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Eugine_Nier comments on Separating the roles of theory and direct empirical evidence in belief formation: the examples of minimum wage and anthropogenic global warming - Less Wrong Discussion
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Comments (65)
Well, I constantly see headlines that say the opposite, i.e., about places with record cold.
Also, what do the headlines mean, do they mean hottest in some particular place, or hottest global average? If the former, statistically you'd always expect temperatures to hit a record somewhere; if the latter, see my remark in the parent about how hard it is to compute "average temperature".
Also, on the occasions when global warming believers make independently verifiable predictions with definite dates they inevitably fail to occur as shown by the fact that Britain still has snow and Manhattan isn't under water.
Yes, some global warming believers have made predictions that have been falsified, but "inevitably fail to occur" is wrong. Here's a counterexample.
Julia Hargreaves does a lot of work evaluating predictive climate models, and her conclusion is that there are reliable models for predicting broad global climate response to anthropogenic forcing, but we don't currently have trustworthy predictions at the sub-continental scale. So I think it is appropriate to be skeptical about confident and precise predictions about what will happen in particular parts of the world.
The only example of a successful prediction in your article is a rise in "mean surface temperature" which as I mentioned in the grand-parent is not hard to fudge, heck I also linked to data that gives opposite conclusions in the grand-parent. The rest of said article reads like an attempt to (preemptively?) explain away failed predictions.
And yet for some reason all said predictions fail in the same direction.
Your evidence that the weights used to calculate mean surface temperature are fudged in favor of global warming is a link to the "VERY ARTIFICIAL correction" in the CRU code. But that correction was not applied to global mean surface temperature data. It was applied to historical tree-ring data in order to account for the discrepancy between recent temperatures calculated using tree-ring data and recent temperatures calculated using other means known to be more reliable.
Uncorrected, the tree ring data suggests a decline in temperatures beginning around 1940 and continuing to the present. We have plenty of evidence that this is not in fact correct from actual thermometer-based records, so the correction was applied as a proxy for the unknown cause of this recent divergence. Now this does perhaps "hide" the fact that tree-ring records are not trustworthy (although CRU published papers explicitly mentioning this supposedly hidden fact), but it does not show that actual thermometer-based temperature records are being artificially tampered with to produce global warming.
It seems to me that ESR misrepresents this fact (although perhaps he was unaware of it) when he characterizes the "correction" as being applied to "Northern Hemisphere temperatures and reconstructions", with no mention of tree rings.
And I am very skeptical that temperature records over a very recent decade (the basis for the article I linked) have had significant external weighting applied to them to "fudge the results". The problem of changing station locations may necessitate differential weighting over longer time frames, but just from 2002 to 2011? I don't believe you. If you have any evidence suggesting that this is what is going on, I'm interested to see it.
It doesn't read that way to me.
Probably due to politically motivated reasoning. I'm not denying that climate change activists often make exaggerated and unwise predictions about the impact of climate change, especially in the popular media. I am denying your claim that the predictive record of climate science is entirely negative. There are climate models that have done pretty well, at least when it comes to global trends.
Here is the article I linked to above. Note that it implies a different conclusion about recent temperature trends. Do you have any evidence for preferring your letter to the editor over the article Eric discusses besides it confirming your pre-existing belief?
Have you even read the article you linked to? Here are the first four sentences:
Not sure what you mean by "different conclusion". Both papers are based on the exact same data (the HadCRUT4 data set). There is no conflict between the articles that I can see. Curry's paper is about discrepancies between the data and the CMIP5 model simulations. The paper I linked is about the success of the HadCM2 model. It also says some stuff about the CMIP5 model, but as far as I can tell it doesn't say anything that is inconsistent with what Curry says.
So I don't "prefer" one article to the other. It seems to me that both articles are making perfectly valid points. Are you sure you're not falling for "arguments are soldiers" thinking? Just because I posted evidence that climate predictions don't "inevitably" fail doesn't mean I think that all climate model predictions are accurate at a 2% confidence level.
