Quote of the week – on the usefulness of climate models

qotw_cropped

From Dr. Judith Curry:

They seem to obliquely admit the inadequacy of climate models by saying that they have not been falsified by the recent pause.  Well, even if they have not been falsified, the climate models are not looking very useful at the moment, and climate model-derived values of climate sensitivity are seeming increasingly unconvincing.

From this post: UK Met Office on the pause

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the Met Office believes its “vital role” and duty to be the provision of “advice and services” on climate change
http://www.metoffice.gov.uk/about-us/who
if the models aren’t useful the whole edifice crumbles. They can’t possibly admit to that.

Mk Urbo

The climate models have been incredibly useful in exposing the bias of the warmers…

michel

Why is it referred to as a ‘pause’? It may or may not have paused, but what we know for sure is that it has stopped.

rgbatduke

“Climate models have not been falsified by the recent pause”?
Really? Not a single one? There are what, order of 100 distinct climate models out there, each one of which generates an entire Monte Carlo ensemble of spaghetti as one perturbs their parameters and initial conditions. Each one has to be validated against the recent pause independently. And not one of them is far enough off to throw out the window?
Or under the bus?
What about the ones that are falsified by virtue of getting rainfall, drought, or the patterns of heating or cooling just plain wrong? What about the ones that incorrectly predict LTT?
Or do they mean that there exist some climate models that have not yet been falsified by the recent pause?
Finally, if “climate models” in general are not yet falsified, just how long does the pause have to be before they are?
And please, no handwaving pulled out of butt-cheeks arguments. Let’s actually use the theory of statistical analysis to answer the question. Since “climate models” are not pulled out of an iid hat, their collective mean and variance are meaningless. That means the “envelope” of model results presented in various AR figures is meaningless, except when it is built for a single model, one at a time, and generated by e.g. Monte Carlo. So how, exactly, can such a statement be validated?
rgb

I agree with Michel. The warming period that started the whole panic about catastrophe was only 8 years long. We’re fully twice that and more with this the non-warming/cooling period, plenty enough to put the panic in perspective and the brakes on.
It’s more and more obvious the alarmists are playing with two sets of rules, one for us and one for them – we should remind people of that every chance we get.

Juraj V.

Models have been already falsified by first half of 20th century, since they can not model 1910-1945 warming and subsequent cooling. “Recent pause” is actually a peak similar to that of 1945.

Those climate models are like a class full of imbeciles which, when tested, show that no individual scored better than 20% in a test. Nevertheless, the teacher finds that every single question has been answered correctly by at least one imbecile so awards an A+ to the whole class.
It took me a while to work out thesimile after reading this article at The Constipation.

Brian H

michel says:
July 24, 2013 at 12:31 am
Why is it referred to as a ‘pause’? It may or may not have paused, but what we know for sure is that it has stopped.

A permanent pause?

Disko Troop

So let me see….If I open the front door, catch my nads on the handle, trip over the carpet, step on the cats tail, fall down the step, hit my head on the stone lions, get bitten by the dog, fall into the gooseberry bush, sit on poison ivy, trip over the lawn sprinkler, stand in a pile of doggy do do, fall into the rose bushes, climb over the picket fence, get my shoe lace caught in the fence spike and end up flat on my face in the road with a broken nose and then promptly get run over by the school bus…… Then the model I developed for exiting the house, walking down the path and catching the bus is a successful one, because it started at the door and ended at the bus. Now I think I understand how this is done.

Brian H

rgb;
The rabbit hole is that they are projections exploring scenarios, not initialized predictions, hence are not subject to falsification. They’re merely suggestive speculations, doncha know? Which are 95% likely, by expert consensus.

Peter Miller

The Met Office offers incentive bonuses to its senior people.
Presumably that was intended as a reward for getting their forecasts right.
Any chance of the maximum bonuses not being awarded for inaccurate forecasts and fantasy climate modelling?
Stupid question really, just wondered if anyone knew of one single instance?

dcfl51

………… even if they have not been falsified ……….. ??
Can someone point to any model which has actually been validated ? Is the above phrase another example of reversal of the null hypothesis ?

