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back to article Error found in climate modelling: Too many droughts predicted

An international team of top boffins say that current climate models are based on faulty assumptions which lead them to predict more drought than will actually be the case. A storm is brewing (Mali, Sahel). Foto: F. Guichard & L. Kergoat, AMMA project, CNRS copyright. OK, the drought didn't turn up. Again At the moment, …

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Joke

Cue the ranters

A prize for the first one to post that Lewis Page is a crazy denialist.

The prize? Your own sense of smug self-satisfaction.

You do know that Lewis personally pays all these scientists to 'discover' this stuff in his endless quest against Warmists, right?

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This didn't ought to provoke any particular ranting.

It's nothing to do with human contribution to global warming which seems to be the polarised issue.

This is about an entirely different piece of modelling and while LP might possibly want to keep the idea that models and predictions of negative effects arising from these models are often wrong in the forefront of people's minds there's nothing directly provocative in this article.

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Anonymous Coward

Scientist admit's model to be wrong

After securing a new 10 year budget with their previous scaremongering

who would have thought it

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Headmaster

'This didn't ought to provoke any particular ranting.'

This shouldn't provoke any particular rant.

This ought not to provoke any particular rant.

You're welcome.

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drawing conclusions

"It would seem that in one important respect at least, science to date has been predicting a future grimmer than will actually be the case."

This seems a really bold conclusion given the data presented - my guess is that changes like this will be slightly chaotic to the output of the model rather than linear as you suggest.

all that this shows is that a particular part of a model is wrong. Its not until the system as a whole is modeled that you can say what the overall implication is - I'd suspect that it will be extremely dependant upon the layout. At the extreme consider a ring shaped dry area encircling a damper area, this change to assumptions could presumably lead to the damp region being progressively dried out over a period of years. If it then turns out that the "damp" area is where we currently live and grow food thats not a good result.

For what its worth I'm personally of the opinion that most climate models are probably overstating the effects at present, however if you're going to report something like this please think about your conclusions. This shows part of a model is wrong - not what implications are on a systemic level.

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Stop

Re: drawing conclusions

Was going to post the exact same thing - all the study does is say that an assumption is wrong. No studies as yet have been made with corrected assumptions, ergo the statement "science to date has been predicting a future grimmer than will actually be the case" is inaccurate with current data.

I'm not saying it will prove inaccurate when models are updated, though.

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Re: drawing conclusions

"This seems a really bold conclusion given the data presented - my guess is that changes like this will be slightly chaotic to the output of the model rather than linear as you suggest. All that this shows is that a particular part of a model is wrong. Its not until the system as a whole is modeled that you can say what the overall implication is - I'd suspect that it will be extremely dependant upon the layout. "

If you are saying that changing the basic assumptions of the AGW model are not going to change the model's prediction then I agree with you completely... except that the reasons for the predictions remaining unchanged have *nothing* to do with science...

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Re: drawing conclusions

What I'm saying is that changing an assumption in a model this complex probably has an equal chance of making the prediction "better" or "worse", of course thats a global view.

At a small scale I suspect this change in assumptions will create local predictions of drought and flooding in different locations. The question will be are those currently the useful / productive areas of the planet?

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Re: drawing conclusions

Here's a relevant quote from the study's authors:

http://www.livescience.com/23128-dry-soils-more-rain.html

The researchers emphasize "it's important to recognize that we are comparing storm statistics between nearby places with the same climate," Taylor told OurAmazingPlanet. "We are not saying that rain is more likely in the Sahara than the Amazon Basin."

Moreover, "I should add that we can only see this signal when regions get quite dry, ruling out places like the United Kingdom," Taylor added.

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"It's complex" shocker

I don't get how some think that they can predict climate change accurately while failing to be able to predict the weather we'll get next week with any accuracy.

Hopefully this will lead to better data and improve both these kinds of forecasting.

