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Leto at 12:11 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Thanks Tom and Jason B.
Thats sounds perfectly reasonable.
I presume the conclusions do not materially differ if 2013 is used as the endpoint for both models and observations? The comparison might be neater, though, with all the talk on both sides of apples and oranges.
Of course, it is a shame that such an important issue gets bogged down in minutiae in the first place, so it is with regret that I raise such trivia. Thinking defensively, though, there may be advantages in using 2013 in such a table.
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StealthAircraftSoftwareModeler at 12:05 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Opps. Moderator, the URL for larger image @117 is:
http://tinypic.com/r/5c105z/5
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Tom Curtis at 12:04 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Several people have suggested that the first graph in post 79 may be useful for a post. Thanks. Several decisions should be made if it is to be so used. First, I have used the full ensemble rather than just one per model as is used by AR4. This may lead to accusations of deliberate cluttering as a cheat, so, if the post authors want to use the graph, do they want a new version with just one member per model? Further, in such a new graph, would they also like? the 2.5th and 97.5th (or 5th and 95th) percentiles marked as well as the minimum and maximum on the inset? Further, currently if you know what you are looking for you can pick out the observed data because:
a) They are the two top most lines, and hence are never overlaid by model runs;
b) They end in 2012; and
c) They track each other closely (unlike all other model runs) making it possible to distinguish them easily if you look closely, and know what you are looking for.
Do you want just one observed temperature series to obviate (c) above?
And finally, do you want a similar graph for AR5?
If the authors can answer the questions fairly promptly, I can get the graphs done up by this weekend. On the other hand, if you are happy with what is currently available you are more than welcome to use it as is (or to not use it, if that is your preference).
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StealthAircraftSoftwareModeler at 12:02 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
I have updated my chart to show min/max model boundary conditions. Basically, this is the same chart as Tom Curtis has drawn @88, except I continue to show the raw monthly HADCRUT4 temperature data and a 5-year center moving average. IMO, there is more meaningful information in all the data as opposed to showing simple trend lines for GISS and HADCRUT4. Depending on how the trends are selected the data can be skewed. Tom’s chart @88 shows HADCRUT4 and GISS trends as being between the CMIP3 mean and min values, whereas my chart shows the actual temperature as pushing the limits of the lower boundary conditions. Please examine the data closely: look at the temperature data, the point of origin of the CMIP3 min/max points, and the slopes of the lines. They all match Tom’s data. But I have more information and it leads to a slightly different conclusion, I think.
Dana goes to great length to attempt to explain that the left draft chart was a mistake due to baselining issues. My chart of the raw temperature data and Tom’s min/max model looks very similar to the draft IPCC chart. I doubt the people developing the draft chart made a major baseline mistake as claimed by Dana. If you look hard that the final IPCC chart, is does look similar to the draft chart, except that the scale is zoomed way out making the interesting area very small, and then they splattered spaghetti lines all over it. I can see why the skeptic crowd went nuts over the final IPCC chart.
A larger verison of this chart is here. -
Tom Curtis at 11:51 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
leto @113, I originally downloaded the data to check on AR4 with respect to the second graph in the original post, and on issues relating to the comparison between Fig 1.4 in the second order and final drafts of AR5. As I am manipulating the data on a spreadsheet, I decided to follow the 2nd order draft and limit the data to 2015, that being all that is necessary for the comparison. Consequently, model trends are to 2015 unless otherwise stated. Observed trends are to current using the SkS trend calculator unless otherwise stated.
Jason B's point about uncertainty ranges of observations is quite correct, but unfortunately I have yet to find a convenient means to show uncertainty ranges conveniently on Open Office Calc graphs without excessive clutter.
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JasonB at 11:35 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
I should out that the second figure in the OP, from Tamino, captures this point perfectly. It includes the uncertainty ranges of both the various model forecasts and the actual records. Anybody arguing that the models have done a bad job is essentially saying that the overlaps between those two groups are so low that we can dismiss the models as unskillful (and therefore ignore what they project future consequences to be and continue BAU).
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chriskoz at 11:32 AM on 8 October 20132013 SkS Weekly Digest #40
Interesting experiment about peer review:
Hundreds of open access journals accept fake science paper
Just to quote the most interesting aspects:
The paper, which described a simple test of whether cancer cells grow more slowly in a test tube when treated with increasing concentrations of a molecule, had "fatal flaws" and used fabricated authors and universities with African affiliated names, Bohannon revealed in Science magazine.
He wrote: "Any reviewer with more than a high-school knowledge of chemistry and the ability to understand a basic data plot should have spotted the paper's shortcomings immediately. Its experiments are so hopelessly flawed that the results are meaningless."
So, can you so easily get away with such bogus stuff in bio-technology? Is it the only area where PR process is so broken? I'm sure climate science is not like that because it attracts a hell lot of attention...
