Bishop Hill More Curry
Sep 26, 2014 Climate: Models Another day, another Judith Curry paper. This time it's in Geophysical Research Letters and is concerns the much-neglected question of just how good climate models are at hindcasting:
The bulk of our knowledge about causes of 20th century climate change comes from simulations using numerical models. In particular, these models seemingly reproduce the observed nonuniform global warming, with periods of faster warming in 1910–1940 and 1970–2000, and a pause in between. However, closer inspection reveals some differences between the observations and model simulations. Here we show that observed multidecadal variations of surface climate exhibited a coherent global-scale signal characterized by a pair of patterns, one of which evolved in sync with multidecadal swings of the global temperature, and the other in quadrature with them. In contrast, model simulations are dominated by the stationary — single pattern — forced signal somewhat reminiscent of the observed “in-sync” pattern most pronounced in the Pacific. While simulating well the amplitude of the largest-scale — Pacific and hemispheric — multidecadal variability in surface temperature, the model underestimates variability in the North Atlantic and atmospheric indices.
Reader Comments (18)
What's up with the Bern Model?
This is almost on topic.
just how good climate models are at hindcasting:
there much better ‘after’ they been adjusted so that their initial results ‘ which turned out to be juke, are corrected for what happened in reality . But despite this their accurate enough to provide a good enough basis to spend trillions and make massive changes to people’s lifestyles on. HTH
I must have written:
Only in the last quarter of the last century was the correlation with temperature rise and CO2 rise good.
a hundred times on the Blackboard.
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Ignorant as I am, Kravtsov is new to me, but Curry, Wyatt, and Tsonis together impresses me tremendously and biases me unbearably. Now, on to the abstract.
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"these models seemingly reproduce the observed nonuniform global warming, with periods of faster warming in 1910–1940 and ....."
what actually caused the warming from 1910-1940??
"The bulk of our knowledge about causes of 20th century climate change comes from simulations using numerical models"
Hmmm. I don't think knowledge comes from simulations. I think you need the knowledge first, so you can create the simulations. This position is flawed.
Andrew
What's up with the Bern Model?
Sep 26, 2014 at 1:44 PM | Registered CommenterEuan Mearns
Apart from anything else that might be up with it, it has an impulse response that is nonphysically realisable.
I think that its impulse response was arbitrarily obtained by numerically fitting a sum of exponentials to the model's simulated results, even though a so-called box model cannot actually have such an impulse response.
One other thing that is up with the Bern model is that it is intrinsically incapable of being validated. As someone said, what comes out of an unvalidated model is an illustration of somebody's hypothesis - it is not evidence.
"Only in the last quarter of the last century was the correlation with temperature rise and CO2 rise good." --kim
Even a broken clock is right twice a day.
"The bulk of our knowledge about causes of 20th century climate change comes from simulations using numerical models"
"Hmmm. I don't think knowledge comes from simulations. I think you need the knowledge first, so you can create the simulations. This position is flawed." --Andrew
The position is flawed, but the statement is close to accurate, if you'll allow that knowledge can be either true or false or zero.
"Only in the last quarter of the last century was the correlation with temperature rise and CO2 rise good." --kim
Even a broken clock is right twice a day.
"The bulk of our knowledge about causes of 20th century climate change comes from simulations using numerical models"
"Hmmm. I don't think knowledge comes from simulations. I think you need the knowledge first, so you can create the simulations. This position is flawed." --Andrew
The position is flawed, but the statement is close to accurate, if you'll allow that knowledge can be either true or false or zero.
Euan, I posted this at your blog, but it seems to have disappeared into the aether:
"Its a bit strange that the model used to predict global CO2 has so little prominence on Google. Is no one interested in this?"
Well I am, Euan. But what is prominent on Google, and for what reasons, is something Google wouldn't tell you!
Something very interesting (IMO) in the carbon-cycle is actually happening right now (or the next 2-3 years). And I'm not referring to the new OCO-2 satellite.
The atmospheric 14C isotope experiment is reaching a critical point, where the measured 14C atmospheric level is approaching the same level as it was before the atmospheric weapons tests. This means the "natural" removal rate should become zero (or rather the exponential decay approaches zero and is lost in the noise). The ongoing human contributions of cold carbon should then drive the relative 14C levels below the previous base line by ongoing dilution, which several authors say is now the biggest influence on 14C levels.
