By Steven Goddard
I recently had the opportunity to attend a meeting of some top weather modelers. Weather models differ from climate models in that they have to work and are verified every hour of every day around the planet. If a weather model is broken, it becomes obvious immediately. By contrast, climate modelers have the advantage that they will be long since retired when their predictions don’t come to pass.
Weather and climate models are at the core very similar, but climate models also consider additional parameters that vary over time, like atmospheric composition. Climate models iterate over very long time periods, and thus compound error. Weather modelers understand that 72 hours is about the limit which they can claim accuracy. Climate modelers on the other hand are happy to run simulations for decades (because they know that they will be retired and no one will remember what they said) and because it provides an excuse to sink money into really cool HPC (High Performance Computing) clusters.
But enough gossip. I learned a few very interesting things at this meeting.
1. Weather modelers consider the realm of climate calculation to be “months to seasons.” Not the 30 year minimum we hear quoted all the time by AGW groupies. That is why NOAA’s “Climate Prediction Center” generates their seasonal forecasts, rather than the National Weather Service.
2. The two most important boundary conditions (inputs) to seasonal forecasts are sea surface temperatures and soil moisture. No one has shown any skill at modeling either of those, so no surprise that The Met Office Seasonal forecasts were consistently wrong.
For example, just a few months ago the odds of La Niña were considered very low. Compare the December forecast with the May version. How quickly things change!
SST modeling capabilities are very limited, and as a result seasonal weather forecasts (climate) are little more than academic exercises.
Oh and by the way, Colorado will be exactly 8.72 degrees warmer in 100 years. But they can’t tell you what the temperature will be next week.
“If I don’t understand it, it must be simple.”
– Dilbert Principle
In the top picture, which boxer is weather and which one is climate? What do readers think?
Feedback is by definition iterative. Suppose that a climate model assumed clouds to be a positive feedback, and it turned out they were actually negative. Each successive iteration of the model would produce increasingly inaccurate results.
The belief system seems to be that two wrongs makes a right.
Even knowing the mechanism of a model does not mean you can predict the future to 100% at any time.
No one but you is talking about “predict[ing] the future to 100% at any time.” No one but “Steven” is saying that “Colorado will be exactly 8.72 degrees warmer in 100 years.” It’s the reductio ad absurdum where the wheels fall off you guys’ arguments.
There is no mechanism for climate models to correct themselves, which is why they consistently predict higher than observed temperatures.
Do they “consistently predict higher than observed temperatures?” Do you have a source for that assertion or is it just an article of faith?
Others might disagree.
Bruce Cobb,
If you accept that we can predict that a sun with much lower radiation output would lead to a colder climate, and that a sun with a much higher radiation output would lead to a warmer climate, then you are accepting that it is possible to use physics to make some estimates of how climate may change over the long term in response to changes in the energy flows into and out of the system.
Suppose that a climate model assumed clouds to be a positive feedback, and it turned out they were actually negative. Each successive iteration of the model would produce increasingly inaccurate results.
Yup, and hindcasting would show whether that was the case: the model would show different results than what was actually observed. And yet they don’t. Why do you suppose that is?
WMO, IPCC, AMS, etc, etc, all define “Climate as average weather”,
but do not define, in a reasonable scientific manner: WEATHER,
which means there is no chance to interpret anything from CLIMATE, as discussed
at: http://www.whatisclimate.com/
According the AMS-Glossary:
___ “The “present weather” table consists of 100 possible conditions”
____ with 10 possibilities for “past weather”,
_____while popularly, weather is thought of in terms of temperature, humidity, precipitation, cloudiness, visibility, and wind.
Funny that there seems to be big, medium, and small weather, just as it pleases. More serious: WEATHER is used by science in completely unscientific manner, just as layman used it since the Ancient Greeks. That makes a fruitful discussion impossible.
Paul Daniel Ash
Climate models are backfitted with thousands of empirically derived parameters, so not surprising that they work backwards.
I tried a stock forecasting program once which generated a fifth order polynomial to backfit past behaviour of stock prices. It was incredibly accurate looking backwards, and demonstrated zero skill looking forward.
“With four parameters I can fit an elephant, and with five I can make him wiggle his trunk”
Johnny Von Neumann
PD Ash,
Wake up. If models could consistently make accurate predictions, there would be no argument about any of this.
But the plain fact is that climate models fail to accurately predict anything worthwhile, and when on occasion they happen to be right, it’s for the same reason that a broken clock is occasionally right. The climate is inherently unpredictable; the IPCC stated exactly that in AR-1.
The only thing predictable about climate models is that their perpetrators will continue to suck money out of the public trough and waste it on their toys.