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JasonB at 11:27 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Leto,
The table is referring to trends in the CMIP3 models, not the actual temperature record, therefore future dates are not a problem.
Going back to Tom's trend graph @ 79, and the attempts to argue that the actual temperature record is in some way inconsistent with the forecasts, I'd just like to point out that while the range of model trends is plotted, the actual temperature trends plotted do not include their ranges!
A quick check on the SkS trend calculator shows HadCRUT4 to be 0.140 ±0.077 °C/decade (2σ) and GISS to be 0.152 ±0.080 °C/decade (2σ). What that means is that there is a ~95% chance that the actual HadCRUT4 trend for 1990 to the present is somewhere between 0.063 and 0.217 °C/decade. There's a lot of overlap between the range of model projections and the range of possible actual trends.
For someone to argue that the models had failed to predict the actual temperature trend, these two ranges would need to have very little overlap indeed.
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Bob Loblaw at 11:02 AM on 8 October 2013CO2 is just a trace gas
Tom:
I have managed to download the full paper you refered to, and I gave it a quick read this evening.
Although I agree with your summary of the contents of the paper, and I agree that it is a very useful way of quantifying the relative importance of various atmospheric constituents, I still contend that "the Greenhouse Effect" writ large must include consideration of the atmospheric transparency wrt solar radiation.
Two interesting aspects of the paper:
1) the dual approach of adding consituents one at a time to the model, verus subtracting them (with others prreset). Various constituents have overlapping absorption bands, which are accounted for in the radiation code. Adding consituents one at a time and watching the changes tells the maximum effect (as any "overlap" won't be an overlap). Removing them one at a time leaves the overlap active in the remaining constituents, and shows a minimum effect. THis puts bounds on the range of values.
2) the use of a 3-d climate model gives a more realistic account for the spatial effects, compared to other estimates that used 1-d models. The exact effect of any constituent depends on local effects of temperature, cloud cover, etc. As a 1-d model can only deal with a single "average" condition, it is more limiting than the 3-d model approach.
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Leto at 10:52 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Hi Tom,
That is very clear, thank you. Could you please comment on your table, though, which refers to trends that extend to 2015:
_____________17.00%_83.00%
1975-2015:__0.149__0.256
1990-2015:__0.157__0.339
1992-2006:__0.128__0.470
1990-2005:__0.136__0.421Is the "2015" a typo? If so, could the mods please edit the post to fix it (no point getting distracted over typos). If not, how were trends derived for years in the future?
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Tom Curtis at 08:09 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin in varius comments has presented two quotes from the IPCC. The first is from the technical summary of WG1, while the second was from the Synthesis report.
The first reads (properly formatted):
"A major advance of this assessment of climate change projections compared with the TAR is the large number of simulations available from a broader range of models. Taken together with additional information from observations, these provide a quantitative basis for estimating likelihoods for many aspects of future climate change. Model simulations cover a range of possible futures including idealised emission or concentration assumptions. These include SRES[14] illustrative marker scenarios for the 2000 to 2100 period and model experiments with greenhouse gases and aerosol concentrations held constant after year 2000 or 2100.
For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected. {10.3, 10.7}
- Since IPCC’s first report in 1990, assessed projections have suggested global average temperature increases between about 0.15°C and 0.3°C per decade for 1990 to 2005. This can now be compared with observed values of about 0.2°C per decade, strengthening confidence in near-term projections. {1.2, 3.2}
- Model experiments show that even if all radiative forcing agents were held constant at year 2000 levels, a further warming trend would occur in the next two decades at a rate of about 0.1°C per decade, due mainly to the slow response of the oceans. About twice as much warming (0.2°C per decade) would be expected if emissions are within the range of the SRES scenarios. Best-estimate projections from models indicate that decadal average warming over each inhabited continent by 2030 is insensitive to the choice among SRES scenarios and is very likely to be at least twice as large as the corresponding model-estimated natural variability during the 20th century. {9.4, 10.3, 10.5, 11.2–11.7, Figure TS.29}"
(Original formating and emphasis.)
Since originally quoteing this test, franklefkin has quoted the third seperately, describing it as "a further quote". He has then gone on to quote the second paragraph seperately, saying "This is taken directly from IPCC AR4", and going on to mention the contents of the third paragraph.
Curiously, when franklefkin quoted the third paragraph seperately, he describes it as referring to prior assessement reports, saying:
"This is saying that past reports had projected increases of between 0.15 and 0.30 C/ decade, and that observations had increases of around 0.2, which bolsterred their confidence their ability to make these projections."
(My emphasis)
In contrast, on the other two times he quotes or mentions this paragraph, he takes it as referring to the IPCC AR4 projections. Thus he has contradictory interpretations of the same passage.
For what it is worth, I agree with the interpretation that this refers to past assessment reports (first given by Dikran Marsupial in this discussion). That interpretation makes the most sense of the chosen trend period, which starts with the first projected year in all prior reports, and ends in the last full year of data when AR4 was being reported. In contrast, AR4 strictly does not project from 1990 but from 2000 (up to which time they have historical data for forcings).
