Bishop Hill Apples, oranges, whatever...
Jul 30, 2015 Climate: Models Climate: Surface A new paper by Kevin Cowtan et al claims that the divergence of models and observations is not as big as we thought.
Global mean temperatures from climate model simulations are typically calculated using surface air temperatures, while the corresponding observations are based on a blend of air and sea surface temperatures. This work quantifies a systematic bias in model-observation comparisons arising from differential warming rates between sea surface temperatures and surface air temperatures over oceans. A further bias arises from the treatment of temperatures in regions where the sea ice boundary has changed. Applying the methodology of the HadCRUT4 record to climate model temperature fields accounts for 38% of the discrepancy in trend between models and observations over the period 1975-2014.
It sounds a bit odd to me, but I don't have a copy as yet, so I'm going to hold off further comment for the minute. One assumes though that even if the findings are sound the divergence of satellite temperatures from the models is unaffected.
Bishop Hill
Thanks to readers who have sent the paper along. Here's what the authors have done:
Global averages of the observational temperature records are typically compared to near surface air temperature from an ensemble of climate model simulations...most studies have used the surface
air temperature field from models rather than blended land-ocean temperatures...A true like-with-like comparison would involve blending the air and sea surface temperature fields from the models in a manner consistent with the observational records. The purpose of this work is to evaluate the impact of comparing air temperatures from models with the blended observational data, and to establish guidelines for the determination of blended temperature comparisons.
This seems unexceptionable to me.
Reader Comments (71)
Eli, McKitrick, not a climate scientist, has a far better track record than the climate science experts.
Based on past performance, why would it be logical for an impartial jury to prefer Cowtan, even with his acceptance of previous flaws in climate science?
"Ross seems to have great experience with making wrong assumptions."
Eli knows perfectly well that I published a correction to that paper, putting the old and new results side by side, as soon as the error was brought to my attention. And in the 10+ years since I have gone on to publish a series of papers on the same topic that were just as heavily scrutinized and the issue never came up again.
This is the difference between honest error and dishonest cheap shots. After all this time Tim Lambert has not updated his post to reflect the published correction. He even disabled comments a decade ago so no one else can point to the correction. Eli continues to link to the post also without pointing to the correction. I leave it up to the readers to draw their own conclusions about Eli's integrity.
Jul 31, 2015 at 6:01 PM | Ross McKitrick
It looks like Eli's got the integrity of a Wabbit.
does anyone actually pay attention to anything that comes out of the university of york ? it is full of alarmist arseholes in differing fields. i get the impression cowtan is going to end up with similar credibility to callum roberts of "less than a hundred mature cod in the north sea" infamy.
the place is a toilet full of whackjobs and goons that could not get tenure anywhere else.
Ross McKitrick wrote:
"(4) The big change in the discrepancy (Fig 4b) comes from using updated forcing data from Schmidt"
Just to clarify, when Cowtan et al (2015) refers to "updated forcing data", he really means "adjusted forcing data". And IMO Schmidt's volcanic adjustment, the largest component, is likely excessive.
Ross McKitrick has form when it comes to arithmetic blunders, and the angle/radian confusion is but one example.
"So is the 38% of the discrepancy to be addressed by models being adjusted to run cooler or from adjusting the thermometers to measure higher? Or is this a declaration that models are not modelling what the the temperature records have measured?"
No. The authors did a standard AUDITING task and corrected the bad methods that others had used previously.
The Observations are SAT(surface air temp over land) and SST ( ocean temps)
the past the IPCC bungled the job. they used the wrong model outputs. The used modelled SAT (t2m) for the comparison.
When you do it right the difference between models and observations shrinks.
This is an important piece of work. If the answer had turned out differently people would be applauding the audit job
shub "So by this the authors argue that surface temperatures in climate models should be revised downward by the use of a blending method?"
No:
here is how science works. You have a model of reality. That model makes predictions about what observations will look like.
Then you compare model output to observations.
In the past the IPCC did this:
A) they took observations of SAT
B) they took observtaions of SST
They compared them to model outputs of
A) tm2
tm2 is the AIR TEMPERATURE at 2 meters.
Guess what?
That is the WRONG OUTPUT
So, cowtan and others decided to do it the right way
Modelled SAT versus Observed SAT
Modelled SST versus Observed SST
Turns out when you do it the right way the models suck less.
Is that simple fact so hard for people to grasp? I think the failure to grasp this is telling.
if the models sucked MORE as a consequence of doing it RIGHT, then bishop and others would be impressed.
So.
Acknowledge that they did it right.
Acknowledge that the models suck less than previously thought
and once you make that honest admission people can still argue other points. But its not debatable that the prior approach was simply wrong.
Its not debatable that doing it right narrows the gap.
put another way. the best argument skeptics have is nic lewis. better to just admit that they got this one right and go back to arguing Nics points. There is no credibility to be gained by dismissing Cowtans better approach.
"Guess what?
That is the WRONG OUTPUT
"
Ah - the most heavily scrutinised and peer reviewed document EVA, compiled and examined by the best experts available and no-one noticed they were using the wrong output from the models for 30 YEARS! Worse, they were claiming that models matched (the wrong output!) well, thus increasing their confidence the models were correct!