As far as I know the best/latest data comes from the Jungfraujoch and Schauinsland measuring stations as reported by Levine, Kromer, Hammer, 2013.
Graphs from the paper here:
http://www.tellusb.net/index.php/tellusb/article/viewFile/20092/html/84582
To my eye, the data still looks (predominantly) like a single exponential decay when it should be accelerating downwards due to the rapid recent increases in human emissions. I assume the same authors will be publishing more in future. Lets watch and see if the models have got it right!
[The y-axis on those graphs I posted are incorrectly labelled as % when they should be "per-mill"]
It's almost a given that climate is fluid dynamic chaotic on decadal and also century time scales, given how the cycle time of ocean currents is about 800 years. Models are this a total joke when 90% of the dynamics is by nature unpredictable.
Typo: this > thus.
Is Ms Curry really confident the Chinese communist government were supplying accurate temperature data in the 1950s ? What was the air temp of the mid Atlantic in 1934 ?
Until recently, the met office was run by the MOD because weather data is highly sensitive.
Until researchers like Mann and those behind the Marcott 2013 bladeless input data hockey stick said to vindicate Mann are banned from academia and possibly arrested, even her own papers stand as highly dubious due to the entire field being utterly corrupt in even the very top journals Nature and Science, because every reference to contemporary climate “science” in her own papers also were not subjected to proper peer review, period. Were this the field of genetics, AIDs, or cancer, the hockey stick team would now be in jail. It’s about that simple. The way Curry fails to call for proper investigations of corrupt academics, means she simply does not merit much respect at all. Again, imagine if someone like her knew full well a cancer treatment was fraudulent, but then merely pointed out that oh, it might not work quite as well as claimed. That enabling careerist cancer researcher essentially *is* her, and given that artificial energy rationing is a clearly genocidal policy, corruption-enabling, merely passive-aggressive people like her are truly evil.
It's as clear as day that climate models simply lack real empirical input data for the prewar era in which near perfect precedence for postwar variation occurs, so all claims of human attribution are simply bogus and hindcasts are not based on any input data at all, just parameter tweaking, given how even the IPCC says any anthropogenic greenhouse signal only asserted itself recently. This is the cold hard logic of the situation. Only because the "debate" has lingered on with corruption forming the very core of climate "science," are skeptics themselves mostly blind to the outrageousness of it all. We are dealing with the spawn of Enron and its carbon trading schemes, not science!
Curry keeps giving interviews and talks without even mentioning the Jupiter sized elephant in the room: the latest hockey stick has *no* blade in the input data! It's just like an announcement with media hype about a high risk cure for diabetes that is a pure scientific fraud, yet she goes out and gives a talk about diabetes without mentioning it, in fact merely tweaking it. It's pure insanity.
-=NikFromNYC=-, Ph.D. in chemistry (Columbia/Harvard)
NikFromNYC
I absolutely could not agree more. The same goes for anyone at the GWPF who backs up the modelling spondoogle.
In the link provided in the “Seen elsewhere” section about Judith Curry is this:
(My bold.)I’m sorry – twisted words? The exposed e-mails are what began to open my eyes to the scam, as I read about “the cause” and a quite open discussion to destroy the career of a reviewer who questioned their work (Chris de Freitas, as it happens; how is he doing?). Twisting of words was not required to see that there was something extremely unscientific taking place, all in the name of science, and at great cost to the tax-payer, hence my conversion from dubious believer to outright sceptic.
Connection with the Ministry of Defence
Following the First World War, the Met Office became part of the Air Ministry in 1919, the weather observed from the top of Adastral House (where the Air Ministry was based) giving rise to the phrase "The weather on the Air Ministry roof". As a result of the need for weather information for aviation, the Met Office located many of its observation and data collection points on RAF airfields, and this accounts for the large number of military airfields mentioned in weather reports even today. In 1936 the Met Office split with services to the Royal Navy being provided by its own forecasting services.
It became an executive agency of the Ministry of Defence in April 1990, a quasi-governmental role, being required to act commercially. Following a machinery of government change, the Met Office became part of the Department for Business, Innovation and Skills on 18 July 2011
http://en.wikipedia.org/wiki/Met_Office#Connection_with_the_Ministry_of_Defence