It is possible, however, to interpret this as further qualifying the AR4 projection. That is an unlikely interpretation given the clear seperation into a distinct paragraph within the IPCC report, but it is possible. On that interpretation, however, it probably follows IPCC custom in refering to the "likely" range of temperatures, ie, the 17th to 83rd percentiles. Here then are the likely range for the trends I have reported from CMIP3:
_____________17.00%_83.00%
1975-2015:__0.149__0.256
1990-2015:__0.157__0.339
1992-2006:__0.128__0.470
1990-2005:__0.136__0.421Note that the likely range from 0.136 to 0.421trend over the same period of time reffered to in the quote.
The IPCC used only one run per model in its report, wheras I downloaded the full ensemble. It is possible, therefore, that the upper bound in the restricted ensemble used in AR4 is closer to three. The lower bound is sufficiently close to 1.5 as to create no issue. On this basis, reference to a "likely" range of 0.15-3 C for the 1990-2005 trend is consistent. It is also irrelevant. It would be extraordinary if the missing ensemble members would shrink the 0 to 100th percentile range (Min to Max) that I showed as much as franklefkin desires, and I have already quoted a more restricted 25th percentile greater model trends, showing continuing harping on the 17th percentile to be odd.
With respect to his second quote, as already pointed out, AR4 projections to the end of the century are not linear, and hence not simply interpretable as projections over the early decades of the twenty first century:
Finally, the only clear projection for the first decades of the twenty first century by AR4 is 0.2 C per decade. In my graph I show the ensemble mean trend 0.237 C/decade. So, while I have accurately reported, if anything my graph exagerates the "failings" of observations rather than the reverse.
I see little further point in responding to franklefkin on this point as he is getting repetitive (to say the least). Further, he is neither consistent, nor willing to concede the most straight forward points (such as that trends sited for temperature rise over a century are not the same as projections for the first few decades of that century).
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franklefkin at 05:40 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Dikran,
Another thought. Perhaps the route you are suggesting is correct. If that is the case, why would the IPCC use the wrong ranges in AR4?
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franklefkin at 05:37 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Dikran Marsupial,
This is taken directly from AR4;
For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected. {10.3, 10.7}
In the subsequent paragraph (both this one and the next I have already posted here) it goes on to state the this 0.20 C /decade is bounded by 0.10 and 0.30 C. So it is not I who is taking anything out of context. AR4 made the projection. In his post at 79, Tom Curtis compares actual temps with a minimum trend of 0.10 C /decade in an attempt to show how accurate the models' projections have been. To be accurate, I am saying that a minimum value of 0.15 C/decade should be used. When it is, the models' accuracy at projections does not look as good!
The words are not mine, they came from the IPCC in AR4.
So where did the value of 0.10 c /Decade come from?
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Dikran Marsupial at 05:21 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin Says "I am not looking for a specific CMIP3 trend". O.K., but in that case, you are restricted to using the figures in the report exactly according to their stated meaning, in this case average rates of warming over the course of a century. In that case, you can't use them for comparison with the observations until we have observations for the whole century and you can do an "apples versus apples" comparison.
If you want to do a comparison with the observations over some arbitrary interval (as discussed in the main article), an explicit answer is not given in the reports and you need to go back to the CMIP3 model runs to get an "apples versus apples" comparison.
Your question has been answered, the problem is that you don't appear to know exactly what the question is, and you appear unable to accept that you have not appreciated what the figures in the report that you have quoted actually mean.
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gws at 05:10 AM on 8 October 2013A rough guide to the components of Earth's Climate System
John, the difference is that permafrost is overwhelmingly (mineral and organic) soil, not water. If it consisted mostly of the latter, we would not worry so much about its greenhouse gas emissions as it would be just water melting. The difference is similar than that between frozen bagles and frozen juice. The soil is still there (and active) when it thaws, it does not run off like water would.
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John Mason at 04:58 AM on 8 October 2013A rough guide to the components of Earth's Climate System
Not a lot of difference, gws. If H2O (s) turns into H2O (l) then it's nit-picking to argue whether a thaw or a bloody melt is underway!
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franklefkin at 04:46 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin It has already been pointed out to you several times that the figures you have quoted are not representative of the range of trends the IPCC would consider plausible for recent decades.
Dikran,
I believe that you are not understanding something. I was quoting the IPCC in AR4. I am not looking for a specific CMIP3 trend. Since you told me I was incorrect about what the IPCC had projected in AR4, I am simply asking you what they had projected. Surely since you know I was wrong, even though I quoted them directly, you know what the answer is.
I answerred your question, please answer mine.
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Rob Painting at 04:42 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Tom Dayton @ 86. Agreed, responders here tend to get a bit carried away with long-winded complex comments that are lost upon many readers. The beauty of that particular image is that it immediately cuts through all the technobabble. Readers can immediately see an apples-to-apples comparison, and realize that contrarians are trying to pull the wool over their eyes.