Gary Hladik

rgbatduke says (July 24, 2013 at 12:35 am): “Really? Not a single one?”
Heh. As soon as I saw the title of the article, I suspected/hoped RGB would comment. I’ll keep my eye on this thread. 🙂

SAMURAI

As the old Rolling Stones song goes, “Time Is On Our Side”.
In order to meet CAGW’s hypothetical minimum climate sensitivity of 2.0C (current anomaly 0.5C) by 2050, a temperature trend of roughly 0.4C/decade over the next 37 years is required, starting from tomorrow… Every month below this minimum 0.4C/decade trend requirement simply increases it in the future.
Over the past 150 years, the fastest decadal trend lasting over a decade has been around +0.16C/decade, which is less than half of what is required to validate CAGW. Further complicating matters for the Warmunistas are: 1) the 30-year PDO cool phase just started in 2008, 2) the lowest solar cycle since 1906 just peaked and weakens from here, 3) the AMO enter it’s 30-year cool phase around 2020, 4) the weakest solar cycle in 300 years starts around 2020 and 5) there hasn’t been any statistically significant HADCRUT4 warming trend since January 1995.
NOAA’s previous criteria for concern was 15 years of no statistically significant warming, which has already been surpassed; we’re into the 18th year now…
The most important thing from here is to nail the IPCC to an immovable goal post, which they’ll NEVER agree to. They’ll ALWAYS come up with some excuse as to why the goal posts need moving: Albedo flux, Vulcanism, “missing heat in oceans”, natural variability (i just love that squishy excuse), coal particulates, dust, 20 years is too short, 30 years is too short, in ad nauseum..
How long with this CAGW charade continue?

Brian H says:

A permanent pause?

Just a Mann-opause.
The temporary instability in the rise is projected to be overcome soon.
Management apologises for any convenience.

AlecM

They are desperately trying to persuade UK Government that if they only spend another £80 million on a supercomputer they will be able to make the models works despite the whole shebang failing because of the major errors in physics from Sagan, Houghton, Hansen, Trenberth and Ramanathan.

Reblogged this on Tallbloke's Talkshop.

steveta_uk

For RGB, the Nick Stokes reply (or my guess at what it will be):
You cannot throw out ‘some’ of the climate models because it is the ensemble result that counts.
For example, a particular model may produce ludicrous precipitation patterns but be very good at temperature. If you throw it out, then the ensemble temperature data would be unbelievable, but on the other hand, another model with superb precipitation projections might provide daft temperature data, but again you have to keep it in else the precipitation data becomes ludicrous.
This is crowd-sourcing of computer models at work!

Stephen Wilde

My model works well enough.
Active sun causes poleward, zonal jets with less clouds allowing more energy into the oceans for a warming world.
Inactive sun the opposite.
The global air circulation pattern being the only necessary diagnostic indicator to establish the current trend.

steveta_uk

“A permanent pause?”
Sure – why not? After all, when you press “pause” on your CD player, there is no rule that says that one day you must press “play”. You may even press “rewind” next, pr “eject” – tho not sure how that analogy works with climate 😉

Rob

We simply don’t have a good enough understanding of the complex climate system.

