’m not going to look at solar partly because others are. Either Anthony and Basil will find a smoking gun there, or they won’t. I’m currently looking try to find how much ‘energy’ people believe exists in other long cycles– like the PDO and the AMO.
In those cases, when I find literature, I’ll try to do a back of the envelope calculation to see if those explain the slow down, and also, to see what that same explanation says about the initial empirical support for warming during the 1970-now run up.
I’m also trying to learn better statistics to deal with ENSO. (Because the method I’m using isn’t quite up to snuff.)
terry (Comment#2049) April 22nd, 2008 at 9:13 am
ok, thanks Lucia, I think I have it now.
John V (Comment#2051) April 22nd, 2008 at 10:50 am
I’m disappointed that you’re not going to look at the solar cycle. Next to the seasons and ENSO it’s the clearest cycle in the climate system. Its timing from max to min matches your 7-year trend very well. Even without correcting for ENSO, the solar cycle amplitude need be only ~0.02K to de-falsify (is that a word?) the “2C/century” trend. With your ENSO compensation, a solar cycle amplitude of ~0.11K would be sufficient to falsify the “no-warming” hypothesis.
From my back-of-envelope calculations, it is clear that even a modest solar cycle effect on temperature can make a substantial difference to a 7-year trend. It would also have very little effect on the 38-year trend preceding 2008 (the “1970-now run up”).
None of this necessarily means that PDO and AMO are not factors — but surely an explanation as simple (and seemingly complete) as the solar cycle is worthy of investigation.
lucia (Comment#2053) April 22nd, 2008 at 10:57 am
John,
Are you saying that if I account for the decline in temperature expected due to a drop in the solar intensity from 2001 to now, then we would see the AGW signal?
John V (Comment#2057) April 22nd, 2008 at 11:20 am
lucia,
If I understand your question, then my answer is yes. Allow me to clarify that I’m answering the right question:
The trend from Jan2001 to Mar2008 can be written as:
(1)
T = A + E + S + O + W
where
A is the AGW trend,
E is the ENSO trend,
S is the solar-cycle trend,
O is the trend from other sources (AMO, PDO, etc)
W is weather noise
The IPCC trend is basically just A. You have shown that E is fairly small and have attempted to correct for it. Your ENSO-corrected trend can be written as:
(2)
Te = A + S + O + W
W is the remaining error bars, which you have estimated as plus or minus 1.7K/century.
That leaves S and O (plus the W noise). I can’t say anything intelligent about O, but S has been estimated. If the solar cycle temperature amplitude is between 0.06K and 0.16K (references that I found from a quick search), then S is between -0.9K/century and -2.3K/century for the last 7 years. To keep it simple, I’ll define S = -1.5K/century (a little less than the average of the range).
Re-writing (2) to solve for A:
(3)
A = Te - S - O - W
Substituting your computed trend of 0.1K/century:
(4)
A = 0.1 + 1.5 - O - W
Neglecting O and expanding W as error bars at plus or minus 1.7K/century:
(5)
-0.1 K/century < A < 3.3K/century
or,
(6)
A = 1.6 K/century plus or minus 1.7K/century
This is very close to the IPCC trend of 2.0K/century. The results are similar using the temperature trends without ENSO correction.
lucia (Comment#2058) April 22nd, 2008 at 11:44 am
JohnV–
Hmmm…Do you have references on the magnitude of those effects?
I’ll look a bit through the SRES, but the normal 11 year solar cycle, being entirely predictable, should in principle already be included in the IPCC projections and incorporated into the mean trend. (Unlike ENSO, PDO, AMO, it’s should be something in the error bars. But, I’ll need to read a bit on the forcings used in the IPCC document.
So, basically, if the 2C/century was projected with full accounting for the 11 year solar cycle at the strength the modelers think it has, a correction to give credit for that would be inappropriate.
With respect to the IPCC ‘falsification’ it matters who says that effect exists. Because, if I understand those at Real Climate, NASA etc. at this point, the solar cycle is supposed to be buried in the noise. So, in a sense, if their projection is only ’saved’ by the impact of the solar cycle, then their models are…well… wrong!
Still, if you can say who suggests those numbers, it might still be interesting to examine.
BenSolar (Comment#2066) April 22nd, 2008 at 12:24 pm
I am no statistician, but I will comment that I think the window you are taking data from is way too small to make the claims you are making, lucia. At least include a full solar cycle, preferably two. You aren’t capturing the full amount of noise in the system when you only sample from solar maximum to solar minimum, and so your error bars on your trend line are not nearly wide enough, IMO.
I’d have a look at what the variance is in the temperature record going back to the introduction of satellite records, I think you’ll find that 7 year trends vary a lot more than you are estimating.
The IPCC never issued a forecast for what the trend would be 7 years out, IINM, for good reason.
John V (Comment#2067) April 22nd, 2008 at 12:25 pm
The 11-year solar cycle averages out so does not need to be considered in a multi-decade trend. That is, it has little effect on the *mean* trend just as ENSO has little effect on the *mean* trend. It only affects the trend over short time scales. I doubt there is any discussion of the solar cycle in SRES.
As for the IPCC error bars, I don’t believe you are using them. Instead, you have been using the IPCC mean trend and deriving the error bars from observations. That’s a valid choice but means that the size of the IPCC error bars is irrelevant to your analysis.
Camp&Tung (2007) is the most recent study that I know of (link below). They found 0.16K (0.06K to 0.26K) for the solar cycle. At the low end, they reference Stevens & North (1996) which finds a model-predicted cycle of 0.06K. (My results for the underlying AGW trends for 0.06K and 0.16K are in comment #2046).
http://www.amath.washington.ed....._2007b.pdf
Using NASA’s numbers from one of your earlier posts (link below), the solar cycle has a peak-peak amplitude of ~0.3W/m2. Coincidentally, the GHG forcing is increasing at roughly 0.3W/m2/decade or ~0.2W/m2 in 7 years. The net change in forcing from GHG and solar effects over the last 7 years is thus about -0.1W/m2.
http://rankexploits.com/musing.....nt-matter/
Ironically, those who are most convinced that the IPCC is wrong tend to argue for a strong solar cycle effect on temperature (and vice-versa). In this case, the two arguments negate each other. If the solar effect is weak, the IPCC trend is falsified. If the solar effect is strong, the IPCC trend for AGW is validated. Nobody can have it both ways.
lucia (Comment#2069) April 22nd, 2008 at 1:12 pm
JohnV–
In the first post, I showed the IPCC error bars for the mean trend. The IPCC doesn’t communicate these in words, or even very well. So, unfortunately, it’s a bit difficult to talk about them. Here’s the graph:
There are other graphs for other SRES, but they are all similar in the short term projection.