May have to write a post/rebuttal based upon it - given that this myth is one of the most common of late.
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Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin - Over what period? As has been pointed out, given the expectation of faster warming over the next century or so under most emission scenarios, warming over the next few decades will be less than warming at the end of the 21st century.
And, given natural variability of the climate, it is entirely to be expected that observations will vary widely as per the CMIP3 and CMIP5 projected boundaries. Climate projections are a boundary problem, not a detailed initial value problem, and describe what the long term mean of the weather will be given the physics and various emissions scenarios. Past variability from ENSO, volcanic activity, and basic weather will continue to take observations both above and below the mean of the the most accurate model projections - and those short term variations by no means disprove the science.
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Dikran Marsupial at 04:26 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin It has already been pointed out to you several times that the figures you have quoted are not representative of the range of trends the IPCC would consider plausible for recent decades. If you are not going to pay attention when the errors in your reasoning are pointed out, there is very little chance of any progress being made in this discussion.
If you want to know what the minimum value was expected to see, download the model runs from the CMIP3 archive and find out, because it is unreasonable to expect every possible permutation of every question to be explicitly answered in the report.
Perhaps it would help if you were to specify exactly the trend you are interested in (start and end date, and the level of uncertainty for the range of values).
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franklefkin at 04:18 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Dikran Marsupial,
The IPCC in AR4 made projections as to what temperature increases it expected. You have alread indicated that you did not believe that 0.15 C/decade was the appropriate minimum, that you thought it was a leftover from FAR.
What was the minimum value that this increase was expected to be?
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Dikran Marsupial at 04:00 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
frankefkin Thank you. It was important that you agree that Tom's representation of the CMIP3 models was essentially correct, becase the answer to your question is that the IPCC report was written in 2006/7, and they didn't anticipate absolutely every question that could be asked (including specifications of the level of confidence), so the report itself doesn't give direct answers to every single question. So if none of the answers matches the question you want to ask sufficiently closely, you have to go back to the CMIP3 models, on which the AR4 WG1 projections are made. Which is just what Tom did.
Now it appears that you do not understand some of the subtleties in the figures given in the reports (for instance that decadal warming rates given for centennial scale projections will be an over-estimate of the warming for the present decade, or that a "likely" range will not include the "minimum"). In interpreting the IPCC report you need to pay close attention to what is actually written and understand the limitations that places on the inferences you can draw.
The "apples and oranges" things is exactly the point, the figures that you have been quoting from the IPCC report are "apples" when compared with observed trends over the last decade or so ("oranges"). Fortunately the IPCC made a publicly accessible archive of the model runs, so there is nothing to stop you from going to the archive and finding out the answers to your exact question.
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franklefkin at 03:55 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Dikran Marsupial,
Yes, I accept that Tom presented the CIMP3 trends accurately. But that is apples to oranges. Only one of those trends is over 30 years long. The question that I am asking has to do with the minimum expected temperature increase rate predicted in AR4. Is it 0.10 C/ Decade as Tom depicted in his trend graph (and Dana1981 in his "better than you think" post), or is it 0.15 C /Decade as I maintain? The answer has a large impact on the graph presentative that Tom did on trends in @79.
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gws at 03:49 AM on 8 October 2013A rough guide to the components of Earth's Climate System
JohnM, the permafrost is thawing, not melting. You got it right in your clonclusion section.
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franklefkin at 03:49 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
I'll answer your question, but then please answer mine.
I'll take Tom's CMIP3 trends at face value (He has a stellar reputation after all). However, you'll note that those trends are for differring lengths of time, and not what the IPCC has based their predictions on.In fact,only one of them is longer than 30 years. This is apples and oranges.
What is the min temp increase rate predicted in AR4? Is it 0.10 C / Decade, or is it 0.15 C /Decade?
The answer has a large impact on Tom's trend graph.
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Dikran Marsupial at 03:34 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin the request was for you to give a link to the source along with the quote so that we could easily check up on the context of the quote (and see the table itself), we ought to be able to do that without having to go back through your previous posts to try and find out where it is from.
Now, please could you answer my question: "Forgetting for a moment the text of the report, do you accept that the CMIP3 model trends are as Tom presents in his diagrams?"
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franklefkin at 03:29 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
The two posts of mine above used the following links:
LINK:
and
LINK:
Both of these are obviously from the IPCC, and both address their projections.
A further quote from that report is as follows:
"
Since the IPCC’s first report in 1990, assessed projections have
suggested global averaged temperature increases between about 0.15
and 0.3°C per decade from 1990 to 2005. This can now be compared
with observed values of about 0.2°C per decade, strengthening
confidence in near-term projections.