Again, not sure what you're talking about. Why do those four sentences read like an attempt to explain away false predictions? The whole point that the authors are making is now that we do have independent observations taken over one and a half decades, we can evaluate the success or failure of models constructed in the mid-90s.
http://xkcd.com/1321/ (SCNR).
More seriously, are you implying that any increase in the variance is irrelevant so long as the mean doesn't change much?
Who predicted that Britain would no longer have snow or Manhattan would be under water by 2014?
I never said anything about an increase in variance, temperature records haven't been around long enough for it to be hard to find record setting temperatures somewhere. Also, I notice you're shifting your hypothesis from "temperatures are rising" to "variance is rising".
As for the argument in the linked comic, when wine grapes can be grown in England and Newfoundland, as was the case during the medieval warm period I'll start taking arguments of that type seriously.
The Climatic Research Unit for the no more snow in Britain. The Manhattan underwater one (or at least the West Side Highway) is Jim Hansen.
Regarding the wine point, it is doubtful if wine grapes ever grew in Newfoundland, as the Norse term "Vinland" may well refer to a larger area. From the Wikipedia article:
Also, wine grapes certainly do grow in England these days (not just in the Medieval period). There appear to be around 400 vineyards in England currently.
Reading your referenced article (Independent 2000):
Clearly the Climatic Research Unit was not predicting no more snow in Britain by 2014.
Regarding the alleged "West Side Highway underwater" prediction, see Skeptical Science. It appears Hansen's original prediction timeframe was 40 years not 20 years, and conditional on a doubling of CO2 by then.
Yes, but some googling suggests that average snowfall in England hasn't changed very much over the 2000s, which doesn't seem consistent with the linked article.
"Over the 2000s" is certainly too short a period to reach significant conclusions. However the longer term trends are pretty clear. See this Met Office Report from 2006.
Figure 8 shows a big drop in the length of cold spells since the 1960s. Figure 13 shows the drop in annual days of snow cover. The trend looks consistent across the country.
I think the first question here is whether we have reached agreement on the forecasts being wrong, not what excuses should be made or conclusions drawn from said wrongness.
Yes, I'm sure they were, and that those were the basis for the mistaken prediction. Your point?
I think we have agreement that:
A) The newspaper headline "Snowfalls are now just a thing of the past" was incorrect
B) The Climatic Research Unit never actually made such a prediction
C) The only quoted statement with a timeline was for a period of 20 years, and spoke of heavy snow becoming rarer (rather than vanishing)
D) This was an extrapolation of a longer term trend, which continued into the early 2000s (using Met Office data published in 2006, of course after the Independent story)
E) It is impossible to use short periods (~10 years since 2006) to decide whether such a climatic trend has stopped or reversed.
I can't see how that counts as a failed prediction by the CRU (rather than the Independent newspaper). If the CRU had said "there will be less snow in every subsequent year from now, for the next 20 years, in a declining monotonic trend" then that would indeed be a failed prediction. However, the CRU did not make such a prediction... no serious climate researcher would.
From the article:
Does heavy snow cause chaos in England now?
Is snow a 'very rare and exciting event' in England now?
If we asked them, would they not know first-hand what snow is, anymore than they know first-hand what wolves are?
You can't?
What's the date?
By your reaction, and the selective down votes, I have apparently fallen asleep, it is the 2020s already, and a 20-year prediction is already falsified.
But in answer to your questions:
A) Heavy snow does indeed already cause chaos in England when it happens (just google the last few years)
B) My kids do indeed find snow a rare and exciting event (in fact there were zero days of snow here last winter, and only a few days the winter before)
C) While my kids do have a bit of firsthand knowledge of snow, it is vastly less than my own experience at their age, which in turn was much less than my parents' experience.
If you are a resident of England yourself, and have other experiences, then please let me know...
I notice you're shifting your hypothesis from ‘it's not getting any warmer than in the 1990s’ to ‘it's still not as warm as it was in the 1000s’. ;-)