What I found then is, given the data at that point, the climate trends predicted were not consistent with the trends in the data. The range of trend consistent with the data are based on the data. The climate trends the IPCC projects were those discussed in the report.
But one must always compare trends to trends, and that’s what I do.
But yes, at this point, in my table, I’m focusing on talking about the central tendency for the trend, and seeing if that is consistent with the data. The central tendency is important in and of itself. From time to time, I’ll show the full uncertainty intervals, but admittedly not in the table.
With respect to the solar cycle: When I said I needed to read, that’s what I meant. Either they included those when running the “simple tuned models” used to project or they didn’t. I’m reading table 10.1 on page 756 of the WG1 part of the AR4, and solar is listed as “C”. Reading sideway, the seem to let it vary in AOGCM’s but treat it as a constant or annually cyclic in scenario integrations. This would mean you are correct and they don’t include the 11 year cycle in scenario integrations– which I think is what they ultimately use for their projections. I think they do this because they consider the variation over the 11 year cycle weak. So…
Yes, I agree that it is ironic that those who disagree the IPCC modeling efforts suggest the strong effect, while those who think the IPCC models are great think the solar effect is weak. (In fact, evidently sufficiently weak as to neglect it when projecting trends!? If we are both reading correctly?)
Still, it seems to me that if the only way to “redeem” the IPCC models is the solar cycle… well… (But I think we agree on this?)
Ben:
If you read the IPCC AR4, it’s not clear what the time scale for their projections are. They never discuss how one would verify or falsify, what time scales etc. That’s one of the reasons Roger Pielke Jr. recently advised they should state these things more clearly.
The issue of needing several solar cycles is puzzling since those who make the projections seem to insist the solar cycle doesn’t matter. So, in a sense, if it matters, the basis for their projections is somewhat undermined! (You can see that’s why John V and I are trying to puzzle this out.)
I’d be willing to agree on the need for more data if anyone brought up a relevant phenomena with a large time scale with sufficient “energy” in terms of temperature variation. But so far, no one does. They just decree things in terms of numbers of years. When analyzing data, there are actually quantifiable things one can state, and for some reason, no one will suggest particular known cycles.
So, in the meanwhile, I’m trying to read the literature to see if estimates of the amount of variability due to the PDO or AMO matter. (If they matter a lot, that has the potential to affect the issue of empirical proofs of AGW in the first place, because these cycles are L-O-N-G. Long enough to encompass the full recent run up! But, based on most my reading, the estimates are that they are not strong enough to impact that assessment. If so, they aren’t strong enough to affect this one. But, I admit, I’m still not sure– as you can see from my comment above.)
lucia (Comment#2070) April 22nd, 2008 at 1:21 pm
John V– OOpps.. I didn’t read everything.
First: Thanks for the numbers and papers.
The problem with the amplitude of the forcing from my previous post is it doesn’t tell us the amplitude of the response. One of the difficulties in the theory is the “in the pipeline” issue. Based on that, about 1C/century (roughly) of the projected run up was due to the GHG’s already being too high, and the planet being low relative to equilibrium for that current level of GHG’s. The second +1C/century was sort of due to the increase after 2001.
So, you can’t just say: we expected GHG’s to go up an amount ‘A’ resulting in a temperature rise of ‘dT’. So, if solar goes up ‘B’, but we neglected that, we would expect the temperature to rise an amount (1 + B/A) dT.
So, I’m a bit puzzled as to how to estimate that. But the numbers in the paper you suggest should help me do order of magnitude calculations (after I read them! )
John V (Comment#2072) April 22nd, 2008 at 2:00 pm
Ah yes, I remember that graph now.
Care must be used when stating that the solar cycle “doesn’t matter”. It’s true that it has little effect on long-term trends. It’s true that even an extended solar minimum would make little difference on a multi-decade trend. But it does have the potential to *substantially* impact a 7-year trend that starts at solar max and ends at solar min.
Just for fun, I did OLS and C-O fits going back to the last solar minimum (June 1996). I used the average temp from Atmoz’s data file. The trends with 95% confidence intervals are:
OLS: +1.1K/century (+0.5 to +1.8 K/century)
C-O: +0.9K/century (-0.9 to +2.7 K/century)
I made no attempt to correct for ENSO. I realize that I cherry-picked the starting point so I’m not going to make any claims about these trends.
Although the Jan2001 starting date for the IPCC falsification was justified by publication dates, it starts at a solar maximum and ends at a solar minimum. Is an un-intentional cherry-pick still a cherry-pick?
=====
Re-reading my previous post, I see that I left the impression that the negative trend in forcing would give a negative trend in temperature. That was a mistake. You are right to say that there is warming “in the pipeline”.
My gut feeling is that the “pipeline” warming is mostly in the oceans. The atmosphere should respond quickly to any forcing. The atmosphere’s response is damped by the slower ocean response.
Raven (Comment#2073) April 22nd, 2008 at 2:06 pm
It pretty obvious from the beginning that the 7 years coincided with falling edge of the solar cycle. I am pretty suprised that it took so long for someone like John V. to point that out. It seems like many in the warmer camp are afraid of admiting that the sun does have an observable influence on climate. Is suspect it is because they know that a strong cooling effect on the trailing edge also means a strong warming effect on the leading edge.
I used the solar data here: http://solarscience.auditblogs.....r-minimum/
And I eyeballed the temperature trends for the falling edge of the last three solar cycles using the graphs here: http://junkscience.com/MSU_Temps/Warming_Look.html
It is clear that there is a roughly 0.2 degC drop for the surface and satellite datasets and this drop is consistent with the drop observed since 2001. This is consistent with the conclusions made in the Camp and Tung paper.
However, It seems to me that removing a 0.2 degC oscillation from the temperature dataset over the last 30 years would also result in a trend much lower than what IPCC claims. For example, eyeballing from the 1982 max to the 2002 max gives a trend around 0.05 degC/decade. Similarily, eyeballing from the 1987 min to the 2008 min gives a trend of 0.05 degC/decade too.
