Reader Jimbo advises in WUWT Tips and Notes about something Dr. [Kevin Trenberth] wrote that makes you wonder what he’s talking about when there are so many uses of the word “prediction” in the IPCC AR4. It also makes me wonder what the Economist author Oliver Morton was doing running a blog by Nature. Is there no separation between science journalists and science journals?
Trenberth suggests that after the last report “…the science is settled or done and now is the time for action.”. Here we are six years later, and another IPCC report is coming out on that “settled science” and there is no successor to Kyoto. I wonder how many times the word “prediction” will be used in the upcoming AR5?
Jimbo writes: I stumbled on a quote from [Kevin Trenberth] over at the Nature Blog dated 04 Jun 2007.
Source: http://blogs.nature.com/climatefeedback/2007/06/predictions_of_climate.html
I thought I’d take a look because I was sure I had seen the IPCC use the word ‘predict’.
[My bolding throughout]
This subsection focuses on the few results of initial value predictions made using models that are identical, or very close to, the models used in other chapters of this report for understanding and predicting climate change.
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch8s8-4-11.html
—————–
…Some qualitative inconsistencies remain, including the fact that models predict a faster rate of warming in the mid- to upper troposphere which is not observed in either satellite or radiosonde tropospheric temperature records….
…The first IPCC Scientific Assessment in 1990 (IPCC, 1990) concluded that the global mean surface temperature had increased by 0.3 to 0.6°C over the previous 100 years and that the magnitude of this warming was broadly consistent with the predictions of climate models forced by increasing concentra- tions of greenhouse gases. However, it remained to be established that the observed warming (or part of it) could be attributed to the enhanced greenhouse effect. Some of the reasons for this were that there was only limited agreement between model predictions and observations,…
…However, models generally predict an enhanced rate of warming in the mid- to upper troposphere over that at the surface (i.e., a negative lapse-rate feedback on the surface temperature change) whereas observations show mid-tropospheric temperatures warming no faster than surface temperatures….
…..“historical” indicates the signal is taken from a historical hindcast simulation, “future” indicates that the pattern is taken from a prediction……
…Changes in the annual mean surface temperature were found to be highly significant (in agreement with previous results from Hegerl et al., 1996, 1997). The predicted change in the annual cycle of temperature as well as winter means of diurnal temperature range can also be detected in most recent observations….
…Estimation of uncertainty in predictions
The scaling factors derived from optimal detection can also be used to constrain predictions of future climate change resulting from anthropogenic emissions (Allen et al., 2000b). The best guess scaling and uncertainty limits for each component can be applied to the model predictions,……
… An example based on the IS92a (IPCC, 1992) GS scenario (whose exact forcing varies between models, see Chapter 9, Table 9.1 for details) is shown in Figure 12.13 based on a limited number of model simulations. Note that in each case, the original warming predicted by the model lies in the range consistent with the observations….
…The range is significantly less than one (consistent with results from other models), meaning that models forced with greenhouse gases alone significantly overpredict the observed warming signal….
…All but one (CGCM1) of these ranges is consistent with unity. Hence there is little evidence that models are systematically over- or under- predicting the amplitude of the observed response/ under the assumption that model-simulated GS signals and internal variability are an adequate representation (i.e. that natural forcing has had little net impact on this diagnostic)….
…Original model prediction under IS92a greenhouse+sulphate forcing…
…The SAR predicted an increase in the anthropogenic contri-bution to global mean temperature of slightly over 0.1°C in the five years following the SAR, which is consistent with the observed change since the SAR (Chapter 2). The predicted increase in the anthropogenic signal (and the observed change) are small compared to natural variability, so it is not possible to distinguish an anthropogenic signal from natural variability on five year time-scales….
http://www.ipcc.ch/ipccreports/tar/wg1/pdf/TAR-12.PDF
——————-
…During the early summer season, October to December, both models predict drying over the tropical western side of the continent, responding to the increase in high-pressure systems entering from the west, with MM5 indicating that the drying extends further south and PRECIS further east….