{WGI 1.2, 3.2}
3.2.1 21
st
century global changes
Continued GHG emissions at or above current rates would
cause further warming and induce many changes in the global
climate system during the 21
st century that would
very
likely
be larger than those observed during the 20th
century.
{WGI 10.3}
"
This is saying that past reports had projected increases of between 0.15 and 0.30 C/ decade, and that observations had increases of around 0.2, which bolsterred their confidence their ability to make these projections. Furthermore, they went on to state that further GHG emmissions make it very likely that warming would be even greater in the coming decades than what had been observed in the 20th century.
So how do we go from there, to saying that the projection had been for between 0.10 and 0.30 C/decade? That is obviously lower than 0.15, not greater.
Please point out in the AR4 where the minimum rojection of 0.10 C /Decade warming is.
Moderator Response:[RH] Shortened links that were breaking page format.
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Fergus Brown at 03:02 AM on 8 October 2013A rough guide to the components of Earth's Climate System
Thanks, John, this is useful. In fact I have already stolen it. :0 to start a discussion. Best wishes. btw; I am a bit miffed that JC has taken out all references to our (rejected) survey in 2007/8. 97%? Got there first!
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John Mason at 02:48 AM on 8 October 2013A rough guide to the components of Earth's Climate System
Perhaps a more appropriate term for 1997-8 would be a super El Nino. However, as stated in the intro, this is primarily aimed at beginners, so I have tried to keep it pretty simple and not overly technical, which is where it contrasts with our usual posts. I see no harm in having a few very basic primers in among our output.
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Dikran Marsupial at 02:36 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Thanks Tom, it appears that it is indeed the case that franklefkin has missed a few important points. One should be wary of stating a "bottom line" unless you have first made sure that you really understand all of the details, true skepticim needs to start with self-skepticism.
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Tom Curtis at 02:18 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Dikran, he is quoting from the Synthesis Report.
I am not sure why he imagines quoting "likely" trends (ie, the 66% confidence interval) for mean trends to the end of the century would contradict 90% confidence intervals for trends to 2015.
franklefkin, projected temperature increase is not linear across the twenty first century, so quoting mean trends to the end of the century has no bearing on trends from 1990-2015 (which may be much lower, and have a wider spread to boot given that they are short term trends).
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Dikran Marsupial at 01:48 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin The AR4 WG1 report is available online in HTML format here:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html
It would be far easier if you were to just post a link to the relevant page. I looked up page 45 and it doesn't have any of that in my paper copy.
An important point to make here is that if inspection of the CMIP3 models says X and you think the report says Y, then do bear in mind the possibility that there isn't an error in the IPCC report (written by climatologists who generally know what they are talking about) but instead there is some point that you do nt understand and are misinterpreting the report.
Forgetting for a moment the text of the report, do you accept that the CMIP3 model trends are as Tom presents in his diagrams?
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franklefkin at 01:32 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
This is from AR4.
Table 3.1.
Projected global average surface warming and sea level rise at the end of the 21st
century. {WGI 10.5, 10.6, Table 10.7, Table SPM.3}
Temperature change Sea level rise
(°C at 2090-2099 relative to 1980-1999)
a, d
(m at 2090-2099 relative to 1980-1999)
Case Best estimate Likely range Model-based range
excluding future rapid dynamical changes in ice flow
Constant year 2000
concentrations
b
0.6 0.3 – 0.9 Not available
B1 scenario 1.8 1.1 – 2.9 0.18 – 0.38
A1T scenario 2.4 1.4 – 3.8 0.20 – 0.45
B2 scenario 2.4 1.4 – 3.8 0.20 – 0.43
A1B scenario 2.8 1.7 – 4.4 0.21 – 0.48
A2 scenario 3.4 2.0 – 5.4 0.23 – 0.51
A1FI scenario 4.0 2.4 – 6.4 0.26 – 0.59
Notes:
a) These estimates are assessed from a hierarchy of models that encompass a simple climate model, several Earth Models of Intermediate
Complexity, and a large number of Atmosphere-Ocean General Circulation Models (AOGCMs) as well as observational constraints.
b) Year 2000 constant composition is derived from AOGCMs only.
c) All scenarios above are six SRES marker scenarios. Approximate CO
2
-eq concentrations corresponding to the computed radiative forcing due to
anthropogenic GHGs and aerosols in 2100 (see p. 823 of the WGI TAR) for the SRES B1, AIT, B2, A1B, A2 and A1FI illustrative marker scenarios
are about 600, 700, 800, 850, 1250 and 1550ppm, respectively.
d) Temperature changes are expressed as the difference from the period 1980-1999. To express the change relative to the period 1850-1899 add
0.5°C.
(table 3.1 AR4 pg 45)
(hopefully a moderator can fix the formatting)
Anyway, only the first 3 scenarios have projected warming less than .15 C/ decade, with the other 3 well above that. Bottom line, AR4 predicted temperature increases greater than the 0.1C /decade used in your trend graph.
