If you can’t accurately model the climate next month, then you certainly can’t model it for next year. If you can’t model it next year, you certainly can’t model it for 50 years.
The whole point of climate models is to run them iteratively in order to compound feedbacks – which means that errors increase exponentially. People claiming that errors average out have no idea what they are talking about.
If you drive faster and faster in the wrong direction, you get further and further away from your destination.
Feedbacks become forcing for other conditions.
The effect of one cause becomes the cause for a different effect and it eventually comes full circle. Maybe! Random chance probably rules a return to exact state but approximate similar conditions are achieved.
The Dust Bowl is an example as one day in the future a very similar condition will occur again.It is natural long term regional weather patterns. One day the New York region will again experience a major hurricane land fall.
More research needs to be done on natural climate factors before any meaning full predictions can be made. They have come a long way from the 60s but it is only a small step towards the goal!
Peer reviewed paper:
“On the credibility of climate predictions”
…results show that models perform poorly, even at a climatic (30-year) scale. Thus local model projections cannot be credible, whereas a common argument that models can perform better at larger spatial scales is unsupported.
http://www.scribd.com/doc/4364173/On-the-credibility-of-climate-predictions
Royal Meteorological Society peer reviewed
“A comparison of tropical temperature trends with model predictions”
ABSTRACT:….Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean. In layers near 5 km, the modelled trend is 100 to 300% higher than observed, and, above 8 km, modelled and observed trends have opposite signs. These conclusions contrast strongly with those of recent publications based on essentially the same data. Copyright?2007 Royal Meteorological Society
http://www.scribd.com/doc/904914/A-comparison-of-tropical-temperature-trends-with-model-predictions#
In case anyone missed it:
…above 8 km, modelled and observed trends have OPPOSITE SIGNS
Feedback Is By Definition Iterative
Definitions do not apply in manmade global warming. Global warming is happening. Man is the cause.
;O)
To be fair, I’d argue that only the systematic errors will propagate out exponentially. Random errors should largely cancel out over time, although because the system is exponential in nature the early errors may have a slight advantage over later random errors.
Anyway, this topic is one I’d thought about recently. If we’re at the very low end of the IPCC prediction 3 years after its release, doesn’t that preclude (or at least dramatically lower) the possibility of us reaching +6 C by the end of the century? For example, if the same models were run from this day forward to 2100, wouldn’t the upper limit now be something like 5.7 C? Any thoughts on that?
-Scott
Scott:
They threw out the model runs showing lower results as being unrealistic. They are now claiming the high end estimate was to low. The estimated energy is hiding in the system and growing stronger. When it emerges from its hiding place it will overcome all attempts to control it and it will consume all the major urban centers as the polar ice will melt overnight and the entire globe will experience the Mother of all flash floods. Build your Ark now and place it at 1500 ft elevation because that is where the future sea side docks will be!
“If you can’t accurately model the climate next month, then you certainly can’t model it for next year. If you can’t model it next year, you certainly can’t model it for 50 years.”
What you have basically said is that if I can’t accurately predict the temperature next month, I can’t accurately predict that next winter will be colder than the summer.
The whole AGW house of cards is based on feedback
Even if that were true, (and it isn’t – Arrhenius never needed it), so what? Feed backs clearly exist and you seem ill qualified to untangle them.
I post an article, and the alarmists feed back the usual nonsense.
I’m no alarmist Steve. I just accept science and point out nonsense.
Then obviously you don’t understand how GCMs work.
Laz:
It seems you missed some history. Arrhenius had to correct his calculations as the original ones were wrong and his work was basically ignored until a group was looking for a research project many years later.
Feed backs and forcing constitute weather. An over responsive feed back becomes a forcing fore another effect.
It is all relative.
“Then obviously you don’t understand how GCMs work.”
Weather and climate modelling is one of the very few things I have studied post grad – so I might understand a little.
So why don’t you understand that errors in feedbacks compound with each iteration?
Mike, I have no objection to what you say – but how does that support Steve’s apparent claim that feedbacks are so mysterious they can’t be predicted within known limits?
LAZ:
they can not predict the temperature 3 hours from now to within 5F
Models are based on anomaly to overcome the issue of seasonal weather. Climate is the estimated diversion from the estimated average of the estimated mean not absolute temperature change.
Yet they think they can project a possible anomaly to within 2c 90 years from now.
“Yet they think they can project a possible anomaly to within 2c 90 years from now.”
And why wouldn’t it be possible? Try this; find a graph with the 20th-21st century temperature trend and continue the line – use a crayon if it helps.
http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.lrg.gif
Try extrapolating one leg of a sine wave and see if you predict the shape accurately.
Steve – an irrelevance. There is a known temperature trend, if it continues, you get warming within the same ball park as model averages.
Lazarus says:
November 30, 2010 at 2:50 am
And there’s the crux of the matter, if it continues. Skeptics say it’s a big if, warmists consider it a “when”. It’ll be interesting to see what happens.
-Scott