DirkH

Juraj V. says:
July 24, 2013 at 12:43 am
“Models have been already falsified by first half of 20th century, since they can not model 1910-1945 warming and subsequent cooling. “Recent pause” is actually a peak similar to that of 1945.”
Of course. They never validated them because they knew it would fail.
So. What we have now is that the Western crony governments have diverted trillions into the climate scam, mostly via the renewable energy ruse. And they can’t admit that; the omnipresent windmills are testimony to their crookedness. So they must maintain that GCM’s are good as Gold; and Gavin continues to fiddle GISTEMP higher as we speak.
Ok, we can work with that.

rtj1211

Try reading yesterday’s London Times article by Hannah Devlin to see some truly vomit-inducing back-tracking by scientists about ‘accelerating warming’.
They combine having signed up to things they were ‘apparently not comfortable with’ with taking shedloads of public cash and excoriating those who remained true to their beliefs and expressed skeptical doubt.
The term ‘Nazi orderly at a concentration camp’ comes to mind: that bunch did what they were told, turned the other cheek and then claimed that it was just the evil officer class who made them do it.
How did history treat those orderlies, eh????

LarsDane

Predictably, the “Pro’s” – this time at DMI (the Danish Met Office) just a few days ago said the opposite: http://www.dmi.dk/nyheder/arkiv/nyheder-2013/klimamodel-genskaber-de-seneste-aars-temperaturopbremsning/
Google translation:
“New study of climate model EC-Earth, which is used in DMI’s climate research, suggest that increased intake of energy in the oceans play a key role for the past year slowdown in the growth of the global mean. In the past 10 to 15 years, the global average temperature has risen more slowly than in the past – and slower than most climate models predicted. This deceleration has occurred in a period during which atmospheric concentration of CO2 has remained growing and where the total external forcing (from solar radiation, greenhouse gases and particles) have been
largely unchanged. The slow down is also done in a period in which both the models and observations show that the climate system overall, has taken up as much energy as previously.
The climate, however, also exhibit natural variations in both short and long term. and several studies point. to deceleration may be due to natural variations in the atmospheric and ocean circulation in a period led to increased accumulation of energy in the oceans. Tha lead a Spanish research team to investigate whether the climate model EC-Earth could simulate the last year’s temperature slowdown if they started model based on an observed state and thereby could hit the contemporary flow pattern. The natural variations in climate models is in fact not automatically in line with the observed.
The results show that the climate model EC-Earth is better at representing the recent years deceleration in surface temperature when it is forced into the right flow pattern. They also show that the extra energy in the climate system during this period actually used to heat the oceans. This confirms that it is the natural variations in flow patterns that determine how much of the energy that actually accumulates in the oceans, and how much goes to heat the surface.
Further model studies with an exaggeration that is comparable to the one we have experienced in the past decade, confirm that global temperatures are increasing. However, there will be periods where the temperature change at the surface can be small or even negative. During these periods is recorded more energy in the oceans deeper layers.
The new results generally increases confidence in the climate models. At the same time, the results indicate some of the possibilities offered in the short-term climate forecasts. Forecasts, which among other things can become a valuable tool in relation to climate change adaptation.”
Well, well – follow the taxpayer money spent by politicians.

IanE

‘on the usefulness of climate models’
Chocolate and teapot spring to mind.

The Ghost Of Big Jim Cooley

Permanent pause? A few years ago where I live in England, the local council removed the road surface ready for a new layer and put up a sign saying ‘Temporary road surface’. However, it dragged on for months, so a local put up a sign next to the other sign saying ‘Permanent Notice’. I think that says it all.

Bill_W

Why would we not look at the differences in slope and length in years and magnitude of temperature change between the 1910-40 warming compared to the similar period from ~1980 on and say that this is the added effect due to CO2? Now throw in an unknown lag between 5 and 1000 years depending on how efficiently the heat is mixed into the oceans and there we have our model for effect of CO2.

Paul Vaughan

Lot more water in southern hemisphere.
Circulation is a function of temperature gradients.
Temperature gradient geometry is a function of distribution of continents.
Water has much higher heat capacity than air.

Attention UK Met Office:
With attention to the thermal equator you can quickly refine this dead simple tip:
http://img845.imageshack.us/img845/6451/1xx.gif (2-slide animation — N vs S)
Supplementary: http://tallbloke.files.wordpress.com/2013/03/scd_sst_q.png
Temperature, mass, & velocity are coupled.
Turbulence details are not needed to determine the central limit of coupled mechanical processes.