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch11s11-2-3-2.html
——————-
…The IPCC commissioned a Special Report on Emissions Scenarios (SRES). Four “marker scenarios” representing different world storylines are used to estimate emissions and climate change to 2100 (IPCC, 2000). Table 16-1 summarizes these climate projections for the polar regions. In almost all cases, predicted climates are well beyond the range of variability of current climate. …
http://www.ipcc.ch/ipccreports/tar/wg2/index.php?idp=599
——————-
…The chemical and physical properties of aerosols are needed to estimate and predict direct and indirect climate forcing….
…Modelled dust concentrations are systematically too high in the Southern Hemisphere, indicating that source strengths developed for the Sahara do not accurately predict dust uplift in other arid areas….
…For summertime tropopause conditions the range of model predictions is a factor of five for sulphate. The range of predicted concentrations is even larger for some of the other aerosol species. However, there are insufficient data to evaluate this aspect of the models….
Here’s Jim Sallinger’s latest prediction for NZ:
http://www.stuff.co.nz/dominion-post/news/9085224/Capitals-balmiest-winter-on-record
Is Prof. Trenberth aware of the difference between his a**e and his elbow?
[Language. Mod]
In some cases, there is an acceptable rebuttal, because the IPCC is referring to the predictions of others. However, that only applies in a few cases. In others, it is clear that any reasonable reader of the document would conclude that the IPCC is making predictions.
Hey Trenberth! It looks like someone has found the missing predictions you say are not there! Too bad you can’t find your hotspot.
Clearly Trenberth’s hotspot is midway between the cheeks he can’t find with both hands.
That had crossed my mind until I saw this:
SAR is short for ‘Second Assessment Report’ of the IPCC.
There are more uses of the word ‘prediction’ used by the IPCC in other pages. I don’t have 12 hours to spare. 🙂
Now you are jamming, Anthony. Trenberth must be held accountable for what he has said or written about prediction and we must not allow him to get away with casual denials of his record.
Perhaps the most important word in scientific method is ‘prediction’. To this day, no one who is an Alarmist, such as Trenberth, has set forth a consistent position on the role of prediction in climate science and no Alarmist has shown a consistent use of the word. One reason is that they are terrified of falsification. Another is that they are unconcerned with showing some relationship between their “theories” or “models” and reality. They are totally averse to assessing their ideas in light of the real world.
I seem to recall that Keith Trenberth has also stated that he is a nobel laureate. So is it surprising that he does not know the difference between projection and prediction?
I have been told many times that climate scientists don’t make predictions. So I was wondering about these. Do you think the word kinda slipped through by mistake?
I predict he won’t change his claim about no predictions.
Perhaps all these “predictions” are taken out of context.
Technically, Kevin is correct. They are projections and not predictions. It’s not surprising that a political body like the IPCC uses the words interchangeably thinking they are the same. Kevin, though, seems to be calling this out to be -er- cleverly evasive and not in the spirit of setting the facts straight.
Seems to me they are splitting hairs of the length and width found on the anal end of a gnat.
There’s a big difference between the terms, Pamela.
An example of a projection: It’s cloudy so it might rain soon.
An example of a prediction: It will rain soon.
The latter can be verified while the first can’t be.
The article refers to him as Kenneth. I thought his name was Kevin This is the same Trenberth who lost the heat, right?
Any suggestion that the IPCC and GCMs claim to make merely “what-if projections” and not “predictions” is utterly dishonest. After all, if these “projections” were merely that, then what would be the point? (For the benefit of those who don’t understand what a rhetorical question is: That was one.)
