Arguments
Recent Comments
Prev 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 Next
Comments 41451 to 41500:
-
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?
-
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.
-
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.
-
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!
-
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.
-
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.
-
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.
-
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).
-
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?
-
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.
-
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.
-
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.
-
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.
-
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?"
-
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.
-
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!
-
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.
-
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.
-
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).
-
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?
-
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.
-
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.
-
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.
-
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.
-
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.
-
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.
-
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”.
-
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.
-
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.
-
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).
-
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).
-
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?
-
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.
-
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.
-
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.
-
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.
-
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!
-
Klapper at 16:41 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
@Tom Curtis #79:
What is your rationale for continuing to use the CMIP3 data instead of the more recent CMIP5 as the model reference?
-
Tom Curtis at 16:12 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
SAM @77, I believe what you were trying to produce was an honest comparison between observations and the CMIP 3 (AR4) model ensemble. Is that right?
Is that not fair? Can't you pick out the observations from the model runs? Isn't that rather the point! If you cannot easilly pick out the observations from the model runs, then the model runs have predicted the observations within the limits possible for stochastic processes (such as short term climate variations).
Of course, despite Rob Honeycutt's sage advice, you may be more interested in short term trends. Nothing in science dictates what you are interested in, regardless how futile for advancing knowledge. Of course, if you are interested in trends, compare with trends:
Doing otherwise is an apples and oranges comparison. The only justification I can think of for doing so is a deliberate intent to mislead.
You will now find a number of CMIP3 - observation comparisons produced by me above. All are done with based on sound methods of comparison; and none show a significant divergence between models and observations. It is only by doing illegitimate comparisons - by poor baselining, by comparing individual observations to trends, etc - that you can create the impression that something is radically wrong with the models. The effort various deniers are expending on justifying such illegitimate comparisons is, IMO, a fair mark of how little regard we should have of their opinion.
-
One Planet Only Forever at 15:06 PM on 7 October 2013A rough guide to the components of Earth's Climate System
The list of Latent Heat items should include the Heat of Fusion to melt ice.
It takes 334,000 J to melt 1.0 kg of ice with no temperature increase occurring.
If snow and ice volumes fluctuate about a steady or unchanging normal amount of total frozen water then the Heat of Fusion simply goes into ice to melt it and comes out of water as it freezes with no net imbalance. However, if the volume of frozen water is trending down there is a capture of energy into the water without any increase in temperature. If energy is coming in and is creating a net melting of ice, when the rate of loss of ice reduces the energy that was going into creating less frozen water would show up as increased heat content of other parts of the system which would experience rising temperatures.
Also, it may help to add a section that describes the way the Earth's energy will rebalance. There are many factors that can affect how rapidly the global average surface temperature increases (including a net melting of ice), but the expectation is that excess CO2 and other GHG's will eventually rebalance in a state that will have a higher global average surface temperature.
Of course the global average surface temperatures should be measured and tracked as the average of 30 years or longer, since there are many factors that could significantly affect the global average surface temperature for a short period of time. Most of those effects are reasonably averaged into a 30 year period. The 30 year averages of global surface temperature based on the NASA/GISS data set are currently increasing at about 0.17 degrees C per decade, in spite of the lack of any annual average temperatures since 1998 significantly exceeding the 1998 value. And though it is not really important, every new month of global average temperature is warmer than the month 30 years before. That is still likely to be the case when 2028 rolls around (it will be warmer than 1998), but it would be absurd for anyone to suggest we would have to wait until then to “prove anything”. The stronger claim to make is that until an El Nino event as strong as the 1997/98 event occurs nothing can be claimed about a “lack of comparative warming of global average surface temperatures (unless a significant volcanic eruption occurs at that same time of course)”
-
Rob Honeycutt at 13:47 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
StealthAircraftSoftwareModeler... There's a big problem with the Excel graph you've created. You're only looking at the trend. Modelers know they can't project short term (10-15 year) surface temperature changes.
I keep stating this over and over, but I'll say it again. Climate modeling is a boundary conditions experiment. You're treating like an initial conditions experiment.
Stealth, what you've done with your chart is to completely remove the boundaries established by the modeling. Thus, you've removed the most relevant aspect of the climate models.
Modeling is not about the mean. It's not about the trend (except >30 years). It's about the boundaries that are established by the range of model runs.
-
JasonB at 13:47 PM on 7 October 20132013 SkS Weekly News Roundup #40B
chriskoz #1,
The Australian system is actually not that complicated.