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FAIL

Re: "It's complex" shocker

Could it be because weather and climate are 2 completely different things? I can accurately predict that it will be colder in the winter than in the summer this year, next year and any year afterwards. That's climate.

Predicting where a particular rain cloud will go over the next few days based on satellite photos is much harder. This is weather. Weather predictions are nowadays amazingly accurate 3-4 days in advance and predict rain and sunshine with about an hour of accuracy.

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Anonymous Coward

Re: "It's complex" shocker

Except.....

1) we can predict next weeks weather with remarkable accuracy

2) if you don't get that weather <> climate, please don't try and walk and chew gum at the same time.

I do however agree - this is the way science works, incremental improvements building on observations and fed into models that gradually get better at forecasting the future.

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Re: "It's complex" shocker

"I can accurately predict that it will be colder in the winter than in the summer this year, next year and any year afterwards. That's climate."

That's climate, but it is not a climate prediction. It is a prediction that Earth will continue to orbit the sun. A climate prediction would put numbers on how much hotter or colder it will be down here on Earth. And yes it's different from weather, but so far we've no evidence that short term (a century or so) climate prediction is any easier than long-term (a month or so) weather prediction.

You could always ignore climatology and stick with astronomy and geology. In the medium term, you are probably safe to guess that Milankovic cycles will continue for the next million years or so. Longer than that, you are probably safe to assume that ocean circulation will be predominantly pole-to-pole rather than round-and-round (because continents don't shift too quickly) and therefore we're unlikely to return to the sort of climate seen at various points in the past which saw 20C at the poles. But these aren't climate predictions either.

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Re: "It's complex" shocker

If you don't get that climate is the time average of weather, please don't try and walk and chew gum at the same time.

100 cold winters in a row may individually be weather, but the overall result is climate change

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Mushroom

Re: "It's complex" shocker

"Weather predictions are nowadays amazingly accurate 3-4 days in advance and predict rain and sunshine with about an hour of accuracy."

Obviously not a UK resident then!

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Re: "It's complex" shocker

Actually I am in the UK. Hint: predictions for the UK as a whole are not accurate for most people, watching the weather on the news is useless except for whole country predictions such as big storms or snow. Get predictions for where you actually live on BBC weather. And yes, it does rain pretty much when the forecast says it does, so I use it to decide whether to cycle to work or not.

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Re: "It's complex" shocker

@Matthew 3:

Fill the sink with water. Drop in a spot of ink. Pull out the plug.

You'll have great difficulty saying whether the ink will make it to any particular spot or not but you can say with certainty that it will all go down the plug hole.

We can often say something useful about global behaviour of a system without being able to specify in detail the evolution of every point.

Climate modelling is about large-scale behaviour; weather, about more detailed behaviour.

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Mushroom

weather <> climate

Alright, you're boring me now.

I see this trotted a LOT. Usually when there's some report showing that the Apocalypse is not about to occur tomorrow and that the New Gaians might in fact be spouting a religion rather than actually using the scientific method to study anything beyond their articles of faith.

What this means to the victim on the street is "that thing you thought we were talking about where there's floods and droughts and apocalypse and the weather KILLS YOU DEAD? It's not weather. It's a special magic thing called climate that you don't understand. But I understand it. I can bless you and save you from your sins. Give me thirty-five million pounds for a new wind farm or GAIA WILL BE ANGRY".

Wankers.

(Note - no opinion on whether the climate is changing due to human activity or indeed whether any alteration of human activity is required, sensible or not was made in this post. Only the assertion that all priests are scammers, Gaian as much as any other).

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Re: "It's complex" shocker

They can predict the tomorrow's weather quite accurately in aggregate -

According to the latest computer models, the weather for the next 100 million years will be 'moderate'

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Happy

Re: "It's complex" shocker

If only! The forecasts appear to be no better than guessing by sticking one's head in a cupboard. A few times they get a forecast of wind right and once recently we had some rain, more or less on forecast. Perhaps I live in a rainless bowl as some round here suggest. After a summer of record rain we are still wondering if the cracks in the garden will get much bigger and if we should try to fill them with sand or compost.

