On 29/11/2011 10:50, dennis@home wrote:

Those who claim that they are inaccurate have prejudices rather than
more accurate models to support their assertions.

You can know how inaccurate the models are without having to have a more
accurate model.
Those that think you need a more accurate model to prove the other one
is bad don't understand the basics.

You only know how inaccurate the predictions are after the event. As it
is the models are predicting continuously rising temperatures and all
that is really at stake is the rate of rise. By contrast those who are
predicting that global temperatures are now falling have no model and
nothing to hang their hat on bar the 1998 figure which sticks out like a
sore thumb. The Met Office still has 1998 as the warmest year yet but
the two American centres (it is not clear exactly how independently)
producing their own temperature record both conclude that 2010 and 2005
are first equal and 1998 only third.

To give an example of a very common but frequently very inaccurate model
just look at weather forecasting.

Weather forecasting is frequently very accurate. It is very rare for
there to be a major cock-up.

What's more we know why its inaccurate and we don't need a more accurate
model to prove it, without prejudice.

But you do not have another model to make a more accurate prediction.

Funny enough many of the reasons weather forecasts are inaccurate also
apply to climate models, like not knowing the initial conditions very well.

At least some of the apparent inaccuracy we see now is as a direct
result of the furore over that hurricane when the Met Office got the
track of the storm wrong. Caution now rules and bad weather will now
almost always be less extreme than forecast and turn up latter than
forecasted.

--
Roger Chapman