Think of the tachometer in a car. One need NOT know how to model the mechanical processes occurring in the car to figure out that the rate of coupled mechanical processes is related to revving. (Duh!!)
It’s also a no-brainer to see that heating ice water to boiling water on a stove is an integral.
Circulation geometry in the southern hemisphere is comparatively a simple ring, whereas angled steep land-ocean gradients are adjustable meridional deflectors in the northern hemisphere.

Julian in Wales

If the temp begins to go down, as is beginning to happen, will that falsify them? One wonders if they will simply say they hae seen dips in their models too. In fact they have so many models running at once every eventuality has been covered.

Ken Hall

“rgb;
The rabbit hole is that they are projections exploring scenarios, not initialized predictions, hence are not subject to falsification. They’re merely suggestive speculations, doncha know? Which are 95% likely, by expert consensus.”

If they are not falsifiable, then they are NOT scientific tools and should be rejected as useless.
Another mistake the alarmist scientists make is in using the models for experimentation. To see what the effects of different input conditions are on the system. Models are coded according to the warmist theory. Therefore the models can only ever be expressions of variants of that theory. They can never be used as experimental tools and have zero predictive value at all.
The real actual physical earth, comprising the earth and its climate, do not work to some theory. It obeys all the known and unknown (and if unknown, therefor un-modelable) laws of chemistry and physics and biology.
The only way to scientifically validate the theory, (and therefore the models), is by empirical data acquired through observation of this planet through accurate and consistent measurement.
The “inconvenient truth” is that the real actual earth is NOT behaving how the models projected based on the variants of the theories upon which they were coded. There is no known mechanism for surface heating to suddenly switch to being deep ocean heating. They are unscientifically using this alleged ocean heating as a desperate and pathetic excuse to try to keep their reputations and funding.
They are being grotesquely anti-scientific in this. Igoring their own theory that posits that CO2 absorbs more radiative heat in the atmosphere as it bounces off the land and has no known mechanism for increased levels of CO2 suddenly stopping warming the atmosphere over land and then pushing the atmospheric heat DOWNWARDS into the oceans instead. If the oceans are warming more, then the atmosphere above them should also be warming more and it is not.
The theory has been falsified. The earth is NOT going to fry to a crisp any time soon. We should celebrate.

Ken-
Great post but the new K-12 education reforms in the US and the Maastricht reforms the EU is pushing and all the reforms I am seeing all over Asia and Australia and NZ are ALL premised around creating a belief in systems thinking and the idea that this is all true. The reason is that it becomes an excuse to get desired mass behavioral changes without that being so obvious or appearing authoritarian.
But AGW is thoroughly embedded in ed as a so-called global challenge because it creates an excuse for political power and politically directing the economy and cronyism. We have to get the science right but we cannot stop there in cleaning this all up. Or forget why science itself is under attack. See Sokal Hoax.

DC Cowboy

michel says:
July 24, 2013 at 12:31 am
Why is it referred to as a ‘pause’? It may or may not have paused, but what we know for sure is that it has stopped.
================
It is innaccurate to claim the recent cessation of temperature rise as ‘paused’ unless you can explain why and give some idea when the ‘pause’ itself will stop (and that needs to be somehting more than ‘in the near future’). If you can’t you have to say it has stopped.

DC Cowboy

Ken,
“They are being grotesquely anti-scientific in this. Igoring their own theory that posits that CO2 absorbs more radiative heat in the atmosphere as it bounces off the land and has no known mechanism for increased levels of CO2 suddenly stopping warming the atmosphere over land and then pushing the atmospheric heat DOWNWARDS into the oceans instead.”
=================
Not only pushing the energy downwards into the oceans, but somehow skipping the first 700 meters of ocean and moving the heat to the ocean below.

