I really don't think you realise how complicated these climate prediction are.

What sort of numerical forcasts are you after?

I've already suggested that this year's hurricane season is set to be one of the worst ever. Can you wait as long as September to bear that one out?

And then if it isn't, you can jet off to the Seychelles or the Maldives safe in the knowledge that we were all wrong (that is until the sea rises and the Seychelles disappear under the waves).

Maybe some of our climate scientist friends in the forum can give you a few numbers, just to keep you quiet in the meantime...

quote:

Originally posted by Lucibee:
I really don't think you realise how complicated these climate prediction are.

Yes, I do. I am a modeller myself, and I am filled with admiration for the complexity of these models. However, that is no use if they are pure works of fiction (I'm NOT saying they are that - I just want to test them)

quote:

Originally posted by Lucibee:

What sort of numerical forcasts are you after?

I have actually dealt with this one previously, but just off the top of my head, let's go for:

For each of the next twenty years, the following temperatures:

Northern hemisphere day time
Northern hemisphere night time
Southern hemisphere day time
Southern hemisphere night time
Northern hemisphere sea surface
Southern hemisphere sea surface

That should provide 120 predictions, and 120 observations. I don't think 20 years is too long to wait.

quote:

Originally posted by Lucibee:
I've already suggested that this year's hurricane season is set to be one of the worst ever. Can you wait as long as September to bear that one out?

I'll be interested, but one observation is not sufficient. After all, last year was a quiet one.

quote:

Originally posted by Lucibee:

Maybe some of our climate scientist friends in the forum can give you a few numbers, just to keep you quiet in the meantime...

Maybe - I've been asking in vain for some months now.

quote:

After all, last year was a quiet one.

Yes, because last year El Nino was prevalent. This year it's La Nina - and given the effect on our end of the jet stream, I'd guess it means trouble for the US and Central America later on this year.

BTW, the Hadley Centre have some info on the predictions, and there's a nice short piece on the BBC science site.

quote:

Originally posted by Lucibee:
... the Hadley Centre have some info on the predictions, and there's a nice short piece on the BBC science site.

Forecasting the past is not legitimate, because the data has been used in building the model (so, of course it predicts it correctly!). What is needed is sepcific future forecasts. Since I know that they are simulation models, what I would be looking for is the best estimate, plus the distribution of predicted outcomes by 10% probability bands.

Try reading past the first paragraph. You have to use the past to test your model before you use it to predict what may happen in the future.

It's extremely difficult to make specific future forecasts - you're only likely to get a best estimate based on the information you put in. But the models are improving all the time.

And unfortunately we may not have 20 years to wait - we've already wasted 20 years since climate change was widely recognised as a impending problem. Some think that we have to act now to have any chance of reversing the situation or even to stay where we are. In 20 years, it is very likely to be too late.

quote:

Originally posted by Lucibee:
Try reading past the first paragraph. You have to use the past to test your model before you use it to predict what may happen in the future.

I did read past the first paragraph. I know perfectly well how to construct and test models, so I would ask you not to assume that I don't know what I'm talking about. When I don't know, I say so.

quote:

Originally posted by Lucibee:
It's extremely difficult to make specific future forecasts - you're only likely to get a best estimate based on the information you put in. But the models are improving all the time.

Without testing how do you know they are improving all the time? They might be getting more complex, they might be better at "predicting" the data from which they were constructed, but are they any better at predicting the future????

quote:

Originally posted by Lucibee:
And unfortunately we may not have 20 years to wait - we've already wasted 20 years since climate change was widely recognised as a impending problem. Some think that we have to act now to have any chance of reversing the situation or even to stay where we are. In 20 years, it is very likely to be too late.

Some may say it. I don't, and I won't be panicked into accepting restrictions on my freedom purely because someone thinks a 0.8 degree rise in 150 years is a cause for panic.

quote:

Originally posted by JL(SFC58,AFCB):

quote:

Originally posted by Lucibee:
Try reading past the first paragraph. You have to use the past to test your model before you use it to predict what may happen in the future.

I did read past the first paragraph. I know perfectly well how to construct and test models, so I would ask you not to assume that I don't know what I'm talking about. When I don't know, I say so.

quote:

Originally posted by Lucibee:
It's extremely difficult to make specific future forecasts - you're only likely to get a best estimate based on the information you put in. But the models are improving all the time.

Without testing how do you know they are improving all the time? They might be getting more complex, they might be better at "predicting" the data from which they were constructed, but are they any better at predicting the future????

quote:

Originally posted by Lucibee:
And unfortunately we may not have 20 years to wait - we've already wasted 20 years since climate change was widely recognised as a impending problem. Some think that we have to act now to have any chance of reversing the situation or even to stay where we are. In 20 years, it is very likely to be too late.

Some may say it. I don't, and I won't be panicked into accepting restrictions on my freedom purely because someone thinks a 0.8 degree rise in 150 years is a cause for panic.

YES BUT, what about loss of bio diversity, population explosion, mass migration, habitat destruction, polution, sea level rise, resource wars, religious wars, Roger58 etc?

quote:

Originally posted by Lucibee:
Try reading past the first paragraph. You have to use the past to test your model before you use it to predict what may happen in the future.

It's extremely difficult to make specific future forecasts - you're only likely to get a best estimate based on the information you put in. But the models are improving all the time.

And unfortunately we may not have 20 years to wait - we've already wasted 20 years since climate change was widely recognised as a impending problem. Some think that we have to act now to have any chance of reversing the situation or even to stay where we are. In 20 years, it is very likely to be too late.

The only thing that doesn't have "have 20 years to wait" is NOT the world - but the daft AGW theory itself! That's why there's such an 'urgency' - to terrify as many people into 'believing' NOW... before the thing has a chance of being exposed as the enormous fraud it is. The terminally-discontented failed to get their own way by convincing people with sane political theory, now they're back having another try by manipulating people with mad science.