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Coat

Re: "It's complex" shocker

> According to the latest computer models, the weather for the next 100 million years will be 'moderate'

Although the longer term forecast is for it to get a bit toasty

http://www.newscientist.com/article/dn13369-hope-dims-that-earth-will-survive-suns-death.html

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FAIL

Re: "It's complex" shocker

@Wilco1:"Get predictions for where you actually live on BBC weather."

Have they launched a new service? I haven't seen it, can you provide a link?

The service I've seen only provides hourly forecasts for the next 48 hours (and in my area you wouldn't believe how often those change between rain and sun some days), but then they expand the time interval to 3 hourly.

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Re: weather <> climate

Try approaching this problem with logic instead of blind hatred. You might see a different result.

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Re: "It's complex" shocker

Yes, I get that they're different. But both processes of forecasting rely to a greater or lesser extent on models: that's where I see a parallel. Weather and climate predictions don't always deliver what the model said would happen or when it might happen.

Personally I'd like better weather forecasts. For society as a whole I'd like accurate climate modelling. It's why I said that I hoped that this result improves both.

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Stop

Re: weather <> climate

@Steve Knox -

I might. Joe Average shouldn't unless clear definitions are given, which they pretty much never are.

Usually Joe gets "the climate is getting warmer". Then he sees record cold winters. Then he's told "that's just weather, not climate you ignorant fool. Gaia will smite you!" which is not the behaviour of responsible scientists. Neither, incidentally, is RTFM - that's the behaviour of the smug geek. What Joe Public gets to listen to is a priesthood which condemns those who argue with it and threatens apocalypse unless it is placated with vast amounts of money.

Without a move to a) educate and b) genuinely debate - ie, stop calling people deniers and abusing their intellect - this situation can only worsen.

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Anonymous Coward

Re: weather <> climate

As I'm fairly sure I've observed to you before: Your knowledge of Gaia theory seems to be less than zero. Using Gaia as an insult when you don't understand what it is seems not the wisest of things to do.

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Re: "It's complex" shocker

BBC weather forecasts for 3-5 days out *usually* change back and forth over the 3 days leading up to them. That is, the forecasters will issue 3 different forecasts in three days, for the fourth day. They aren't *that* accurate.

OTOH, the forecast for the next 12 hours is fairly accurate and you'll be OK planning your bike ride. Back on the first hand, simply travelling hours upwind and seeing what the weather is currently like there will probably give a pretty accurate forecast, without any profound understanding of meteorology. I don' t know (in percentage terms) how much better the computers are than the "12 hours upwind" methodology.

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Re: weather <> climate

Educate me then.

Criticism without education is what I've grown to expect from the Anthropomorphic Climate Change religion. Break the pattern. Show without sneering.

I'll wait.

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Joke

Re: "It's complex" shocker

But predicting rain in the UK is much like predicting that water will feel wet isn't it?

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Facepalm

Re: "It's complex" shocker

So the news is "The climate model that we have been using to garner attention and government grants is really based off of a bunch of information that we padded to give us the results that we wanted and fundamentally flawed ideas on how the ecosystem works. Thus is it not representative of anything that will actually occur and more akin to a gigantic hole where the government can stuff a bunch of money to support green companies that they own stock in."

Well Duh. I'm a stoopid 'Merican and I know that.

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Li'l Clarification.

"There's broad agreement on all sides of the environmental debate that climate change is occurring: and indeed that it always has been. Disagreement generally begins on exactly what it is that the future holds, who is responsible, and what is to be done.."

I added a li'l clarification there. I don't that anyone will object.

(And, appropriately, a little echo of tt. Lenin & Herzen there, no? кто виноват? и что делать? And we all know how *that* worked out. But then again they also thought they knew what the future held.)