RC Saumarez

According to the Berkley Earth Temperature study, the World has been heating since the 1820s.
This is often attributed to “recovery from the little ice age” – whatever caused that.
If the physics of the LIA and its recovery can be explained and then modelled successfully, one might have more faith in the basis of climate models.

NickM

@rgb
In paper 3 from the MO, figure 4 purports to show that the actual data is within the range of error of computer models.
However, a few things are missing from this. The computer models used are not those from IPCC AR4, or even TAR, they are from SAR. As it happens, (must just be a coincidence) the IPCC SAR was the report that made the lowest projections. Although the MO hasn’t said so – this is pretty much an admission that TAR and AR4 are massive overestimates of global warming.
Next, they haven’t even checked the model runs as they were run back in 1995/6. Instead they have re-run the models adjusting them downwards a little bit.
Also, they’ve chosen to compare the results of the models with HadCRUT4. But HadCRUT4 didn’t exist when these projections were originally done. HadCRUT3 would be a better choice. HadCRUT4 runs 0.05degC warmer than 3 . Not using v3 makes it look a little bit like they’ve changed the actual data to fit the model. And I’m sure they wouldn’t want to be seen to have done that.
Seems to me the correct approach would be to use all the IPCC reports or just the most recent. The model runs should be compared with the temperature record that was being used when the models were run (HadCRUT3).
All talk of uncertainty range/errors can be omitted. If there were no bias in the models, you would expect about half the models to be above actual data and about half under. We can say the models are biased – and we can estimate by how much.

Jimbo

I’m not sure whether the climate scientists Judith Lean, of the US Naval Research Laboratory, and David Rind (GISS) used models but exactly 4 years ago they basically said that the world would warm faster than predicted by the IPCC in the next 5 years.
http://onlinelibrary.wiley.com/doi/10.1029/2009GL038932/abstract

I’ve discarded models of chemical processes that were much better system predictors than the climate models and I never was smart enough to average failures to get the correct answer. And this is settled science and beyond debate?

John

Bill Marsh
“It is innaccurate to claim the recent cessation of temperature rise as ‘paused’ unless you can explain why and give some idea when the ‘pause’ itself will stop (and that needs to be somehting more than ‘in the near future’). If you can’t you have to say it has stopped.”
Actually to be accurate you can not say there is a pause or that warming has stop. There is no statistically significant pause or decrease in temperatures. The only statistically significant trend to now is an increase in temperatures.
You could consider other evidence such as ocean heat content data, ocean thermal expansion data, energy imbalance data. None of which supports the theory temperatures have paused or stopped. Most likely, in my view, it will start to warm faster again soon. It’s just a question of how much and what significance the slow down has on predicting that.

michael hart

I expect the Met Office might say “The level of convincing-ness of the climate models is experiencing a pause.”

Kev-in-Uk

no need for further comment really – just sit back and wait for the usual warmista to come and defend the model rubbish!

Tom J

Climate models that have not been falsified remind me of voting in Chicago.
Despite the fact this person has been dead for 100 years their vote for the perpetual incumbent has not been falsified.

rgbatduke

Those climate models are like a class full of imbeciles which, when tested, show that no individual scored better than 20% in a test. Nevertheless, the teacher finds that every single question has been answered correctly by at least one imbecile so awards an A+ to the whole class.
Very much indeed; a very apt simile as you say. Only it is slightly worse. Because every question has been answered correctly by at least one imbecile, and because the teacher finds that every imbecile wrote the correct laws of physics somewhere on their page (it was, after all, an open book test), the teacher concludes that the errors the students make must cancel out. The teacher then takes the average of the answers of this “A+” class and uses it to grade the actual answer key of the author of the textbook who originally wrote the problems and who is not, I repeat not, an imbecile.
The real question is, who is dumber, the students or the teacher?
rgb