For the House of Representatives, voters number candidates in order of preference. If no candidate receives 50% of the vote, then the least popular candidate is eliminated and their next preferences are distributed as if they were first preferences — effectively asking "What would the outcome be if this candidate didn't run?" This process repeats until a candidate has 50%. That candidate may well have started out with a low first preference percentage, but the fact that they won in the end means that more than half preferred that candidate to the alternative.
The Senate is complicated by the fact that there is more than one position being filled and a "quota" of votes is required to be elected. (The House of Representatives method can be seen as a special case where there is only one position and therefore the quota is 50% + 1 vote.)
The Senate vote count proceeds in the same way as above when unpopular candidates are eliminated, but the wrinkle is that when a candidate has reached the quota and been elected, their voters' subsequent preferences are also reallocated in proportion to the "surplus" that the successful candidate had (so the second preferences of a really popular candidate will be worth more than the second preferences of a candidate that only just got over the line.)
In the case in question, the PUP candidate was elected because he had a quota and the Green's candidate did not. The fact that the PUP candidate received preference flows from similarly-minded organisations who are likely to be voted for by similarly-minded voters means that if you asked all of those voters who they would have preferred out of PUP and the Greens, they would probably pick PUP.
The "gaming of the Senate vote" that people are complaining about is related to the short-hand Senate voting system introduced by the Hawke government in the 80s. Traditionally you would have to number every candidate in order, just like you do with the House of Reps candidates. However, because there are so many more candidates in the Senate, Hawke introduced the "above the line" voting option, where you could simply put a "1" in the box above the line that belonged to the party you supported, and your ballot paper would be treated as if you had filled it out according to the template that the party had registered. (I normally vote below the line even though it takes a lot longer.)
In this particular election, there were quite a few surprising preference flows registered by the various minor parties, which might have meant that those voting for those parties might not have agreed with the order of the other parties had they bothered to look it up before the election.
In this case, however, the final Senate seat was a battle between the Greens and Labor anyway, so the outcome wouldn't make a difference to the Carbon Tax. PUP leapfrogged both to win the fifth seat thanks to some late flows from the Libs, Nationals, and Liberal Democrats, which have similar ideologies to PUP, so it seems the system worked in this case even if the outcome is undesirable.
It seems that Tony Abbott is going to get his way when the new Senators take their positions next year. It's also very unlikely that he would back down on his plan to "Axe the Tax" given the opportunity. The best we can hope for, it seems, is a major groundswell in support for doing something about climate change that paints the Libs as Luddites that caused us to miss an opportunity because their heads were firmly buried in the sand and unable to accept reality and forces climate change back onto the agenda at the next election. It's possible that having the country take a step back from having "solved" the problem will focus people's attention on it again. In addition, the fact that he's likely to get his way next year might mean it takes some of the heat out of the issue until then and avoids any attempt he might have otherwise made to get rid of it in the meantime. Until then, we'll just be getting on with the business of living with a carbon pricing scheme that is doing its job and not causing the end of the world, making most people wonder what all the fuss was about and hopefully making it easier to bring back in the future.
-
StealthAircraftSoftwareModeler at 13:16 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Moderator [DB] @ 39: I read the OP again and it doesn’t address my question @39 at all. The discussion in the OP is about the baseline is the location of zero on the Y axis scale. I want to know why the IPCC zoomed out so far and covered the actual temperature with messy spaghetti lines. So, I have gone off and gathered raw data from original sources and plotted it. This is my first time trying to post an image -- hopefully it works.
I have downloaded HADCRUT4 (baselined 1961 to 1990) and plotted the data in Excel. I have also plotted a center weighted 5 year moving average. I then have digitized the original IPCC AR3 and AR4 model projections from the IPCC’s website and plotted those in the chart. Note that both the AR3 and AR4 projection are aligned to the year they were projected – 1980 for AR3 and 1990 for AR4 – and at the location of the 5 year moving average for those years. This aligns the trend projections of AR3 and AR4 to the center of the HADCRUT data for their respective years. While the chart speaks for itself, it is clear that the actual temperatures generally run a little cooler than model projections. In 2005 the actual temperatures have clearly departed from model projections.
Moderator Response:[DB] Please constrain image widths to 450.
As this thread concerns the AR5 projections, please take your course of inquiry to this discussion of the TAR and the AR4 IPCC projections.
-
Klapper at 12:04 PM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
@Tom Curtis #72:
You pre-empted my next post somewhat since I was going to agree the 1990-1992 to 2006/now trends didn't prove much other than the models overcool during major volcanic episodes and we should instead focus on McIntyre's 1979 to 2013 model vs observations analysis. Since you've basically done the analysis from 1975 showing the same thing as McIntyre we can skip the argument of whether the models run too hot or not.