A net trend of 0.05 degC/decade over 20 years would invalidate many of the predictions made by the IPCC.
Raven (Comment#2075) April 22nd, 2008 at 2:15 pm
I also eyeballed the MEI index here: http://www.cdc.noaa.gov/people/klaus.wolter/MEI/
I noticed that every solar min coincides with a La Nina which and the rising edge of the solar cycle always corresponds to a El Nino.
This observation could imply that ENSO and the solar effect are one in the same.
Raven (Comment#2076) April 22nd, 2008 at 2:19 pm
John V says:
“My gut feeling is that the “pipeline” warming is mostly in the oceans. The atmosphere should respond quickly to any forcing. The atmosphere’s response is damped by the slower ocean response.”
I don’t buy it. The oceans may have damped the initial response, however, enough time has passed that we should be seeing some of the warming coming out of the pipe. I more likely explaination is the CO2 sensitivity estimates are wrong.
John V (Comment#2077) April 22nd, 2008 at 2:22 pm
Raven,
I’m also surprised nobody else has brought up the solar cycle.
I strongly doubt your conclusions about its effect. Since it is *cyclic* it has no effect on the overall trend (by definition). Eyeballing and subtracting is not the right way to calculate trends. The OLS trends for the dates you picked are:
1982 to 2002: 1.9 degC/century
1987 to 2008: 1.8 degC/century
John V (Comment#2078) April 22nd, 2008 at 2:23 pm
Raven — you are a conclusion-making machine!
Raven (Comment#2079) April 22nd, 2008 at 2:34 pm
John V says:
1982 to 2002: 1.9 degC/century
1987 to 2008: 1.8 degC/century
I realize that eyeballing is not the right way to do things but I don’t think that an OLS trend that includes all of the data is the right way to do it either. If it was then it should have given something close to the peak-to-peak and min-to-min estimates. I suspect the difference is due to the volcanoes which pull down the OLS trend in the 80s and 90s. Eyeballing a 1 year average around the max/min removes the volcanic effect even if it lacks precision.
John V (Comment#2081) April 22nd, 2008 at 3:18 pm
lucia,
Section 9.2.2.1 of IPCC AR4 WG1 discusses the effect of the solar cycle on temperature:
“A number of independent analyses have identified tropospheric changes that appear to be associated with the solar cycle (van Loon and Shea, 2000; Gleisner and Thejll, 2003; Haigh, 2003; White et al., 2003; Coughlin and Tung, 2004; Labitzke, 2004; Crooks and Gray, 2005), suggesting an overall warmer and moister troposphere during solar maximum. The peak-to-trough amplitude of the response to the solar cycle globally is estimated to be approximately 0.1°C near the surface. Such variations over the 11-year solar cycle make it is necessary to use several decades of data in detection and attribution studies.”
http://www.ipcc.ch/pdf/assessm.....apter9.pdf
(I tried to include the entire pertinent paragraph — I apologize in advance if there is missing text that contradicts the excerpt above).
Using IPCC AR4’s value of 0.1C from peak to trough, the expected trend from the solar cycle alone is approximately -1.4C/century (0.1C / 7years). Referring back to comment 2057 the ENSO- and solar-corrected underlying AGW trend using Cochrane-Orcutt is:
A = 1.5 K/century plus or minus 1.7K/century (-0.2K to 3.2K/century)
Note that I am not extrapolating from the solar forcing but instead looking directly at the empirical temperature response. I never should have mentioned the net forcing — it was an unnecessary complication.
The confidence limits are actually wider because the solar effect is not known with much accuracy. Nevertheless, the 7-year trend does seem to be consistent with the IPCC. I think it’s de-falsified.
Boris (Comment#2083) April 22nd, 2008 at 4:07 pm
I’m also surprised nobody else has brought up the solar cycle.
Actually, James Hansen mentioned it.
Boris (Comment#2084) April 22nd, 2008 at 4:09 pm
Oh, BTW, a stronger solar response would also support a higher sensitivity to CO2–even given the different nature of the forcings.
Raven (Comment#2085) April 22nd, 2008 at 4:26 pm
Boris says:
Actually, James Hansen mentioned it.
I mentioned it a number of times to warmers who were complaining about Lucia’s falsification. I had thought that the IPCC did not take the solar cycle into account so its projections were still falsified even if there was an explaination. Unfortunately, the CYA statements in the IPCC doc that John V found mean that solar cycle must be accounted for before one can claim falsification.
Boris says:
Oh, BTW, a stronger solar response would also support a higher sensitivity to CO2–even given the different nature of the forcings
Right. More have your cake and eat it too logic. If the trailing edge of the solar cycle causes cooling that cancels the CO2 effect then at least half of the warming during the leading edge must be due to the solar effect. Any other outcome implies the solar cycle does not average out over time.
lucia (Comment#2087) April 22nd, 2008 at 4:44 pm
Raven– John’s convinced me to look at it. That said, I don’t know what I’ll finally make of it. I’m going to discuss AMO first.
The things I’d note about Boris:
1) He says Hansen said something, but not what, and did not provide a link.
2) He claims something (though heaven knows waht) about the sun mattering would mean sensitivity is higher, but provides no other details.
So, for now, I will take those statements for what they are: not only unsupported, but so vague as to be meaningless. Should Boris be moved to add details, I might read them. But in the meantime, what he says is not worth wasting time thinking about.
Yes. Obviously, if the down trend of the solar cycle explains non-warming, the up-trend could explain heating for about a decade. That’s actually important. The difficulty is quantifying. The other difficulty is that if there is thermal mass– and so a time constant– then there is a phase lag in heating and cooling. So, the cooling and heating would be out of phase with the warming. This is why it’s going to take me a bit of time to look at this and figure out what I think.
In my view, everyone gets to figure things out in their own time, and have their own opinions. So, my not immediately agreeing with John V (or him with me) causes me no distress. In the long run, we each try to puzzle together what we think and why. (If the IPCC would be a bit more quantitative about info in their document– or even RC in their blog, I would be grateful. But alas, that is not the case. So, in the meantime I look at things and post what I think and say why.)
John V. (Comment#2088) April 22nd, 2008 at 5:14 pm
lucia, I’m glad I’ve convinced you to look at it.