That’s not necessarily a foregone conclusion. If the Sun suddenly increased its output, there would undoubtedly be a fairly immediate short-term warming response, but that would be accompanied by increased evaporation from the oceans, which would result in greater cloud cover, which would inhibit the inflow of solar energy and counteract the increase in temperature. Similarly, if the Sun’s output were to suddenly drop, there would be short-term cooling, but then the evaporation would decrease, producing fewer clouds, and allowing a higher proportion of the energy from the fainter Sun to penetrate to the ground, thus counteracting the decrease in temperature.
From the geological record, Earth appears to have “hard walls” at 12°C and 22°C, and the temperature has always been somewhere in that range, through many cataclysmic changes of every kind over hundreds of millions of years. In more recent times (mere millions of years), that ±5°C has been more like ±3°C or less. Nobody knows why either of these things is true, but somehow here we are, with all of the other abundant life on the planet, still in one piece, and every single one of our ancestors has managed to survive (at least long enough to procreate).
/dr.bill
Enneagram says: July 1, 2010 at 9:25 am
AMO is now in as well !
http://www.vukcevic.talktalk.net/NFC1.htm
@Stephen Fisher richards says:
July 1, 2010 at 7:09 am
Ulric Lyons says:
July 1, 2010 at 5:03 am
If you think about it, an accurate climate forecast would be totally dependant on deterministic long range weather forecasts, and that can only be done by predicting changes in the solar signal.
“You are assuming only one variable, which is surely wrong.”
Not if the Sun is driving all terrestial variables.
The coin toss argument can be seen in a post here at WUWT a couple of months ago if i remember correctly. Noticed some new trolls lately here and JONOVAs site, carrot eater seems to be getting the hang of things. Myself just a laymen, dont understand all the math used but this site and some others are very good about helping you to understand it all. It is nice to see some [very few] do stay around and find just how nutty the alarmist view really is in a lot of ways. side note: Pamela Gray what happened have not seen your post in a while hope all is well?
Some will have been long dead as well. We had a 10 year tipping point from the UN back in 1989 and in 2010 we have a pasturised tipping point of 2200.
Doesn’t the Independent ever get tired of reporting utter rubbish.
20 March 2000 “Snowfalls are now just a thing of the past”
Verified as rubbish
Unverified rubbish
Ulric Lyons
I think it is safe to say that all weather variables can ultimately be traced back to the sun. There would be essentially no heat and thus no weather without the sun.
the plain fact is that climate models fail to accurately predict anything worthwhile
Smokey,
I know that you tend to be a “belief” rather than “evidence” guy, but that’s not a factual statement. It’s just not.
Wake up.
Wake up.
Wake up.
http://journals.ametsoc.org/doi/abs/10.1175/1520-0442%281998%29011%3C0109%3AAPSPWA%3E2.0.CO%3B2“>Wake up.
Models have been shown to be accurate – not perfect, but accurate within reason, and improving – so the “fail to accurately predict” claim is false on its face.
Again: overreach. It is possible to make meaningful objections and critiques without going overboard into “ITZ ALL A HOKES!!1!” territory.
Coin flipping isn’t a good model to use when thinking about climate. It’s all predicated on a human manufacture known as the fair coin. Where is the fair coin in a climate? You only get even balance in coin flips because someone has troubled themselves to create a uniform, unvarying, even object. As Steven Goddard points out there is too much variance in things like positioning of ocean heat, soil moisture, cloud cover, and snow cover to think there is anything like an even coin with a easily readable heads and tails. The better metaphor than flipping coins for climate modeling would be augury or forecasting based on the reading of entrails.
Steven:
“If [GCMs] were simple statistical models as you imagine, there wouldn’t be need for running them on supercomputers. Your view of a climate model could be run on an abacus.”
Are you saying that if you run a weather model out over many years, it won’t capture the seasonal cycle? Of course it does, because we understand very well how solar insolation varies by latitude during the course of a year. To leading order, predictability of the seasonal cycle is not dependent upon the chaotic dynamics that make weather prediction localized in space and time so difficult, but instead is simply dependent upon the predictability of the orientation and position of the Earth relative to the Sun.
Similarly, when I blow air onto my hand, the dynamics of the individual particles moving out of my mouth are chaotic and thus totally unpredictable beyond some very short time-frame, but predicting the aggregate–that I will feel air hit my hand–is highly predictable.
In this way, then, the logic of this article is incorrect. If you disagree, please feel free to respond.
Cheers,
Dan
dr. bill:
None of that changes what I said. If the solar output increased by 20%, and all other forcings remained the same, then the climate on earth would on average be warmer.
What you are describing are various feedbacks. The feedbacks determine how sensitive the climate would be to the imposed change in solar – precisely how much warmer it would be, as the system responds and reacts. Some feedbacks could strengthen the initial warming, some would counteract it. But overall, it’d still be warmer, than had the sun not done that.
