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Flakmeister at 14:45 PM on 8 October 2013SkS social experiment: using comment ratings to help moderation
Well, I may be proven wrong but the up/down system doesn't do a job of moderation... Witness Zero Hedge where a high number of "greenies" only demonstrates the resonance within the echo chamber...
Call me skeptical....
Moderator Response:[PW] I'm fairly sure JC and the rest of the SkS team aren't intending the thumbing system to take the place of regularmoderators: quite the contrary--and speaking as a moderator--if/when I see multiple thumbs-down, *geenrally* it can be taken as a sign of a *possible*vtroll/contrarian, and, for me, just aids in my 'drive-bys,' daily, of the threads.
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John Mason at 14:42 PM on 8 October 2013A rough guide to the components of Earth's Climate System
OK I have edited the text accordingly. However, although the term 'strong' was in retrospect incorrect, 2010 did see moderate El Nino conditions for a time:
http://iri.columbia.edu/climate/ENSO/currentinfo/archive//201001/QuickLook.html
Tom - I'd call one of the five biggest El Ninos in a century pretty darned impressive!
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JasonB at 13:13 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Another way of illustrating the problem with SASM's graph:
Keep the minimum and maximum trend lines the same as they are now but instead of plotting HadCRUT, plot instead the individual model realisations (Tom's spaghetti graph @ 79).
Now the model realisations will be going outside of the "minimum" and "maximum" trend lines, and many of them will be "pushing the limits" — if fact, no doubt some of them go outside those "limits". How is it possible that the actual model realisations that are used to create those "limits" could go beyond them? Because those "limits" are not the limits of the monthly (or five-yearly moving average) temperature realisations, they are the range of the trends of those realisations. And they certainly do not start at that particular point in 1990 — each realisation will have its own particular temperature (and five-year moving average) at that point in time.
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Rob Honeycutt at 13:01 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
SAM... Actually, I find your chart interesting in terms of illustrating why there is a problem centering on 1990.
Look at your chart for a moment. Do you notice how 1990 is at the peak of the 5 year trend? Try centering the start point forward or back a few years and see if you get a different picture.
Do you see how you can get a very different interpretation by just adjusting a few years? That indicates to me that that method doesn't provide a robust conclusion. Centering on 1990 certainly provides a conclusion that skeptics prefer, but it's not at all robust.
But again, as JasonB just restated, you're treating this as an initial condition problem when it's a boundary condition problem. You have to look at the full band of model runs, including both hindcast and projections, and compare that (properly centered) to GMST data.
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Paul Pukite at 12:46 PM on 8 October 2013A rough guide to the components of Earth's Climate System
My eyes lit up when I noticed how seriously you are treating the various realms of the Earth's climate system. I am starting up an earth sciences semantic web server and blog at http://ContextEarth.com. This is designed to encompass the various realms of the earth and its natural resources, using an organization provided by the SWEET ontology from JPL. It's all open sourced so I intend to open it up to those who have some interest in the topic.
An example of a recent post is on compensating the GISS temperature record with the SOI time series. This analysis was inspired by charts that Kevin C and Icarus posted on SkS recently.
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JasonB at 12:41 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
SASM @ 117,
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.
No, it's not. Tom's chart draws trendlines only. As a consequence, there is no initial value problem and all trend lines can safely start at the same point.
You show actual temperature anomalies and compare them with trendlines. This has two problems:
1. You anchor the trendlines to start the on the 5-year centred moving average temperature in 1990. If you really want to go down this path and you want to do it "properly", then you should use a much longer average than 5 years. Given that climate is commonly defined to be the average of 30 years, you should use the 30-year centred moving average at 1990. By my calculation that would drop the starting point by 0.04 C, making a big difference to the appearance of your chart.