Here is a quote from the latest post on my blog at http://climatesense-norpag.blogspot.com relative to climate models.
“Fig 1 is but one illustration among an ever increasing number, of the growing discrepancy between model outputs and reality.This disconnect has been acknowledged by the establishment science community which is now busy suggesting various epicycle like theories as to where the “missing” heat went.Some say its in the oceans (Trenberth) some say its due to Chinese aerosols (Hansen) but the all main actors still persist in the view that it will appear Lazarus like at some unspecified future time.This is like the Jehovah’s witnesses recalculating the end of the world each time a specified doomsday passes.
In Britain , the gulf between the Met Office expectations for the last several years and the actual string of cold and snowy winters and wet summers which has occurred has made the Met Office a laughing stock-
to the point of recently holding a meeting of 25 “experts” to try to figure out where they went wrong.
The answer is simple.Their climate models are incorrectly structured because they are based on three irrational and false assumptions. First that CO2 is the main climate driver ,second that in calculating climate sensitivity the GHE due to water vapour should be added to that of CO2 as a feed back effect and third that the GHE of water vapour is always positive.As to the last point the feedbacks cannot be positive otherwise we wouldn’t be here to talk about it .
Further ,Trenberth in a presentation at :
http://www.cpc.ncep.noaa.gov/products/outreach/proceedings/cdw31_proceedings/S6_05_Kevin_Trenberth_NCAR.ppt
proposes a strong natural negative feedback which has not been included in the IPCC- Met Office models and which independently of all the other evidence would necessarily substantially reduce model warming predictions.
Temperature drives both CO2 and water vapour independently,. The whole CAGW – GHG scare is based on the obvious fallacy of putting the effect before the cause.As a simple (not exact) analogy controlling CO2 levels to control temperature is like trying to lower the temperature of an electric hot plate under a boiling pan of water by capturing and sequestering the steam coming off the top.A corollory to this idea is that the whole idea of a simple climate sensitivity to CO2 is nonsense and the sensitivity equation has no physical meaning unless you already know what the natural controls on energy inputs are already ie the extent of the natural variability.
Furthermore the modelling approach is inherently of no value for predicting future temperature with any calculable certainty because of the difficulty of specifying the initial conditions of a large number of variables with sufficient precision prior to multiple iterations. There is no way of knowing whether the outputs after the parameterisation of the multiple inputs merely hide compensating errors in the system as a whole. The IPCC AR4 WG1 science section actually acknowledges this fact. Section IPCC AR4 WG1 8.6 deals with forcings, feedbacks and climate sensitivity. The conclusions are in section 8.6.4 which deals with the reliability of the projections.It concludes:
“Moreover it is not yet clear which tests are critical for constraining the future projections,consequently a set of model metrics that might be used to narrow the range of plausible climate change feedbacks and climate sensitivity has yet to be developed”
What could be clearer. The IPCC in 2007 said itself that we don’t even know what metrics to put into the models to test their reliability.- ie we don’t know what future temperatures will be and we can’t calculate the climate sensitivity to CO2.This also begs a further question of what mere assumptions went into the “plausible” models to be tested anyway.
This quoted statement was necessarily ignored by the editors (censors) who produced the AR4 Summary for Policymakers. Here predictions of disaster were illegitimately given “with high confidence.” in complete contradiction to several sections of the WG1 science section where uncertainties and error bars were discussed. Almost all the worlds politicians, media and eco-activist organisations uncritically accepted and used these predictions as infallible guides to the futrure and acted on these delusions of certainty which are now, six years later ,seen to be just that -delusions.
In summary the projections of the IPCC – Met office models and all the impact studies which derive from them really have no useful place in any serious discussion of future climate trends and represent an enormous waste of time and money.”

Bill Marsh says:
July 24, 2013 at 3:43 am

It is inaccurate to claim the recent cessation of temperature rise as ‘paused’ unless you can explain why and give some idea when the ‘pause’ itself will stop….

According to
http://wattsupwiththat.com/2011/12/07/in-china-there-are-no-hockey-sticks/ the pause goeth before the fall, the fall has started, and will last some 60 years.