I’m only writing comments in blogs, so I have not looked at it from every angle yet. My question from my original comment in this thread is still important — have I missed anything obvious?
Rather than going at it from first principles, in my opinion you should start with observations of the solar cycle temperature signal. Doing so avoids all the complications of modelling time lags, etc. I look forward to your analysis.
lucia (Comment#2089) April 22nd, 2008 at 5:46 pm
JohnV–
I’ll try to see if there are any observations of the temperature signal. The difficulty is… are there any? I’m not sure there are as they may be buried under volcanos etc. But, I’ll look at it.
Boris (Comment#2091) April 22nd, 2008 at 6:31 pm
Well, the solar forcing is known in terms of Wm`2, so the difference in the analyses of how the known variation in the solar cycle corresponds to temperatures will be the difference in strength of feedbacks. Feedbacks apply no matter what the forcing is–though there can be some differences (I’d imagine ice albedo feedback is faster with solar than with GHGs–but I don’t have a source for that, sorry.) If you want strong feedbacks for solar, you have to give strong feedbacks to CO2 as well. You cannot have your cake–oh, Raven already said that.
John V. (Comment#2092) April 22nd, 2008 at 7:14 pm
lucia,
Camp & Tung (2007) derive their estimate of 0.16K for the solar cycle from observations only. I have only skimmed the paper and it’s fairly new so I can’t vouch for how well it will stand up to scrutiny. I believe the references in the IPCC AR4 quote above are also based on observations.
I don’t have time to look into it because it’s Hockey Night in Canada!
Niche Modeling » Rahmstorf 7 Finale (Pingback#2093) April 22nd, 2008 at 7:25 pm
[...] has been flat here, and that a number of climate indicators are showing decadal stability here. The Blackboard has been spear-heading rigorous statistical methods for checking IPCC projections and finding post [...]
Neil Fisher (Comment#2094) April 22nd, 2008 at 7:29 pm
Hi Lucia,
de-lurking for a moment…
Like your blog, but I’m curious to know why global average temperature is calculated as the mean.
It seems to me that in terms of heat content at least, median would be more physically meaningful. Any chance you could do a post on this - the pros and cons of median vs. mean?
Thanks in advance.
back to lurking… 
Bob B (Comment#2110) April 23rd, 2008 at 3:46 am
Lucia, you’d better watch how you choose your end points and scale factors because Tamino the Cherry Picker will haul you off for perjury:
lucia (Comment#2114) April 23rd, 2008 at 5:01 am
I saw that title. I thought “Accusations of Perjury? On a blog with the self proclaimed name of ‘Open Mind’?”
Wouldn’t someone with an open mind be more likely to consider other possibilities, like a) incompentence, b) mistakes, c) different point of view, or d) other?
Anyway, whats with all the legal theories flying around the web. Some blogger accused Krysten Byrnes of libel against Hansen? Does that blogger not read movies to learn the definition of libel in the US??!
steven mosher (Comment#2115) April 23rd, 2008 at 5:02 am
JohnV perhaps a note to gavin would help. In the “projections” do they model a change in solar forcing, the
11 year cycle?
FWIW you can get ModelE results for 1880 to present for the response of GSMT to solar forcing alone.
lucia (Comment#2116) April 23rd, 2008 at 5:10 am
Steve- Do you have a link to those Model E results?
John V. (Comment#2117) April 23rd, 2008 at 5:51 am
steven mosher, in the context of multi-decade trends I don’t think it matters if the IPCC models include or exclude the solar cycle. The solar cycle is important for this analysis only because it is short *and* runs from a solar max to a solar min. It’s the worst case for determining underlying trends in the presence of a cyclic forcing.
lucia (Comment#2119) April 23rd, 2008 at 6:08 am
JohnV–
I concur about the multidecadal. Certaintly after 22 years (2 cycles) we would expect this to mostly wash out (though, oddly, it would still be measurable if it’s large!)
But, in the context of any verification/validation done to date, it would matter. So, for example, Rahmstorf et al. using “slide and eyeball” to assess agreement uses only 17 years of data. If there are relatively large 11 year cycles in 17 years of data, then one might want to at least know whether one started at the bottom and ended at the top or vice versa when both sliding and eyeballing!
So, if this does matter, there is a problem with the IPCC’s method of communicating and with the climate scientists method of communicating etc.
In my opinion (and it is that) if solar does make a difference of 0.18K peak to peak (which one reading of Camp and Tung suggests for surface temperatures(!)) or 0.1K, or even 0.05K, then, since the 11 year cycle is more predictable than the increase in GHG’s the IPCC should be including those either in error bars, or their nice smooth trend lines. (There is no reason they can’t have wiggles and mention those are due to the solar cycle.)
But, where I totally agree with you: If they leave it out, we need to see if the decision to leave it out is what “falsifies” in the short term.
In which case, the message to the IPCC might be: Why don’t you add this into your graphs? Then the “stalls” in warming would be communicated as not just mere random events but predictable anticipated events, and we’d even know when to expect them. Equally importantly, we would better assess whether a sudden run up is due to the sudden increase in solar!
And even more importantly– knowing whether the models correctly predict the response to solar really would give people more confidence. (And it would ally lots of skeptics who are going nuts over the solar cycle.)
So… right now, I’m trying to read various discussions of this and trying to figure out my opinion on a)what’s the possible range of solar influence based on the literature (I think JohnV may have that pegged, b) should there be a time lag, c) how does this jive with the AOGCM’s. etc.
Raven (Comment#2122) April 23rd, 2008 at 7:06 am
Here are Leif’s comments on Camp and Tung: http://www.climateaudit.org/?p=2983#comment-233060
Here are few choice quotes from the paper:
The problem of solar-cycle response is interesting in its own right, for it is one of the rare natural global phenomena that have not yet been successfully explained
Currently no GCM has succeeded in simulating a solar-cycle response of the observed amplitude near the surface. Clearly a correct simulation of a global-scale warming on decadal time scale is needed before predictions into the future on multi-decadal scale can be accepted with confidence.
Leif notes:
There is also a strictly periodic [hence known forcing] variation during each year of 90/4 W/m2 due to the eccentricity of Earth’s orbit. This variation, being strictly periodic, and 100 times larger than the solar cycle variation should allow for even more sophisticated analysis. It would seem to me that unless we can model and understand the response to this very large signal, it is premature to look for the much weaker solar cycle signal.