2. More importantly, comparing monthly data with straight trendlines will naturally show periods where the monthly data (and even smoothed data) goes outside those trendlines, even when those trandlines are minimum and maximum trend lines. That's because they're the minimum and maximum range for the trend, not the minimum and maximum values for the monthly figures at any point in time! Plot the trend line for HadCRUT starting at the same point and ending today. Does it lie well within the minimum and maximum trend lines? Obviously it must, this is what Tom showed. Include the range of uncertainty for the trend itself. What is the likelihood that the true trend does not lie within the minimum and maximum range forecast? As a bonus, if you include the range of uncertainty for the trend itself then you can generate shorter and shorter trends for comparison, and if you do, you'll find that the forecast trends continue to overlap the range of trend values despite the actual trend value swinging wildly because the range will naturally grow wider as the time period becomes shorter.
The bottom line that you have to ask yourself when generating these charts is "How is it possible that I can reach a different conclusion by looking at my chart to what I would infer from looking at Tom's or Tamino's chart (second figure in the OP)?" If the answer is not immediately obvious to you then you need to keep working on what the charts mean.
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.
You shouldn't need to "doubt", it's obvious that they made a mistake. It makes no sense to anchor your projections on the temperature record for a particular year. The fact that you think Tom's chart "looks very similar to the draft IPCC chart" means you haven't understood the fact that by comparing trends alone Tom has completely sidestepped the issue.
If you really think you're onto something, then to prove it you should be able to do so using either Tom's chart or Tamino's. If you cannot, and you cannot say why Tom's chart or Tamino's chart do not support your claims, then you need to think a little bit more.
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Tom Curtis at 12:40 PM on 8 October 2013A rough guide to the components of Earth's Climate System
One Planet Forever, I like graphs because they convey quantities (approximately) very quickly. In that context, the 97/98 El Nino was not a super El Nino. It was only the fifth largest on record. It had the misfortune of not coinciding with a major volcanic eruption (unlike the largest), and of occuring in a time of elevated global temperatures (unlike the other four stronger El Ninos). 2010 was so weak an El Nino that it almost qualified as a La Nina.
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One Planet Only Forever at 12:28 PM on 8 October 2013A rough guide to the components of Earth's Climate System
John Mason,
I am not a fan of unquantifiable terms like "Super vs. Strong" to indicate a difference. As an engineer I tend to prefer the more precise presentation of differences. The clarification of El Nino strengths could be made by saying the 1997/98 event was significantly stronger than the 2009/10 event and referring the reader to the NOAA ENSO History. Even saying one was significantly stronger really doesn't "quantify the difference". And I think a reference directly to the NOAA ENSO history helps a person figure it out for themselves. It may also lead a person to explore more of the information that is avaialble. They might decide to open a few of the other links at NOAA.
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Tom Curtis at 12:20 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
SAM, there are several problems with your graph as is.
The largest problem is that you do not show the observed trend. If you are showing the natural variation of the data, you should also show the variation in the models for a fair comparison, ie, something like the inset of my graph @79. Alternatively, if you want to compare trends, compare trends!
If you also want to show the actual data, that is fine. The way I would do it would be to show the actual 1990-2013 trend for the data, properly baselined (ie, baselined over the 1990-2013 interval. I would then show the range and mean (or median) of the model trends baselined to have a common origin with the observed trend in 1990.
Doing this would ofset the origins of the trend comparison from the temperature series. That has the advantage of making it clear that you are comparing trend lines; and that the model trend lines shown are not the expected range of observed temperatures. Ie, it would get rid of most of the misleading features of the graph.
You may also want to plot the 2.5th to 97.5th percentiles (or min to max) of the model realizations set with a common 20-30 year baseline (either 1961-1990, or 1981-2000) to allow comparison with the expected variation of the data on the same graph. That may make the graph a little cluttered, but would allow comparison with both relevant features of the model/observation comparison.
As is, you do not compare both. Rather you compare one relevant feature of observations with the other relevant feature of models; and as a result allow neither relevant feature to actually be compared.
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Leto at 12:15 PM on 8 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Tom @ 118,
The 2.5th and 97.5th centiles would be of interest, given the traditional (but arbitrary) interest in the central 95% of a spread of values.
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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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