Hi ED
Sorry for the delay. I watched both Corbett videos, and wasn’t very impressed with his signal to noise ratio. Lots of sly insinuation, a few errors and some fairly mundane observations. I’ll lay out some of my thinking below in a bit more detail. I’ll try to be comprehensive.
As far as I understand his issues, they are:
First set of issues
- determining a true, exact, average global surface temperature is hard
- weather station data is not evenly distributed around the globe
- trying to merge different data from different stations is tricky
- this merging requires a lot of statistics, and other adjustments
So far, that’s all true, and seems pretty reasonable to me. This is not an easy data problem, and raw data of any kind often requires processing and calibrating before you can use it for anything. All of the people involved would agree that this is an approximation of the global average temperature. That approximation gets better over time as more stations are added, interpolation and other data cleaning and calibration techniques improve, etc. But it’s still only an approximation.
The question really is, does the approximation calculated by the teams in their own ways actually map onto the observed physical world in some testable way?
Interestingly, Corbett never asks that question - by far the most important question to ask. He just ignores it.
Moving on, he further states that:
Second set of issues
- the satellite measurement of temperature is much more reliable than surface or sea measurements
- these different records don’t agree and the satellites show less warming
- in fact the satellites show a pause in warming that lasted 18 years
- neither surface measurements nor sea measurements show this pause, so (as he deems then less reliable) they must be wrong
As far as I know, its simply not true that satellite measurements are more reliable. Every system has its issues. Combining multiple satellites’ data into a global temperature record is just as tricky as surface measurements. In fact, most scientists that I’ve read believe that the surface sensors are more reliable than the satellite data. Whatever, we have both and are using both. As a general rule, I would argue that if two out of three data sets show one thing, and the third something else, my first inclination is to look at the third data set very closely and wonder what went wrong. Again, an obvious point that seems to have gone over Corbett’s head. As it turns out, when they did look closely at the satellite data, there were things that had not been corrected for, so it was that data record that needed updating.
It’s true that satellite data shows a bit less warming than surface data (even after the corrections) but the overall picture is pretty similar. Corbett gets all hot under the collar about data corrections and adjustments, but I’ll come to that in a moment.
Corbett spends a lot of time on this 18 year supposed pause, but doesn’t explain what the significance of such a pause might be. Neither does anyone here on 5F, incidentally. The pause takes up a good chunk of his videos, and is worth thinking about.
Let’s assume the pause was true (its generally thought to have been an artefact caused by problems in orbital drift and calibration of new satellite sensors launched in 2000 btw, but let’s come back to that later). My question is, so what? The climate is a complex, evolving system. I’m sure that you can find a decade (or even 18 years) here or there which looks to be off-trend. The question is what happens long term. Has global warming now stopped for ever? Has the mechanism driving global warming somehow changed?
So what did happen after the 18 years? The warming trend continued. As it is continuing today. This is true even if you reject the most recent adjustments and corrections to the data record. The warming trend picks up again, and continues as before even in the data record that shows the pause. And remember that it was only one record out of three that indicated a pause in the first place (and from one group out of 4)
What, then, was the special significance of those hallowed 18 years? Absolutely nothing, as far as I can see. It’s just a nice, fat red herring, like arguing about the centering of a PCA analysis years after its been shown to have had no significant effect.
So let’s not waste any more time pondering the pause, or dramatically accusing scientists of trying to hide the pause or whatever. The pause is utterly irrelevant to the main points of climate change.
Moving on. These last set of concerns seem to really get Mr C all upset and suspicious:
Third set of issue
-
All the datasets are continually edited, updated and otherwise changed
- These updates look sneaky and suspicious
- The updates all seem to go in one direction - cooler in the past, warmer in the present
- If you remove the updates from the record then all of global warming disappears
- ergo there is no proof the planet is warming and the data record is unreliable.
This is where I got really disappointed with Corbett’s analysis, and it became clear that he was more interested in pushing propaganda than getting to the truth. A lot like off-guardian in their approach to science, in fact.
The data are updated very regularly, that’s true. Each time it happens there is a public statement explaining what was done and why. There is also a published article alongside. The data is publicly available (as is the previous version) fir anyone who wants to check it out.
So if someone like Corbett, who is clearly a smart chap, wanted to investigate whether bogus changes were being made to the data sets, its a straightforward (though maybe not easy) matter to look at the changes made, examine the rationale, look into the reasons and the consequences, maybe canvas some opinions from other data scientists and then let your audience know if you think that overall the changes are warranted and make the analysis more accurate, or are part of a nefarious scheme to mislead.
He didn’t do any of that. He just casually insinuates fraud, but is careful not to say that outright. Lots of flipping between pictures saying “isn’t that interesting?”. Come on Corbett, you can do better than that!
He makes a big deal about the fact that as the record gets adjusted, it more clearly shows a warming trend.
So what?
If the world is warming as a result of more CO2 in the atmosphere, then this is what you would expect to see. As you get better data, you see the trend more clearly.
If you want to show data fraud, then you need to present at least some evidence for that. Given all the adjustments are made in full view of the public, he should be able to find some evidence. There are precisely zero pieces of evidence for fraud in his videos…
And then he makes some points that are just plain wrong. In actual fact, over the data record, just as many adjustments have been made that reduce the trend as increase the trend.
In actual fact, if you take the raw global data without all the adjustments that have been made, the global warming trend doesn’t disappear and is just as visible.
And so we come to his final point: you can’t trust the data, its all been manipulated, there is no signal for warming.
What a foolish thing to say. I mean, seriously. If he had thought to ask himself the big question that I asked right at the beginning he would have seen how foolish this conclusion is.
Why is it, do you think, that scientists are making these Herculean efforts to construct robust and accurate temperature datasets?
Because there is evidence of unprecedented global warming happening all across the planet.
- ice caps are melting
- sea levels rising
- extreme weather patterns increasing
- ocean acidification
- bird migratory patterns changing
- massive crop failures due to “heat domes”
- permafrost melting
Etc etc etc etc etc etc etc etc
And all the time CO2 in the atmosphere is increasing.
The creation of the global temperature scale is not the proof of global warming, its an effort to understand the observations all around us.
Corbett is so blinkered by his desire to cast doubt on the statistics that he’s missed the entire point.
So, overall I’m not impressed with Corbett. Nor Monckton. Nor McIntyre. Nor Rancourt.
And yes, I have spent time listening to them, reading them, and thinking about them.
Which is a hell of a lot more than I can say for some who are “discussing” this issue.
Hope you found some of this interesting and maybe useful.
Cheers
PP