Leif tried to get Gavin to tell whether the seasonal signal was modelled by the GCMs. I don’t know if he got an answer.
Reference (Comment#2123) April 23rd, 2008 at 7:13 am
Apologies if this question has already been asked and hopefully answered. What does the data say about the AR1-3 projections for 2001-2008?
lucia (Comment#2124) April 23rd, 2008 at 7:32 am
Reference: Do you mean the TAR? (Third Assessment Report?) That was about 1.5C/century for central tendency. Right now, the fit using all five instruments, averaged says -0.7 ± 2.0 C/century. So, the upper trend that is good to 95% confidence is 1.3C/century.
So, the 1.5 C/century central tendency is currently “out”.
Mind you, John and I are trying to see if we can figure out if this could be due to neglecting the effect of solar cycles (and if yes, what that would mean.)
John V (Comment#2125) April 23rd, 2008 at 7:54 am
lucia #2119:
I mostly agree with your points. Rahmstorf et al should have considered the solar cycle. (I have not read it so I can not say for sure if the solar cycle is described).
As far as IPCC communication goes, as far as I know the IPCC authors have been consistent in saying that 7 years is too short for validation or falsification. The effect of the solar cycle is included in the IPCC AR4 WG1 text. Wiggles on the IPCC trend lines might be useful but would give the impression of better accuracy than could be justified (and that would open up a whole new can of complaints). The wiggles would also quickly devolve into noise because of uncertainties in solar cycle lengths and amplitudes.
For determining long-term trends (which IMO is the goal of the IPCC) the solar cycle is just not that important. It’s only an issue in this case because of the unfortunate timing.
Anyways, enough IPCC politics — let’s get back to figuring out the correct answer. That’s way more interesting.
lucia (Comment#2127) April 23rd, 2008 at 9:35 am
JohnV,
Rahmstorf et al. 2007 is a 1 page paper. I don’t see “solar” mentioned and certainly, they don’t wait “several decades” as suggested in the paragraph you quoted from the AR4! “Several” generally implies more than 2 decades, so 16 years is, well… not “several”.
Political or not, what the IPCC said they meant by their documents is important with respect to the discussion of how we are to interpreting what they told people. It’s true that in chapter 8 of the WG1 Technical basis of the AR1, the need to wait several decades to average out solar is mentioned. But it is also true that the authors themselves are somewhat, shall we say, “flexible” in deciding how seriously to take the paragraph you quoted matters– they publish comparisons without waiting “several” decades. Also, it’s worth noting that Chapter 10 itself, where the projections are discussed, gives no particular guidelines are for verifying projections “uncertainty” in the portion discussing the projections themselves matters
Now… the “what might be the effect of solar front”: I’m trying to do some reading. I read the Camp and Tung results, and they do predict a sizeble influence, and evidently in phase with the cycle. (I still haven’t downloaded the solar intensities though. So… I need to get those.)
It turns out that when I reread the table 10.1 on page 756 of the WG1 part of the AR4, listing things like “C” and “Y” telling us whats included in the projections, some of the IPCC model projections appear to explicitly include solar in the SRES integrations. Specifically, Model E does.
Steve Moscher sent me a link to what Model E would predict for the solar influence and I plotted it:
We think this is supposed to be the models prediction of response to solar forcing. If your reading is different, let us know.
You can replicate here:
http://data.giss.nasa.gov/mode......1.06.html
The path to that page is: http://data.giss.nasa.gov/mode.....imsim.html
That page also explains what the data supposedly tell us.
To get the response to solar only, look at table 1 under “miscellaneous”, pick forcing and “lat time”.
I downloaded the 1 month data. (It turns out 2001 temps were predicted as relatively low.)
Unfortunately for our discussion, the calculations at the link Steve provides don’t go past the end of 2003. But as you can see, for the 2001 was at a relative low point as far as their predictions go. (If you go to the GISS site, you can see GISS was hindcasting 2001 as low.) So, this would suggest that starting in 2001, at least GISS would have been expecting the response to solar to amplify the temperature response.
On the other hand, the magnitude of the peak to peaks could be in the range suggested by Camp and Tung. But now I need to see raw solar data they used.
Out of curiosity– do you have solar intensity data based on measurements? That would help me. (If you have any idea what Model E might have projected for Solar after dec 2003, that would be interesting too.)
steven mosher (Comment#2128) April 23rd, 2008 at 9:55 am
JohnV, well the models include the changes in solar forcing due to excintricty.
For hindcast they use the historical TSI ( from lean I think) so the question is, when they do a projection
do they assume a contant 11 year cycle, do they monte carlo that forcing, or do they just ignore the changes in
solar forcing. Same with volcanoes. since its unpredtable do they use an AVERAGE volacanic forcing?
Or do they assume No valcanic forcing becaause its unpredictable?
steven mosher (Comment#2130) April 23rd, 2008 at 10:11 am
JohnV,
I think I should probably get clarification from gavin on this. When I asked him for Hindcast data he sent
me to this page. And I’m just taking that data at face value, so when the feild says solar irradiance forcing
I’m assuming that is TSI from lean and no other forcings. So the response would be the response of solar only.
John V (Comment#2132) April 23rd, 2008 at 12:01 pm
I’m short on time so can’t dig very deeply.
I had a quick look at the Model E results. I agree with your interpretation of what they mean. An FFT analysis shows a strong peak at 11 years, as expected. The amplitude of the solar cycle is only about 0.0075 degC (0.015 degC peak-to-peak) — lower than other results I’ve seen. I do not have time to check the phase of the temperature response.
lucia (Comment#2135) April 23rd, 2008 at 12:55 pm
Thanks for looking at that John. Yeah, with clean data, you expect 11 years. When I first looked, I saw all that scatter, and yet for some reason assumed it was ensemble averaged results. But… I guess the range we are seeing is weather. (That by itself is interesting actually. If that’s weather, we can compare weather noise in the model to real weather noise. But… I better read to see if that’s any sort of ensemble average!)