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That I can't accurately predict what day I'm going to die on doesn't mean I'm not going to die.

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Anonymous Coward

That's such a good analogy I'm going to use it from now on. Not.

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Anonymous Coward

Unfortunately....

... the assumptions that go into the climate models are dominated by positive feedbacks (instead of negative). If the climate as a whole was dominated by positive feedbacks then it would have been far more unstable in the past than reconstructions have shown.

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Re: Unfortunately....

Actually many of the feedbacks happen to be positive. Negative feedbacks primarily slow down the speed of warming, but they cannot stop it (in the short term) due to being overwhelmed by our emissions. For example increased absorption of CO2 from the atmosphere by oceans and extra plant growth only removes 50% of the CO2 we emit. As the ocean heats up it can take on less CO2 - ie. effectively becomes a positive feedback. Other feedbacks such as water vapour can be both positive and negative, with the effects almost cancelling each other out.

Over many thousands of years, assuming humans have either stopped emitting CO2 or existing, negative feedbacks will eventually catch up and slowly stabilise the climate again. But that's not relevant, what matters is they are too weak to reverse the current warming trend over the next 100 years.

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Boffin

Re: Unfortunately....

If climate mode as a whole was dominated by positive feedbacks, we'd see more stability, not less. It would enter a cold spell, and "stick" in an ice age. Some amount of warming, and the ice would melt rapidly, and we'd observe long ice-free (or ice-lite) interglacial periods. A primary mechanism for this would be ice cap albedo. Other mechanisms might be storage and release of methane in methane hydrate formations as the oceans cool and warm.

Whoops, that's what we see. And look what's melting in the Arctic.

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Boffin

@Dr2chase

Nice try at tying long term climate variations with positive and negative feedback loops. However, they are likely a result of periodic orbit fluctuations due to the gravitational effects of Jupiter. In fact, the variance would have been higher without the loops. Earth climate is at a dynamic equilibrium. It's fairly obvious that we're affecting that equilibrium. Possibly stressing it. And if that was what the global warmists claimed, then that would be fine and dandy. But it's not. The extraordinary claim is that we're about to break that equilibrium and that extraordinarily expensive and urgent measures are needed to prevent that. However, the corresponding extraordinary proof is somewhat lacking.

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Anonymous Coward

Re: Unfortunately....

"Over many thousands of years, assuming humans have either stopped emitting CO2 or existing"

Hooray for FUD. You honestly think a 2C rise in temperatures is going to wipe out the entire human race?

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Go

It's a start.

Ok, we now know the assumptions are wrong somewhere.

So amend the assumptions, load with the same data and rerun those predictions, if they still do not match reality, change and rerun until they do.

This does not mean fudge the input data to match your biases (smoothing a time series to get the hockey stick for instance!)

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Meh

Re: It's a start.

Heretic.

You have blasphemed against the Earth Mother in your noticing of inspired* evidence and must be downvoted.

*It's not faked, it's inspired.

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positive-feedbackitis

I understand the difficulty in designing a hypothetical model that seems to most resemble the observations of the climate. Humans are naturally very very good at spotting patterns in random behaviour however (we see faces in clouds all the time...). What I don't understand is how easily it seems that these scientists apply positive feedback, which we all know can only exists for a short period of time (unstable period) before a system falls into a stable (negative feedback) state. Thermodynamics, entropy, control theory, common sense... there are many approaches to this understanding. I don't deny the negative impact that humans are having on the planet, but for me each positive feedback mechanism I hear about discredits an otherwise sound scientific approach. If you must identify a positive feedback mechanism, at least consider the tipping point at which positive feedback can no longer be sustained (unless you have a design for a perpetual motion machine that can solve the worlds energy needs!)

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Re: positive-feedbackitis

The question is what do you call a short period? There is no doubt the climate will eventually stabilise itself (we won't see runaway warming), but it may take many thousands of years. In the meantime we have to live with it.