Again, if Tom Curtis used the min projected temp increase from AR4 of 0.15 C/decade instead of the 0.1 or 0.08 C/decade that he did use, the graph would be significantly different. It would show that observed temps are right at the bottom limit of projections.
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Tom Curtis at 01:15 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin @90, here are the percentiles for various trend periods from CMIP3:
_____________5.00%__25.00%__50.00%__75.00%__95.00%
1975-2015:_0.126__0.164___0.195___0.243____0.284
1990-2015:_0.100__0.176___0.233___0.278____0.389
1992-2006:_0.075__0.167___0.308___0.411____0.527
1990-2005:_0.080__0.177___0.280___0.374____0.487As can be seen, the 90% range for 1975-2015 trends approximates to the values given in the quote, and may be the basis for those values. Alternatively they may have been referring to prior assessment reports as suggested by Dikran Marsupial. Regardless, the quote is insufficiently clear to say, and certainly not clear enough to contradict the data from the CMIP3 database.
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Tom Curtis at 01:08 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Dana @92, in the TAR (at least), I could not find a direct comparison between projections and temperatures in this manner. Rather they compared them using the nifty diagram shown in fig 8.4:
"Figure 8.4: Second-order statistics of surface air temperature, sea level pressure and precipitation simulated by CMIP2 model control runs. The radial co-ordinate gives the magnitude of total standard deviation, normalised by the observed value, and the angular co-ordinate gives the correlation with observations. It follows that the distance between the OBSERVED point and any model's point is proportional to the r.m.s model error (see Section 8.2). Numbers indicate models counting from left to right in the following two figures. Letters indicate alternate observationally based data sets compared with the baseline observations: e = 15-year ECMWF reanalysis ("ERA"); n = NCAR/NCEP reanalysis. From Covey et al. (2000b)."
I assume the temerature series given a common thirty year baseline (as is standard), but that is not specified.
On the other hand, in displaying their projections, they set 1990 = 0 Degrees C on the multimodel means projections. Again, not the same thing, but something that can be misinterpreted as the same.
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dana1981 at 00:24 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Bob @49 - I have seen a couple of comments from 'skeptics' to the effect that, while Tamino may have been technically correct, the corresponding comparisons of models vs observations in earlier ARs used the actual 1990 temperature as a baseline - i.e. had made the same mistake.
I don't know if previous IPCC reports made the same baselining error, but frankly it doesn't matter. This report does it properly and compares warming projections from all previous reports, whilst doing it properly. If the contrarians are arguing that it's okay to improperly baseline because the IPCC has previously improperly baselined, that's a really absurd argument.
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Dikran Marsupial at 00:22 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
franklefkin the range of 0.15 and 0.3 c/decade seems only to be mentioned in the sentence "Since IPCC’s first report in 1990, assessed projections have suggested global average temperature increases between about 0.15°C and 0.3°C per decade for 1990 to 2005.".
The word "since" implies that projections in this range were made after the first assessment report (FAR), but that doesn't mean that they are AR4 projections as it would include projections made during the period covered by the second and third reports as well. If you want to know what the AR4 projections actually say, the best thing to do is to download the CMIP3 archive and find out, as the AR4 projections are based on those model runs.
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franklefkin at 00:01 AM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Tom Curtis, Climate Change 2007: Working Group I: The Physical Science Basis ContentsSPMProjections of Projections of Future Changes in Climate < A major advance of this assessment of climate change projections compared with the TAR is the large number of simulations available from a broader range of models. Taken together with additional information from observations, these provide a quantitative basis for estimating likelihoods for many aspects of future climate change. Model simulations cover a range of possible futures including idealised emission or concentration assumptions. These include SRES[14] illustrative marker scenarios for the 2000 to 2100 period and model experiments with greenhouse gases and aerosol concentrations held constant after year 2000 or 2100. For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected. {10.3, 10.7} Since IPCC’s first report in 1990, assessed projections have suggested global average temperature increases between about 0.15°C and 0.3°C per decade for 1990 to 2005. This can now be compared with observed values of about 0.2°C per decade, strengthening confidence in near-term projections. {1.2, 3.2} Model experiments show that even if all radiative forcing agents were held constant at year 2000 levels, a further warming trend would occur in the next two decades at a rate of about 0.1°C per decade, due mainly to the slow response of the oceans. About twice as much warming (0.2°C per decade) would be expected if emissions are within the range of the SRES scenarios. Best-estimate projections from models indicate that decadal average warming over each inhabited continent by 2030 is insensitive to the choice among SRES scenarios and is very likely to be at least twice as large as the corresponding model-estimated natural variability during the 20th century. {9.4, 10.3, 10.5, 11.2–11.7, Figure TS.29} http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-projections-of.html
In the above, taken from AR4, the predictions clearly state warming will be between 0.15 and 0.30 c/decade. In fact, they state that if ghg (and aerosols) were to remain at 2000 levels - with no increases, warming would proceed at 0.1 C/decade.