I found some Total Solar Irradiation data. Oddly, while 2001 is near the peak, there happens to be a local ‘dip’ for about a year. (Not enough to make it a ‘low’ year– but you’ll see when I show the plot. )
I also need to check how Camp and Tung treated the data– monthly average? Year. (It’s in there, I just don’t remember.) Tamino has a theory about there being some problem with Camp and Tung which he doesn’t reveal. (He also describe problems he does reveal. For example, he doesn’t like that there is a short-ish time frame used, and he doesn’t like the complication, but he said there is something else he doesn’t like, but he evidently wanted to email Camp and Tung about it. So…. who knows?)
Leif Salvgard at least seems skeptical over at CA. He seems to think it’s a big dubious to find the 11 year signal without finding the annual signal. (I’d tend to agree, particularly if the 11 year signal has no phase lag, suggesting near instantaneous response with no phase lag. That said, I haven’t run the numbers.)
I read RayPierre’s comment on the paper after a presentation at AGU. He seemed intrigued by it and was planning to do something with an NCAR model– but I haven’t seen if he reassessed later.
(I left this question:
50.
Raypierre:
These ideas could be tested by more complete diagnostics of heat burial in the NCAR model, and solar-cycle response runs with a two-layer mixed layer model in which the upper layer is shallow. I think I’ll give it a go, if I can find the time.
Did you ever happen to do this? Or do you know anyone who has done anything along these lines?
)
So, maybe we’ll learn more. Anyway, it might be interesting what Raypierre currently thinks of Camp&Tung.
But, on the issue of the magnitude: If the solar causes that much and if it hits “just right” then, yes, that would be big enough to cause issues with testing projections that neglected the existence of this response. (But, I also think if climatologists working on projections thought there is was systematic response to the nearly deterministic external solar forcing that’s that big they surely ought to have included that quite explicitly in projections, and repeated it in fairly obvious ways in thigns like “guide to policy makers”. )
John V (Comment#2137) April 23rd, 2008 at 1:46 pm
lucia,
I saw Tamino’s post about the Camp and Tung results. I’m definitely not advocating for the C&T results since they are so different than the accepted value of ~0.1C.
There is a difference between modelling the solar cycle response and observing the solar cycle response. I believe Leif Svalgaard’s comments were about modelling the annual variation. We would need to move from anomalies to actual temperatures to look for that cycle. As interesting as that may be, it’s not related to the 11-year solar cycle and is not important in terms of falsification of IPCC trends.
Must do real work…
Reference (Comment#2138) April 23rd, 2008 at 1:53 pm
lucia, your comment 2124:
Do you mean the TAR? (Third Assessment Report?) That was about 1.5C/century for central tendency. Right now, the fit using all five instruments, averaged says -0.7 ± 2.0 C/century. So, the upper trend that is good to 95% confidence is 1.3C/century.
So, the 1.5 C/century central tendency is currently “out”.
Mind you, John and I are trying to see if we can figure out if this could be due to neglecting the effect of solar cycles (and if yes, what that would mean.)
Thank you for your near real time reply. Yes, I was trying to refer to the Third, Second and First Assessment reports. So both FAR and TAR are based on unreliable projections. Perhaps it’s not worth the effort but there would be some closure and completeness to knowing if the Second and First Assessments had any skill.
Is it clear how these projections were arrived at? If not then looking for the source of the error will be a hopeless task.
John V (Comment#2139) April 23rd, 2008 at 2:14 pm
lucia,
I know I’m repeating myself, but the solar response is only “that big” when looking at trends over less than a single solar cycle. Its effect is critical for your falsification because of the timing from solar max to solar min. All it takes is -0.03degC from the solar cycle to undo the IPCC falsification (for the average trend).
If the IPCC made 7-year predictions then it would be necessary to prominently discuss the solar cycle — for their multi-decade predictions it is basically irrelevant.
lucia (Comment#2142) April 23rd, 2008 at 3:00 pm
John– Of course there is a difference between observing and modeling.
But I’m pretty sure Leif is talking about observing. The discussion of phenomenology is there because he’s explaining that it should be easier to observe this in the annual record than in the 11 year record because physical arguments should suggest the effect is much stronger in the annual record. (Plus, of course we also know statistically there are 11 years in an eleven year cycle, so that should help on the statistics.)
But no one reports seeing the solar signal in the annual record. So, that doesn’t have to do with modeling. (Maybe the just don’t look?) Still, if they’ve looked and haven’t found, that’s a question. And the fact is believability of the results in these papers does relate to the modeling.
I have a question for you: Are you sure mentioning results and what someone found in in a paper means the idea is “accepted”? That’s not necessarily true in what is essentially a literature survey.
Papers discussing the solar cycle and the 0.1C estimate are mentioned, but that doesn’t always mean the results are “accepted.” The IPCC document as a whole and methodology for developing projections reads as if the solar cycle is not considered important– so I’m trying to gauge that in making up my mind about what the solar stuff means.
(I know you’ve already decided what you think– but that’s because you’d thought about it before you asked me. So for me, I started thinking about it after you thought about it and later asked.)
Still, certainly, it’s mentioned. So, I’m not waving this off– it’s just that I want to read what the papers say, and also find out what different people think of these various findings/ claims.
I’m also looking through the papers to see if anyone says anything about phase lag or to see if the 0.1C is mentioned specifically or to see if they mention other features we should be seeing. But that’s going to take a bit of time. In H Gleisner, P Thejll - Geophys. Res. Lett, 2003, for example, they seem to have no phase lag. So your method of identifying the peak/ trough would make sense according to what they say. In con
But according to H Gleisner, P Thejll analysis, we should be seeing really big swings at 200 hPa- 300 hPA. So, if what they suggest is real, we should have seen the temperatures a loft, and especially in the equatorial to mid latitudes take a big, big noise dive. They supposedly drop 3-4 times as much as the surface during a solar min! Do we see these? If I’m going to think about the solar effect, I think would be interesting to look. (I haven’t.)
All I have from VAN LOON Harry (1) ; SHEA Dennis J. (1) ; is the abstract. They seem to have looked at August July only, and say ” At the earth’s surface an 11-year solar signal is not obvious in the zonally averaged temperatures and pressures in July-August.” This would suggest that we see nothing at the surface. (They see stuff between the mid tropopause and 10 hPa.)
lucia (Comment#2144) April 23rd, 2008 at 3:14 pm
JohnV–
I agree the uncertainty due to solar forcing is only large at small times.