I think some pretty impressive things happen within your limits. The difference between ice age and interglacial is ~ 6 C. I’d say an ice age and an interglacial are fairly different circumstances for the earth to find itself in.
As a follow up to my recent post, I myself do not particularly like our climate models, especially in any context involving regional climate change projections (the scales for which predictability is indeed highly questionable). The models may indeed be very wrong even in prediction of global temperature, perhaps even for reasons given in this article, since the climate sensitivity is dependent upon boundary conditions, which themselves may have limits of predictability due to the internal dynamics of the system. However, this article does not follow that logic, but instead applies the incorrect logic that climate predictability is de facto impossible because weather predictability decreases to zero after only a few days.
Of course, it is not weather vs climate in the real world, for it is all one system of interactions, with the weather/climate system being a chaotic and periodic dynamical system. If it snows in Florida, this is certainly a reflection of both the weather and the climate, for this weather/climate system is the same system, subject to both shorter term and longer term dynamics. Some find it convenient to speak of climate as an average of what the weather does over the longer term, but this is certainly not accurate, as it would miss the longer term dynamics, i.e. such as the Milankovitch cycles or events such as the Maunder Minimum. And certainly weather is more than just a reflection of the climate day by day, for to see it as such would miss the smallest of details that cause the formation of a tornado or thunderstorm for example. It might therefore be more accurate to speak as weather being the shorter term chaotic variations that ride on top of the longer term variations, much as little ripples in the ocean that ride on top of a much larger wave. Both have chaotic dynamic elements, and each is worth studying, but ultimately both are the same ocean.
vukcevic says:
July 1, 2010 at 10:20 am
That page of yours hope to see it in science books texts, after the collapse of current paradigm and holy creed along with the disappearance of the funds which artificially support it. No money=No self indulging post normal science.
Paul Daniel Ash says:
July 1, 2010 at 10:03 am “. . . Yup, and hindcasting would show whether [there was a problem with positive vs. negative feedback]: the model would show different results than what was actually observed. And yet they don’t. Why do you suppose that is?”
When you mention hindcasting, you hit a hot button with me. There are several reasons why GCMs produce good hindcasts, but a particularly troublesome one is their handling of aerosols. The paucity of comprehensive data on global aerosol conditions through the decades enables modelers to use convenient input parameters on this man-made contribution to climate change. Aerosols can essentially become dummy variables which make hindcasts accurate, and thus GCMs suggest a key role of CO2 in increasing temperatures since the LIA.
Coin flipping isn’t a good model to use when thinking about climate.
Agreed, which is why I wasn’t using it as “model” for “thinking about climate” but rather to highlight the clear and trivially obvious difference between predicting discrete events (a single coin-flip, next Tuesday’s weather) and statistically modelling a series of such events (10,000 coin flips, long-term climate).
You get that. I get it. It’s not at all clear that “Steven” gets it.
Paul Daniel Ash
You linked to Scott Mandias excellent site, which states;
“Climate models do have their limitations and modelers are constantly improving their models with newer data as the understanding of climate processes improves with research. According to the IPCC (ibid): “Nevertheless, models still show significant errors. Although these are generally greater at smaller scales, important large-scale problems also remain.”
The IPCC themselves over the years have stated that models are not accurate and should be used with great caution. In hindcasting their own models the Met office say with confidence that temperature variability was very limited until humanity caused emissions to rise and obviously concur with Dr Mann’s view on this.
However, to come to this conclusion they ignore their own -and other-instrumental records demonstrating very considerable variability which is overlaid by a gently warming trend that commenced in the 1680’s.
Scott has a very nice article on the Vikings on his web site (read his disclaimer) which comtradicts Dr Mann’s and the Met Office view.
tonyb
Dan
People run weather models out to two weeks, but they are pretty useless after 72 hours. I check the accuweather two week forecast almost every day – it changes radically from day to day.
stevengoddard says:
July 1, 2010 at 10:46 am
Ulric Lyons
I think it is safe to say that all weather variables can ultimately be traced back to the sun. There would be essentially no heat and thus no weather without the sun.
________________
The energy from the sun is certainly the major supply of energy on earth, but for example, the Milankovitch cycle is not the sun per se, as the sun is not changing its output significantly, but it is the Earth’s eccentricity, axial tilt, and precession that are changing. So some distant alien astronomer trying to predict the Earth’s longer term climate by studying the small variations of just the total solar irradiance would fail miserably if they didn’t take the Milankovitch cycles into account. So too they would fail if they didn’t undertand the cycles of weathering of rock on earth and the changes in CO2 in the atmosphere that can be altered greatly by these geological cycles. The level of GHG’s directly impacts the climate, so in this case, it once more is not the sun per se, but the energy balance of the planet dictated by how much of that sunlight actually stays in the system.