NikFromNYC

That the contemporary high CO2 warming swing is indistinguishable from the one before suggests that CO2 attribution is just silly, albeit highly profitable for some and most of that profit being tax dollars or recession era high energy prices, highly unprofitable for others.
Temperature chart: http://oi45.tinypic.com/5obajo.jpg

Tom in Florida

At the beginning of the linked article:
“The recent pause in global surface temperature rise does not, in itself, materially alter the risks of substantial warming of the Earth by the end of this century. – UK Met Office”
Now to me that reads as such: “Even though there has been a pause in global surface temperature rise, the risks associated with substantial warming, if it ever occurs, are still valid”.
They have carefully switched their argument from their failed point of certain warming to a position of “yeah but what if it does warm, it will be dangerous”. The object is to keep the fear factor at the front and center of the argument so that the money keeps coming in.

rgbatduke

However, a few things are missing from this. The computer models used are not those from IPCC AR4, or even TAR, they are from SAR. As it happens, (must just be a coincidence) the IPCC SAR was the report that made the lowest projections. Although the MO hasn’t said so – this is pretty much an admission that TAR and AR4 are massive overestimates of global warming.
Agreed. And it is stressing SAR. Which is why estimates of sensitivity are in freefall. The really interesting thing will be when the IPCC formally gives up on the projections from AR4, TAR and eventually SAR, and when they formally acknowledge that their use of statistics to average them all together was complete crap. At that point, I “predict” a climate of pitchforks and torches, led not by citizens but by lawmakers who have been lied to.
Not a good time to be a climate scientist, especially one that vocally defended the use of such averages or high sensitivity climate models as predictive tools capable of generating confidence intervals as in AR4’s Summary for Policy Makers, one of the all time greatest travesties in science.
rgb

David

‘Its in the deep ocean, I tell you – the missing heat ..
No – you can’t detect it – its there, trust me – I’m a climate scientist…’

Latitude

they have not been falsified by the recent pause…..
…their expectations are extremely low

Some of these issues and many more are discussed in my new (invited review) paper in details
SOLAR AND PLANETARY OSCILLATION CONTROL ON CLIMATE CHANGE:
Hind-cast, Forecast and a Comparison with the CMIP5 GCMs
by Nicola Scafetta
take it from
http://people.duke.edu/~ns2002/pdf/Scafetta_EE_2013.pdf
or visit my web-site
http://people.duke.edu/~ns2002/
Abstract:
Global surface temperature records (e.g. HadCRUT4) since 1850 are characterized by climatic oscillations synchronous with specific solar, planetary and lunar harmonics superimposed on a background warming modulation. The latter is related to a long millennial solar oscillation and to changes in the chemical composition of the atmosphere (e.g. aerosol and greenhouse gases). How- ever, current general circulation climate models, e.g. the CMIP5 GCMs, to be used in the AR5 IPCC Report in 2013, fail to reconstruct the observed climatic oscillations. As an alternate, an empirical model is proposed that uses: (1) a specific set of decadal, multidecadal, secular and millennial astronomic harmonics to simulate the observed climatic oscillations; (2) a 0.45 attenuation of the GCM ensemble mean simulations to model the anthropogenic and volcano forcing effects. The proposed empirical model outperforms the GCMs by better hind-casting the observed 1850-2012 climatic patterns. It is found that: (1) about 50-60% of the warming observed since 1850 and since 1970 was induced by natural oscillations likely resulting from harmonic astronomical forcings that are not yet included in the GCMs; (2) a 2000-2040 approximately steady projected temperature; (3) a 2000-2100 projected warming ranging between 0.3°C and 1.6°C , which is significantly lower than the IPCC GCM ensemble mean projected warming of 1.1°C to 4.1°C; (4) an equilibrium climate sensitivity to CO2 doubling centered in 1.35°C and varying between 0.9°C and 2.0°C .