We have a difference of opinion about the likely interpretations of those graphs by readers. Those documents, and those graphs are communicated the the wide spread public and policy makers, and the sorts of caveats you are finding are buried in small paragraphs amounting to literature surveys separted from the projections by pages and pages of text, graphs etc. (The caveats you find are in Chapter 8. The projections are in chapter 10 and repeated in the summaries– with no ‘reminder’ of what’s in Chapter 8.)
You can think smooth graphs starting with projections at time “0″, surrounded by small uncertainty intervals is clearly communicating “Don’t test for decades (unless you are Rahmstorf in which case, start in 16 years)”, but I think they mislead.
So, I think the IPCC is wrong not to either
a) make increase the uncertainty intervals at small time periods so as to accomodate any uncertainty in response to solar forcing or
b) incorporate supposedly “known” -0.1C per 6 year excursions in the central tendency for the trend due to response to nearly deterministic variations in solar forcing.
You are not required to agree with me on this, but it’s what I think. -0.1 C in six years is huge compared to what they are communicating to people. But no matter what the result, if as this line of argument seems to suggest, that -0.1C was accepted, anticipated and fully explained that excursion belonged on the graph illstrating the projections because it overwhelms the projections actually communicated to the public.
steven mosher (Comment#2150) April 23rd, 2008 at 4:33 pm
Ya lucia, I think part of the problem is that inthe short term, lets say 1-10 years the
uncertainty is dominated by short cycles ( like solar, enso etc and noise), so that modellers
are basically reading tea leaves and chicken bones. beyond 10 years the short cycle variability
is assumed to cancel out and the trajectory is dominated by GHG forcings, that is the various guesses
at GHG emisions. the SRES. The question is how to present such a quizzical beast. In the short term
emmissions dont matter, but what matters is stuff we cant model, but in the long run the stuff we cant
model evens out, and the stuff we guess at ( emissions) matter.
So for me GHG go up, temp go up. I’ll guess 1.7C per century, sres be damned. that’s my naive forecast.
John V. (Comment#2153) April 23rd, 2008 at 5:24 pm
It seems like you’re saying an annual cycle in temperature has not been observed. Let me know if I misunderstood.
There is a clear annual pattern in observed temperatures. Since we’re discussing climate we tend to work with monthly anomalies. The baseline for the anomalies removes the annual cycle — that’s the purpose.
I’m not certain of the amplitude of the solar cycle temperature response (as I’ve said in previous comments). I am confident that the response is large enough to affect a 7 year trend, and I am glad that you’re looking into it.
This discussion is slipping from collaboration to argument. I really don’t care if the IPCC should have stamped a solar cycle warning on every page in big red letters. The goal is supposed to be testing the validity of the trend — not analyzing the prominence of certain words.
steven mosher (Comment#2154) April 23rd, 2008 at 6:00 pm
JohnV no argument here, just a suggestion about how better to frame the claims.
Lukewarmers.
Ian Castles (Comment#2155) April 23rd, 2008 at 6:17 pm
John V observes that ‘If the IPCC made 7-year predictions then it would be necessary to prominently discuss the solar cycle.’ It’s surprising therefore that some leading members of the IPCC milieu join in making 7-year and even annual predictions without discussing the solar cycle (so far as I know). Specifically, Phil Jones of the CRU at the University of East Anglia was a coordinating lead author of Chapter 3 of AR4 and David Parker of the UK Met Office (Hadley Centre) was a lead author of the same chapter. The organisations with which these scientists are affiliated have produced a joint forecast of the coming year’s global mean temperature anomaly every year since (I think) 1999. I’ve seen claims (at Climate Audit, if I remember correctly) that these estimates have consistently overpredicted the following year’s temperature. And in 2007 the CRU/Hadley Centre produced for the first time a prediction for a longer time span: 2014 would be 0.3 C warmer than 2004 (an error range was provided).
Even more puzzlingly, in December 2003 Phil Jones told the BBC that “Globally, I expect the five years from 2006 to 2010 will be about a tenth of a degree warmer than 2001 to 2005.” This was a brave prediction, and it now seems almost certain to have been too high. The average HADCRUT3 global mean temperature anomaly for the first 27 months of the 2006-10 quinquennium (Jan. 2006-Mar.2008) was BELOW the average for the 2001-05 quinquennium (Jan.2001-Dec.2005), and the average global mean temperature anomaly for the rest of the 2006-10 period (Apr.2008-Dec.2010) that would be required to reach Jones’s forecast is now 0.3 C higher than the Jan.2006-Mar.2008 average. Yet the Hadley Centre/CRU predicts a relatively cool 2008 and also, I think, 2009.
If there are indeed ‘0.1C per 6 year excursions in the central tendency for the trend due to response to nearly deterministic variations in solar forcing’, it is puzzling that Dr. Jones did not mention this. This is a comment on the impression communicated by the institutions concerned, not on the quality of their research.
Raven (Comment#2156) April 23rd, 2008 at 6:54 pm
John V says:
There is a clear annual pattern in observed temperatures. Since we’re discussing climate we tend to work with monthly anomalies. The baseline for the anomalies removes the annual cycle — that’s the purpose
The earth’s orbit is elliptical which means the TSI at the winter solstice is 90 w/m2 higher than the TSI at the summer solstice. This variation is 100 times the purported effect of the TSI over the solar cycle. If the small change in TSI over a solar is enough to cause a 0.10 degC change in temp then we should see a 10 degC difference between the GMST at the solstices. The data is always reported in anomalies so it is not easy to check for this signal. If this 10 degC difference does not exist then the 0.1 degC variation over a solar cycle must be treated with skepticism.
I don’t know about you but a 10 degC difference in GMST between the soltices sounds awfully large.
lucia (Comment#2157) April 23rd, 2008 at 6:59 pm
It seems like you’re saying an annual cycle in temperature has not been observed. Let me know if I misunderstood.
Leif seems to be saying that. I actually have no idea. You can’t get it out of the anomalies which is the only thing I’ve looked at.
But, presumably, it would make sense for these various papers to compare what they discover about the annual effect to what they find as the two analyses should confirm each other. But the papers I’ve read so far are silent on any confirmation. That is odd. (Odd doesn’t mean wrong. It just means, odd.)
Do you know of any papers where they have linked the results from both? If so, I’d like to see them and I’m guessing Leif would too.