Dear Mr Watts,
To be honest with you, I think this is a non-issue. I see no evidence of dishonesty in Trenberth’s words. Just look beyond the region you have marked yellow. You’ll see he defines conditional statements (“what if”) as distinct from predictions, and says all statements in the reports are conditional, e.g. based on certain possible emissions scenarios. I’m not sure this last strict assertion is true, but I don’t see that his credibility depends on it.
Anyway, this distinction certainly explains some of the statements you cite and requires you to check some of the others for their context. For instance:
“The IPCC commissioned a Special Report on Emissions Scenarios (SRES). Four “marker scenarios” representing different world storylines are used to estimate emissions and climate change to 2100 (IPCC, 2000). Table 16-1 summarizes these climate projections for the polar regions. In almost all cases, predicted climates are well beyond the range of variability of current climate.”
The report makes quite clear that this is a prediction within a scenario, so it does not conform to Trenberth’s momentary definition of the word. The report evidently uses the word prediction more liberally, which is quite acceptable. I agree that maximum clarity would be achieved if everyone agreed what “prediction” means. But I have no problem understanding Trenberth here, as he explains himself properly.
Some of your citations also refer to history:
“The first IPCC Scientific Assessment in 1990 (IPCC, 1990) concluded that the global mean surface temperature had increased by 0.3 to 0.6°C over the previous 100 years and that the magnitude of this warming was broadly consistent with the predictions of climate models … ”
This is a ‘prediction’ of the past, a retrodiction. Evidently, Trenberth isn’t considering these. He’s talking about the future. The “what if” principle, which includes wildly different scenarios, doesn’t apply to the recent past, because we know past emissions scenarios quite well. We also have a fair idea what the sun and other forcings have been doing over the last century.
Cheers,
Thomas
It all makes sense. For a scare story all you need is a “projection”.
To do something usefully scientific you need a “prediction” that turns out to fit the facts – much harder and not necessary if all you want to do is produce scare stories.
It seems like a deliberate strategy: immunize against falsification by making a pro forma statement that any “predictions” are really just projections, and then using the term (and the meaning and context) to try and force political action anyway. Lies, damned lies, and predictions.
You make a good point but it does make you wonder why they call the IPCC’s works the ‘Gold Standard’ when the IPCC says:
They need to get their act together. How did this slip through the peer reviewers I wonder? Or did they actually used to predict then changed tack? If yes then Trenberth is wrong to say:
@Graphicconception and David, UK: How are you supposed to predict if it will rain in three months if you don’t know what the humidity will be. It is perfectly sound that the IPCC uses projections, because it doesn’t know what the emissions will be. Anything else would be too simple. And to answer your rhetorical question: If, as a young man/woman you you are told that you will probably produce children if you have regular, unprotected intercourse, that is a very useful conditional statement. I am mystified how you can generalise them as being pointless.
(You’ll have to imagine the accent)
“Pree-dictions?! We don’ make no steenkin’ pree-dictions!”
Well, I guess I didn’t read what I just read.
Semantics aside, what does the average person believe the IPCC is doing?….PREDICTION!
DAV:
At August 25, 2013 at 1:32 pm
http://wattsupwiththat.com/2013/08/25/trenberths-ipcc-claim-of-no-predictions-by-ipcc-at-all-refuted-by-ipccs-own-words/#comment-1399866
you wrote
More than a decade ago scientists from around the world were invited to give a briefing on the science of climate change at the US Congress in Washington, DC. The briefing was on the science of climate change, and it consisted of three Sessions each with a Chairman who was one of the invited speakers. Fred Singer chaired the first session, I chaired the second, and David Wojick chaired the third.
Questions were invited after the presentations of each session. Attendees included politicians and scientists from US Agencies.
Following my presentation one questioner made a rather long statement which contained no clear question. I replied,
“Sir, I agree much of what you say, but not all. For example, you say “The IPCC does not make predictions”. The IPCC says the world will warm. I call that a prediction.”
The questioner did not respond.
Richard
Like all religious texts, most of the ipcc language can be interpreted differently at different times and by different people