Well, who'd be surprised? After all, these are the same people who produced projected warming trends of decreasing strength in successive reports while screaming "it's worse than we thought!", so logic is not a particular strong point for them. Obviously, neither is data collection - look at all the corrections required, even to data from the last decade.
Bad data, continued use of wrong data, use of data "upside-down", faulty stats, bad projections, adjusting data to fit models - why would anyone doubt these "experts" except someone "anti-science", eh?
Anyone surprised (confidence in climate projections) <<< (shark #2s)?
So government climate policy worldwide is underpinned by total incompetence. Unfortunately politicians too are totally incompetent. "Blind leading the blind" comes to mind.
Mosh, sorry man, but don't mind me as I take your categorical assertions with a grain of salt.
First, it is somewhat implausible that surface air temperatures in the models heat up a lot when the underlying ocean surfaces don't. If they actually do, the models are that broken? Already a fail.
Second, it was a talking point for many years (I say was) that the global surface instrumental record anomaly closely matched the satellite record ups and downs. You can ask BBD, he used to post graphs arguing the same point over and over again. If global satellite tropospheric records match surface records well, model surface air temperatures ought to match instrumental surface records well. What's good for the real world is good for the models.
Third, and to me this is important, this is the typical Hausfather/Cowtan style of open-ended 'adjustment' where a mechanism is proposed and a change in measurement is derived that can neither be tested nor validated but has to be merely accepted. 'Not debatable', as you say. I'm less and less interested in this sort of thing. It's not science, it does not excite.
What sections and paragraphs discussed all this wrongness in the IPCC FAR, SAR, TAR, AR4 and AR5?
But they could at least clear the air by first starting with an apology for previous incompetencies. It doesn't have to be Japanese-style apology, or even a grovelling apology. Just an indication of self-awareness, and a genuine willingness to correct past mistakes. Not always easy, I know.
"Ah - the most heavily scrutinised and peer reviewed document EVA, compiled and examined by the best experts available and no-one noticed they were using the wrong output from the models for 30 YEARS! Worse, they were claiming that models matched (the wrong output!) well, thus increasing their confidence the models were correct!
Well, who'd be surprised? After all, these are the same people who produced projected warming trends of decreasing strength in successive reports while screaming "it's worse than we thought!", so logic is not a particular strong point for them. Obviously, neither is data collection - look at all the corrections required, even to data from the last decade.
1. so you admit that Cowtan got it right? yes or no, you want a debate? well, debate the issue.
2. The corrections required if you use ALL THE DATA are relatively small. the BIGGEST corrections
COOL THE RECORD. you want a science debate? start there.
Bad data, continued use of wrong data, use of data "upside-down", faulty stats, bad projections, adjusting data to fit models - why would anyone doubt these "experts" except someone "anti-science", eh?
1. Again, you get no debate from from me that science is riddled with flaws.
2. Cowtan did it right. Debate that. You cant. so lets agree that it is settled. he did it right
Anyone surprised (confidence in climate projections) <<< (shark #2s)?
"So government climate policy worldwide is underpinned by total incompetence. Unfortunately politicians too are totally incompetent. "Blind leading the blind" comes to mind."
1. So you admit that cowtan got it right. Or will you run away from that debate? you want a science debate?
lets start by debating whether the IPCC got it wrong or that cowtan got it right. You wanna defend the IPCC?
or defend Cowtan. your choice... debate the science.. you wont. Science question number one
how do you test a model? go!
2. Politicians are incompetent. please go tell them that cowtan did it right and that models are better than they thought
Clearly, rabbits in holes have no alternative but to continue digging.
Mosh, I find it surprising to see you affected by Single Study Syndrome. Anyway...since none of the authors is a stranger to the IPCC process, is this correction something they never ever thought about, before?
Steven Mosher, since 1995 we have been told that climate scientists got things right. We have been told that since their model output matched historical records, they had models that were trustworthy and could be relied upon for predictions of climate 100 years into the future.
Now you are saying that previously the model output matced the records, and everything was dandy. But recently, the model output has not matced the records. By decomposing the output, we now find a somewhat less serious discrepancy. So everything is dandy again.
Is this what you call science these days? What do you do when the decomposed output starts disagreeing more and more with the observations? Decompose more? Go back to the "previously correct answer"? How do you justify that you have found the right answer this time, when you have been telling us that you had the right answer all along?
How would you know?
And since you are screaming for "the debate" to be re-started (when it was settled/over/finished etc), would you be willing to admit that skeptics were right in saying that there has been something rotten in the state of climate science and that climate science would be well off listening to skeptics rather than fighting them all the way? Oh, I forgot. You probably already said that...somewhere....in some fashion....
What are you so afraid of?
@ Aug 2, 2015 at 2:22 AM | Steven Mosher
"Turns out when you do it the right way the models suck less. ..."
you forgot "at the moment"
in 5 years, "the right way" will suck just as much as "the wrong way" does now ...
and Cowtan et al. will have to find and even righter way ...
and so on ...
remember Comical Ali ? ... they will all end up Climatical Ali's" ...
At least 97% of climate scientists haven't been able to tell apples from oranges.
Geronimo, would that that were all.
http://judithcurry.com/2012/06/21/three-new-papers-on-interpreting-temperature-trends/#comment-211553
As Eli said Ross has form.