This discussion is slipping from collaboration to argument. I really don’t care if the IPCC should have stamped a solar cycle warning on every page in big red letters. The goal is supposed to be testing the validity of the trend — not analyzing the prominence of certain words.
I know you don’t care. However, I strongly suspect low prominence about the +0.1C exits because the author, collectively, mostly believed there is no +0.1C. However, if the opposite is true and they truly believe is a +0.1 effect, I think the low prominence of the discussion is a poor choice.
The issue of what they believed about the effect of solar on the trend even over 6 years is important with regard to testing the validity of the projected trend.
FWIW: I’m checking papers and numbers. But, I’m going to also check the things that seem important to me and also discussing them. One of those is: Does it appear the author’s or climatologists believe there is an 0.1C, or 0.2C or 0.01 C trend.
pliny (Comment#2163) April 24th, 2008 at 2:19 am
Lucia,
I realise that I am late to this discussion, and I may have missed something in past threads. But I note that the diagram in AR4, Fig 10.26, that you use for your falsification did not actually predict a trend. It predicted a range of temperatures. You are falsifying your own deduced trend.
Now the trend you have chosen seems a reasonable best guess. But it would have an error range consistent with the AR4 error range, and by eyeball, it looks as if that might be very large, given the few years in the range. Shouldn’t you be falsifying relative to the error range of the IPCC model data, rather than the variance of your residuals.
To take this a but further, all the IPCC has really projected is that the temperature will lie between certain bands. Can you falsify that?
steven mosher (Comment#2164) April 24th, 2008 at 4:38 am
pliny, in the text the ipcc notes that the trend from 2001 for the next two decades will be .2c per decade,
regardless of emissions scenario , warming in the pipe. after 2011 the provide ranges that go from .21C and up
depending upon different emission scenario. claerly they where free to say ” we make no projection for the next 10 years, however from 2011 and on warming will fall within these ranges.” but they didnt take this conservative uncertain view of the first decade of the century. alternatively one can say that the observed trend after 6 years
is what is +- 3sig, which is what it is. short peroid, big error bars, but some trends are ruled out as unlikely.
like a trend of .2c per decade is ruled out, for now. this will change as more data comes in
lucia (Comment#2165) April 24th, 2008 at 5:47 am
Hi Pliny,
The AR document described the central tendency of 2C/century both in words and in the graph. They predict an underlying climate trend of with a central tendency 2C/century for the beginning of the century.
It appears you are suggesting I should compare a the trend experienced on earth to the IPCC model weather.
Falsifications are traditionally done by comparing one underlying ‘noise free’ to a different underlying ‘noise free’ trends. One does not traditionally compare trends to weather. So, I find the range of trends consistent with the weather we experienced and compare that range of climate trends to the IPCC projected climate trends.
If I had the IPCC weather data, I could find the range of trends consistent with the model weather and still compare trends to trends. But, since the IPCC already did that step and published the trend with the uncertainty on the trends, I just compare the trends for the weather to the trends they published.
The IPCC did not predict the temperature would be within certain bands. If you examine the plots, they are “relative to 2001″. However, the value in 2001 is never stated. This may seem a subtle point, but I discuss the difficulty earlier.
However, if you are asking, can the weather data for GMST be made to consistently stay inside the uncertainty bands shown? The answer is: I haven’t exactly checked, but probably not. A test for the TAR would fail– that everyone has seen. The weather almost never stays inside plots like that. Those bands aren’t meant to encompass weather noise. In fact, generally when people do “slide and eyeball”, even the first few data points are outside that bands.
No one considers individual weather data falling outside those bands meaningful because those bands aren’t intended to encompasse the weather noise– they are intended to describe trends.
John V. (Comment#2167) April 24th, 2008 at 7:03 am
lucia,
I’m trying to get a feel for just how large 0.1C really is. My gut feeling is that its closest analog is ENSO (in terms of frequency and amplitude, although I realize ENSO is internal). For comparison, do you recall the size of your adjustments for ENSO? I am also curious about the prominence of ENSO and its effect on trends in the IPCC reports.
–
Raven,
I really like this kind of comparison. I believe there are some complicating factors to consider. Give me a little time to think about it…
lucia (Comment#2168) April 24th, 2008 at 7:18 am
John–
The “slope” with MEI is 0.061 and the standard deviation of MEI is 0.588 So it’s about 0.035C as far as “correlation” goes. So, 0.1 is strong.
The positive empirical points in favor of the “sun” correction are:
* If I apply an cosine amplitude of 0.05C with 11 year cycle to the fit, the 1979-now correlation is improved a bit. (The slope during that period goes up also– but so far this is OLS.)
* At least one paper actually directly claims this amount. (That’s out of the two cited I read. ) I’m still not sure it’s “accepted” in the sense of everyone believes it, but presumably, it’s not “totally crackpot”.
So… I’m going to do this, and run the C-O. Then, I’ll add it to the cycle. It may piss everyone off, since on the one hand, it will (likely) redeem the IPCC projections, but on the other hand, it does it by considering the solar effect important.
On the other hand, we’ll see what happens in a few years.
Raven (Comment#2169) April 24th, 2008 at 7:19 am
John V,
The Camp and Tung approach appears to extract a signal from the temperature data by looking for correlations. This means it would find a signal even if the signal is not caused by TSI (e.g. GCR, magnetic fields, ENSO interactions etc). This could explain why they found a significant signal even if the annual signal due to TSI variations is very small. OTOH, the IPCC completely discounts the possibility of non-TSI related forcings nor do we know if any non-TSI related forcing would really cancel out over time.
John V (Comment#2170) April 24th, 2008 at 7:31 am
lucia,
Just to confirm, is the “slope” in units of degC/MEI? I don’t understand how you got 0.035C — please explain.
I downloaded the MEI data you linked in your “Accounting for ENSO” post (link below) and got very different results. Using the MEI range from -2.2 to +3.1 I get a full-scale ENSO effect of:
(3.1 + 2.2) * 0.061 = 0.32degC
Or using the standard deviation (0.97) I get 95% confidence limits (peak-to-peak) of roughly:
(4*0.97) * 0.061 = 0.24degC
Where did I go wrong?
Raven (Comment#2028) April 21st, 2008 at 4:22 pm
Lucia,
Does your analysis presume that the datasets are independent? For example, all of the surface measurements use some of the same thermometers and the satellite measurements use the same satellite data.