Now we can discuss the significance of the models running too hot. I think the models run too hot since they have tuned their feedbacks to radiative forcing during only the warm phase of ocean cycles. (-snip-).
(-snip-).
I'll leave the discussion of Figure 1.4, the politics and personalities of global warming to others (for today anyway).
Moderator Response:[DB] Sloganeering snipped.
-
John Hartz at 11:31 AM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
@Tom Curtis #73:
Not exactly. I'm trying to draw attention to the fact that manmade climate change is real and is happening now.
Unless we have a time machine, we'll never know how well the models perform their primary task, i.e., long-range forecasts say to the year 2100.
In the meantime, we're wasting valuable time by arguing over minutiae.
-
Tom Curtis at 11:30 AM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Further to the discussion above, here are the observed trends from 1990 to current relative to the CMIP 3 (AR4) trends from 1990-2015:
On the left hand side, the number of models in each 0.025 C/decade bin is shown, with values shown being the upper limit of each bin. It should be noted that observed trends are also assigned to a bin.The trend of the GISS record is 0.152 C/decade, resulting in it being assigned to the 0.15-0.175 bin. It is not shown as having a 0.17 C per decade trend as might be assumed from casual inspection of the graph. In a similar manner, the HadCRUT4 and NOAA records are shown in a bin, rather than having trends as low as might be assumed from a casual inspection.
On the right hand side, the 54 member ensemble mean, maximum, minimum and mean plus or minus two standard deviations with are shown with the actual observed trends. Observed trends place by hand, so are only approximately accurate.
The key point for this discussion is that the 2nd order draft version of Fig 1.4 shows the observed data falling below the AR4 envelope, suggesting visually that the trend would fall below the minimum value in the ensemble (green line), whereas in fact they lie well above that value. That is shown much better in the final draft version of 1.4.
Obfusticate as much as they like, the deniers cannot alter the fact that the 2nd order draft version of figure 1.4 was a misleading graphic for comparing models and data for AR4, due primarilly to poor baselining. The final draft version corrects the baseline issues and is far superior.
-
Tom Curtis at 10:36 AM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
John Hartz @71, are you trying to draw attention to the fact that the models are underestimating some effects of global warming; and that assessing the validity of the models base on just one number (GMST) rather than on their total output is rather facile? If so, I agree with you. Personally I think there is little doubt that the CMIP5 models perform worse than the CMIP3 models with regard to GMST. It does not follow that the models are worse. To make that assessment we must consider the whole range of model data.
-
Tom Curtis at 10:32 AM on 7 October 2013Why Curry, McIntyre, and Co. are Still Wrong about IPCC Climate Model Accuracy
Klapper @70, yes. The models currently run hotter than observations. Specifically, taking the trend since 1975, the observations run 16.5% (HadCRUT4, GISS) to 21.5% (NOAA) cool compared to CMIP3, and 27.6% (HadCRUT4, GISS) to 31.9% (NOAA) cool compared to CMIP5. Alternatively expressed, the observations run 0.64 (HadCRUT4, GISS) to 0.84 (NOAA) standard deviations cool compared to CMIP3, and 1.29 (HadCRUT4, GISS) to 1.49 (NOAA) standard deviations cool compared to CMIP5.
Do you think these facts falsify the models? Even though observations are running within 2 Standard Deviations of the ensemble means?
Alternatively, do you think that if temperatures run 15% cooler than AR4 projections for BAU, that is sufficient lee way to not have to do anything about global warming (the effective current policy setting in most of the world). That the difference between 3.65 C and 4 C at the end of the century makes all the difference in the world?
Or more to the point (ie, the actual topic under discussion), do you think the final draft version of figure 1.4 inaccurately represents the relationship of these trends? Or do you think it is more accurate to show the 1990-2015 trend with observations lying below the model envelope (as shown by Fig 1.4 in the 2nd order draft), even though with the same baseline the observations (and trends) lie well within the two sigma envelope for AR4 (as the final draft shows)?
-
Jim Eager at 10:25 AM on 7 October 20132013 SkS Weekly Digest #40
First, the difference between what the models predicted and observed temperatures is not "huge", as observed global mean temperature has been well within the projected range of the model ensembles. Try reading the approriate post: skepticalscience.com/curry-mcintyre-resist-ipcc-model-accuracy.html
Second, that observed global mean temperature has been in the lower portion of the projected range of the model ensembles has been due to natural variability, e.g. 1) a string of neutral or relatively strong la nina years and the total absence of a strong el nino year, and 2) an unusually deep and long solar minimum and unusually weak solar max.
Prev 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 Next