Moderator Response:[JH] The readibility of your posts would be greatly enhanced if you were to avoid composing lengthy paragraphs such as the first one above. If you group your thoughts into shorter paragraphs, readers will be better able to understand what your points are.
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One Planet Only Forever at 00:00 AM on 8 October 2013A rough guide to the components of Earth's Climate System
The El Nino that led to the 2010 temperature should not just be called a strong El Nino, an event in the same category as the one that led to the 1998 temperature.
The ENSO values from NOAA should be referred to for the El Nino and La Nina relative magnitudes.
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml
It is clear that the 2009/10 event was shorter than the 1997/98 event and had a significantly lower "peak" temperature value. The resulting higher global average surface temperature from a less significant event is more significant than if the thought is that the El Ninos are “comparable”.
Of course, the duration and “peak” value are not the only factors affecting how much heat is transferred from the Pacific surface into the lower atmosphere but they are major factors in how much “warmer” the global average surface temperature is.
On a related point, it may be helpful to track the rolling averages for every new month of data, like Dr. Roy Spencer has done for the satellite data results. There is no need to wait for the “end of a year” to identify what the trend is. And during an El Nino event the peak result can spread over 2 years rather than more significantly increasing one year.
Of course, I would recommend the average meant to represent an annual average be a true 12 month average not the “13 month average” used by Dr. Roy. He may have chosen this to be able to declare the month in the middle as the “middle of the average” but that is a little lazy.. Every 12 month set of temperatures represents the same data as 12 months ending in December or January. 13 month averages do not as accurately represent an “annual average”.
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Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Tom Curtis - Very clear reply to SAM, thank you.
Cynicus - As Tom Curtis pointed out, McIntyre is only using the HadCRUT4 data, which is notably missing polar areas with higher temperature trends. A comparison between global model trends and not-global observations is inaccurate unless the model data is masked to the same extent - and I see no sign that McIntyre has done so.
McIntyre has not shown the real distributions over the model runs, de-emphasized natural variability, compared masked observations with unmasked models, on and on and on. He has not made his case. Far from his claims - Observations continue to validate the models.
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Tom Curtis at 23:04 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Franklefkin @85, thankyou for your inquiry. Following it up I discovered that I had mistakenly used trends from 1975 rather than the trends from 1990. Here is the graph reproduced with the correct trends:
From 1990, the minimum trend is 0.08 C per decade. That is literally the minimum trend from any member of the ensemble over that period. There are 6 (out of 54) ensemble members with a lower trend than HadCRUT4, and 8 with a lower trend than GISS. I cannot comment on your quote from AR4 unless you actually cite it.
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Tom Curtis at 22:45 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Cynicus @84a, how has he fudged it? Let me count the ways:
1) To start with, only 42 models were used to explore the RCP 4.5 scenario. With 13 named models in the box plot, that leaves 29 singletons. In turn that means that there are only 80 model runs by those 13 models, or an average of 6.15 model runs each. If your thinking it's a bit of a statistical stretch doing a box plot on just six data points, you are right. It is worse than that, for while some models such as the CSIRO Mk3 have all of 10 runs, others such as the CESM-CAM5 have only 3 runs. The CESM-CAM5 still gets its own little box plot, with median, 25th and 75th percentiles, and the 90% range whiskers all of its own, and all of just three runs. That is a bit of a joke statistically. In fact, even the CSIRO Mk 3, with its box plot and whiskers based of 8 runs, plus two outliers (I'm cracking up here) is essentially meaningless statistically. McIntyre had too few samples to make any statistically meaningful claims about individual models, and he knew it. More importantly, the restricted range of the 90% range reflects only the very few samples rather than being a real indication of the variability to be expected from the model.
That means the only meaningful statistic in the entire figure is the box plot coloured gold on the right, ie, the full ensemble.
2) McIntyre compares with only HadCRUT4. HadCRUT4 excludes some of the fastest warming regions in the world. Most notably the Arctic, but also large sections of north Africa, the middle east and areas north of India. Curiously those later areas are where most of the 19 nations that set new national temperaturerecords in 2010 are located. Therefore we know that HadCRUT4 understates the actual trend in GMST, although we don't know exactly be how much. (GISS, in constrast, may either overstate or understate it.) Therefore, absent the use of a HadCRUT4 mask (almost impossible to set up on the KNMI explorer), we know the HadCRUT4 record understates the trend in that period. A reasonable estimate of how much it understates it by is 0.1 C/decade.
3) As can be seen in the graph @69 above, using a 1979 start point introduces a significant negative trend to observed temperatures due to ENSO fluctuation. This is exagerated in the HadCRUT4 record because it includes most areas affected by ENSO, but excludes many areas that are not. Absent this effect, the observed record would be about 0.1 C higher.