Also can you point us to a strong negative feedback machanism that will kick in shortly? So far there aren't any signs of strong negative feedbacks, but there are signs that the existing negative feedbacks (such as CO2 absorption by oceans, ice/snow coverage) are turning into positive feedbacks (as ocean temperature rises, it absorbs less CO2, and snow/ice coverage is declining fast, eg. arctic ice).

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Re: positive-feedbackitis

It's actually worse than that. The models use formulas that don't have have corresponding real world phenomena because using those formulas makes the data sort of work, where as using the formula you'd get from the real world phenomena produces an obviously bad result. A mathematician friend of mine who works in the field doesn't see a problem with this approach as long as the model produces reasonably accurate predictive results. I do because it indicates that while we may have maths that are helpful, we understand nothing about the way the system really works. To me it's the ancient Greeks being able to chart where the planets would be even though they put the Earth at the center of the universe and thought heavy objects fell faster than light ones. I wouldn't have as much of a problem with it if the people behind the models would admit as much and work at getting a better understanding of the real physics involved rather than heading off on a political jihad.

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Re: positive-feedbackitis

In terms of AGW if you sift through the hyperbole to the actual basics of the AGW proposition it works like this.

Lets define some variables.

We will lump all the things that affect climate into one generic lump, and call it K, for known variables and driver affecting climate.

So we observe that in the late 20th century, ΔT != f(ΔK).

That is temperature changes can not be accounted for by currently known variables.

So we pick on one known unknown, CO2 gas concentration (lets call that C) and try

ΔT = f(ΔK) + f(ΔC).

Sadly this does not work either. The effect of CO2 is too small to account for observed ΔT!

Now at this point you have a known unknown . Your model does not work as it is. So you have two choices.

(I) introduce an unknown feedback term to multiply the effect of CO2. (lambda factor) giving you an equation of the form:- ΔT = f(ΔK) + λ f(ΔC). This is the essence of the IPCC model.

(ii) simply accept that there is in addition to carbon dioxide, something else (U for unknown) going on as well giving rise to climate changes, so we have : ΔT = f(ΔK) + f(ΔC) + f(ΔU).. This is the essence of say - Svensmark et al's hypotheses where cloud cover is modulated by cosmic rays etc etc.

There is an important point here. Both models assume an known unknown element. In the IPCC model its a feedback system - positive feedback as well. It is not clear whether in fact they don't make a rather logically absurd assumption here as well, because the lambda factor should multiply ANY climate change due to other effects. I.e. the proper IPCC equations should be of the form:

ΔT =λ( f(ΔK) + f(ΔC)).

The problem is that this leads to a very unstable climate - which is simply not borne out by the historical record.

In short the 'CO2 is not the whole story' models of Svensmark and co actually fit the data better.

So if you compare the two possible models you have the following broad conclusions from the IPCC

- most warming in the late 20th century was man made

- feedback only applies to carbon dioxide created warming. Or the historical records don't fit.

- the lambda factor necessary to make the data fit this model produces really scary climate change predictions, justifying massive expenditures on products Al Gore and his chums sell.

Whereas lumping the known unknowns into a separate function with NO overall positive feedback gives rather different conclusions

- most warming in the late 20th century was not man made

- climate change will happen independently of any human attempts to stop it

- there is no point spending money on products and technologies to make the attempt: better is to spend the money on dealing with it

- we can't say whether or not scary climate change is happening/will happen, or not.

Naturally enough the political movements and industries geared to taking your money and spending it on stuff that either doesn't work at all, or doesn't work well enough to make any real difference (but we have to make the attempt, right?) have a lot riding on the IPCC general equation form.

Feedback is essential to keep the green machine on track printing money.

THAT'S why everyone loves it. Nothing else produces scary warming. In fact the non lambda models tend to suggest that we are more likley to be about to enter a global cooling period with far more drastic impacts on human life.