When this one bites the dust, they'll be back to religion again, I suppose.

quote:

Originally posted by JL(SFC58,AFCB):

I did read past the first paragraph. I know perfectly well how to construct and test models, so I would ask you not to assume that I don't know what I'm talking about. When I don't know, I say so.

Without testing how do you know they are improving all the time? They might be getting more complex, they might be better at "predicting" the data from which they were constructed, but are they any better at predicting the future????

Some may say it. I don't, and I won't be panicked into accepting restrictions on my freedom purely because someone thinks a 0.8 degree rise in 150 years is a cause for panic.

You could start by being a bit less arrogant. You think you know better than thousands of scientists who've done this stuff for decades?

You could find Hansen's 1988 projections and see how they match the reality. (I'm fed up with taking the trouble to find links and have my posts rejected by this forum because of those links.)

I'm intrigued JL - what sort of things do you model? Swimsuits? Underwear?

quote:

Originally posted by Seskinreay:
YES BUT, what about loss of bio diversity, population explosion, mass migration, habitat destruction, polution, sea level rise, resource wars, religious wars, Roger58 etc?

What is the AGW theory predictions for the numbers of relgious wars per years? Roger58 can hardly be predicted - he is a one-off event, thankfully.

quote:

Originally posted by TrueSceptic:

You could start by being a bit less arrogant. You think you know better than thousands of scientists who've done this stuff for decades?

Ah, the "Wise Man He Say" approach. I know perfectly well how to build and test models, and I am filled with admiration for the complexity of some of the models created. All I have asked is that they be tested to see whether they bear any resemblance to reality.

quote:

Originally posted by TrueSceptic:

You could find Hansen's 1988 projections and see how they match the reality. (I'm fed up with taking the trouble to find links and have my posts rejected by this forum because of those links.)

Thanks for the link (on another thread). I'd have to work on the numbers (when I have a little bit more time), but my initial impression is that none of the three scenarios has a particularly good correlation with the observations.

quote:

Originally posted by TrueSceptic:

You could start by being a bit less arrogant. You think you know better than thousands of scientists who've done this stuff for decades?

And you could be less arrogant too. I am sure they know as well as I do how to model. What I have asked for is evidence (not bland statements from the Wise Men) that the impressively-complex models actually match reality.

quote:

Originally posted by TrueSceptic:

You could find Hansen's 1988 projections and see how they match the reality. (I'm fed up with taking the trouble to find links and have my posts rejected by this forum because of those links.)

Thanks for the link (on another thread). I'll need to work on the numbers, but at first glance I have to say that none of the three scenarios outlined there seems to have any particularly good correlation with reality. Probably marginally better than a series of random numbers, but not by much.

What is this MB playing it - it tells me my posting has failed, so I laboriously re-type it. Then both versions appear at once!

quote:

Originally posted by Lucibee:
I'm intrigued JL - what sort of things do you model? Swimsuits? Underwear?

Sight for sore eyes!

I have to be a bit careful, because some of it is (seriously) covered by the Official Secrets Act. Which makes it sound more interesting and important than it actually is.

My current batch of models concern the criminal justice system; I have previously done (or contributed to, which is probably a more accurate description) work on the rail network to aid platforming, and the electricity supply industry (to aid construction of parts replacement programmes)

quote:

Originally posted by Roger58:
The terminally-discontented failed to get their own way by convincing people with sane political theory, now they're back having another try by manipulating people with mad science.

When this one bites the dust, they'll be back to religion again, I suppose.

Roger only yesterday you said: "If you reply, PLEASE try to steer clear of relying on name-calling, guilt-tripping, and tear-jurking."

What happened?

quote:

Originally posted by JL(SFC58,AFCB):
What is this MB playing it - it tells me my posting has failed, so I laboriously re-type it. Then both versions appear at once!

This is one of the worst I've been on. It often just stops dead and times out, sometimes it appears to reject posts (so you resend and get dupes), and posts get removed or edited with no explanation.

BTW I am in the habit of saving my posts before posting to avoid retyping!

quote:

Originally posted by JL(SFC58,AFCB):

And you could be less arrogant too. I am sure they know as well as I do how to model. What I have asked for is evidence (not bland statements from the Wise Men) that the impressively-complex models actually match reality.

How am I being arrogant? I'm just suggesting that we recognise that there are many experts out there who know far more about this than we (most of us anyway) do.

quote:

Originally posted by TrueSceptic:
How am I being arrogant? I'm just suggesting that we recognise that there are many experts out there who know far more about this than we (most of us anyway) do.

Truce?

But you will need to accept that I know what I am doing regarding model creation and testing (although not specifically climate modelling)

Do you ever hear the people you do your modelling for say, "Thanks for the model, JL, but I think we'll wait for reality instead, because it's only a simulation..."?

quote:

Originally posted by JL(SFC58,AFCB):
Truce?

Sure.

But you will need to accept that I know what I am doing regarding model creation and testing (although not specifically climate modelling)[/QUOTE]
I don't doubt it, but the level of complexity might be several orders of magnitude greater.

quote:

Originally posted by Lucibee:
Do you ever hear the people you do your modelling for say, "Thanks for the model, JL, but I think we'll wait for reality instead, because it's only a simulation..."?

Good Lord - JL your redundant !

quote:

Originally posted by TrueSceptic:

quote:

Originally posted by JL(SFC58,AFCB):
Truce?

Sure.

But you will need to accept that I know what I am doing regarding model creation and testing (although not specifically climate modelling)

I don't doubt it, but the level of complexity might be several orders of magnitude greater. [/QUOTE]

Indeed they might. But that doesn't change the principles