If we ignore the nonsense about doing box plots for models with just three samples, the comparison is interesting. There is nothing wrong with making such comparisons, provided you are aware, and make your readers aware, of potentially misleading aspects of the comparison (as in points (2) and (3) above). Further, even using GISTEMP, or an ENSO adjusted GISTEMP, it is likely the observed trend would still have fallen between the 75th and 90th percentile of model trends. The CMIP5 models do run hot relative to observations. Just not as hot, perhaps, as is suggested by the comparisons with HadCRUT4 (unless it is ENSO adjusted, and the models have a HadCRUT4 mask applied).
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Tom Dayton at 22:32 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
JasonB's comment and Tom Curtis's top image and the paragraph immediately underneath it, I think should be part of the new post that mammal_E is working on, about prediction intervals versus confidence intervals (I hope).
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CBDunkerson at 22:22 PM on 7 October 2013Global Warming’s Missing Heat: Look Back In Anger (and considerable disbelief)…
I've been thinking about where, other than the deep oceans, we might have missed measuring some of the 'missing heat' lately and wondering if transformation of energy might be a factor. For example, more energy hitting the planet's surface means more surface heating... which means more/stronger thermal updrafts... which presumably means stronger winds. Similarly we might see changes in the rate of ocean currents. Wouldn't the energy required to move these masses of air and water at greater speeds ultimately be coming from the 'global warming' energy imbalance? Basically this is the transformation of light into heat and heat into kinetic energy. If so, has any research been done on how wind and ocean circulation have changed and how much energy would be required to drive these changes?
I haven't seen these factors listed in previous 'energy budget' analyses so they either somehow aren't applicable, are too minor to have a significant impact, have been included but generally not mentioned, or have been left out. Could some of the 'missing heat' be missing because it is no longer 'heat' at all, but rather has been transformed into motion?
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franklefkin at 22:09 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Tom Curtis @79,The trend graphs tell a concise story. What value did you use for the Min trend line? Was it 0.10 C/Decade? In another thread "IPCC models did better than you think", I posted that in AR4, the IPCC actually quote the min to be 0.15 C/Decade. If you were to use this trend line, it would be obvious that the min and actual were very close. This would tell a very different story than the graph you have shown. -
chriskoz at 21:28 PM on 7 October 20132013 SkS Weekly News Roundup #40B
Thanks JasonB, your explanation is very helpful.
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cynicus at 20:48 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
In an earlier post McIntyre als showed a box-plot from 1979-2013 that suggest that the trend in the AR5 models run significantly 'hotter' than the observed temperature trend (HADCRUT4) over the same period.
The box-plot:
I notice this boxplot don't include the uncertainty in the HADCRUT4 trend, which included (using the SkS trendcalculator) shows that the uncertainties overlap (0.158 ±0.044 °C/decade (2σ)), thus may in fact be the same trend afterall. Is there more to critique? Thanks.
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JasonB at 18:25 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
SAM @ 39,
Furthermore, what does the spaghetti add to the information? It doesn’t appear to add much, but it certainly clutters up the chart, making it nearly impossible to see the actual temperature plot. The simple banded range of model projections in the draft image make it easier read the chart.
The point of the spaghetti rather than the simple banded model is to compare like-with-like — individual climate model realisations with the actual temperature record, which is also an individual climate realisation. "Skeptics" love to compare an actual temperature record with the ensemble mean — which, as predicted by the Central Limit Theorem, is a lot less noisy and fails to show important but unpredictable short-term effects like ENSO because of differences in timing from one realisation to the next — and then use the difference between them to claim that the models do not do a good job, ignoring the true spread of the model realisations and even adjusting the baseline.
If the models truly did not do a good job, then the actual temperature record would still stand out when plotted with the individual model runs, as Tom did @ 79. If it went outside the banded range, it would also go outside the spaghetti, since the former is merely an indication of the spread of the latter.
If a "Skeptic" cannot pick out the actual temperature record from one of those spaghetti charts, then how can they claim the models are not doing a good job?
The magnitude of the apparent random variations of the individual realisations is also valuable to illustrate, because it shows that climate models also have wild swings and plateaux when you carefully cherry-pick a high point for the starting point of a trend calculation.
As for the OP:
Suppose the draft version of Figure 1.4 had used 1992 as the starting point rather than 1990. I can guarantee that all those "skeptics" who are so confused about baselining now would instead be instant experts on the subject and endlessly pointing out how the IPCC had tried to mislead readers by using an inappropriate baseline that exaggerated the temperature record compared to the projections.
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Tom Curtis at 17:43 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Klapper @80, the rationale is that the topic of the post is the treatment of the comparison between CMIP3 and observations in AR5. Specifically, the difference in treatment of figure 1.4 between the 2nd order draft and the final draft. I am happy to discuss the CMIP 5 results, but this is probably not the correct thread to do so.
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Rob Painting at 17:38 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Tom @ 79 - that's quite brilliant. I hadn't thought of expressing it in that way, but the image you provided gets the point across very clearly. Nice work!
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