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Black Helicopters

Re: positive-feedbackitis

..and naturally enough, the shills from the green industry are downvoting this post as I review it, without actually offering any critiques...

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Re: positive-feedbackitis

re itzman:

"So we pick on one known unknown, CO2 gas concentration (lets call that C) and try"

CO2 concentration, and it's forcing, is in no way unknown! It's a known known. Definitely.

"It is not clear whether in fact they don't make a rather logically absurd assumption here as well, because the lambda factor should multiply ANY climate change due to other effects. I.e. the proper IPCC equations should be of the form:

ΔT =λ( f(ΔK) + f(ΔC))."

The lambda factor does multiply ANY climate change due to other effects. That's the whole point of the concept. Climate sensitivity (λ) is measured in units C/wm-2. Anything that induces a forcing (wm-2) will produce a temperature range according to: ΔT = λ x F, precisely because things like albedo feedback and water vapor feedback will kick in response to a temperature change from whatever source.

And by the way the idea of a climate without feedbacks is complete nonsense. Albedo, water vapor and cloud feedback are known to exist. Any model that assumes feedbacks don't exist is simply wrong. Climate modellers didn't decide to arbitrarily add some "feedback term" to the models to fit the warming as you claim. They added feedbacks because they are known to exist, ie they HAD to add them.

"The problem is that this leads to a very unstable climate - which is simply not borne out by the historical record."

Yes I guess it would cause unstable behaviour where the climate might switch between two very different states in response to small orbital forcings. Perhaps we could cause these states "glacial" and "interglacial" periods....oh wait.

"In short the 'CO2 is not the whole story' models of Svensmark and co actually fit the data better."

Except Svensmark and co don't have a quantified mechanism. There's no "wm-2" value that's been calculated for any change in cosmic rays from physical principles. In any-case the biggest problem is that cosmic rays show no trend in the past 50 years so they CANT possibly explain the warming in the late 20th century.

On the otherhand the wm-2 value for rising CO2 is very big, much bigger than anything else that is known to be happening. Sure maybe scientists have missed something else with an even bigger forcing (although I doubt it, if it's big it should be obvious), but to assume that some unknown unknown exists and trumps what is known is both unfalsifiable and the height of wishful thinking. It just aint science.

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Thumb Down

Re: positive-feedbackitis

I presume that is because your post had no actual information content in it. Do you seriously think you can make a claim about actual climate models based on your misunderstanding how they actually work?

I suggest you first read up on climate science and how modelling is actually done. Here is a good article describing the 23 models used in AR4, and a link to more papers about those models, including actual source code:

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter8.pdf

http://www.easterbrook.ca/steve/?p=667

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Re: positive-feedbackitis

The problem with that is not that feedback doesn't exist, its that it has to be overall negative, or the planet would be uninhabitable.

The standard excuse that water vapours is a positive feedback element is of course nonsense. The more the world gets hotter, the more the oceans generate water vapour, the bigger the thermal activity there is that carries that warmth into the stratosphere well above any greenhouse effects and the more it radiates into space, this cooling the planet.

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Re: positive-feedbackitis

"The problem with that is not that feedback doesn't exist, its that it has to be overall negative, or the planet would be uninhabitable."

Not true. The planet would be habitable even with positive feedback. Positive feedback means changes are amplified, not that they run away to infinity.

"The standard excuse that water vapours is a positive feedback element is of course nonsense. The more the world gets hotter, the more the oceans generate water vapour, the bigger the thermal activity there is that carries that warmth into the stratosphere well above any greenhouse effects and the more it radiates into space, this cooling the planet."

And which model shows that? The model in your head? Yes what a great argument, we should ignore all those models running on supercomputers and written by physicists and instead trust your imaginings about what happens.

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Re: positive-feedbackitis

"Positive feedback means changes are amplified, not that they run away to infinity."

But unconstrained amplification takes you infinity. At some point, the feedback needs to go negative for the system to find a new stable point.

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